Effect of temporary prosthetic mandibular advancement on velopharyngeal closure for speech

Transcription

1 University of Iowa Iowa Research Online Theses and Dissertations Summer 2015 Effect of temporary prosthetic mandibular advancement on velopharyngeal closure for speech Kyungsup Shin University of Iowa Copyright 2015 Kyungsup Shin This thesis is available at Iowa Research Online: Recommended Citation Shin, Kyungsup. "Effect of temporary prosthetic mandibular advancement on velopharyngeal closure for speech." MS (Master of Science) thesis, University of Iowa, Follow this and additional works at: Part of the Orthodontics and Orthodontology Commons

2 EFFECT OF TEMPORARY PROSTHETIC MANDIBULAR ADVANCEMENT ON VELOPHARYNGEAL CLOSURE FOR SPEECH by Kyungsup Shin A thesis submitted in partial fulfillment of the requirements for the Master of Science degree in Orthodontics in the Graduate College of The University of Iowa August 2015 Thesis Supervisor: Assistant Professor Lina M. Moreno-Uribe

3 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 Kyungsup Shin has been approved by the Examining Committee for the thesis requirement for the Master of Science degree in Orthodontics at the August 2015 graduation. Thesis Committee: Lina M. Moreno-Uribe Thesis Supervisor Michael P. Karnell Jerald B. Moon Thomas E. Southard

4 ACKNOWLEDGMENTS I would like to thank my wife, Angela, and my son, Jayden, for their immeasurable support and encouragement during my residency. I would also like to thank Drs. Lina M. Moreno-Uribe, Michael P. Karnell, Jerald B. Moon, and Thomas E. Southard for their knowledge and input while serving on my thesis committee. ii

5 ABSTRACT Introduction: Velopharyngeal inadequacy (VPI) may result in inappropriate oral/nasal coupling during the production of speech sounds, resulting in unwanted nasal resonance and/or nasal air emission. Orthognathic surgeries such as maxillary and/or mandibular advancements are also known to change skeletal and muscular structures resulting in changes affecting velopharyngeal closure (VPC). Although many studies have reported on the effect of maxillary advancement surgery on VPI for patients with cleft lip and palate, the effect of mandibular advancement on VPI has not been studied at length. The purpose of this study was to elucidate the effect of temporary prosthetic mandibular advancement on velopharyngeal function. Methods: Fourteen subjects (7 males, 7 females) with no history of craniofacial abnormalities or speech disorders were recruited. The mean age was 35 years (range = 26-60). Acoustic nasalance measurements were obtained during nasal sentences and during sentences without nasal consonants in two conditions; normally, and while wearing an elastic mandibular advancement (EMA) appliance to advance the mandible by 13mm. In addition, subjects were asked to produce five repetitions of the sentence "Ten men came in when Jane left" while recordings were obtained with a videoendoscopy/phototransducer system that sensed the amount of light passing through the velopharyngeal orifice. The endoscope and fiber optic light were inserted through the subject's middle nasal meatus and positioned above the velum. The phototransducer fiber was extended through the velopharyngeal port into the upper oropharynx to detect light passing through the orifice as the velopharyngeal mechanism opened and closed. Individual subject's outcomes with and without the EMA appliance were analyzed statistically using paired t-test for Nasalance test, and one-way ANOVA/independent samples t-test for phototransducer test. iii

6 Results: Nasalance did not deteriorate, but significantly decreased for the nasal sentences after mandibular advancement, whereas changes in nasalance were not significant for the sentences containing no nasal consonants after mandibular advancement. Mandibular advancement by a 13 mm using an EMA appliance did not significantly affect VPC. Instead, large variability among subjects in response to mandibular advancement. For 7 of the 14 subjects, the extent of VPC decreased significantly (p <.05) under the advanced mandible condition compared to the normal condition (without the EMA appliance). On the other hand, 5 subjects showed significantly (p <.05) increased VPC when their mandibles were advanced. For 2 subjects, VPC was not significantly changed with the advanced mandible. Conclusions: The outcomes of this study suggested that there was no statistical evidence to support that nasality was deteriorated by a 13mm mandibular advancement, which agreed with recent studies describing velopharyngeal function and nasality after orthognathic surgeries. VPC was not affected by mandibular advancement. Responses of the nasalance and VPC to mandibular advancement were dependent on the individuals. Further investigation such as electromyography method is needed to understand how velopharyngeal function and speech respond to mandibular advancement more definitely. iv

7 PUBLIC ABSTRACT Incomplete closure of the velopharyngeal (VP) port may result in inappropriate production of some speech sounds. Surgeries for upper and/or lower jaw advancements are known to change bone and muscular structures resulting in changes affecting the soft palate closure on the throat. The purpose of this study was to elucidate the effect of temporary advancement of the lower jaw on soft palate closure and speech. Fourteen subjects with no history of craniofacial abnormalities or speech disorders were recruited. A nasometer detects the % of the acoustic energy coming through the nose out of overall acoustic energy through the mouth and the nose, which is nasalance. Nasalance values were obtained during speech production of nasal sentences and sentences without nasal consonants in two conditions; normally, and while wearing an appliance for sleep apnea to advance the lower jaw by 13mm. Subjects were also asked to produce five repetitions of the nasal sentence "Ten men came in when Jane left" in two conditions. Movements of the soft palate were assessed using a videoendoscopy/phototransducer system, which sensed the amount of light passing through the velopharyngeal port. Nasalance was significantly decreased for the nasal sentences after the lower jaw advancement, but remained within a normal range. Velopharyngeal closure (VPC) did not significantly change after mandibular advancement, and was variable in response to the lower jaw advancement condition. Outcomes of this study demonstrated the effect of lower jaw advancement on VPC and speech. Implications for speech therapy and surgery are considered regarding individuals who require surgical advancement of the mandible. v

8 TABLE OF CONTENTS LIST OF TABLES... viii LIST OF FIGURES... ix INTRODUCTION... 1 REVIEW OF THE LITERATURE... 4 Orthognathic Surgery... 4 Benefits of Mandibular Advancement... 5 Complications of Mandibular Advancement Surgery... 5 Effects of Orthognathic Surgery on Velopharyngeal Function... 6 Velopharyngeal Closure after Maxillary Advancement... 6 Velopharyngeal Closure after Mandibular Advancement Assessment Methods of Velopharyngeal Status and Speech Perceptual Speech Assessment Cephalometric Analysis Pressure-Flow Measurement Phototransducer/Videoendoscopy Nasalance Measurement MATERIALS AND METHODS Subjects Instrumentations Elastic Mandibular Advancement (EMA) Appliance Mandibular Advancement Nasometer Phototransducer Systems Fiberoptic Endoscope/Fiber Array Procedures Nasalance Test Phototransducer Speech Testing Processing Edited Phototransducer Utterance Data Statistical Analysis RESULTS Nasalance Test Phototransducer Test for Velopharyngeal Closure (VPC) vi

9 DISCUSSION LIMITATIONS AND DIRECTIONS FOR FUTURE RESEARCH CONCLUSION REFERENCES vii

10 LIST OF TABLES Table 1. Three utterance groups for nasalance test Average percent velopharyngeal closure of the subjects before and after mandibular advancement Overall outcomes for changes in velopharyngeal closure before and after mandibular advancement on subjects #1-# viii

11 LIST OF FIGURES Figure 1. Elastic Mandibular Advancement (EMA) appliance Lateral cephalometric radiograph in a normal condition (OUT) Lateral cephalometric radiograph with EMA appliance (IN) Superimposition of the tracing on lateral cephalometric radiographs under the conditions of OUT and IN Nasometer for nasalance test Lateral cephalometric image with the endoscope and fiberoptic fiber in situ Nasoendoscopic image of velopharyngeal area Data processing: arrow indicates translucency factor (TF) Data processing: arrow indicates rectifying factor (RF) Nasalance outcomes for all the utterance groups: Nasal, High Pressure Oral, and Low Pressure Oral Statistical analysis on changes in nasalance before and after mandibular advancement with EMA appliance Nasalance outcomes for the utterance group of Nasal Nasalance outcomes for the utterance group of High Pressure Oral Nasalance outcomes for the utterance group of Low Pressure Oral Velopharyngeal closure without mandibular advancement on the subject # Velopharyngeal closure with mandibular advancement on the subject # Changes in velopharyngeal closure before and after mandibular advancement on the subject # Comparison of VPC before and after mandibular advancement for all 14 subjects ix

12 INTRODUCTION Orthognathic surgery is a surgical procedure to correct conditions of maxilla and mandible related to growth disorder, obstructive sleep apnea, temporomandibular joint (TMJ) disorder, congenital disorder such as cleft lip/palate, and severe malocclusion typically secondary to skeletal hyper/hypoplasia of the maxilla and/or mandible. Maxillomandibular advancement surgery is one of the most common types of the orthognathic surgery. These procedures anteriorly reposition the maxilla, mandible or both to improve the disharmonies in jaws. Specifically, procedures such as Le Fort osteotomy for maxillary advancement and bilateral sagittal split osteotomy (BSSO) for mandibular advancement, have been performed to treat maxillary skeletal hypoplasia, mandibular skeletal hypoplasia, obstructive sleep apnea (OSA), and craniofacial anomalies such as cleft lip and palate. Multiple benefits can be achieved from maxillomandibular advancement by orthognathic surgery. Facial profile and severe malocclusion can be improved for the patients with maxillary and/or mandibular hypoplasia. Retrognathic maxilla in patients with cleft palate can be predictably normalized relative to the mandible. Maxillomandibular advancement is also known to be an effective surgical intervention for obstructive sleep apnea (OSA) by increasing the nasopharyngeal and oropharyngeal space. Coordinated relationships between the maxilla and the mandible can lead to improved speech articulation and intelligibility, as the relationship between the lips and teeth are normalized. The relationship between the maxilla and mandible has the potential to affect speech. Maxillary advancement may improve velopharyngeal (VP) function and resonance for the 1

13 patients with constricted VP area and decreased nasalance pre-operatively, whereas it may lead to deteriorations such as velopharyngeal inadequacy (VPI) for the patients, whose VP function and resonance are on the borderline of the normal limit. Although enhanced outcomes have been typically associated with articulation pattern after orthognathic surgery, the post-operative effect of maxillary advancement orthognathic surgery on velopharyngeal function is equivocal. Most of the studies have reported either improved or essentially no change in velopharyngeal function following the surgery (Harada 2002, Chanchareonsook 2006, 2007, Pereira 2008), whereas others have shown increased area on the velopharyngeal port resulting in velopharyngeal insufficiency (VPI) (Janulewicz 2004, Chanchareonsook 2006, Nohara 2006). The impact of mandibular advancement on VP function, compared to that of maxillary advancement, has not been studied at length. A few studies have shown that the sectional area on the velopharyngeal port increased following mandibular advancement (Okushi 2001, Fairburn 2007). Although immediate decline has been reported in articulation and VP function following mandibular advancement, performance typically resumed to the pre-operative level when evaluated for a long-term follow-up, which could be due to the post-operative neuromuscular retraining. Anatomy of the velum area may explain differences in velopharyngeal function when the maxilla is advanced versus the mandible is advanced. Soft palatal muscles involved in VP closure comprise musculus uvulae, tensor veli palatini, levator veli palatini, and palatoglossus. VP closure occurs when these velar muscles contract. Maxillary advancement orthognathic surgery protrudes the skeletal maxilla and the hard palate, which may directly pull the muscles such as musculus uvulae, tensor veli palatini, levator veli palatine anteriorly resulting in deteriorated VP closure. The palatoglossus muscle connects the mandible to the velum by way 2

14 of its connection with the tongue. This muscular connection may affect VP closure when the mandible is positioned anteriorly. The purpose of this study was to measure the temporary effects of mandibular advancement on velopharyngeal function and speech. It was hypothesized that mandibular advancement with a temporary prosthetic appliance would decrease velopharyngeal closure and affect speech performance. A specific aim of the study was to quantify velopharyngeal closure and nasalance during speech using a videoendoscopy/phototransducer system, and to statistically compare the outcomes when speech is produced with and without the EMA appliance. 3

15 REVIEW OF THE LITERATURE Orthognathic Surgery Orthognathic surgery is commonly used to correct maxillary and mandibular growth disorders, obstructive sleep apnea, temporomandibular joint (TMJ) disorders, and congenital disorders such as cleft lip/palate. It is necessary to correct severe malocclusion typically secondary to skeletal hyper/hypoplasia involving the maxilla and/or mandible (Tauner 1957, Dal Pont 1961). Orthognathic surgeries can be categorized based on the directions of the reposition and whether the upper or lower jaw is involved. Maxillary surgeries include superior repositioning of the maxilla, down-grafting of the maxilla, maxillary advancement, maxillary setback, and maxillary expansion. Mandibular surgeries include mandibular advancement and mandibular setback (Bailey 2004). Mandibular advancement surgery is one of the most common types of the orthognathic surgery (Watzke 1990). Mandibular advancement is intended to anteriorly reposition the mandible to improve the position of the mandible relative to the maxilla. It may be used to treat disorders related to airway deficiency. Specifically, procedures such as unilateral or bilateral sagittal split osteotomy (SSO) for mandibular advancement have been performed to treat mandibular skeletal hypoplasia, obstructive sleep apnea (OSA), airway problems associated with craniofacial anomalies. Sagittal split osteotomy (SSO) was first described by Tauner and Obwegeser in 1957 and later modified by Tauner (1957) and Dal Pont (1961). SSO consists of soft tissue dissection, osteotomy and fixation for stability (Proffit 1990). A horizontal cut is made on the inner side of the mandible, extending anteriorly to the ascending ramus. The cut is then made inferiorly on 4

16 the ascending ramus to the descending ramus extending to the lateral border of the mandible in the area between the first and second molar. A vertical cut then extends below to the body of the mandible to the inferior border. All cuts are made into the middle of the bone where bone marrow is present. A chisel is then inserted and tapped gently to split the mandible into left and right sides. From here, the mandible can be moved either forwards or backwards. It is stabilized using stabilizing screws and plates and the jaw is wired shut for 4 5 weeks to promote healing. Benefits of Mandibular Advancement Multiple benefits can be achieved from mandibular advancement surgery (Proffit 1990, Watzke 1990, Chan 2010). Facial profile and severe skeletal malocclusion can be improved for patients with mandibular hypoplasia. Better alignment between the maxilla and the mandible may improve relationships between the lips, teeth and tongue assisting speech articulation. When used to manage obstructive sleep apnea (OSA), surgical advancement of the mandible increases the velopharyngeal and oropharyngeal spaces. Mandibular advancement to treat OSA can also be achieved non-surgically. Advancement of the mandible using prosthetic dental devices has been demonstrated to reduce the severity of OSA (Isono 1995, Chan 2010, Lowe 1990). Complications of Mandibular Advancement Surgery Complications of mandibular advancement surgery can be categorized in three groups according to when they occur (Martis 1984). Intra operative complications refer to problems during the surgical procedure itself and include uncontrolled bleeding, fracture of bony 5

17 fragments, and displacement of the proximal segment. Short-term complications are the ones occurring within a relatively short period after completion of orthognathic surgery. These include acute infection (Chow 2007), paresthesia, facial nerve palsy, severe edema, and impaired speech. Long-term complications include relapse, chronic infection, TMJ dysfunction, and chronic aseptic bone necrosis. Effects of Orthognathic Surgery on Velopharyngeal Function The impact of orthognathic surgery on speech production has been the focus of several studies. Most examined velopharyngeal closure after maxillary advancement. A few have considered velopharyngeal closure after mandibular advancement. Findings have been mixed. Velopharyngeal Closure after Maxillary Advancement Harada, Ishii, Mibu, and Omura (2002) followed six cleft patients for a minimum 12 months after maxillary advancement via distraction osteogenesis. The mean advanced length was 11.7 mm (range of mm). Hypernasality ratings using a scale of four levels (no, mild, obvious and severe) were recorded by a speech pathologist before and after surgery. The ratings remained unchanged in all patients except the one patient whose distraction magnitude was 15.0 mm. Hypernasality increased post-surgery for this individual. The authors suggested their findings support the conclusion that maxillary distraction less than 15mm may not markedly deteriorate velopharyngeal function in individuals with cleft palate. Chanchareonsook, Samman, and Whitehill (2007) reported similar findings. They randomized twenty-two patients into two groups: those who received Le Fort I osteotomy (10 6

18 subjects) and those who received Le Fort I distraction osteogenesis (12 subjects). In the osteotomy group, mean advancement magnitude was 3.28 mm (range = ). In the distraction group, mean advancement magnitude was 7.39 mm (range = 2.38 to mm). Speech production was independently assessed by three experienced speech pathologists, who were the second co-author and two Ph.D. students specializing in cleft palate and resonance disorders. Perceptual speech evaluations included judgments of resonance and nasal emission. Hypernasality was rated on a 4-point scale: 0 = no hypernasality, 1 = mild hypernasality, 2 = moderate hypernasality, and 3 = severe hypernasality. Hyponasality and nasal emission were rated on a 2-point scale: 1 = hyponasality and 0 = no hyponasality for the hyponasality rating, and 1 = presence of nasal emission and 0 = absence of nasal emission for nasal emission rating. Acoustic measurements were obtained using nasometry, and velopharyngeal physiology was evaluated using nasoendoscopy. All the assessments were performed preoperatively and 3 months postoperatively. For changes in nasoendoscopic findings, resonance, nasal emission, the subjects were categorized into three groups; improved, no change, or deteriorated after the osteotomy or the distraction. Both groups showed no significant difference between number of subjects who showed improvement, deterioration and no change of VP status between the two types of surgery. Statistical analysis showed no significant difference between preoperative and postoperative mean nasalance score in all subjects, in the osteotomy group and in the distraction group respectively. In addition, there was no significant difference in mean nasalance change between the osteotomy group and the distraction group. It was also shown that there was no significant correlation between magnitude of maxillary advancement and percentage nasalance change before and after the procedure within each of the groups. 7

19 Pereira, Sell, Ponniah, Evans, and Dunaway (2008) also reported that there was no significant effect of maxillary advancement on speech. In their prospective study, fifteen patients who underwent either osteotomy (n=8) or distraction osteogenesis (n=7) for maxillary advancement were examined for speech performance 0 to 3 months preoperatively and 8 to 15 months postoperatively. Average magnitude of maxillary advancement was 10.3mm (range 5 to 18mm). Speech articulation, nasality, and velopharyngeal function were assessed according to the Cleft Audit Protocol for Speech-Augmented (CAPS-A). Consonants production and hyper/hyponasality were assessed based on consensus listening undertaken by a specialist speech and language pathologist in the field of cleft lip and palate/velopharyngeal dysfunction, and a specialist speech and language pathologist in craniofacial conditions (author Pereira). Nasalance was assessed using the nasometer. The authors showed that no statistically significant differences were found between groups for pre- and postoperative changes in percentage of consonant correct and nasalance. They also showed that there was no statistically significant correlation between amount of forward advancement and changes in nasalance and percentage of consonants correct. In a retrospective study with a larger sample size (n=54), Janulewicz et al. (2004) reported that maxillary advancement surgery can result in symptoms of velopharyngeal inadequacy. The patients all had repaired cleft lip and palate and underwent maxillary advancement surgery between 1981 and Perceptual assessment of velopharyngeal function and speech was performed by a speech pathologist preoperatively and postoperatively from 3 months to 6 years. The authors used the Weighted Values for Speech Symptoms Associated with VPI established by the University of Pittsburgh. Hypernasality and hyponasality was evaluated perceptually and classified according to the following categories: 0 = 8

20 normal, 1 = mild hypernasality, 2 to 3 = moderate hypernasality, 4 = severe hypernasality, 0 = hyponasality, and 2 = hyponasality/hypernasality. Articulation was evaluated perceptually, and the presence or absence of a pharyngeal flap was noted on the evaluation form. Finally, a total speech score was calculated based on the previous variables, as well as nasal emission, facial grimace, and phonation. The summated score was classified as follows: 0 = normal, 1 to 2 = borderline competent, 3 to 6 = borderline incompetent, and 7+ = incompetent VP valve. The number of patients who had adequate velopharyngeal function decreased from 42% before surgery to 18% after the surgery. The number of individuals reported to have borderline incompetence increased after surgery from 9% to 22%. The number of individuals with velopharyngeal inadequacy increased from 13% to 20%. The authors concluded that speakers with clefts of the lip and palate or palate alone can be predisposed to velopharyngeal alteration after maxillary advancement. Nohara, Tachimura, and Wada (2006) reported post-surgical deterioration of velopharyngeal function based on electromyography measurements of the levator veli palatini muscle. Electromyographic measurements recorded preoperatively were compared with postoperative perceptual speech judgment. Velopharyngeal function was evaluated 3 month after surgery by means of perceptual judgment and nasoendoscopy. An experienced speech pathologist and one of the authors (Nohara) assessed the speech quality of the subjects before and after surgery. Subjects with excessive levator muscle activity preoperatively demonstrated increased hypernasality and deteriorated velopharyngeal closure via endoscopy after maxillary advancement. The authors suggested that preoperative levator muscle electromyography may help predict which patients are at high risk of speech deterioration after maxillary advancement surgery. 9

21 Chanchareonsook et. al. (2006) reviewed thirty-nine articles that presented the effect of osteotomy and distraction for maxillary advancement on velopharyngeal status and speech. Over a period of 30 years, 747 cases were reported. The authors found that there was no influence on velopharyngeal status and speech in the majority of cases. In patients with constricted velopharyngeal area and hyponasal speech, maxillary advancement may improve oronasal respiration and resonance. Some studies reported deteriorated velopharyngeal function and/or speech but this was found mostly in patients with anatomical predisposition such as preexisting velopharyngeal impairment or borderline velopharyngeal function. Chanchareonsook et. al. suggested that better controlled randomized trials with larger sample sizes and long-term followup are needed. Velopharyngeal Closure after Mandibular Advancement As indicated above, many studies have described the effects of maxillary advancement surgery on speech in patients with cleft lip and palate. However, the effect of mandibular advancement surgery on VPI has not been studied at length. Guyette, Polley, Figueroa, and Cohen (1996) described a case study where two surgical cases of mandibular advancement resulted in decreased articulation skills and transient velopharyngeal inadequacy. In this study, two patients underwent mandibular lengthening by 35mm and 45mm respectively. Velopharyngeal inadequacy was observed immediately after distraction for both patients. However, velopharyngeal function returned to normal within 1 month in one patient and within 8 months in the other. Guyette, Polley, Figueroa, and Smith (2001) reported changes in speech following mandibular advancement by distraction osteogenesis in seven patients with severe hemifacial 10

22 microsomia. The average length of mandibular advancement was approximately 10.9 mm with a range between 3.8 mm and 16.0 mm. Changes in articulation were evaluated using the Goldman-Fristoe Test of Articulation, and the total number of articulation errors out of a possible 73 items was used as an index of speech skills. A speech pathologist judged each patient s speech for hypernasality/hyponasality, and audible nasal emission before and after surgery. Judgments of resonance and nasal emission were made using a 4-point scale: 0=normal, 1=mild, 2=moderate, 3=severe. Perceptual judgments were performed by two Ph.D.-level speech pathologists. Two out of seven (28%) patients experienced transient deterioration in speech articulation. Three of seven (42%) demonstrated deterioration in nasal resonance. However, speech had returned to preoperative levels at the time of long-term follow-up (average 21 months with a range of 11 to 35 months). Niemi et al. (2006) examined the effect of mandibular advancement surgery on phonetic quality of speech by analyzing the main acoustic features of eight vowel sounds. They recruited five subjects who underwent mandibular advancement surgery. The subjects produced eight vowels (/i/, /y/, /e/, /ø/, /æ/, /a/, /o/, /u/). The acoustic features of vowels were measured and analyzed before surgery, 6 weeks after surgery, and 30 weeks after surgery. No significant acoustic changes were observed between three different time points. The authors concluded that no long-term perceptually significant deterioration in vowel production occurred in patients undergoing mandibular advancement surgery. 11

23 Assessment Methods of Velopharyngeal Status and Speech Perceptual Speech Assessment Perceptual speech assessment based upon clinical judgment by trained, experienced speech pathologists is one of the most commonly used methods to evaluate speech affected by velopharyngeal inadequacy. This approach involves the use of rating scales, assessment of controlled and spontaneous speech samples, and one or more clinicians. In most studies, the severity of hypernasality, nasal emission, and nasal turbulence was evaluated based of multiple scales that range from normal speech to severely abnormal speech (Chanchareonsook 2006). Diverse speech samples have been used, but repetition of consonant-vowel syllables, single words, sentences and conversational speech were the most frequently used speech samples (Chanchareonsook 2006). Such methods have been used to evaluate speech outcomes after maxillary advancement distraction osteogenesis (Cedars 1999). In this study, articulation was tested and compared before and after surgery. Analysis of the findings demonstrated increased severity of articulation impairment postoperatively. Cephalometric Analysis Lateral cephalometric x-ray analysis has been used to visualize soft and hard tissue around the velopharyngeal area (Ko 1999, Harada 2002, Heliovaara 2002). This method provides a static two-dimensional radiographic view of the velopharyngeal area. It permits measurement of space between the velum and posterior pharyngeal wall as well as velar length, velar angle and the ratio of pharyngeal depth to palatal length (Ko 1999, Harada 2002). Mason et. al. (1980) reported that a 3-mm distance between the nasal surface of the velum and the 12

24 pharyngeal wall on a lateral cephalometric analysis was sufficient to present a clinically perceived level of hypernasality. They suggested that patients with repaired cleft palate may have an increased risk of developing hypernasality and VPI due to their greater nasopharyngeal depth dimensions and decreased amount of velar tissue. Ko et. al. (1999) evaluated the static changes in velopharyngeal area on lateral cephalograms in patients who underwent maxillary advancement through distraction osteogenesis and correlated these anatomical changes with clinical speech data. They found an increase in the velar angle of 1.6 per millimeter of maxillary advancement, and concluded that an increase in nasopharyngeal depth and an increase in velar angle may result in compromised VP closure for speech (Ko et. al. 1999). Pressure-Flow Measurement Warren and DuBois (1964) first demonstrated a method for measuring velopharyngeal port area during speech using pressure-flow measurements. They demonstrated that air pressure differences measured across the velopharynx and measurements of airflow through the nose can be used to estimate the size of the velopharyngeal orifice area. They reported that VPI could occur when the velopharyngeal port area during speech was larger than 20 mm 2. Mason et. al used the same methodology described above to demonstrate that a port size of less than 5 mm 2 was associated with competent velopharyngeal closure. Watzke et al. (1990) applied aerodynamic measurements with individuals with cleft palate who underwent maxillary advancement. They defined the classification as adequate (0 to 4.9mm 2 ), borderline adequate (5.0 to 9.9 mm 2 ), borderline inadequate (10 to 19.9mm 2 ), and 13

25 inadequate (20 mm 2 or more). The authors concluded that there was no relationship between the magnitude of maxillary advancement and changes in velopharyngeal port area. Increases in postoperative velopharyngeal area usually disappeared within nine months, on average, after surgery. Phototransducer/Videoendoscopy In 1982, Dalston et. al. originally suggested simultaneous videoendoscopy and phototransducer methodology. Videoendoscopy provides direct, qualitative visual information about velopharyngeal function. Phototransducer system provides a means to quantify the magnitude of velopharyngeal closure. Combining videoendoscopy and phototransducer may result in better understanding of velopharyngeal function for speech. Okushi et. al. (2011) reported changes in anteroposterior and left-right diameters of the velopharyngeal space before and after jaw advancement surgery by using videoendoscopy. They suggested that the mode of dilation of the velopharyngeal space differs between maxillary and mandibular advancement due to differences in muscular function of the velum. Nasalance Measurement Nasalance measurements are obtained using a nasometer. Nasometry is an indirect method used to measure the oral and nasal acoustic energy produced during speech. Oral and nasal components of a subject s speech are transduced by microphone on either side of a horizontal sound separator that rests between the nose and the upper lip (Dalston 1991). The authors compared nasalance measured with a nasometer with aerodynamic measurements of 14

26 nasal cross-sectional area and judgements of hypernasality. Specific values were suggested as nasalance cutoff scores. For example, values less than 43% for the nasal text were considered abnormally lower nasalance, and values higher than 27% for the oral text were for counted as increased nasalance (Trindade 2003). However, these nasalance cutoff scores appear to vary across the studies (Haapanen 1997, Ward 2002, Trindade 2003). 15

27 MATERIALS AND METHODS Subjects Fourteen subjects (7 males, 7 females) were recruited. The mean age was 35 (minimum 26, maximum 60). All the subjects confirmed no history of speech or hearing disorders and no health history associated with velopharyngeal pathology. The subjects were provided with the description of the study and consent forms were filled out prior to participation. Instrumentations Elastic Mandibular Advancement (EMA) Appliance Alginate impressions were taken for each of the subjects, and sent to Dental Prosthetic Services for fabrication of the EMA appliance (Myerson LLC, Chicago) (Fig. 1). The EMA appliance consisted of upper and lower plastic trays customized to each subject. Button hooks were located bilaterally on the buccal side of the trays, at the cuspid region on the maxillary tray and at the molar region on the mandibular tray. Mandibular Advancement Lateral cephalometric radiograph for the subject under normal condition indicated normal condylar position within glenoid fossa, stable occlusion between maxillary and mandibular dentition, and lip competence (Fig. 2). With the mandible advanced in the same subject, condyles were dislocated from the glenoid fossa and mandible was advanced (Fig. 3). Superimposition of the tracings demonstrate that mandibular advancement protruded the lower 16

28 lip and the lower dentition, protracted the velum resulting in enlarged velopharyngeal anteroposterior depth (Fig. 4). The posterior pharyngeal wall did not change after mandibular advancement. Nasometer Nasal resonance was measured using the Kay Pentax Nasometer II model 6450 (Fig. 5). A headset, containing a sound separator just above the upper lip and microphones on either side, detected the oral and nasal acoustic components of the participant s speech. The microphone signals were input to a Windows computer with Kay Nasometer II software. Nasalance was computed as the nasal microphone amplitude divided by the sum of the nasal plus oral microphone amplitudes. Phototransducer Systems Two independent recording systems were used during in vivo speech recordings. In one, the audio speech signal and phototransducer output were recorded. An audio speech recording was obtained using a standard microphone (Shure Model SM48). The microphone and the phototransducer output were digitized at 10 khz per channel using WinDaq data acquisition hardware and software (Dataq Instruments, Inc.). The second recording system was used to record an acoustic speech sample with videoendoscopic images. The voice signal was recorded using a head mounted microphone (AKG 420; Harman Consumer Group) coupled with a Symetrix SX 202 (Symetrix, Inc.) pre-amplifier. The audio preamplifier output was input to a Pentax Medical Model 9200 multicomponent videostroboscopic recording and display system. 17

29 Fiberoptic Endoscope/Fiber Array A flexible fiberoptic endoscope (Olympus America Model LF-DP) with an internal instrument channel was coupled with a Pentax Medical (Model 9100-B) light source for in vivo testing. A single flexible fiberoptic fiber (Poly-Optical Products) of 0.8 mm diameter was used to channel light to the phototransducer circuit. The fiber was custom fit with a barrel shaped tip (diameter = mm, length = mm) that served to maximize the fiber s light reception capability and to facilitate passage of the fiber through the velopharyngeal port. During testing, the fiber was passed through the endoscope s internal instrument channel. The distal end of the fiber could be extended so it was positioned in front of the endoscope s light emitting lens (Figure 6). The proximal end of the fiber was coupled to the phototransducer. Procedures Nasalance Test The subject was seated in a standard chair. The nasometer mask was placed on the subject s face in the appropriate position. The subjects produced each of the three utterance groups, nasal, high pressure oral, and lower pressure oral without the EMA appliance (Table 1). Then, the subject wore an EMA appliance and repeat the same three utterance groups. The sentences were recorded on the nasometer in order to allow for detailed analysis according to type of sentence category. 18

30 Phototransducer Speech Testing Movements of the velopharyngeal mechanism, as represented by orifice cross-sectional area, were transduced using a videoendoscopy/phototransducer system as previously described by Karnell and Moon (2014). The subject was seated on a dental chair. The phototransducer fiber was inserted through the endoscope instrument channel. After application of a topical anesthetic solution (1 ml 4% lidocaine, 1% phenylephrine) to the nasal passage, the endoscope was inserted through the subject s middle nasal meatus. It was positioned so that the posterior edge of the nasal septum was just out of the field of view and a view of the nasal surface of the velum and posterior pharyngeal wall was achieved. With the scope optimally positioned, the velum, lateral pharyngeal walls, and posterior pharyngeal walls were all in view. The fiber was then extended so that the endoscope light-emitting lens was located at the level of the subject s uvula. The distance between the fiber tip and the endoscope light-emitting lens was measured with calipers, after the testing was completed. When the scope and fiber were in the desired position, phototransducer output voltage, acoustic speech waveforms, and videoendoscopic images were recorded simultaneously while the subject was asked to follow the protocol. The protocol was repeated under two conditions: normally, and while wearing an elastic mandibular advancement (EMA) appliance to advance the mandible by 13mm. It was performed for normal condition first for every subject. For simulating the condition of complete velopharyngeal closure, the subject was told breathe through the nose quietly with mouth closed. While the subject exhaled, the light was turned off and turned on back to establish phototransducer response levels during maximum light emission (light on) and minimum light emission (light out). Then, the subject was told to make a /s/ sound for the same reason. Then 19

31 the light was turned off and turned on back. After that, the subject produced five repetitions of the utterance Ten men came in when Jane left. Between each utterances, the subject was told to breathe gently through the nose to re-establish rest position. Once this protocol was completed under normal condition, then we repeated the same protocol with the elastic mandibular advancement (EMA) appliance inserted. Baseline data were recorded when the endoscope light was temporarily turned off (lightout condition) and turned on again while the subject sat quietly at rest breathing through his nose (light-on-at-rest condition). During these two conditions, phototransducer output was used to establish the limits of the in vivo phototransducer measurements. The light-on condition simulates the expected phototransducer output when maximum light is emitted through the velopharyngeal port at rest. For simulating the condition of complete velopharyngeal closure, the subject was instructed to gently blow orally or sustain an /s/ sound (Figure 7). Subtracted phototransducer values between the light-out condition and the complete velopharyngeal closure established the full range of phototransducer response for the subject. The phototransducer analysis window for each utterance was limited to data recorded between acoustic speech onset and offset as determined visually from the audio waveform display. Processing Edited Phototransducer Utterance Data In order to process edited phototransducer utterance data, three factors were identified: translucency factor (TF), rectifying factor (RF), and normalization factor (NF). The difference between the phototransducer output during the light-out condition and the phototransducer value during quiet oral blowing was considered the Translucency Factor (TF), the effect of ambient light passing through the translucent velopharyngeal tissue during complete 20

32 velopharyngeal closure. TF was established as the phototransducer output threshold for complete velopharyngeal closure. The difference between the phototransducer output during the nasal respiration (maximum opening or 0% velopharyngeal closure) and TF (complete or 100% velopharyngeal closure) was considered the full-range of velopharyngeal function for speech. The phototransducer measurements during speech were normalized to this range so that all values were expressed as a value from 0% to 100% closure. Statistical Analysis Nasalance data for the two conditions (control and mandibular advancement) for each of the three utterance groups were compared using a paired-t test. Phototransducer outcomes were statistically analyzed for the two conditions (control and mandibular advancement) using two methods of statistical analysis. One-way ANOVA was used for the entire subjects to test if mandibular advancement significantly affected velopharyngeal closure. Dependent variable was average percentage of the velopharyngeal closure after five repetition of the utterance. EMA appliance was an independent variable with two levels (EMA appliance not used for control and used for mandibular advancement groups). Within each subject, independent samples t- test was used to test if average mean values of velopharyngeal closure significantly changed after mandibular advancement. Briefly, for each utterance, phototransducer data were transferred to % of velopharyngeal closure, and the data points of VPC % from the beginning to the end of each utterance were averaged. Percentage values of velopharyngeal closure from five repetition were averaged again per each condition of each subject ( control and mandibular advancement ). 21

33 RESULTS Nasalance Test The nasalance data measured for each subject are presented in Figure 10. Data are included for the three sentence types (nasal, high pressure oral, and low pressure oral) and for the two conditions (normal and mandibular advancement). For the nasal sentences, average nasalance for the 14 subjects during the normal condition was 64.7 (STD=5.02). When these sentences were produced with the EMA appliance inserted and the mandible advanced, average nasalance reduced to (STD=5.13). Differences between the average nasalance measurements were smaller for the oral sentences. The average nasalance for the high pressure oral sentences was (STD=4.74) in the normal condition and (STD=5.39) in the mandible advanced condition. For the low pressure oral sentences, average nasalance was (STD=6.79) in the normal condition and (STD=6.28) in the mandible advanced conditions. Although average nasalance measures were lower during the mandible advanced condition for all three sentence types, the magnitude of the differences in all cases was small. Statistical analysis (paired t-tests for each sentence type, Figure 11) found that the difference in average nasalance measurements across mandible advancement conditions was significant for the nasal sentence type. The differences among the average nasalance measurements across conditions for the high pressure and low pressure oral utterances were not significant. All of the differences were small and, therefore, were not clinically relevant despite a clear trend toward lower nasalance measurements in the mandible advanced condition. Among the 42 comparisons across conditions (14 subjects in each of the 3 utterance groups), nasalance 22

34 decreased in 69% (29 out of 42), increased in 21.4% (9 out of 42), and remained the same in 9.5% remained the same (4 out of 42) after mandibular advancement (Fig ). Changes in nasalance during production of the nasal sentences after mandibular advancement varied over the subjects (Fig. 12). Nasalance decreased for ten subjects (#1, 2, 4, 6, 7, 8, 9, 12, 13, 14), increased for three subjects (#5, 10, 11), and did not change for one subject (#3). During production of the high pressure sentences (Fig. 13), changes in nasalance after mandibular advancement decreased for eight subjects (#1, 2, 4, 6, 7, 9, 10, 14), increased for five subjects (#3, 5, 8, 11, 12), and did not change for one subject (#13). Similar to the high pressure sentences, nasalance decreased during production of the lower pressure sentences (Fig. 14) due to mandibular advancement for eleven subjects (#1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14), increased for one subject (#5), and did not change for two subjects (#3, 10). The subjects who showed at least one increase in nasalance measurements out of three utterance groups included #3, 5, 8, 10, 11, and 12. Nasalance increased for all three utterance groups ( nasal, high pressure oral, low pressure oral ) in subject #5, for two utterance groups ( nasal, high pressure oral ) in subject #11, and for one utterance group ( high pressure oral ) in subjects #3, 8, 10, and 12. Phototransducer Test for Velopharyngeal Closure (VPC) Phototransducer measurements of velopharyngeal closure for each subject were recorded for all 14 subjects during five repetitions of the utterance Ten men came in when Jane left (Fig ). This task was performed twice by each subject, once during the normal condition and again during the mandible advanced condition (Fig ). Average percentages of 23

35 velopharyngeal closure (VPC) were calculated for each subject (an example of the subject #3, Fig. 17). Average measurement for all 14 subjects appear in Table 2. Subject responses to mandibular advancement (Table 2-3, and Fig. 18) varied. A oneway analysis of variance (F-statistic= 0.20, P=0.66, Table 2) calculated with phototransducer measurement as the dependent variable and mandible advanced condition (normal-prosthesis out vs. mandible advanced-prosthesis in) confirmed no significant affect across conditions. Close examination of the data across subjects may lead to identification of expected subgroups. Some subjects responses across conditions showed increased VPC in response to mandibular advancement. Others responded with decreased VPC. To verify if VPC within each subject changed significantly after mandibular advancement, independent samples t-tests were completed on each subject s data (Table 3, Fig. 18). VPC significantly decreased after mandibular advancement for seven subjects. (P<0.05 for subjects # 07, #11, and P<0.01 for subjects #02, #03, #08, #10, #13). VPC significantly increased after mandibular advancement for five subjects. (P<0.05 for the subject # 12, and P<0.01 for the subjects #01, #04, #09, #14). Two subjects (#5, #6) did not show significant changes in VPC after mandibular advancement (P>0.05). It was observed that there could be a certain subject-dependent subgroups. Subjects who presented with increased nasalance after mandibular advancement also tended to show decreased VPC under the mandibular advancement conditions (#3, 8, 10, 11). Subject #10 presented with increased nasalance on nasal sentences and no change in nasalance on low pressure oral sentences, where VPC after mandibular advancement significantly decreased (from 56.7% to 51.0%, p<0.01). A similar pattern was observed on subject #11. This subject s nasalance values from both nasal and high pressure oral sentences increased after mandibular advancement 24

36 (statistical significance not applicable), and VPC in this subject decreased significantly (from 83.0% to 78.6%, p<0.05). Subject #3 also supported this pattern. Nasalance values in subject #3 also increased for high pressure oral sentences and remained the same for both nasal and low pressure oral sentences after mandibular advancement. VPC again decreased significantly after mandibular advancement (from 72.9% to 54.9%, p<0.01). Subject #8 presented with the most significantly decreased VPC (from 67.3% to 43.2%, P<0.01) and this subject s nasalance on high pressure oral sentences was increased from 22% to 23%. Subject #5 presented with the most notable increases in nasalance for all three utterance groups. However, VPC did not change significantly after mandibular advancement. An exceptional feature was found with subject #12: both the nasalance of the high pressure oral sentences as well as the VPC increased after mandibular advancement. On the contrary, the subjects who presented with decreased nasalance after mandibular advancement tended to show increased VPC under the same condition (mandibular advancement). Nasalance values of seven subjects (#1, 2, 4, 6, 7, 9, 14) decreased for all three utterance groups ( nasal, high pressure oral, and low pressure oral ). Four subjects out of these (#1, 4, 9, 14) presented with a statistically significant increase in VPC after mandibular advancement. Change in VPC of the subject #6 was not statistically significant (p>0.05). Two exceptional cases were the subjects #2 and #7, where VPC decreased after mandibular advancement. However, these potential subgroups need to be identified with caution. The data in this study are limited, and they might not adequate to prove the existence of the subgroups. More data and statistical analysis would be necessary to support this findings of subject-dependent subgroups. 25

37 Table 1. Three utterance groups for nasalance test. Nasal Sentences Mama made some lemon jam. Ten men came in when Jane rang. Dan s gang changed my mind. Ben can plan on a long rain. Amanda came from bounding main. High Pressure Oral Sentences Look at this book with us. It s a story about a zoo. That s where bears go. Today it s very cold out of doors. But we see a cloud overhead. That s a pretty white fluffy shape. Low Pressure Oral You were away. Where were you? Why were you away? You were away all year. We were away earlier. Will you wear a Lilly? Roll a yellow wheel. Sentences 26

38 Table 2. Average percent velopharyngeal closure of the subjects before and after mandibular advancement and statistical analysis (one-way ANOVA) Subjects EMA OUT (Control) (%) EMA OUT (Control) STD EMA IN (Mandibular Advancemen t) (%) EMA IN (Mandibular Advancement) STD F-statistic from one-way ANOVA (P=0.66)

39 Table 3. Overall outcomes for changes in velopharyngeal closure before and after mandibular advancement on the subjects #1-#14 (independent samples t-test). EMA OUT < EMA IN (CONTROL < MAN. ADV.) NO CHANGE EMA OUT > EMA IN (CONTROL > MAND. ADV.) P VALUE P<0.01 P<0.05 p>0.05 P<0.05 P<0.01 SUBJECTS #1 #12 #5 #7 #2 #4 #6 #11 #3 #9 #8 #14 #10 #13 28

40 Figure 1. Elastic Mandibular Advancement (EMA) appliance 29

41 Figure 2. Lateral cephalometric radiograph without EMA appliance in a normal condition (OUT). The subject was asked to have nasal tidal breathing at rest. 30

42 Figure 3. Lateral cephalometric radiograph with EMA appliance (IN). The subject was asked to have nasal tidal breathing at rest. Please note that the mandible is advanced anteriorly and inferiorly, velum was protracted and the pharyngeal depth was increased compared to the one under OUT condition (Fig 1.) 31

43 Figure 4. Superimposition of the tracing on lateral cephalometric radiographs under the conditions of OUT and IN. Under the condition of mandibular advancement (IN), condyles were relocated anteriorly and inferiorly within the glenoid fossa, velum was protracted and the pharyngeal depth was increased compared to those under the condition of OUT. 32

44 Figure 5. Nasometer for nasalance test 33

45 Figure 6. Lateral cephalometric image with the endoscope and fiberoptic fiber in situ 34

46 Figure 7. Nasoendoscopic image on velopharyngeal area 35

47 Phototransducer output (volts) 0.00E E E E E Time (seconds) Figure 8. Phototransducer trace demonstrating translucency factor (TF) 36

48 Phototransducer output (volts) 0.00E E E E E Time (sec) Figure 9. Phototransducer trace demonstrating rectifying factor (RF) 37

49 Figure 10. Nasalance outcomes for all the utterance groups: Nasal, High Pressure Oral and Low Pressure Oral. 38

50 Figure 11. Statistical analysis on changes in nasalance before and after mandibular advancement with EMA appliance (paired t-test). 39

51 Nasal 100 Nasalance (%) MA01 MA02 MA03 MA04 MA05 MA06 MA07 MA08 MA09 MA10 MA11 MA12 MA13 MA14 Subjects OUT IN Figure 12. Nasalance outcomes for the utterance group of Nasal. 40

52 High Pressure Oral 25 Nasalance (%) MA01 MA02 MA03 MA04 MA05 MA06 MA07 MA08 MA09 MA10 MA11 MA12 MA13 MA14 Subjects OUT IN Figure 13. Nasalance outcomes for the utterance group of High Pressure Oral. 41

53 Low Pressure Oral Nasalance (%) MA01 MA02 MA03 MA04 MA05 MA06 MA07 MA08 MA09 MA10 MA11 MA12 MA13 MA14 Subjects OUT IN Figure 14. Nasalance outcomes for the utterance group of Low Pressure Oral. 42

54 Figure 15. Velopharyngeal closure without mandibular advancement for subject #3. 43

55 Figure 16. Velopharyngeal closure with mandibular advancement for subject #3. 44

56 90 VPC Comparison (subject #3) VP Closure (%) OUT IN OUT IN Figure 17. Changes in velopharyngeal closure (VPC) without (OUT) and with (IN) an EMA appliance for mandibular advancement for subject #3 45

57 Figure 18. Comparison of velopharyngeal closure before and after mandibular advancement for all 14 subjects (Independent samples t-test). Asterisk indicates changes with statistical significance, and bar indicates no statistical significance. 46