Anatomical changes in the pharynx resulting from changes in head and neck position

Transcription

1 University of Iowa Iowa Research Online Theses and Dissertations Spring 2012 Anatomical changes in the pharynx resulting from changes in head and neck position Megan Elizabeth Dean University of Iowa Copyright 2012 Megan Elizabeth Dean This thesis is available at Iowa Research Online: Recommended Citation Dean, Megan Elizabeth. "Anatomical changes in the pharynx resulting from changes in head and neck position." MA (Master of Arts) thesis, University of Iowa, Follow this and additional works at: Part of the Speech Pathology and Audiology Commons

2 ANATOMICAL CHANGES IN THE PHARYNX RESULTING FROM CHANGES IN HEAD AND NECK POSITION by Megan Elizabeth Dean A thesis submitted in partial fulfillment of the requirements for the Master of Arts degree in Speech Pathology and Audiology in the Graduate College of The University of Iowa May 2012 Thesis Supervisors: Clinical Associate Professor Karen N. Bryant Associate Professor Michael P. Karnell

3 Copyright by MEGAN ELIZABETH DEAN 2012 All Rights Reserved

4 Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL MASTER S THESIS This is to certify that the Master s thesis of Megan Elizabeth Dean has been approved by the Examining Committee for the thesis requirement for the Master of Arts degree in Speech Pathology and Audiology at the May 2012 graduation. Thesis Committee: Karen N. Bryant, Thesis Supervisor Michael P. Karnell, Thesis Supervisor Jerald Moon

5 For my parents, Steve and Barb Dean, for their never-ending support, compassion, and love. Also, for my fiancé, David Light, for his unwavering patience, Microsoft Excel skills, and love. ii

6 ACKNOWLEDGMENTS This work would not have been possible without the support from my committee members: Karen Bryant, Ph.D., CCC-SLP, Michael Karnell, Ph.D., and Jerry Moon, Ph.D. Whether it was a long distance phone call from Chicago, or a quick office meeting, my committee members supported me each step of the way. Together, they taught me more than I could ever give them proper credit for here. I am forever thankful to have worked with such an esteemed group of speech-language pathologists, researchers, and outstanding individuals. iii

7 TABLE OF CONTENTS LIST OF TABLES... vi LIST OF FIGURES... viii CHAPTER I REVIEW OF LITERATURE...1 Introduction...1 Chin Down Posture...3 Benefits of the Chin Down Posture...3 Risks of the Chin Down Posture...5 Inconclusive Results about the Chin Down Posture...8 The Role of Fiberoptic Endoscopic Evaluation of Swallowing and the Chin Down Posture...9 Chin Down versus Chin Tuck...11 Conclusion...14 CHAPTER II METHODOLOGY...18 Introduction...18 Subjects...18 Data Collection...19 Data Analysis...23 ImageJ...24 Microsoft Excel...27 Statistical Analysis...28 CHAPTER III RESULTS...36 Introduction...36 Anatomical Changes without Bolus...36 Area of Airway Opening...37 Distance from Posterior Pharyngeal Wall to Epiglottis...38 Distance between the Lateral Walls...40 Distance from Epiglottis to Base of Tongue...41 Anatomical Changes with Bolus...41 Area of Airway Opening...42 Distance from Posterior Pharyngeal wall to Epiglottis...43 Distance between the Lateral Walls...44 Distance from Epiglottis to Base of Tongue...45 Posture versus Water Hold Condition...45 Visual Differences between Chin Down and Chin Tuck...45 Statistical Analyses...46 Pearson Product-Moment Correlation Coefficient...46 CHAPTER IV DISCUSSION...80 Overall Anatomical Changes across Postures...80 Posture versus Bolus Hold...81 Area of Airway Opening and Distance between Posterior Pharyngeal Wall and Epiglottis...81 Distance between Lateral Walls...83 iv

8 Epiglottis to Base of Tongue...83 Standard Deviation...85 Chin Down versus Chin Tuck...85 Clinical Implications...86 Limitations...87 Further Research...87 Conclusion...88 BIBLIOGRAPHY...95 v

9 LIST OF TABLES Table 1. Ways Cited in Literature to Perform the Chin Down and Chin Tuck Postures...16 Table 2. Different Names for the Chin Down and Chin Tuck Posture Seen in the Literature...17 Table 3. ImageJ Scale Default Setting...30 Table 4. ImageJ Scale Set to Still Image Measurements...31 Table 5. Excel Spreadsheet Containing Measurement Data from ImageJ...34 Table 6. Completed Final Data Sheet in Excel...35 Table 7. Area of Airway Opening Raw Data Analysis...49 Table 8. Fixed Effects Analysis for Bolus, Posture and Bolus by Posture for Area Measurement...49 Table 9. Linear Mixed Model Analysis Comparing Different Positions for Non- Bolus Condition of Area Measurement...50 Table 10. Posterior Pharyngeal Wall to Midpoint of the Epiglottis Raw Data Analysis...52 Table 11. Fixed Effects Analysis for Bolus, Posture and Bolus by Posture for Posterior Pharyngeal Wall to Epiglottis Measurement...52 Table 12. Linear Mixed Model Analysis Comparing Different Positions for Non- Bolus Condition for Posterior Pharyngeal Wall to Epiglottis Measurement...53 Table 13. Right to Left Lateral Wall Distance Raw Data Analysis...55 Table 14. Fixed Effects Analysis for Bolus, Posture and Bolus by Posture for Distance between the Right and Left Lateral Wall...55 Table 15. Linear Mixed Model Analysis Comparing Different Positions for Non- Bolus Condition for Right to Left Lateral Wall Measurement...56 Table 16. Linear Mixed Model Analysis Comparing Different Positions for Bolus Condition for Area Measurement...59 Table 17. Linear Mixed Model Analysis Comparing Different Positions for Posterior Pharyngeal Wall to Epiglottis Measurement, Bolus Condition...61 Table 18. Linear Mixed Model Analysis Comparing Different Positions for Right to Left Lateral Wall Distance, Bolus Condition...63 Table 19. Area of Airway Opening Condition Comparison...65 vi

10 Table 20. Posterior Pharyngeal Wall to Epiglottis Distance Condition Comparison...65 Table 21. Right to Left Lateral Wall Distance Condition Comparison...66 Table 22. Epiglottis to Base of Tongue Distance Condition Comparison...66 Table 23. Pearson Correlation Coefficient between Authors One and Two...79 Table 24. Comparison of Subjects with Increasing versus Decreasing Area Measurements...91 Table 25. Comparison of Subjects with Increasing versus Decreasing Measurements of Distance between the Posterior Pharyngeal Wall and Epiglottis...92 Table 26. Number of Subjects that the Epiglottis to Base of Tongue Measurement was Unable to be Measured...93 vii

11 LIST OF FIGURES Figure 1. Examples of Analyzed Still with Measurement Figure 2. Example of Analyzed Still without Measurement Figure 3. Percent Change per Subject in Area of Airway Opening from Neutral, Non-Bolus Condition...48 Figure 4. Percent Change per Subject in Distance between the Posterior Pharyngeal Wall and Epiglottis from Neutral, Non-Bolus Condition...51 Figure 5. Percent Change per Subject in Distance between the Right and Left Lateral Walls from Neutral, Non-Bolus Condition...54 Figure 6. Percent Change per Subject in Distance between the Anterior Tip of the Epiglottis and Base of Tongue from Neutral, Non-Bolus Condition...57 Figure 7. Percent Change per Subject in Area of Airway Opening from Neutral, Bolus Condition...58 Figure 8. Percent Change per Subject in Distance between the Posterior Pharyngeal Wall to Epiglottis from Neutral, Bolus Condition...60 Figure 9. Percent Change per Subject in Distance between the Right and Left Lateral Walls from Neutral, Bolus Condition...62 Figure 10. Percent Change per Subject in Distance between the Epiglottis to the Base of Tongue from Neutral, Bolus Condition...64 Figure 11. Still Image of Subject 16 in Neutral with Bolus...67 Figure 12. Still Image of Subject 16 in Chin Down with Bolus...68 Figure 13. Still Image of Subject 16 in Chin Tuck with Bolus...69 Figure 14: Still Image of Subject 8 in Neutral with Bolus...70 Figure 15. Still Image of Subject 8 in Chin Down with Bolus...71 Figure 16. Still Image of Subject 8 in Chin Tuck with Bolus...72 Figure 17. Still Image of Subject 15 in Neutral with Bolus...73 Figure 18. Still Image of Subject 15 in Chin Down with Bolus...74 Figure 19. Still Image of Subject 15 in Chin Tuck with Bolus...75 Figure 20. Still Image of Subject 20 in Neutral with Bolus...76 Figure 21. Still Image of Subject 20 in Chin Down with Bolus...77 Figure 22. Still Image of Subject 20 in Chin Tuck with Bolus...78 viii

12 Figure 23. Composite Data of Percent Change from Neutral Position, Condition Matched...90 Figure 24. Average Percent Change Standard Deviation from Neutral Base, Conditions Matched...94 ix

13 1 CHAPTER I REVIEW OF LITERATURE Introduction Dysphagia is the difficulty or inability to move food from the mouth into the stomach. It is derived from the prefix dys, meaning disorder or abnormal, and the Greek root phagein, meaning to ingest or eat (Logemann, 1998). Dysphagia, or swallowing disorders, can occur across the lifespan: from a newborn infant to the elderly. In children, dysphagia can result from premature births, congenital anomalies (e.g., cleft lip and palate), and neurologic disorders (e.g., periventricular leukomalacia). In adults, swallowing disorders may be secondary to neurological disorders (acute and progressive disorders such as a stroke, Parkinson s disease, Myasthenia gravis), rheumatoid disorders (e.g., Sjogren s disease), structural disorders (e.g., head and neck cancer), and iatrogenic causes (e.g., prolonged intubation, postsurgical cervical spine fusion). The oropharyngeal swallow can be broken down into four phases. The first is the oral preparatory phase, which begins once the bolus is placed in the mouth. It involves the ability to manipulate, masticate, and prepare the bolus for oral transfer. The oral phase, the second phase of the swallow, is the transfer of the bolus from the oral cavity to the oropharynx. This phase is initiated when the tongue tip elevates and begins to move the bolus posterior. The pharyngeal transport phase, the third phase of the swallow, involves moving the bolus through the pharynx. This phase contains the pharyngeal swallow response, which is a preprogrammed sequence of events that occurs when the leading edge of the bolus passes the ramus of the mandible. Six events occur during the pharyngeal swallow response:

14 2 1. Elevation and retraction of the velum for velopharyngeal closure, 2. Elevation and anterior excursion of the hyoid and larynx, 3. Closure of the airway at three levels: the true vocal folds approximating, the false vocal folds approximating and the inversion of the epiglottis, 4. Opening of the cricopharyngeal sphincter to allow the bolus to move from the pharynx into the esophagus, 5. Posterior movement of the base of tongue to propel the bolus into the pharynx, and 6. Top-down pharyngeal wall contraction to propel the bolus through the pharynx. The final phase is the cervical esophageal phase, which begins with the first peristaltic wave of esophageal musculature (Groher & Crary, 2010; Logemann, 1998). One serious complication of dysphagia is aspiration pneumonia. This occurs when food and/or liquid enters the airway below the level of the true vocal folds. Aspiration and other symptoms of dysphagia that can significantly increase the risk of aspiration, can result in death from chocking, increased hospital stay due to aspiration pneumonia, dehydration and/or malnutrition. Therefore, it is important to treat dysphagia in order to prevent grave health complications. Treatment of dysphagia can be broken into two categories: compensatory and restorative strategies. Compensatory strategies include ways to augment or adapt swallowing, without changing the underlying physiology of the swallow. These include changing posture and positioning, food consistency, bolus size, or using swallowing maneuvers, such as the supraglottic swallow. According to a study by Horner, Masey,

15 3 Riski, Lanthrop, and Chase (1988), compensatory strategies were able to eliminate aspiration in 75-80% of all patients with dysphagia. Restorative strategies include ways to improve and restore one s swallowing by altering the underlying physiology of the swallow. Along with compensatory strategies, patients may be prescribed swallowing therapy and exercises in order to change the physiology of the patient s swallow. These include range of motion exercises, resistance exercises and swallowing maneuvers, such as the effortful swallow, the Mendelsohn Maneuver, and the Shaker Exercises. Chin Down Posture The chin down posture is a commonly used compensatory strategy for patients with dysphagia exhibiting a pharyngeal delay. Logemann (1998) defines a pharyngeal delay as when the head of the bolus enters the pharynx prior to initiating a pharyngeal swallow, as indicated by the onset of laryngeal elevation in the context of the rest of the pharyngeal swallow. Specifically, a swallow is considered delayed when at the time of onset of laryngeal elevation the bolus head is below the point where the tongue base crosses the lower edge of the mandible. It is thought that the chin down posture results in widening of the vallecular space and narrowing the airway entrance, thus adding a level of airway protection prior to initiating the pharyngeal swallow. During the delay, the bolus pools in the vallecular space prior to initiating the swallow reflex, protecting the airway by closing off the larynx (Logemann, 1998). Benefits of the Chin Down Posture The chin down posture may minimize the risk of penetration and aspiration in those patients with head and neck cancer who present with a pharyngeal delay or reduced laryngeal elevation (Bülow, Olsson, & Ekberg, 2001; Lewin, Hebert, Putman, &

16 4 DuBrow, R. A., 2001; Logemann, Rademaker, Pauloski, & Kahrilas, 1994). Logemann and colleagues (1994) found that the chin down maneuver was beneficial for reducing aspiration in some patients with head and neck cancer including patients with: post surgery supraglottic laryngectomy, oral cancer (composite re-section), hemilaryngectomy, glomus vagal tumor, parotid resection, tracheal resection, palatal resection, pharyngeal wall resection, mandibular/floor of mouth resection, thyroid resection with radical neck dissection, and supraglottic laryngectomy and oral composite resection. Thirty-two patients with aspiration of thin liquids were evaluated with videofluoroscopy. Of the 32 patients, six who had pharyngeal delay or reduced laryngeal elevation were asked to perform the head down position in isolation (i.e., not used in combination with other postural techniques). Patients were instructed to move their chin downward so that it touched their neck. Logemann chose to use the head down position with these patients because it results in better airway protection due to the positioning of the epiglottis over the airway and the widening of the vallecular space to collect the bolus prior to initiating the pharyngeal swallow. The head down posture eliminated aspiration in five of the six patients (83%) who had a pharyngeal delay or reduced laryngeal elevation. Logemann discovered that patients with more than one structure undergoing a resection benefitted less from postural changes. Lewin et al. (2001) studied the chin down posture in 26 patients, 23 of whom were men, who were referred for videofluorographic swallow study due to aspiration concerns postesophagectomy. Patients included in this study had adenocarcinoma, squamous cell carcinoma, or Barrett s esophagus with highgrade dysplasia. The chin tuck was introduced after a patient aspirated on one trial and the patient had to repeat the same trial in the chin tuck before continuing with the

17 5 swallow study. After the patient aspirated, the chin-tuck maneuver was introduced. The researchers defined the chin-tuck maneuver as touching the chin to the neck. Of the 21 patients who aspirated, the chin-tuck eliminated aspiration in 17 (81%). The researchers hypothesized that the chin-tuck narrowed the entrance to the airway in some, but not all patients. Bülow and colleagues (2001) examined the effects of the chin-tuck in eight patients with pharyngeal dysfunction resulting from cerebrovascular accident or unspecified head and neck cancer using videomanometrics and videoradiography. Five patients presented with severe pharyngeal dysfunction with a high frequency of penetration and aspiration and three patients had moderate pharyngeal dysfunction resulting from delayed initiation of the pharyngeal swallow. The patients received instruction about the swallow technique of chin down. They were asked to perform the maneuver three times with 10mL of thin liquid barium swallows. To perform the chin tuck maneuver, the patients were instructed to move their chin downward and swallow after being presented with the barium liquid. The researchers found that the chin-tuck did not eliminate aspiration in these patients, but it did reduce the depth of penetration of the bolus into the larynx and trachea. Furthermore, the chin-tuck maneuver did not influence the retention of the bolus in the pharynx. Risks of the Chin Down Posture Other studies have reported that the chin-down posture may increase risk of aspiration in patients with weak pharyngeal contractions, others who have spillage of the bolus to the pyriform sinuses before initiating the pharyngeal swallow, those patients that are not cognitively intact, or may have reduced range of movement (Bülow, Olsson, Ekberg, 1999; Rasley, Logemann, Kahrilas, Rademaker, Pauloski, & Dobbs, 1993;

18 6 Shanahan, Logemann, Rademaker, Pauloski, & Kahrilas, 1993). Shanahan et al. (1993) examined pharyngeal dimensions of the chin-down posture in 30 patients with a delayed pharyngeal swallow secondary to neurological damage. The researchers defined a delayed pharyngeal swallow as when the head of the bolus passed the point where the ramus of the mandible crossed the tongue base before the pharyngeal swallow was initiated. Videofluorography was performed and a variety of angles and distances were measured from chin upright and to chin down. This study was performed as a follow-up to the Welch, Logemann, Rademarker, and Kahrilas (1993) study (discussed below); therefore, the methods are very similar between the two studies. The two angles analyzed include a postural angle, from the inferior border of the mandible to the posterior pharyngeal wall, and the epiglottic angle, from the posterior surface of the epiglottis to the anterior wall of the laryngeal vestibule. Two distances, measured in millimeters, were analyzed. They include the epiglottic distance, from the most posterior point of the epiglottis to the posterior pharyngeal wall, and the airway entrance distance, from the most anterior point of the arytenoid cartilage to the anterior wall of the laryngeal vestibule. This study did not include a measurement for change in valleculae, as the Welch et al. (1993) study did. Patients swallowed 1, 3, 5, and 10 ml of liquid barium in a neutral upright position. When aspiration occurred, the patient was instructed to swallow the same amount with the chin in a maximally lowered position (Shanahan et al., 1993, p.736). The results showed that the chin down position only benefited those patients who aspirated material from the valleculae. The researchers concluded that patients who aspirated from the pyriform sinuses did not benefit from the use of the chin down because by the time the chin down was initiated, the bolus was already too low in the pharynx to

19 7 stop aspiration. Rasley et al. (1993) examined 165 consecutive patients with oropharyngeal dysphagia through videofluoroscopy. Dysphagia resulted from surgically treated head and neck cancer patients, cerebrovascular accidents, closed head injury, spinal cord injury, and other disorders resulting in damage to the central nervous system. Of the 165 patients in the study, 84 performed the chin-down posture after aspirating on one of the 1, 3, 5, or 10 ml liquid boluses due to either a delayed pharyngeal swallow (i.e., when the head of the bolus passes the ramus of the mandible but the pharyngeal swallow has not been initiated) or reduced laryngeal elevation. To perform the chin down position, patients were instructed to move their head down so that their chin touched their neck. Of the 84 patients instructed to perform the chin down maneuver, only 21 (25%) benefitted (eliminated aspiration) from it. The researchers concluded with two possible explanations as to why the chin-down was unsuccessful in many of the patients. First, patients had difficulty in properly executing the chin-down due to restricted head movement (possibly due to spinal cord injury braces) or age. Secondly, many of the patients were not cognitively aware or had language deficits due to traumatic brain injuries and strokes, which resulted in their inability to understand and follow directions. Bülow and colleagues (1999) examined the chin down through videoradiography and solid-state manometry on eight healthy patients. The patients were instructed to place the 10mL liquid-barium bolus in their mouth, tuck their chin downward, and swallow. Several variables were analyzed through videoflouroscopy. These include bolus transit time, maximal hyoid movement, maximal laryngeal elevation, maximal and minimal laryngohyoid distance (from the rima glottis to lower margin of the hyoid bone), PES opening, and hyoid-mandibular distance. The results of the videoradiography showed that

20 8 the chin down resulted in shortening the length of the pharynx. The authors hypothesized that the chin down maneuver is effective because it shortens the length of the pharynx; therefore, the structures of the larynx need to move less to close off the airway. The results from the solid-state manometry study showed that the chin down maneuver resulted in decreased pharyngeal contraction pressures. From these data, the researchers hypothesized that the chin down position could be harmful to patients with weak pharyngeal constrictor muscles, due to the increased risk of post-swallow retention and aspiration. Inconclusive Results about the Chin Down Posture An earlier study by Ekberg (1986) reported inconclusive results about the effectiveness of the chin down posture in patients with dysphagia. Fifty-three patients with dysphagia of unspecified origins were examined through cineradiography while producing the chin down and head extended positions. Patients were instructed to tilt their head forward or backward as much as possible and then swallow a barium bolus. Results showed that of 18 patients with defective closure of the laryngeal vestibule in resting position, only nine improved when using the chin down. Of ten patients with defective movement of the epiglottis while in resting position, two improved with the chin down. The researchers stated that laryngeal closure that resulted from the use of postural changes occurred due to intrinsic closure of the laryngeal vestibule, and was not dependent on movement of the epiglottis. More than half of the patients with defective closure of the laryngeal vestibule and movement of the epiglottis did not benefit from the use of the chin down posture.

21 9 The Role of Fiberoptic Endoscopic Evaluation of Swallowing and the Chin Down Posture Until 1988, clinical bedside evaluations and modified barium swallow studies were the two leading methods to assess dysphagia. Langmore, Schatz, and Olsen (1988) published the first research article describing the use of flexible endoscopy for swallowing diagnostics. Since then, flexible endoscopy has become a commonly used instrument for assessing dysphasia in hospitals. In the literature, Langmore has described flexible endoscopic evaluation of swallowing (FEES) to consist of five diagnostic components. FEES allows clinicians to assess the structural changes in the larynx and pharynx, movement and sensation of structures (e.g., vocal folds, epiglottis), and secretion management. Finally, it allows visualization of a patient s response to therapeutic maneuvers (e.g., supraglottic swallow, Mendelsohn maneuver) and postural changes (e.g., chin tuck, head rotation) (Hafner, Neuhuber, Hirtenfelder, Schmedler, & Eckel 2008; Langmore, Schatz, & Olsen, 1988; Langmore, Schatz, & Olsen, 1991; Langmore, 1998; Langmore, 2003). FEES allows for the visualization of the events before and after the pharyngeal stage of the swallow. An advantage to FEES is that the clinician is able to visualize the movement of the arytenoid cartilages and vocal folds. Furthermore, it allows for visualization of the patient s secretions, which cannot be seen via videofluoroscopy. In the current dysphagia literature, FEES has been reported to be a useful examination to diagnose dysphagia and identify symptoms of dysphagia including aspiration and penetration in specific clinical populations (e.g., critically ill patients, pediatrics; Hafner et al, 2008; Leder & Karas, 2000), in prospective studies concerning

22 10 pneumonia incidence (Aviv, 2000), and in comparison studies with videofluoroscopy (Aviv, 2000; Kelly, Drinnan, & Leslie, 2007; Langmore, 1991, Logemann, Rademaker, Pauloski, Ohmae, & Kahrilas, 1998; Madden, Fenton, Hughes, & Timon, 2000; Perie, Laccourreve, Flahault, Hazebroucq, Chaussade, & St Guily, 1998; Rao, Brady, Chaudhuri, Dibzekku, & Wesling, 2003; Chih-Hsiu, Tzu-Yu, Jiann-Chyuan, Yeun- Chung, & Shiann-Yann, 1997). Several research studies and review articles have discussed the use of postural changes during the FEES examination to evaluate the use of swallowing strategies and postures to reduce the risk of aspiration (e.g., Aviv, 2000; Hafner et al., 2008; Hiss & Postma, 2003). Despite the increased popularity of using FEES to evaluate swallow function, there is only one study, to the best of this researcher s knowledge, that has described the changes observed in the pharyngeal structures as a result of postural changes using endoscopy. Aviv, Kim, Thomson, Sunshine, Kaplan, and Close (1998) examined the use of fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST) on 20 healthy controls. Subjects were instructed to swallow with their chin tucked during thin and thick liquids, pureed, mechanical soft, and regular foods. The researchers reported predictable changes in the pharyngeal anatomy using the chin down position. Endoscopic view of the chin down position resulted in the tongue base being pushed closer to the posterior pharyngeal wall, widening of the vallecular space, and posterior displacement of the epiglottis. This study did not provide information on how the chin tuck posture was achieved.

23 11 Chin Down versus Chin Tuck One of the difficulties of determining if the chin down posture is effective at eliminating aspiration is the variability on how to perform it. Table 1 contains a list of different instructions given to research subjects and patients on how to create the chindown/chin-tuck posture. There are at least five different names use to describe the posture. These names are used interchangeably by some to describe the same movement of the head and neck or are used by others to differentiate between the postures (e.g., chin down versus chin tuck). In Table 2, names for chin down are listed along with the research articles that correspond to them. Finally, the terms chin down and chin tuck have been used interchangeable within research articles (Kagaya et al., 2011; Shanahan et al., 1994; Welch et al., 1993). By switching between these terms, studies have assumed that the chin-tuck and chin down position are the same. None of these studies have given a clear definition as to how the anatomy changes when performing the position. Only one study showed that the chin tuck posture resulted in narrowing of the vallecular space. Welch et al. (1993) discovered that widening of the vallecular space, which was thought to occur when performing the chin tuck, was not consistently observed in all patients. Radiographic examination of postural effect was completed on 30 patients with unspecified origins of dysphagia. Prior to their swallow assessment, the patients performed different static positions (neutral upright position and chin tuck). The researchers measured different angles and distances of the pharynx from the static positions. These measurements included three angles (postural, epiglottic, and vallecular-

24 12 angled formed between the tongue base and the anterior surface of the epiglottis) and three distances (from the posterior point of epiglottis to posterior pharyngeal wall, from anterior wall of laryngeal vestibule to most anterior surface of the arytenoid cartilage, and from the most posterior surface of the arytenoid cartilage to the posterior pharyngeal wall). The researchers found that the vallecular space remained relatively constant or decreased when moving from neutral upright position to the chin tuck. The researchers concluded that the protection of the airway does not come from the enlargement of the vallecular space, but instead the posterior movement of the anterior pharyngeal structures (e.g., the tongue base and epiglottis). A few studies have looked specifically at changes in positioning of structures using the chin tuck assessed through videofluorography or high-tech cameras (Okada et al., 2007; Steele et al., 2011; Welch et al., 1993). Steele and colleagues (2011) examined the angle of head flexion in patients after being presented with an instruction from the researcher. One hundred and seventy six healthy individuals volunteered to participate in this study. Patients sat in a chair facing 90 degrees away from the camera, to provide the researchers with a sagittal view. A vertical line was drawn on a screen behind the chair. Patients wore dark goggles with bright yellow dots to allow the identification of head position during a constantly recording video being taken. The researchers measured the angle between the goggles in the head-neutral position to the chin down position. Patients performed five water swallows in the head neutral position first before moving onto the chin down posture. Patients started in a head-neutral position, received a bolus of water and then received verbal instructions on how to tuck their chin. The instructions stated that patients were to move their head downward so that their chin touched their chest and

25 13 they could see their knees. Steele discovered that there was not only variance in the degree of head flexion, but also in the resting position. In the head-neutral resting position, older patients had a greater degree of head flexion than younger patients did. In the chin-down position, head angle varied up to 25 degrees across patients. From the instructions provided by Steele, the average flexion across patients was 19 degrees. Due to the large variance in execution of the chin down posture given in one verbal prompt, the researchers concluded that more specific instructions need to be given in clinical practice to ensure that the patient is flexing their head to a proper degree that will aid their swallowing. In a recent survey of speech-language pathologists, there was wide disagreement on the degree of head flexion, neck flexion, and head and neck flexion needed to create the posture (Okada et al., 2007). The survey consisted of six lateral view pictures of a woman performing different head postures based on biomechanical and functional anatomic research of the cervical spine. In the spinal literature, the first two cervical vertebrae have special names. C1, the first cervical vertebrae, is the atlas and C2, the second cervical vertebrae, is know as the axis. The occipito-atlanto-axial complex, the articulation between C1 and the occipital bone, offers the greatest degrees of flexion and extension. However, it does not contribute to lateral bending or head rotation. Head rotation results in movement of the atlantoaxial joint, the articulation between C1 and C2. Flexion can also result from movements in C5, C6, C6-C7 joint, and C4-C5 joint. (Kirshblum, O Connor, Benevento, & Salerno, 1998). Therefore, movement of the occipito-atlanto-axial complex results in flexion of the head on the neck (i.e. head flexion), while flexion of the lower cervical spine (C5, C6) results in flexion of the neck

26 14 (i.e. neck flexion) (Hislop & Montgomery, 2002). This study examined six postures including a neutral position, head flexion on the neck, neck flexion, combined head and neck flexion, head extension neck flexion, and head extension. Speech-language pathologists were asked to look at the pictures and mark which picture they considered the chin-down posture and which they considered the chin-tuck posture, if the speechlanguage pathologist thought there was a difference between the two postures. The results showed that 58% of United States respondents and 23% of Japanese respondents did not differentiate between the chin down and chin tuck posture. Three different postures were chosen by the respondents to represent the chin down posture: head flexion neck flexion, head flexion, and neck flexion. In addition, the same three postures were also chosen by speech-language pathologists as representing the chin tuck. Conclusion There are inconsistencies concerning the chin down maneuver: different terms (Table 1), different instructions (Table 2), and differences in structural dimensions. All of the studies thus far have used videofluorography as the primary method to evaluate the effectiveness of the posture and to measure structural changes. However, nasoendoscopy is now routinely being used clinically to assess patient s swallowing abilities and examine the effectiveness of compensatory strategies to minimize the risk of aspiration. As far as this author is aware, only one study to date has mentioned structural change resulting from posture using endoscopy (Aviv et al., 1998). All of these factors have lead to the following research questions: 1. What anatomic changes occur without a bolus in the oral cavity? 2. What anatomic changes are associated with a bolus in the oral cavity?

27 15 3. Is there a significant difference between the two conditions for each position? 4. Are there visible differences between the chin down and chin tuck posture across subjects? The researchers hypothesized that the chin tuck posture will result in a greater airway protection than the chin down posture, and that these results will be significantly different from each other. Further, the researchers hypothesized that anatomical changes will occur when a bolus is in the oral cavity.

28 16 Table 1. Ways Cited in Literature to Perform the Chin Down and Chin Tuck Postures Instruction/Description Chin to Chest Research Articles Steele, Hung, Sejdić, Chau, & Fraser (2011) Chin to Neck Lewin et al. (2000); Logemann (1994); Rasley et al. (1992); Welch et al. (1993) Chin downward looking at knees Steele et al. (2011) Tuck chin downward to look at a Hori et al. (2010) marked spot on the floor Have chin lowered maximally Shanahan et al. (1993) Use a pillow to create different Ayuse et al. (2006) degrees of head flexion Use a protractor to create different degrees of head flexion Tuck chin downward J. Castell, D. Castell, Schultz, & Goergeson (1993) Bülow et al., 1999; Bülow et al. (2002) Flexion of the neck Nagaya, Kachi, Yamada, & Sumi (2004) Tilt head forward Ertekin et al. (2001); Logemann (1986)

29 17 Table 2. Different Names for the Chin Down and Chin Tuck Posture Seen in the Literature Name of Posture Research Articles Head Flexion Castell et al (1993); Ekberg (1986) Head Down Logemann (1994) Head Tilt Logemann (1986) Chin Down Baylow, Goldfarb, Taveira, & Steinberg (2009); Hind et al. (2009); Hori et al. (2010); Kagaya, Inamoto, Okada, Saitoh (2011*); Logemann (1993); Nagaya et al. (2004); Okada et al. (2007); Rasley et al. (1992); Robbins et al. (2008); Shanahan et al. (1993); Steele et al. (2011); Welch et al. (1993*) Chin Tuck Ayuse et al. (2006); Bülow et al. (1999); Bülow et al. (2001); Castell et al. (1993); Ertekin et al. (2001); Kagaya et al. (2011*); Langmore & Miller (1994); Lewin et al. (2001); Logemann (1987); Miller & Langmore (1994); Okada et al. (2007); Shanahan et al. (1993*); Welch et al. (1993*) Note: * denotes that these studies used the terms interchangeably throughout

30 18 CHAPTER II METHODOLOGY Introduction This research is an experimental study designed to examine the anatomical changes of the pharynx in normal, healthy individuals in regard to changes of head and neck position. Four positions were used in this study: a head neutral position, chin down, chin tuck, and head extended. Nasoendoscopy was performed on all subjects in order to visualize the pharynx. Still images from the endoscopic examination were analyzed using Scion Image. Analysis included measuring the change in pharyngeal structures across the four positions: head neutral, chin down, chin tuck, and chin extended. Subjects Twenty women between the ages of years old who were fluent English speakers without a history of swallowing problems were recruited to participate in the study. Individuals with history of allergy to topical anesthesia, neurological conditions, dysphagia, head or neck cancer or tracheotomy were excluded. Additionally, children under 18 years old and men were excluded from the study. This was to ensure that changes in anatomy were not due to the anatomical differences between sexes nor different stages of the growth cycle. Written consent was obtained from each subject prior to involvement in the study. All procedures were performed in accordance with the University of Iowa Institutional Review Board (IRB) for use of human subjects in research.

31 19 Data Collection All data were collected within the Department of Otolaryngology at the University of Iowa Hospitals and Clinics. Subjects attended one, 1-hour session. The session was designed to obtain endoscopic data on the change of anatomy between a head neutral position, chin down, chin tuck and head extended in two conditions for each posture: one without a bolus held in the oral cavity and one with a bolus held in the oral cavity. First, subjects completed the informed consent form. Only the examination section of each session was recorded. The first author taught the different head postures to the subject to ensure that the subject was able to follow the directions and properly perform each posture. The verbal prompts are listed in detail below. A KayPentax digital chip scope (VML-1070STK) was used to perform all endoscopic procedures. The scope was connected to the KayPentax 9200C. All subjects received the option to receive lidocaine 4% phenylephrine 1% prior to the procedure and the endoscope was covered in viscous lidocaine prior to insertion. Once the scope was prepared, the researcher instructed the subject to sit straight in the chair while looking forward. The endoscope was inserted through the nares on whichever side felt most open to the subject and placed at a high position, through the inferior or middle nasal turbinate, in order to visualize the pharyngeal anatomy and physiology (Logemann et. al., 1998). Four anatomical structures had to be visible on the video screen prior to beginning the recording of the endoscopic examination. These included the base of the tongue (at the bottom of the screen), the posterior pharyngeal wall (at the top of the screen), and the lateral pharyngeal walls (on the right and left sides of the screen). With this broad area being visible, the vallecular space was identifiable. The vallecular space consists of the

32 20 area of tissue between the epiglottis and the base of the tongue along with the tissue that continues to run to each lateral wall. Once the scope was in place and all structures were visible on the screen, the researchers placed a piece of tape on the scope where it entered the subject s nares. This ensured that the distance of the scope to the anatomical structures did not change when the subject altered her head position. Because of the change in the subject s head position, the endoscopist used the toggle function on the endoscope to ensure that all structures, as described above, were always visible. The second author, who is an experienced endoscopist with more than seven years of experience performing endoscopy on adults, completed all the endoscopic procedures. After the scope was in place and the tape was added, the researcher began to record the endoscopic examination. Four different head positions were used in this study: a neutral position, chin down position, chin-tuck position, and head extended. As reviewed in Kirshblum, O Connor, Benevento, & Dalerno s (1998) chapter discussing spinal and upper extremity orthotics, the chin down position has been defined as resulting from flexion of the occipito-atlanto (C1) and occipito-axial (C2) complex, which creates flexion of the head. In contrast, the chin tuck position results from the flexion of the head mentioned above, along with the flexion of the lower cervical spine (C5, C6), which results in flexion of the neck. The chin down and chink tuck positions have been used interchangeably by some researchers, but by others to designate differences in maneuver execution (Steele, C. M. et. al., 2011). This study treated them as two separate postures to identify any differences in the anatomy corresponding to the given position. The following instructions were given to each subject when performing the postures without the bolus in their mouth.

33 21 1. Head Neutral Position: Drop your shoulders from your ears and place your hands in your lap. Have your legs uncrossed, resting flat on the floor. Sit up straight and hold your head still while looking forward. Breathe slowly through your nose and relax. Hold this position until I tell you to move. 2. Chin Down: From this first position, I want you to lower your head so that you are looking at your knees. Hold this position while you continue to breathe only through your nose. Hold this position until I tell you to move. 3. Chin Tuck: Start from the first position. Move your head downward so that your chin touches your throat. Remember to breathe only through your nose. Hold this position until I tell you to move. 4. Head Extended: Start from the first position. Move your head upward so that you are looking directly at the ceiling. Hold this position until I tell you to move. For the trials with the bolus in the oral cavity, the instructions were as follows. 1. Head Neutral Position: Drop your shoulders from your ears and cross/hold your hands in your lap. Have your legs uncrossed, resting flat on the floor. Sit up straight and hold your head still while looking forward. Take small sip of water and hold it in your mouth. Breathe slowly through your nose and relax. Hold this position and the bolus in your mouth until I tell you to move and swallow. Now, swallow. 2. Chin Down: From this first position, I am going to give you a bolus of water. Hold the bolus in your mouth and lower your head so that you are looking at your knees. Hold this position while you continue to breathe only through your nose.

34 22 Hold this position and the bolus in your mouth until I tell you to move and swallow. Now, swallow. 3. Chin Tuck: Start from the first position. I will give you a bolus of water that you need to hold in your mouth. With the bolus in your mouth, move your head downward so that your chin touches your throat. Remember to breathe only through your nose. Hold this position and the bolus until I tell you to move and swallow. Now, swallow. 4. Head Extended: Start from the first position. Again, I will give you a bolus of water to hold in your mouth. With the bolus in your mouth, move your head upward so that you are looking directly at the ceiling. Hold this position and the bolus in your mouth until I tell you to move and swallow. Now, swallow. All subjects started in the head neutral position without a bolus in the mouth. The researcher ensured that all structures were visible and verbally mark (e.g., Ok, good ) when each position was obtained. Subsequently, the subject assumed the chin down, chin tuck, and head extended positions. In between each position, the subject returned to neutral. The researcher provided the subject with verbal cues regarding when to hold the position and when to move back into neutral. Next, the researcher presented the subject with a small straw sip of water before each of the next four trials. Again, subjects began in neutral, then moved to chin down, chin tuck, and head extended. After all eight of the positions were performed and recorded, the scope was removed and placed immediately into disinfecting solution. The researchers reviewed each video and selected still frames of each posture. All images were saved using the following code: subject number, the posture the subject was making, and whether or not water was present (W= water hold,

35 23 N= posture only e.g., 001TuckW, 001TuckN). The verbal marking helped provide the researchers with fast and easy identification of each posture. The videos were saved on the hard-drive of the KayPentax machine and then transferred onto the OTO (i.e., Otolaryngology) drive on the University of Iowa Hospitals and Clinics secured drive. All stills were saved as.tiff files to ensure proper formatting for analysis. The still images were uploaded onto a portable junk drive in order to transfer the pictures to the lab where they were analyzed using ImageJ. All images were deleted from the junk drive after they were uploaded onto the computer in Wendell Johnson Speech and Hearing Clinic. Data Analysis The researchers reviewed the videos and screen shots of the different positions captured and uploaded them onto ImageJ. Four measurements were made for each still image in order to address the research questions: what are the anatomical changes occur with and without a bolus in the oral cavity and are there visible differences between the chin down and chin tuck posture. (1) Measure 1: the area of airway opening; (2) Measure 2: the distance from the left lateral wall to the right lateral wall; (3) Measure 3: the distance from the posterior pharyngeal wall to the midpoint of the posterior aspect of the epiglottis; and (4) Measure 4: from the tip of the epiglottis to the base of the tongue. All measurements were initially made in inches, and then converted to millimeters in Microsoft Excel. The most prominent point on the posterior pharyngeal wall served as a marker for consistency in measurements made across the different postures. If there was an obstruction of the point (e.g., cervical osteophyte), a perpendicular line from the

36 24 epiglottis was used to measure the opening. These four measurements were selected to test previous and current hypotheses regarding effects of the chin-down and chin-tuck postures on pharyngeal dimensions discussed in the previous section. Thirty-two measurements were made for each subject, 16 measurements (four per still image) without a bolus in the oral cavity and 16 measurements (four per still image) with a bolus in the oral cavity. ImageJ After loading ImageJ, the researcher opened a new still from the database. Every time a new still was opened, the following steps had to be completed. First, the scale must be set. This, set scale option, was found in the analyze tab and the scale pop-up appeared on the computer screen as shown in Table 3. To properly set the scale, the known dimensions of the still images were used. For all still images, the dimensions were found on the upper bar of the image in ImageJ (i.e., 2.13x1.6 inches (640x480); RGB; 1.2MB). The distance in pixels was the first number within the parenthesis, 640. The known distance was 2.13 and the unit of length was inches (see Table 4). These numbers were put into the set scale drop box to ensure the proper measurements for the.tiff file and then the researcher selected Ok to the changes in scale. Next, the researcher prepared the stills for measurement. To do so, the researcher began by opening up all four still images for one subject (either without a bolus or with a bolus) and identified the most prominent landmark on the posterior pharyngeal wall that could be seen in all the stills. This allowed the researcher to always be measuring from the same point on the posterior pharyngeal wall in each still within each subject. The

37 25 researcher selected the paintbrush tool and placed a dot on this point of the posterior pharyngeal wall. Following this, the straight line measuring tool was selected from the toolbar. The researcher used this function to mark the middle of the posterior aspect of the epiglottis on each still. The researcher drew a straight line between the most lateral aspects of the posterior surface of the epiglottis. Upon releasing the mouse, the drawn line depicted, with a circle, where the midpoint was located. Using the paintbrush function again, the researcher then marked the area on the epiglottis that corresponded to the midline. This protocol ensured that the researcher would always be measuring to the midline of the epiglottis across all four images. Finally, the researcher identified on each still the most anterior tip of the epiglottis. This tip was marked using the paintbrush function. This allowed the researcher to analyze the distance between the base of tongue and epiglottis. All stills were analyzed and placed in this order on the screen: neutral in the upper left corner, chin down in the upper right corner, chin tuck in the lower left corner, and extended in the lower right corner (i.e., the way they were performed during the endoscopic procedure). Two different buttons were used to create the four measurements. For Measurements 2, 3, and 4, the straight-line tracer was selected. The object tracer, shown as a heart on the toolbar, was used to obtain Measurement 1. For every still, the researcher began with Measurement 1. The researcher selected the heart shaped tracer. The researcher traced from the marked point on the posterior pharyngeal wall, down to the left and right lateral pharyngeal walls, and then across over the tip of the epiglottis. After releasing the mouse, the area drawn was displayed as a yellow circle. The researcher clicked the right mouse button and selected the option draw in the drop

38 26 down menu. Then, the researcher selected the Command button ( ) plus the M button on the keyboard to measure the area on the Apple Laptop Computer. Another way to obtain a measurement in ImageJ was to go to the toolbar and click Analyze, then select Measure from the drop down menu. It was important not to click anywhere else on the image during this process. Clicking on the image would result in loss of the yellow drawn circle, which would result in the loss of the measurement. Once a measurement has been made, ImageJ automatically opened a Results box. This pop-up box continued to report and collect all measurements made until the box was closed out of. Measurement 2 determined the distance from the right lateral wall to the left lateral wall. The researcher selected the straight-line measurement tool and, using the previously drawn area from Measurement 1, found the most lateral point on the right lateral wall. From this point, the researcher pushed and held the cursor down, drawing the line to the most lateral aspect of the left lateral wall as defined by the prior area measurement. The researcher released the mouse, and then right clicked to select the draw option. Then, the researcher measured the distance of the line either by selecting Command + M on the keyboard, or Analyze and Measure from the tool bar. For Measurements 3, the researcher placed the straight-line tracer on the identified point on the posterior pharyngeal wall, held the cursor down, and moved it to the midline of the epiglottis. It was important to make sure that the line started and ended where the area measurement was made. This ensured the proper distance was being measured in relation to the area already measured. The researcher released the mouse and then right-clicked, selecting the draw option, and then measured the distance using one of the two methods described above.

39 27 The final measurement was made after determining if a space existed between the base of tongue and the most anterior tip of the epiglottis. If no space existed, this measurement was not collected. If the space was present, the researcher then selected the straight-line tracer and dropped a perpendicular line from the tip of the epiglottis to the base of tongue. The researcher right clicked, selected the draw option, and then measured the distance using one of the described methods. Figures 1 and 2 provide examples of stills that has been analyzed, one with measurement four visible and one without. The researcher completed this process for the remaining three stills. After all the measurements were made, the researcher selected the Results box that contained all the measurements and selected File, save as. All raw data measurements obtained for the four stills were saved using the following system: Subject#ResultsP (for posture results, e.g., 004ResultsP) or Subject#ResultsW (for water hold stills, e.g., 004ResultsW). Finally, the researcher saved all still images, adding a D in front of their file name to denote the file had been measured, and then closed them. The stills were saved as DSubject#PositionN, for posture only (e.g., D004TuckN), and WSubject#PositionW, for water hold (e.g., D004ExtendW). Microsoft Excel To organize and analyze the measurements, the saved raw measurement files were opened in Microsoft Excel. Table 5 shows an example of how the files from ImageJ appeared on Excel. Given this chart, the researcher first deleted the columns mean, min, max, and angle, as they were not used in the data analysis. Next, the researcher separated and labeled all the measurements into four groups (neutral, down, tuck, and extended) leaving a space in between each. Next, the researcher deleted the numbering along the far

40 28 left side and replaced it with the description of the measurement. For Measurement 1, area was written. For Measurement 2, RLW-LLW was written. Measurement 3 was labeled as PPW-Ep and Measurement 4 as Ep-BOT. To make the spreadsheet easier to read, the researcher color-coded the different measurements. Measurement 1 was green, Measurement 2 was orange, and Measurement 3 was blue. Because Measurement 4 did not always occur in the data, no color was assigned to it. Table 6 shows the same data from Table 5 organized into these requirements. Any notes or comments about the data collected were written to the right of the measurements. Statistical Analysis All 32 measurements for five subjects were repeated by the second author to determine inter-observer reliability. The first author trained the second author how to evaluate and measure all variables on ImageJ. Five subject numbers were randomly selected using random.org. The second author then completed all measurements for the bolus and water conditions and sent the results to the first author. The first author then ran the Pearson correlation coefficient. A Pearson correlation coefficient was run to determine the covariance between the two author s measurements. Additionally, linear mixed model analysis for repeated measures was used to test the effect of bolus and position on airway opening, distance between the posterior pharyngeal wall to epiglottis (PPW-Ep), and distance between the right and left lateral walls (RLW-LLW). The fixed effects in the model were bolus (with versus without), position [neutral (CN), chin down (CD), chin tuck (CT), and extended (CE)], and bolus by position interaction effect. Comparisons of interest included testing for mean difference between with and without bolus at each position and between positions within

41 29 each bolus condition. These comparisons were performed using test of mean contrast with the p-value adjusted using Bonferroni s method to account for the number of tests performed. A Bonferroni adjusted p-value<0.05 was considered statistically significant.

42 30 Table 3. ImageJ Scale Default Setting Distance in Pixels: Known Distance: 1.00 Pixel Aspect Ratio: Unit of Length: Scale: Inch 300 pixels/inch

43 31 Table 4. ImageJ Scale Set to Still Image Measurements Distance in Pixels: Known Distance: Pixel Aspect Ratio: Unit of Length: Scale: Inch pixels/inch

44 Figure 1. Examples of Analyzed Still with Measurement 4 32

45 Figure 2. Example of Analyzed Still without Measurement 4 33

46 34 Table 5. Excel Spreadsheet Containing Measurement Data from ImageJ Area Mean Min Max Angle Length Note: These data contain only 15 measurements because Measurement 4 (anterior tip of epiglottis to base of tongue) was not measurable in one of the stills.

47 35 Table 6. Completed Final Data Sheet in Excel Note: This table only shows the data for the posture only condition. A second, identical Excel graph was created for the bolus condition.

48 36 CHAPTER III RESULTS Introduction Through nasoendoscopy, visualization of the anatomical structures of pharynx and larynx was made possible. Twenty subjects assumed four different positions (neutral, chin down, chin tuck, and head extended) in two conditions (with and without a water bolus in the oral cavity). Still images were captured from the video recording to allow for analysis of pharyngeal airway opening and distances between structures. These measurements have allowed for descriptive and statistical analyses to aid in answering the following questions: 1. What anatomic changes occur without a bolus in the oral cavity? 2. What anatomic changes are associated with a bolus in the oral cavity? 3. Is there a significant difference between the two conditions for each position? 4. Are there visible differences between the chin down and chin tuck posture across subjects? Anatomical Changes without Bolus Overall, general trends of change in anatomy were seen without a bolus in the oral cavity; however, there were inconsistencies noted between the subjects. Percent change analyses were conducted to determine the effect of head position on each measurement within each subject. The neutral positions served as the standard to which the other positions were compared.

49 37 Area of Airway Opening For the first measurement, area of the airway opening (Figure 3), 55% of the subjects in the chin down position exhibited a decrease in airway opening when compared to the neutral position. Chin down created an average decrease of % from neutral. Forty-five percent of subjects exhibited an increase in airway opening, averaging to a percent increase of 17.95%. When combining the data from all twenty subjects, chin down showed a -7.01% decrease in airway opening from neutral. For the chin tuck position, 75% of subjects exhibited a decrease in airway opening averaging %. Five subjects showed an increase in airway opening compared to the neutral position, which resulted in an average increase of 19.86%. When all subjects were combined, chin tuck resulted in an average decrease in airway opening of %. Finally, 85% of subjects in the chin extended position displayed an increase in airway opening when compared to the neutral position. Head extended created a 63.13% increase in airway opening for those subjects. Three subjects, however, exhibited a decrease in airway opening averaging -3.91% from the neutral position. Overall, subjects in the chin extended position showed a 52.90% larger airway opening than opening. There was no significant bolus by position interaction effect (p=0.56) which indicated that mean airway opening difference among positions did not significantly vary by bolus condition; or with versus without bolus difference did not vary by position (Table 7 and 8). Thus, the position main effect averaged across bolus conditions was examined. For the position main effect, the mean airway opening with the extended position was significantly greater by 91.3mm 2 (44.78% increase) compared to neutral position (p<0.0001). Airway opening at the chin down position and at the chin tuck was

50 38 significantly smaller compared to the neutral position (p=0.048 and p<0.0001, respectively). The airway opening was smaller than neutral position by 29.9 mm 2 for chin down (14.67% decrease) and by 69.1 mm 2 for chin tuck (33.89% decrease). In addition, position differences were also tested for the posture only condition, and posture condition differences tested at each position. The results of these tests are tabulated in Table 9 using the adjusted p-values corrected by using Bonferroni s method to account for the number of tests performed. Table 9 depicts that majority of the comparisons resulted in statistically significant differences. Only two comparisons were not found to be statistically different from each other: chin down versus neutral and chin down versus chin tuck. Distance from Posterior Pharyngeal Wall to Epiglottis The second measurement, posterior pharyngeal wall to epiglottis, demonstrated similar trends to the airway opening measurement (Figure 4). In the chin down position, 75% of subjects exhibited a decrease in distance between the posterior pharyngeal wall and epiglottis, creating an average percent change from neutral of -27.4%. Twenty-five percent of the subjects saw an increase in distance for this measure compared to neutral. The average percent increase was 32.2% greater than neutral for these five subjects. Overall, the chin down position resulted in an average decrease in distance of -12.5%. For the chin tuck position, 80% of subjects exhibited a decrease in distance from neutral averaging to a -40.7% change. Twenty percent of the subjects exhibited an average increase of 22.2% in the chin tuck position for the distance between the posterior pharyngeal wall and epiglottis. Overall, the chin tuck posture resulted in an average decrease of -28.1% compared to the neutral measurements. Finally, the extended position

51 39 resulted in an average increase of 66.3% for 85% of the subjects compared to neutral. Fifteen percent of subjects exhibited an average -9.9% decrease in distance compared to their neutral bases. Overall, the extended position resulted in an average increase of 54.9% in distance between the posterior pharyngeal wall and epiglottis compared to the neutral base. There was no significant bolus by position interaction effect (p=0.52) which indicated that mean airway opening difference among positions did not significantly vary by bolus condition; or with versus without bolus difference did not vary by position (Tables 10 and 11). Thus, position main effect averaged across bolus conditions was examined. For the position main effect, the mean posterior pharyngeal wall to epiglottis distance with the extended position was significantly greater by 3.9mm (44.19% increase) compared to neutral position (p<0.0001). The distance between the posterior pharyngeal wall and the epiglottis at the chin down and chin tuck positions were significantly smaller compared to neutral (p=0.005 and p<0.0001, respectively). The measurement was smaller than the neutral position by 1.8 mm (20.40% decrease) for chin down and by 3.1mm (35.13% decrease) for chin tuck. In addition, position differences were also tested for the posture only condition, and posture condition differences tested at each position. The results of these tests are tabulated in Table 12 using the adjusted p- values corrected by using Bonferroni s method to account for the number of tests performed. Table 12 depicts that majority of the comparisons resulted in statistically significant differences. Only two comparisons were not found to be statistically different from each other: chin down versus neutral and chin down versus chin tuck.

52 40 Distance between the Lateral Walls The third measurement (Figure 5), distance between the left and right lateral walls, did not display trends like the prior two measurements. The distance between the left and right lateral walls displayed inconsistent results across all postures assumed. In the chin down position, half of the subjects exhibited an increase in distance between the lateral walls and the other half saw a decrease in this distance. The average decrease from neutral was -5.13%, while the average increase was 7.47%, resulting in an overall average increase in distance of 1.17%. For the tuck position, 60% of subjects exhibited a decrease in distance compared to the neutral position averaging to %, while 40% of subjects displayed an increase in distance averaging to 17.53%. Overall, the tuck position resulted in an average decrease of -0.80% from the neutral position. Finally, 60% of subjects in the extended position displayed an increase in distance between the left and right lateral walls from neutral, averaging 10.45%. The remaining 40% of subjects exhibited a decrease in distance averaging -8.94%. Overall, the extended position resulted in an increased distance between the left and right lateral walls of 4.64%. There was no significant bolus by position interaction effect (p=0.61) which indicated that mean airway opening difference among positions did not significantly vary by bolus condition; or with versus without bolus difference did not vary by position (Tables 13 and 14). Thus, position main effect averaged across bolus conditions was examined. The distance between the right and left lateral walls at the chin down, chin tuck, and extended positions did not differ significantly from neutral (p=0.96, p=0.38, and p=0.11, respectively). In addition, position differences were also tested for the posture only condition, and posture condition differences tested at each position. The

53 41 results of these tests are tabulated in Table 15 using the adjusted p-values corrected by using Bonferroni s method to account for the number of tests performed. There were no statistically significant differences across all comparisons for right to left lateral wall distance in the non-bolus condition. Distance from Epiglottis to Base of Tongue The final measurement of distance between the anterior tip of the epiglottis and the base of tongue was difficult to obtain in the still images (Figure 6). Sixty percent of subjects had measureable distances between these structures in the neutral position. In the chin down, 30% had measureable distances, while in the chin tuck only 15% of subjects did. The extended position resulted in 60% measurable distances. For the other subjects in the neutral position 35% of the distances equaled zero, while 5% could not be measured. In chin down, 60% equaled zero, while 10% could not be measured. Fifty five percent of subjects in chin tuck has an epiglottis to base of tongue measurement equaled zero and 30% were unable to be measured. Finally, for the extended position, 10% equaled zero and 30% could not be measured. Anatomical Changes with Bolus Similar trends were depicted across the four measurements in the water hold condition, however, there was less variability between subjects. Again, percent change analyses were conducted to determine the effect of head position on each measurement for each subject. The neutral positions served as the standard that all the other positions were compared to it.

54 42 Area of Airway Opening First, as the subject moved their head from neutral to down, airway opening decreased on average by %. Airway opening continued to decrease as subjects moved their head from chin down to chin tuck by an average of % relative to neutral. When assuming the extended position, airway opening increased by 45.45% when compared to neutral. Fifteen percent of subjects exhibited an increase in airway opening by an average 12.18% in the chin down position compared to the neutral position. Only five percent of subjects exhibited an increase in airway opening for the chin tuck position compared the neutral. The average increase was 9.09%. Ten percent of subjects exhibited a decrease in airway opening when comparing the extended position to the neutral position. The average decrease for these subjects was %. (Figure 7). Table 7 reports the raw data analysis completed for the bolus condition measurements of airway opening. Table 8 delineates the results of the fixed-effect model for bolus, posture and bolus by posture. As stated above, there was no significant bolus by position interaction (p=.56), which allowed analysis of bolus main effect that was averaged across positions. The bolus main effect showed a mean airway opening without bolus that is significantly larger by 23.4mm 2 (12.19% increase) compared to with bolus (p=0.004). The linear mixed model analysis comparison (Table 16) with Bonferroni s method of adjusting p-values for repeated measurements showed that all comparisons except for chin down versus neutral and chin down versus chin tuck were significantly different from one another.

55 43 Distance from Posterior Pharyngeal wall to Epiglottis The second trend seen across subjects followed the same pattern as the airway opening trend (Figure 8). When the subject moved from neutral to the chin down position, the distance between the posterior pharyngeal wall and epiglottis shortened by an overall average of -25.9%. When the subject moved into chin tuck, the distance became even smaller from neutral, averaging a -41.4% decrease in distance. Finally, the distance increased when the subject assumed the extended posture by an average 48.6% increase from neutral. All subjects exhibited a decrease in distance when assuming the chin down position. However, ten percent of subjects in the chin tuck position showed an average increase in distance between the posterior pharyngeal wall and epiglottis of 17.2% from neutral. Five percent of subjects showed a decrease in distance from neutral of -23.9% when in the extended position. Table 10 reports the raw data analysis completed for the bolus condition measurements of airway opening. Table 11 delineates the results of the fixed-effect model for bolus, posture and bolus by posture. As stated above, there was no significant bolus by position interaction (p=.52), which allowed analysis of bolus main effect that was averaged across positions. The Bolus main effect was not statistically significant (p=0.09). The linear mixed model analysis comparison (Table 17) with Bonferroni s method of adjusting p-values for repeated measurements showed that all comparisons except for chin down versus chin tuck were significantly different from one another for the measurement of distance between the posterior pharyngeal wall and epiglottis with a bolus in the oral cavity.

56 44 Distance between the Lateral Walls The measurement between the right and left lateral walls was, again, largely inconsistent across subjects (Figure 9). In the chin down position, 45% of the subjects exhibited an increase in distance between the lateral walls and the other 55% saw a decrease in this distance. The average decrease from neutral was %, while the average for subjects exhibiting an increase was 6.38%, resulting in an overall average increase in distance of 2.88%. For the tuck position, 65% of subjects exhibited a decrease in distance compared to the neutral position averaging to %, while 35% of subjects displayed an increase in distance averaging to 5.66%. Overall, the tuck position resulted in an average decrease of -5.32% from the neutral position. Finally, 70% of subjects in the extended position displayed an increase in distance between the left and right lateral walls from neutral, averaging 8.78% increase. The remaining 30% of subjects exhibited a decrease in distance averaging -5.06%. Overall, the extended positions resulted in an increased distance between the left and right lateral walls of 4.63%. Table 13 reports the raw data analysis completed for the bolus condition measurements of airway opening. Table 14 delineates the results of the fixed-effect model for bolus, posture and bolus by posture. As stated above, there was no significant bolus by position interaction (p=.61), which allowed analysis of bolus main effect that was averaged across positions. The bolus main effect was not statistically significant (p=0.09). This linear mixed model analysis comparison (Table 18) with Bonferroni s method of adjusting p-values for repeated measurements showed that all comparisons except for chin tuck and extended (p=.002) were not significantly different from one

57 45 another for the measurement of distance between right and left lateral walls with a bolus in the oral cavity. Distance from Epiglottis to Base of Tongue Finally, the last measurement of distance between the anterior tip of the epiglottis and the base of tongue was difficult to obtain from the still images (Figure 10). Forty percent of subjects had measureable distances between these structures in the neutral position. In the chin down, 10% had measureable distances, while in the chin tuck 5% did. The extended position resulted in 40% measurable distances. For the other subjects in the neutral position 45% of the distances equaled zero, while 15% could not be measured. In chin down, 50% equaled zero, while 40% could not be measured. Sixty percent of subjects in chin tuck equaled a measurement of zero and 35% were unable to be measured. Finally, for the extended position, 25% equaled zero and 35% could not be measured. Posture versus Water Hold Condition This linear mixed model analysis comparisons (Tables 19-22) with Bonferroni s method of adjusting p-values for repeated measurements was used to determine if a significant difference within position was observed for the two conditions (p<.05). No statistically significant differences were shown for all measurements when comparing the posture condition to the water hold condition for each position. Visual Differences between Chin Down and Chin Tuck Differences were noted through examination and comparison of the still images for chin down and chin tuck when a bolus was in the oral cavity. For the chin down

58 46 position, the laryngeal vestibule and arytenoid cartilages were visible in 40% of all subjects. The epiglottis was visible in 90% of all subjects in the chin down position, 10% of which only contained the tip of the epiglottis. The vallecular space, defined as the airway opening in between the epiglottis and base of tongue, was visible in 70% of subjects while assuming the chin down position. Finally, in 55% of subjects in the chin down position, the base of tongue was touching the epiglottis and an additional 20% of subjects had over 95% of the visible epiglottis covered by the base of tongue. Conversely, the laryngeal vestibule and arytenoid cartilages were only visible in 10% of subjects in the chin tuck position. The epiglottis was visible for 80% of subjects in the chin tuck, with 20% of those having only the tip of the epiglottis visible in the chin tuck position. Extreme medial movement of the lateral walls was noted in 10% of subjects to aid in closure of the airway opening (Figure 22). The base of tongue was touching the epiglottis in 55% of subjects, with an additional 35% of subjects having the base of tongue cover over 95% of the visible epiglottis (Figure 19). Finally, the vallecular space was only visible in 20% of subjects in the chin tuck position (Figures 11-22). Statistical Analyses Pearson Product-Moment Correlation Coefficient A Pearson product-moment correlation coefficient (r) was run to determine the homogeneity of measurements made on each still by the first and second author. Five subject numbers were selected using random.org (i.e., 8, 11, 13, 15, 19). The first and second author had an overall r of 0.98 for all measurements. For the posture measurements, r equaled For the water measurements, r equaled 0.99 agreement.

59 47 Agreement ranged from 0.94 to 0.99 across all five subjects. Table 23 depicts all r products.

60 Figure 3. Percent Change per Subject in Area of Airway Opening from Neutral, Non- Bolus Condition 48

61 49 Table 7. Area of Airway Opening Raw Data Analysis Table 8. Fixed Effects Analysis for Bolus, Posture and Bolus by Posture for Area Measurement Type 3 Tests of Fixed Effects Effect Num DF Den DF F Value Pr > F Bolus Pos <.0001 Bolus*Pos

62 50 Table 9. Linear Mixed Model Analysis Comparing Different Positions for Non-Bolus Condition of Area Measurement Slice Comparison Mean Diff Std Error Adj p-value No CD vs. CN >0.99 Bolus CT vs. CN CE vs. CN < CD vs. CT CD vs. CE < CT vs. CE <0.0001

63 Figure 4. Percent Change per Subject in Distance between the Posterior Pharyngeal Wall and Epiglottis from Neutral, Non-Bolus Condition 51

64 52 Table 10. Posterior Pharyngeal Wall to Midpoint of the Epiglottis Raw Data Analysis Bolus Position N Mean Std Dev Std Error Minimum Maximum Yes No CD CT CE CN CD CT CE CN Table 11. Fixed Effects Analysis for Bolus, Posture and Bolus by Posture for Posterior Pharyngeal Wall to Epiglottis Measurement Type 3 Tests of Fixed Effects Effect Num DF Den DF F Value Pr > F Bolus Pos <.0001 Bolus*Pos

65 53 Table 12. Linear Mixed Model Analysis Comparing Different Positions for Non-Bolus Condition for Posterior Pharyngeal Wall to Epiglottis Measurement Slice Comparison Mean Diff Std Error Adj p-value No CD vs. CN Bolus CT vs. CN CE vs. CN < CD vs. CT CD vs. CE < CT vs. CE <0.0001

66 Figure 5. Percent Change per Subject in Distance between the Right and Left Lateral Walls from Neutral, Non-Bolus Condition 54

67 55 Table 13. Right to Left Lateral Wall Distance Raw Data Analysis Bolus Position N Mean Std Dev Std Error Minimum Maximum Yes No CD CT CE CN CD CT CE CN Table 14. Fixed Effects Analysis for Bolus, Posture and Bolus by Posture for Distance between the Right and Left Lateral Wall Type 3 Tests of Fixed Effects Effect Num DF Den DF F Value Pr > F Bolus Pos Bolus*Pos

68 56 Table 15. Linear Mixed Model Analysis Comparing Different Positions for Non-Bolus Condition for Right to Left Lateral Wall Measurement Slice Comparison Mean Diff Std Error Adj p-value No CD vs. CN >0.99 Bolus CT vs. CN >0.99 CE vs. CN >0.99 CD vs. CT >0.99 CD vs. CE >0.99 CT vs. CE

69 Figure 6. Percent Change per Subject in Distance between the Anterior Tip of the Epiglottis and Base of Tongue from Neutral, Non-Bolus Condition 57

70 Figure 7. Percent Change per Subject in Area of Airway Opening from Neutral, Bolus Condition 58

71 59 Table 16. Linear Mixed Model Analysis Comparing Different Positions for Bolus Condition for Area Measurement Slice Comparison Mean Diff Std Error Adj p-value With CD vs. CN Bolus CT vs. CN < CE vs. CN < CD vs. CT CD vs. CE < CT vs. CE <0.0001

72 Figure 8. Percent Change per Subject in Distance between the Posterior Pharyngeal Wall to Epiglottis from Neutral, Bolus Condition 60

73 61 Table 17. Linear Mixed Model Analysis Comparing Different Positions for Posterior Pharyngeal Wall to Epiglottis Measurement, Bolus Condition Slice Comparison Mean Diff Std Error Adj p-value With CD vs. CN Bolus CT vs. CN < CE vs. CN < CD vs. CT CD vs. CE < CT vs. CE <0.0001

74 Figure 9. Percent Change per Subject in Distance between the Right and Left Lateral Walls from Neutral, Bolus Condition 62

75 63 Table 18. Linear Mixed Model Analysis Comparing Different Positions for Right to Left Lateral Wall Distance, Bolus Condition Slice Comparison Mean Diff Std Error Adj p-value With CD vs. CN >0.99 Bolus CT vs. CN CE vs. CN CD vs. CT >0.99 CD vs. CE CT vs. CE

76 Figure 10. Percent Change per Subject in Distance between the Epiglottis to the Base of Tongue from Neutral, Bolus Condition 64

77 65 Table 19. Area of Airway Opening Condition Comparison Comparison For Pos Mean Diff Std Error Adj p-value CD With bolus vs. No bolus CT CE CN >0.99 Table 20. Posterior Pharyngeal Wall to Epiglottis Distance Condition Comparison Comparison For Pos Mean Diff Std Error Adj p-value CD With bolus vs. No bolus CT CE CN >0.99

78 66 Table 21. Right to Left Lateral Wall Distance Condition Comparison Comparison For Pos Mean Diff Std Error Adj p-value CD With bolus vs. No bolus CT >0.99 CE >0.99 CN >0.99 Table 22. Epiglottis to Base of Tongue Distance Condition Comparison Comparison For Pos Mean Diff Std Error Adj p-value CD With bolus vs. No bolus CT CE CN

79 Figure 11. Still Image of Subject 16 in Neutral with Bolus 67

80 Figure 12. Still Image of Subject 16 in Chin Down with Bolus 68

81 Figure 13. Still Image of Subject 16 in Chin Tuck with Bolus 69

82 Figure 14: Still Image of Subject 8 in Neutral with Bolus 70

83 Figure 15. Still Image of Subject 8 in Chin Down with Bolus 71

84 Figure 16. Still Image of Subject 8 in Chin Tuck with Bolus 72

85 Figure 17. Still Image of Subject 15 in Neutral with Bolus 73

86 Figure 18. Still Image of Subject 15 in Chin Down with Bolus 74

87 Figure 19. Still Image of Subject 15 in Chin Tuck with Bolus 75

88 Figure 20. Still Image of Subject 20 in Neutral with Bolus 76

89 Figure 21. Still Image of Subject 20 in Chin Down with Bolus 77

90 Figure 22. Still Image of Subject 20 in Chin Tuck with Bolus 78

91 79 Table 23. Pearson Correlation Coefficient between Authors One and Two Subject r Posture r Water r All

92 80 CHAPTER IV DISCUSSION The purpose of this study was to examine the anatomical changes of the pharynx in normal, healthy individuals in regard to changes of head and neck position. It was hypothesized that the chin tuck would result in greater airway protection than the chin down posture and that these postures would be significantly different from one another. The findings demonstrated that there are significant differences in anatomical structures of the pharynx related to head position. The chin down, chin tuck, and head extended positions were found to be significantly different from the neutral positions in terms of the area of airway opening created and distance between the posterior pharyngeal wall and epiglottis. Furthermore, the presence of a small liquid bolus in the oral cavity played a significant role in changing the area of airway opening observed in all postures compared to the non-bolus hold postures. Important effects in anatomical structures were noted between the chin down and chin tuck posture, such as differences in the degree of pharyngeal opening and length between structures. These clinical observations will be further discussed below. Overall Anatomical Changes across Postures Through nasoendoscopy, we were able to analyze the changes in anatomy that resulted from four different head positions: neutral, chin down, chin tuck, and head extended. Below in Figure 23, the average percent change from the neutral base (either posture only for the posture positions or water hold for the bolus conditions) is displayed.

93 81 Posture versus Bolus Hold A bolus in the oral cavity proved to significantly decrease the area of airway opening across all four positions. Two structures that may be driving the difference in the airway opening are the base of tongue and velum. During a bolus hold, the velum lowers and the tongue base elevates to contain the bolus in the oral cavity. This may cause the base of tongue and epiglottis to be positioned differently in the oropharynx, resulting in the narrowing of pharyngeal opening. As seen in Figure 23, the measurements (i.e., pharyngeal opening and posterior pharyngeal wall to epiglottis) on average are smaller for the bolus condition than the non-bolus condition. The average percent change in measurements listed in Figure 23 for the head extended bolus condition are also smaller than the extended non-bolus condition. The only difference between these two conditions is holding a bolus in the oral cavity. The researchers hypothesize that the base of tongue and velum play a role in significantly decreasing the area of airway opening across all positions during the bolus hold condition. Area of Airway Opening and Distance between Posterior Pharyngeal Wall and Epiglottis The two major factors depicting differences across all positions and conditions were the measurements of area of airway opening and distance between the posterior pharyngeal wall to midline of the epiglottis. When subjects tilted their heads down in order to look at their knees, the area of airway opening decreased roughly from the neutral bolus condition by -22.3%, along with a -26.0% decrease in the distance between the posterior pharyngeal wall and epiglottis. When the subject tucked their chin to their neck, greater airway protection occurred due to a greater decrease in airway opening,

94 82 which on average was a -40.0% decrease compared to the neutral bolus condition. Additionally, the distance between the posterior pharyngeal wall and the epiglottis decreased further, on average by -41.2% compared to the neutral bolus condition. Furthermore, when subjects extended their heads toward the ceiling, the area of airway opening increased, on average with a bolus by 45.5%. Also, the distance between the posterior pharyngeal wall and epiglottis increased by 48.6% compared to the neutral bolus position. The movement of the epiglottis towards the posterior pharyngeal wall resulted in the area of airway opening to reduce further than in the chin down position. Finally, these two measurements were found to be statistically significant in distinguishing the chin tuck and head extended postures from the neutral base across both conditions. The chin down measurement was not found to be significantly different from neutral position during both conditions in the area of airway opening measurement, however it was statistically significant for the posterior pharyngeal wall to epiglottis measurement. As mentioned in the results, several subjects exhibited opposite trends (e.g., increase in area when assuming the chin tuck posture) from the group. Table 24 below examines the characteristics of the two groups of subjects for the both conditions. As can be seen, subjects who an increase in area of airway opening on average had a smaller neutral area measurement than those subjects who saw a decrease in area with a bolus in the oral cavity. This trend was not seen for the posture hold condition. The same trend can be seen in Table 25, which compares the subjects showing increases and decreases in the distance between the posterior pharyngeal wall and epiglottis. In the bolus condition, the subject that exhibited an increase in this measurement had a smaller distance between

95 83 the two structures on average in the neutral position. For the without bolus condition, the trend is seen for the chin down versus neutral and chin tuck versus chin down, however not for the chin tuck versus neutral. Distance between Lateral Walls The third measurement, distance between the right and left lateral walls, did not show to be significantly contributing to the change between the postures. The measurements between the right and left lateral wall remained relatively constant across subject for all four positions and two conditions. No visible pattern of change was noted in this measurement when subjects assumed the different postures or created the two conditions. However, two subjects exhibited extreme medial movement of the lateral walls when creating the chin tuck posture in the water hold condition. This resulted in the contribution of the lateral walls to decrease the pharyngeal opening and aid in airway protection. For one of these subjects, the medial movement of the lateral walls in the chin tuck position (-23.66% decrease with bolus) resulted in an increase of the distance between the posterior pharyngeal wall and epiglottis for the water condition only (23.3% increase with bolus). The other subject that exhibited extreme medial movement of the lateral walls in the chin tuck position (-21.51% decrease from neutral) displayed the general trend of decrease in distance between the posterior pharyngeal wall and epiglottis (-47% decrease from neutral). Epiglottis to Base of Tongue Statistical analyses could not be completed on the fourth measurement, the distance between the epiglottis to base of tongue, as majority of the measurements equaled zero or were unable to be measured. A breakdown of why the measurements

96 84 were unable to be obtained is shown in Table 26. Throughout the dysphagia literature, researchers, specifically Logemann (1998) and Shanahan et al (1993), state that the chin down posture results in the widening of the vallecular space. Only one study completed by Welch et al (1993) found that the vallecular space narrowed when subjects assumed the chin down posture. The present study found that there was no widening of the vallecular space in all twenty subjects when assuming the chin down and/or chin tuck positions with a bolus in the oral cavity. Only one subject exhibited an increase in vallecular space when assuming the chin down position without a bolus in the oral cavity (Subject 13: neutral= 3.6mm, chin down= 4.7mm, chin tuck= 0mm, extend= 3.6mm). For the majority (95%) of the subjects, if an initial measurement of vallecular space length in the neutral position was obtained, that measurement would decrease, become zero, or immeasurable when assuming the chin down or chin tuck position. Through the endoscopic vantage point, the base of tongue was observed to partially or completely fill the vallecular space in both conditions. Logemann (1998) does not specify exactly how the vallecular space widens when using the chin down posture. It is unclear whether the vallecular space widens laterally or if the posterior movement of the epiglottis separates the epiglottis from the base of the tongue. For this study, we are not able hypothesize about the width of the vallecular space that may be present under the base of tongue, as we were unable to visualize it. Another reason for the difference in findings could be individual differences in human anatomy. This study consisted of 20 females from the ages of years old. Men were intentionally excluded from the study in order to create a homogenous experimental group. Therefore, differences in shape, location, and movement of the epiglottis may differ across sexes and age.

97 85 Standard Deviation Figure 24 depicts the average standard deviations of percent change for all postures compared to their neutral base. Less variability can be seen in the measurement of distance between the lateral walls, especially in the bolus conditions, as this remains mostly stable. The average standard deviation of the percent change of the distance between the posterior pharyngeal wall and epiglottis were significantly higher as these movements are the principle driver of the change in area of airway opening between neutral, chin down and chin tuck. Chin Down versus Chin Tuck We were unable to show that a significant difference exists between the chin down and chin tuck positions across all measurements and conditions. However, important effects of the postures were noted through analysis of the endoscopic still images. When subjects were assuming the chin down posture, visualization of the laryngeal vestibule and/or arytenoid cartilages occurred in 40%, the vallecular space was visible in 70%, and the base of tongue was in contact with the epiglottis is 75% of subject. Conversely, the laryngeal vestibule and/or arytenoid cartilages were visible in only 10% of subjects in the chin tuck position, the vallecular space was visible in 20%, and the base of tongue was in contact with the epiglottis in 90% of subjects. Given these visual differences, greater airway protection resulted from the chin tuck posture due to decreased airway opening. From the percent change data presented in Figure 23, clear differences between the chin down and chin tuck position exist across the measurements. Larger decreases in measurements are seen when subjects are in the chin tuck position than the chin down position. However, due to the small number (n= 20) of subjects that

98 86 participated in the study, the researchers were unable to prove a statistical significance between the postures and conditions. In addition, the chin down posture was not found to significantly differ from the neutral position for the circumference of pharyngeal opening, while the chin tuck position did. Clinical Implications This study shows that it is important to differentiate between the chin down and chin tuck postures. Although there was no statistical significance between the chin down and chin tuck postures, the differences seen via endoscopic evaluation show that the chin tuck posture protects the airway better than the chin down posture. Specific instructions on how to create the desired position are essential. For a patient who is aspirating, providing him or her with the correct instruction on how to perform the chin tuck posture may determine whether or not aspiration will be eliminated. The chin tuck postured resulted in a statistically significant decrease in airway opening and distance between the posterior pharyngeal wall and epiglottis. Therefore, it should be applied when head flexion is at its greatest, thus resulting when touching the chin to the neck is achieved. The chin down posture results in a decrease in airway opening and should be used to describe a degree of head flexion obtained that does not result in the chin touching the chest or neck. The chin down posture may still be beneficial to specific clinical populations, such as patients with reduced mobility. Further research is warranted to determine how much flexion is necessary in order to eliminate aspiration in these clinical populations. Several additional clinical implications can be drawn from the study. The information obtained in this study concerning the change in anatomy secondary to chin

99 87 down, chin tuck and head extended postures serves as a great base knowledge for speechlanguage pathologists. By knowing in healthy, young adults the amount of closure and airway protection achieved with partial head flexion (e.g., chin down) and complete head flexion (e.g., chin tuck), speech-language pathologists have a standard to compare their patient s abilities. Similarly, if a patient cannot fully achieve complete head flexion, the speech-language pathologist will be aware that the patient may not be achieving the maximum benefits of decreased pharyngeal opening and increased airway protection that the chin tuck position provides. Limitations There were limitations to this study. First, endoscopic still images taken before the pharyngeal swallow was initiated were analyzed. Static images only depict part of the story when examining movements as complex as swallowing. In addition, nasoendoscopy does not allow for the visualization of the oropharynx and larynx during the swallow. The other limitation of this study was that videofluorography was not used simultaneously during the nasoendoscopic procedure. This prohibited the researchers from visualizing the vallecular space below the level of the base of tongue and during the peak of the pharyngeal swallow. In addition, the researchers were unable to determine the distance or length of scope insertion for each subject and therefore were not able to standardize the distance between the endoscope and the larynx. Further Research This study was based on the anatomical changes in the pharynx according to head and neck position in healthy, young adult females. Further research is needed to determine the effectiveness of the chin down and chin tuck postures in clinical

100 88 populations. Different clinical populations may show that patients must achieve the chin tuck posture to eliminate aspiration, or that the chin down posture works to eliminate their aspiration, or neither posture is beneficial for patients of a specific population. Repeating this study by use of simultaneous fluoroscopy would be beneficial because researchers would be able to determine the degree and extent of anatomical changes in the pharynx resulting below the level of the epiglottis and base of tongue. It will allow researchers to objectively measure differences obtained in airway opening and distance between structured when subjects assume the four different head positions. Also, videofluoroscopy will show the distance of endoscope insertion, allowing future researchers to measure the distance between the tip of the scope and the epiglottis. In addition, there are several opportunities to expand on the current research. First, a larger normal group study could be conducted to determine if there is a statistically significant difference between the chin down and chin tuck postures measured in this study. Another direction for future research would to complete a study on older adults and determine the role aging plays on movement of structures in the pharynx and the degree of head and neck flexion achieved. Conclusion Using nasoendoscopy to analyze the change in anatomy across different positions, we were able to determine that changes in area of airway opening and length between the posterior pharyngeal wall to epiglottis were statistically significant in determining changes between the different postures. Although we were unable to determine a significant statistical difference between the chin down and chin tuck postures, descriptive analyses of these postures lead to noticeable differences of in airway opening

101 89 and visible anatomy (e.g., laryngeal vestibule, vallecular space) across subjects. The chin tuck posture was found to provide subjects with the greatest decrease in airway opening from the neutral position, thus increasing airway protection. The chin down posture also showed a decrease in airway opening from neutral, however this decrease was not as large as observed in the chin tuck. Further research should simultaneously utilize nasoendoscopy and videofluoroscopy to further determine the differences in anatomy when subject assume the chin down and chin tuck postures in clinical populations, along with larger control groups.

102 90 Figure 23. Composite Data of Percent Change from Neutral Position, Condition Matched "#$##%&!"#$%&#'(#$)#*+%&#',-%*&#'2$.3'4#5+$%6'78/.6%+#9:' '#$##%&!"#$%&#'(#$)#*+',-%*&#' (#$##%& #$##%&!(#$##%&!'#$##%&!"#$##%& )*+,&-./,& )*+,&0123& 4567,878& )*+,&-./,& 9+6*&:.;1<& (./01.*' )*+,&0123& 9+6*&:.;1<& 4567,878&& 9+6*&:.;1<& DD9&6.&4E+A;.F<& Note: All non-bolus conditions are compared to the non-bolus neutral condition and all bolus conditions are compared to the bolus neutral condition.

103 91 Table 24. Comparison of Subjects with Increasing versus Decreasing Area Measurements With Bolus Without Bolus CD vs NE CT vs NE CT vs. CD CD vs. CN CT vs CN CT vs. CD # of Subjects Increasing in Area Average Increase (sq mm) Average Base (NE or CD) Average % Increase 10.8% 9.1% 16.1% 16.6% 20.4% 17.7% # of Subjects Decreasing in Area Average Decrease (sq mm) Average Base (NE or CD) Average % Decrease -28.4% -42.2% -27.5% -27.1% -41.2% -37.9%

104 92 Table 25. Comparison of Subjects with Increasing versus Decreasing Measurements of Distance between the Posterior Pharyngeal Wall and Epiglottis With Bolus Without Bolus CD vs NE CT vs NE CT vs. CD CD vs. CN CT vs CN CT vs. CD # of Subjects Increasing Average Increase (mm) Average Base (NE or CD) Average % Increase 1.2% 16.6% 19.4% 26.6% 17.4% 14.0% # of Subjects Decreasing Average Decrease (mm) Average Base (NE or CD) Average % Decrease -29.2% -75.2% -38.6% -26.7% -40.1% -31.0%

105 93 Table 26. Number of Subjects that the Epiglottis to Base of Tongue Measurement was Unable to be Measured Slice Position BOT Covering Epiglottis Velum Covering Epiglottis BOT Not Visible With bolus CD CT* CE CN Without bolus CD CT CE CN Note: For CT with bolus: One subject had a bubble obscuring the view of the epiglottis