Swallowing in Myotonic Muscular Dystrophy: A Videofluoroscopic Study

Transcription

1 979 Swallowing in Myotonic Muscular Dystrophy: A Videofluoroscopic Study Rebecca J. Leonard, PhD, Katherine A. Kendall, MD, Ralph Johnson, MD, Susan McKenzie, MS ABSTRACT. Leonard RJ, Kendall KA, Johnson R, Mc- Kenzie S. Swallowing in myotonic muscular dystrophy: a videofluoroscopic study. Arch Phys Med Rehabil 2001;82: Objectives: (1) To determine how swallow function in patients with myotonic muscular dystrophy (MD) differs from that of healthy controls, (2) to identify the contributors to and predictors of improvement, and (3) to evaluate strategies that facilitate swallowing. Design: Observational. Setting: University medical center. Participants: Eighteen adults with myotonic MD (age range, 24 58yr) and 60 healthy adult control subjects (age range, 18 73yr). Interventions: Swallow facilitation strategies. Main Outcome Measures: Between-group comparisons of mean bolus transit times, onsets of swallow gestures, and displacement measures obtained by dynamic lateral view videofluoroscopy. Results: The MD patients bolus transit times were significantly longer, and onsets of some swallow gestures were significantly delayed. Upper esophageal sphincter opening was prolonged (myotonic MD,.61.13s; control,.5.11s). Hyoid displacement was significantly less in men with myotonic MD (1.9.05cm) than in male controls (2.4.68cm); this difference was not observed between control and myotonic women. Of particular importance was the markedly reduced pharyngeal constriction found in the MD group. Conclusions: Weakness associated with the disease, as opposed to myotonia, was the most significant contributor to impairment. Persons at risk for aspiration may be identified by a measure of pharyngeal area. Selected strategies to facilitate pharyngeal clearing are worthwhile. Key Words: Fluoroscopy; Myotonic dystrophy; Rehabilitation; Swallowing by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation MYOTONIC MUSCULAR DYSTROPHY (MD) is the most common form of MD diagnosed in adults. It is an autosomal-dominant disease that affects men and women and can occur in childhood or adulthood. One form is congenital. A major clinical feature of this disease is myotonia, which is a delay in relaxation of contracted muscles. Muscle wasting and From the Departments of Otolaryngology, Head and Neck Surgery and Physical Medicine and Rehabilitation, University of California, Davis, Sacramento, CA. Accepted in revised form September 5, The author(s) has/have chosen not to select a disclosure statement. Reprint requests to Rebecca Leonard, PhD, Dept of Otolaryngology, Head and Neck Surgery, University of California, Davis Medical Center, 2521 Stockton Blvd, Ste 7200, Sacramento, CA /01/ $35.00/0 doi: /apmr weakness also occur, and muscles of the head and neck are among the first to be affected. 1 The prevalence of swallowing disturbance in MD has been reported to be from 33% to 40%. 2,3 Some problems are related to the oral stage of swallowing difficulties with chewing and bolus control caused by weakness of the masticatory and lingual muscles, for example. However, Willig et al 2 reported that choking was listed by two thirds of 110 MD respondents surveyed about alimentation, making it the most frequent complaint noted. A fluoroscopic study of swallowing in MD patients by Pruzansky and Profis 3 showed several distinctive abnormalities. In particular, the pyriform sinuses and valleculae were ballooned in the presence of bolus material, and time for clearing of material from the pharynx was, in some cases, greatly prolonged. Passage of the bolus from the mouth to the pharynx was generally not disturbed, despite lingual myotony. Esophageal disturbances were also described 3 and were similar to those identified in the pharynx, ie, ballooning and retention of contrast material. Esophageal atony and weak or absent peristaltic waves in MD have been described by several investigators. 2-5 Johnson and McKenzie 6 described delays in hypopharyngeal transit and a delay in the return of the hyoid to its resting state 7 in MD patients. This evidence of swallowing impairment notwithstanding, our clinical experience is that patients with myotonic MD do not generally complain about swallowing disturbance. It is not clear whether this lack of complaint occurs because the disease progresses gradually and patients adapt to the difficulties it produces, or because of compensations that permit patients to deal effectively with their limitations, or because of other factors. In the present study, we compared swallowing performance in MD patients, as assessed with videofluoroscopy, to swallowing in healthy control subjects. Our intention was to extract from the fluoroscopic studies quantitative timing and spatial measures that would provide insights into the nature of swallowing in MD patients and to identify compensatory mechanisms that may develop in response to specific deficits. METHODS Dynamic videofluoroscopic swallow studies were performed on 60 healthy adult volunteers and on 18 patients with a diagnosis of myotonic MD. Healthy subjects (30 men, 30 women; age range, 18 73yr) were drawn from a pool of controls used in swallow investigations. None of the control subjects had any complaints of dysphagia. None had a history of gastrointestinal disease, central nervous system disorders, or craniofacial abnormalities. None were taking reflux medications at the time of the study. Data for the control group showed no differences in swallow over the age range of MD subjects represented; thus, ages of experimental subjects were within the age range of control subjects, but the groups were not precisely matched for this variable. The MD group consisted of 12 men and 6 women ranging in age from 24 to 58 years. The time since diagnosis ranged from less than 2 to 39 years, and all diagnoses were based on clinical and electromyographic findings. The MD patients were followed by the University of California, Davis, Medical Center s (UCDMC)

2 980 DYSPHAGIA IN MYOTONIC MUSCULAR DYSTROPHY, Leonard Neuromuscular Diseases Clinic, Sacramento, CA, and were asked to participate in the study by their respective physiatrists. All were eating orally at the time of the study; none had sought medical counsel for swallowing difficulty. During preliminary questioning by the investigators, only 3 patients expressed a swallowing complaint the most serious of which was frequent choking and inability to avoid this completely by dietary restriction. However, all subjects in the MD group, when questioned at length, acknowledged 1 or more of the following: food sticking, prolonged times for meals, difficulty with pills, use of liquid washes to get foods down, avoidance of certain foods, and occasional nasal regurgitation or choking on liquids. One patient had a history of recurrent pulmonary infections; 11 patients reported gastroesophageal reflux for which they took prescription or over-the-counter medications. At the time of the study, no MD patient was taking medication for myotonic MD. Of 18 patients, 8 were taking no medications, 3 were taking levothyroxine (Synthroid), 3 were taking antidepressants, 1 was taking belladona alkaloids with phenobarbital (Donnatal) for colonic spasms, 1 was taking asthma medications, and 2 were taking methylphenidate (Ritalin) for sleep disorders. Of 18 patients, 16 had some speech alteration as judged by the speech-language pathologists involved in their care. These impairments were most often characterized as mild distortions of labial and lingual consonant sounds, deteriorating intelligibility with rapid speech, and varying degrees of hypernasal resonance in conversation. The radiographic studies were conducted at UCDMC in accordance with the routine radiographic protocols approved by the institution. Equipment included a properly collimated Philips radiographic/fluoroscopic unit a that provides a 63-kV, 1.2mA-type output for the full field of view mode (9-in input phosphor diameter). Fluoroscopy studies were recorded on high-quality videotape for later playback and analysis. A graphic time display provided by an RCA character generator and a JVC AC Model C412 b adapter was included on the videotape so that timing information at.01-second intervals was recorded. The swallow studies were recorded at 30 frames per second. Drinking from a cup, subjects swallowed liquid boluses c of 1, 3, and 20mL. Each bolus was 60% weight-tovolume ratio; 35 40s viscosity (measured with no. 4 Ford cup) with specific gravity of If a swallow was complete, it was repeated in lateral view. If no aspiration was observed on the largest bolus swallow, it was also repeated in an anteroposterior view. Pauses in radiographic filming were introduced when necessary to allow bolus material to clear before filming of the 20-mL bolus. After the last 20-mL bolus swallow, the clinician was free to introduce, as indicated, strategies to facilitate safer and/or more effective swallow. These attempts were also recorded. Videotapes of the completed studies were returned to a laboratory in the Voice-Speech-Swallowing Center for analysis. A clinician unfamiliar with the study objectives completed all analyses. All quantitative measures were made from lateral views. We obtained timing measures by observing the videotaped studies in slow and stop frame (forward, reverse) modes. These data were reported in seconds. In the analysis scheme used, timing of both bolus transit and selected swallowing gestures was determined. These measures are defined in table 1. Displacement measures were obtained by digitizing the videotaped studies on a Macintosh 9500 computer d at 30 frames per second. We used the Image e software program to analyze the fluoroscopic images. Area and distance measurements were made after calibration of the digitized image to the known diameter of a wire loop taped to the chin of the study subject Table 1: Timing Measures for Bolus Movements and Swallow Gestures: Definitions B1 BV1 BV2 SPstart SPmax SPclose AEstart AEclose H1 H2 H3 H4 Pop Pcl BP1 BP2 PESmax EM Onset of pharyngeal transit: the bolus moves from the hold position and passes the posterior nasal spine. The bolus head enters the vallecula The bolus head exits the vallecula Soft palate elevation begins Soft palate is at its maximum elevation Soft palate elevation ends Aryepiglottic fold elevation (and closure of laryngeal vestibule) begins Aryepiglottic fold elevation to supraglottic closure of laryngeal vestibule ends First superior-anterior movement of the hyoid from hold occurs The hyoid reaches its maximum displacement The hyoid begins its descent to a resting position The hyoid returns to a stable position at the end of a swallow The PES opens The PES closes The bolus head enters the PES The bolus tail exits the PES PES has reached its widest opening The epiglottis returns to its upright (rest) position during filming. Displacement measures included (1) maximal hyoid elevation; (2) maximal hyoid to larynx approximation; (3) maximal upper esophageal sphincter, ie, pharyngoesophageal segment, opening; (4) pharyngeal area with the bolus in a hold position, ie, the bolus was in the anterior oral cavity and the frame selected for measurement was that immediately preceding any posterior movement of the bolus; and (5) pharyngeal area at maximum constriction. A detailed description of these measures, including the rationale for each and its method of acquisition, was presented in Leonard and Kendall. 8 The measures are summarized in the present report in table 2. In the present report, we described only data collected for the 20-mL bolus. Fewer than half of the MD patients exhibited swallow initiation on the 1-mL bolus, and 4 of 18 MD subjects did not exhibit swallow initiation on the 3-mL bolus. That is, the swallow reflex was not initiated, and bolus material was retained in the oropharynx. The measured data for each variable were averaged across all subjects within each group. The mean values for each variable were then compared between groups using Student s t tests. Reliability between the clinician who completed all measurements and 3 additional clinicians who were unfamiliar with study objectives was established on 15 studies selected at random. Reliability among the 4 observers was found to be greater than 90% for all measurements except hyoid to larynx approximation, which was 75%. RESULTS Results of the 20-mL bolus swallow studies are of 3 types. In all cases, the measures included represent events believed to be critical to safe and effective swallow. Data for timing of bolus transit and selected swallow gestures, extent of displacement of selected gestures, and durations for selected bolus transit and swallowing gestures are in figure 1. Timing and displacement data, data reflecting coordination between swallowing gesture and bolus movement, and selected duration values obtained from manipulation of the timing data are included in the present report.

3 DYSPHAGIA IN MYOTONIC MUSCULAR DYSTROPHY, Leonard 981 Table 2: Displacement Measures: Definitions Hmax HLx PESmax PAh PAmax Maximum hyoid elevation. The distance between hyoid position at bolus hold, and at its point of maximal anterior and superior excursion during the swallow. Hyoid to larynx approximation. The difference in distance between the anterior margin of the hyoid bone and the anterosuperior corner of the subglottic air column measured at the hold position, and at the time of maximal hyoid to larynx approximation. A clear and consistently visible landmark on the anterior thyroid cartilage, such as calcification, was used as an alternative to the subglottic air column if it could not easily be visualized. Maximal approximation usually occurred just after maximal hyoid excursion. PES opening. The narrowest point of opening between C3 and C6 during maximal distention for bolus passage. Pharyngeal area (cm 2 ) measured in the lateral view during the hold position. Its outline was defined posteriorly by the posterior pharyngeal wall from the mid-portion of the tubercle of the atlas down to the level corresponding to the height of the top of the arytenoid cartilages. Inferiorly the outline was carried forward from this point over the arytenoid cartilages and anteriorly to outline the epiglottis, vallecula, and tongue base to the point at which the soft palate came into contact with the tongue base. The outline was then carried over the pharyngeal surface of the soft palate to the level, superiorly, of the posterior nasal spine. The superior border was a straight line between the posterior nasal spine and the midpoint of the tubercle. The pharyngeal area at maximal constriction. It was defined by the outline of the same structures during maximal constriction. Data for pharyngeal area are presented as a ratio of PAhold:PAmaximum (PAh:PAmax). (Measures of pharyngeal area are 2-dimensional, and thus only an approximation of actual pharyngeal volume. Nevertheless, we believe the area data provide excellent insights into the degree of pharyngeal constriction that takes place during swallow.) NOTE. Displacement measures are referenced from the bolus hold position; ie, to the bolus held in the oral cavity. Bolus Transit Times All times are measured with reference to the first movement of the head of the bolus from a stable, or hold, position that passes the posterior nasal spine and results in all or part of the bolus entering the oropharynx. This point, referred to as B1, was considered the onset of pharyngeal transit. B1 and subsequent bolus transit times are defined in table 2. If the bolus bypassed the vallecula, or if the valleculae were obscured (as with a large bolus), the time when the bolus head passed the level of the base of the vallecula was designated as BV1, and the interval from BV1 to Pcl was hypopharyngeal transit. A statistically significant (p.0001) difference in overall pharyngeal transit time was found for the 2 subject groups (table 3). Significant differences were also found between the groups for both oropharyngeal (p.0015) and hypopharyngeal transit time (p.0005). The longer times of the MD group were relatively uniform across the swallow, being.14 second longer than the normal group at the end of oropharyngeal transit, and.19 second longer than the normal group at the end of hypopharyngeal transit. Swallow Gesture Times In addition to bolus transit times, we also calculated times for selected swallow gestures. These measures, defined in table 1, were also referenced to B1. The results, summarized below, are presented in table 4. Onset and maximum elevation of soft palate. We found a significant (p.01) difference between groups for the onset of soft palate elevation relative to the onset of pharyngeal transit. MD subjects onset of soft palate elevation was slower than the controls. However, the time between the onset of soft palate elevation and the time of the soft palate s maximal elevation (SPmax SPstart) did not differ between control and MD subjects. Onset and maximum contact of the arytenoid cartilages and epiglottis to close the laryngeal vestibule. The onset of aryepiglottic fold closure, critical to airway protection, 9,10 began later relative to the onset of pharyngeal transit in the MD group (p.04). Furthermore, the time required to achieve closure (AEclose AEstart) was longer (p.05) in the MD subjects. Onset of elevation, maximum elevation, and first descent of the hyoid bone. From these measures, the onset of hyoid displacement relative to the onset of pharyngeal transit (H1 B1) and the duration of maximum hyoid displacement (H3 H2) can be calculated. Hyoid displacement onset relative to the onset of pharyngeal transit occurred significantly (p.01) later in MD subjects than in controls. On the other hand, the time required to achieve maximum displacement and the duration of maximum hyoid displacement did not differ between normal and MD groups (p.27, p.73). The first opening of the pharyngoesophageal sphincter (PES), closure of the PES, and the point at which the PES achieves its maximum opening. Onset of PES opening and PES closing occurred later in MD subjects than in control subjects (p.0001, p.0001). However, in the MD group, opening of the PES was early (p.0001) relative to the arrival of the bolus at the PES. Duration of PES opening was also significantly (p.02) longer in the MD group than in controls. PESmax is the time at which the PES has reached its widest anteroposterior opening. Comparison of this measure for the 2 groups revealed that the PES reached its maximum distention later (p.0001) in the MD subjects. Time of maximum pharyngeal constriction. Relative to the onset of pharyngeal transit, maximum pharyngeal constriction occurred later (p.0002) in the MD group than in the control group. Epiglottis return to upright position. From the data for normal and MD subjects who had epiglottic return, it is apparent that this time was significantly (p.0002) delayed in the MD group compared with the control subjects. In 6 MD subjects, the epiglottis was never observed to invert, perhaps as a consequence of poor pharyngeal constriction, or to the many repeat swallows that were attempted, precluding any relaxation of the epiglottis. Swallow Gesture Displacements Extent of displacement was calculated for selected swallowing gestures (table 2) known to be critical for safe and effective deglutition. The results, summarized below, are presented in table 5.

4 982 DYSPHAGIA IN MYOTONIC MUSCULAR DYSTROPHY, Leonard Fig 1. Swallowing time-displacement-duration plot for healthy and MD subjects. Times for bolus transit and swallowing gestures are in the main body of the plot; displacements and durations are inset into the upper portion of the plot. Abbreviations: HyDis, hyoid displacement; m, male; f, female; Dur, duration; Tran, transit; OPT, oropharyngeal transit; HPT, hypopharyngeal transit.

5 DYSPHAGIA IN MYOTONIC MUSCULAR DYSTROPHY, Leonard 983 Pharyngeal constriction. Poor pharyngeal medialization and shortening and/or tongue base retraction result in incomplete pharyngeal constriction and postswallow residue that may be aspirated. 10,11 To assess pharyngeal constriction, the area of the pharynx at bolus hold (PAhold) was compared with the area of the pharynx at maximum constriction (PAmax). For men and women, the ratio of pharyngeal area at bolus hold to pharyngeal area maximally constricted was significantly larger in the MD group (p.0001 for both comparisons). In all MD subjects, we found residue after the swallow as a consequence of the incomplete pharyngeal constriction. In 2 patients, residue was judged as mild, consisting of small amounts in the valleculae and pyriform sinuses. In the remaining MD subjects, residue was judged as mild-moderate to severe. In 2 subjects, an actual expansion of the pharyngeal space occurred during swallow, that is, the pharyngeal area was larger at maximum constriction than at hold. Residue in the oral cavity after swallowing of the liquid bolus was much less distinctive in the MD group. Hyoid to larynx approximation. During a normal swallow, the larynx elevates and approximates the hyoid bone. This action brings the larynx further under the tongue base and Table 4: Swallow Gesture Times Soft Palate Elevation (s) Onset relative to B1 (SPstart B1) Time to maximum (SPmax SPstart) Aryepiglottic Fold Closure Relative to pharyngeal transit onset (AEstart B1) Time required (AEclose AEstart) Hyoid Displacement Initial (H1 B1) Time to maximum (H2 H1) Maximum duration (H3 H2) PES Opening Relative to pharyngeal transit onset (Pop B1) Relative to bolus arrival (Pop BP1) Duration (Pcl Pop) Maximum relative to pharyngeal transit onset (PESmax B1) PES Closure Relative to pharyngeal transit onset (Pcl B1) Pharyngeal Constriction Maximum relative to pharyngeal transit onset (PAmax B1) Epiglottis Return to upright position (EM B1) NOTE. Values are means SDs. Table 3: Bolus Transit Times Transit Time (s) Healthy MD Pharyngeal (Pcl B1) Oropharyngeal (BV1 B1) Hypopharyngeal (Pcl BV2) NOTE. Values are means SDs. Table 5: Swallow Gesture Displacements Healthy contributes to approximation of the arytenoid cartilages and epiglottis, a maneuver that is associated with airway protection. No difference existed in the extent of hyoid-to-larynx approximation between the 2 subject groups, for either men or women (women p.95; men p.93). Hyoid displacement. The hyoid s anterior and superior displacement during swallow is required for adequate opening of the upper esophageal sphincter. 9,10,12,13 Because our normative data revealed gender differences in this variable, we considered these values separately for men and women. The degree of hyoid displacement was not different (p.68) when we compared the women in the control and MD groups; however, displacement in men with MD was significantly (p.01) less than that of men in the control groups. PES opening. Besides timing the PES opening, we also determined the maximum extent of PES opening (anteroposterior). This measure did not differ significantly between the 2 groups (p.94). Swallow Function Related to Other Variables Linear regression statistics did not reveal a relationship between MD subject age and swallow function or between time since diagnosis and performance on the swallow study. Nor was evidence found, subjectively, to suggest that particular medications might have contributed to swallowing impairment in the MD subjects, although dryness associated with some medications cannot be ruled out as an exacerbating factor. Of the 3 patients who aspirated, 1 took acetaminophen (Tylenol) occasionally, and the other 2 were taking no medications. Similarly, subjects descriptions of their difficulties did not seem to correlate with abnormal findings. Only 3 of the MD patients aspirated during the study, and none presented with a primary complaint of dysphagia. Two of these subjects acknowledged difficulty in the form of occasional choking, foods sticking, or prolonged times for eating a meal. The third denied any dysphagia other than a brief delay in his initiation of chewing. Two of the patients who aspirated failed to cough until bolus material was well into the trachea. Aspiration vs nonaspiration in MD subjects. The3MD subjects who experienced aspiration were subsequently grouped statistically, and a second analysis of all data was performed comparing the 3 aspirators to the remaining MD subjects. No significant differences were found for any variable except PAmax/PAhold. The mean ratio standard deviation (SD) for the group of 15 nonaspirators was.34 12, and for the 3 MD subjects who aspirated (p.0001). In 2 of the latter, pharyngeal area was larger when maximally constricted than when holding the bolus in the oral cavity, thus MD Men Women Men Women Pharyngeal constriction (cm 2 ) Ratio of PAmax to PAhold Larynx elevation (cm) HLx Distance of hyoid Bone elevation Extent of PES opening (cm) NOTE. Values are means SDs Men and women Men and women

6 984 DYSPHAGIA IN MYOTONIC MUSCULAR DYSTROPHY, Leonard causing the ratio to exceed 1. In the third aspirator, the ratio was.65. The largest ratio among the 15 nonaspirators was.50. Effects of bolus size. Although we reported complete measures only for the 20-mL bolus, because it was the only size for which all subjects initiated a swallow, observations from selected swallows of other bolus sizes are of interest. For example, the 14 MD subjects who initiated a swallow on the 3-mL bolus, including the 3 who aspirated on the 20-mL bolus, did not aspirate. Our available data for 1- and 3-mL bolus sizes suggested that prolonged transit times and larger than normal pharyngeal area ratios typical of MD subjects for the 20-mL bolus were characteristic of the smaller bolus sizes as well. Effects of swallow facilitation strategies. After an MD subject s unsuccessful effort to swallow the 20-mL bolus completely and efficiently, the clinician conducting the study implemented strategies to facilitate the swallow. Each subject s compliance with the strategy and its effect on swallow were noted. Most strategies were directed at improving pharyngeal clearing. Repeat swallows, spontaneously engaged in by almost all of the MD subjects, were useful in helping to diminish pharyngeal residue, although several repetitions were frequently not enough to completely clear the pharynx. Positional strategies (head turned to 1 side, side-lying) were generally not helpful, even when 1 side of the pharynx appeared more involved than the other. Alternating thicker consistencies with thinner materials was more helpful. When reduced hyoid elevation or PES opening was identified, hard swallow and chin tuck were partially successful in improving pharyngeal clearing. DISCUSSION Oropharyngeal and hypopharyngeal bolus transit times were prolonged in MD subjects as compared with controls. This finding is particularly significant because previous research 6 showed that prolonged pharyngeal transit (in a different population, stroke patients) correlated with an increased risk of aspiration pneumonia even if no frank aspiration was observed on videofluoroscopy. The onset of several swallow gestures also was delayed in the MD group. The return of the epiglottis to an upright position was relatively slower in MD subjects (1.5.89s) than in healthy subjects ( s). In fact, relaxation of the epiglottis was delayed to a relatively greater extent than other swallow gestures, and occurred well after the closure of the esophagus marking the end of pharyngeal transit. One interpretation of this finding may be that it reflects myotonia that is characteristic of this disease. 6 The primary difference in temporal coordination of bolus transit and swallow gestures between the groups was that, in MD subjects, the PES opened slightly early relative to the arrival of the bolus. In control subjects, these events happened simultaneously. The PES also stayed open longer in the MD group (.61s vs.50s in controls). The evidence of early and prolonged opening of the PES in MD patients suggests a possible compensatory effort to facilitate bolus transfer into the esophagus. Some displacement measures did not clearly differentiate normal and MD groups. For example, neither the extent of hyoid to larynx approximation nor PES maximum opening differed between the 2 groups. Hyoid displacement was significantly reduced in the men with MD but not the women. In contrast, findings for the spatial measure of pharyngeal constriction, PAmax/PAhold, were dramatic. This ratio was elevated in all MD subjects. In 2 subjects, PAmax was actually larger than PAhold. A still frame from an x-ray of 1 of these patients is shown in figure 2A B. This finding was true even though the PES opened early, to a normal or greater than normal extent, and remained open slightly longer, Fig 2. Measure of pharyngeal area (cm 2 ) on lateral view x-ray in an MD patient. (A) At PAhold, bolus is held in the oral cavity; (B) at PAmax, pharynx is maximally constricted during swallow but pharyngeal area is larger than in PAhold position. eliminating any possibility that the pharynx was dilated because of PES obstruction. The presence of the bolus material and the subject s attempt to move the bolus distally by exerting pressure on it apparently caused an expansion of the flaccid pharyngeal space beyond that which was present with the bolus resting in the oral cavity. Increased size of pharyngeal area at maximum constriction was also associated with aspiration of residue. Durations of selected swallow gestures did not differ uniformly between the 2 subject groups. Approximation of the arytenoids to the epiglottis (AEclose AEstart), and thus airway protection, was delayed in the MD subjects. In contrast,

7 DYSPHAGIA IN MYOTONIC MUSCULAR DYSTROPHY, Leonard 985 the time from the start of soft palate elevation to the time of maximum elevation did not differ in control and MD groups. However, because the degree of soft palate elevation was not calculated, we cannot rule out the possibility that the soft palate may have elevated to a lesser extent in the MD subjects. Certainly, the presence of hypernasal resonance in many of the MD subjects and the frequent report of occasional nasal regurgitation suggest that the velopharyngeal mechanism was affected by the myopathy. Duration of hyoid maximum displacement did not differ in the 2 groups. Findings for both swallow gesture and bolus transit times, coupled with the observation of poor pharyngeal clearing and significant postswallow residue, are consistent with other reports for MD populations. Pruzansky and Profis 3 noted that MD subjects in their study required from 1.5 to 90 minutes to clear contrast material from the pharyngeal recesses. Although we did not repeat fluoroscopic scanning of subjects at intervals after their swallow studies, it would appear that incomplete clearing of the pharynx is the primary feature of disordered swallowing in this patient population. We suggest that the major contributor to swallowing impairment in the MD patient population is weakness, as opposed to myotonia. Although the epiglottis s return to an upright position was delayed in those subjects who showed epiglottic down folding, possibly reflecting myotonia, the delay did not seem to affect swallow adversely. Results of the present study prompted us to counsel MD patients carefully regarding possible risks associated with swallowing, and what they might do to reduce these. We considered all patients in the current study to be at risk for aspiration because of their prolonged bolus transit times, and because they had significant residue remaining in the pharynx. If their x-ray study showed a strategy to be effective, the clinician discussed it with the patient. Although reflux was not specifically investigated or observed in the study, conservative reflux precautions are routinely recommended for patients with significant risk for aspiration, and were advised for MD patients in the current study. Avoiding a supine position for 2 hours after a meal, sleeping with the head elevated, and avoiding foods known to cause heartburn or digestive difficulties were included in this protocol. In addition, the importance of family and friends educated in first aid for choking was explained. CONCLUSION A comparison of swallowing in normal subjects and patients with myotonic MD revealed prolonged bolus transit times and delays in the onset of many swallow gestures in the MD subjects. Displacements of most structures did not differ in the 2 groups except that the men with MD had reduced hyoid elevation. Similarly, the duration of critical events, ie, PES opening, maximum hyoid elevation, maximum soft palate elevation, either did not differentiate the groups or did so in such a way that a compensatory strategy was inferred (PES opening was early and prolonged in MD subjects). The most significant difference in the 2 groups was in the distinctly reduced ability of the MD subjects to constrict the pharynx and clear it of bolus material. This finding was consistent for all MD patients, and we conclude that the weakness associated with myotonic MD contributes more to impaired swallowing than does myotonia. The ratio of PAmax:PAhold seems to have some predictive capability in determining which MD subjects may be at greatest risk of aspiration. This issue is of particular concern because two thirds of the patients who aspirated had a delayed response to the aspiration and 1 of these patients had a history of recurrent pulmonary infections. An additional finding of interest was the disparity between MD subject complaints about swallowing, which were generally unremarkable, and findings on the videofluoroscopic study, some of which were markedly aberrant. Whether this disparity reflects adaptation to deteriorating capabilities over a long period of time, compensations that have been more or less effective, or other factors, such as a sensory component in MD that contributes to a distorted view of how well one is managing food, is unclear. It is of further interest that, among the MD subjects, severity of swallow impairment differed in ways that were not predictable by subject age or time since diagnosis. The present study s implications for managing MD patients, in our view, include (1) strict adherence to reflux precautions; (2) education of friends and family members in the performance of a Heimlich maneuver; (3) dietary counseling emphasizing maximum nutritional density within a restricted range of consistencies (identified as safest, most effective); (4) strategies to facilitate pharyngeal clearing, ie, careful chewing and bolus preparation to a liquid consistency, repeat swallows, alternating thin with thick consistencies (if possible without aspiration), and (5) airway protection strategies when aspiration risk is elevated. References 1. Harper PS. Myotonic muscular dystrophy. 2nd ed. Philadelphia: WB Saunders; Willig TN, Paulus J, Lacau Saint Guily J, Beon C, Navarro J. Swallowing problems in neuromuscular disorders. Arch Phys Med Rehabil 1994;75: Pruzansky W, Profis A. Dysfunction of the alimentary tract in myotonic dystrophy. 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