Clinical and electrophysiological evaluation of dysphagia in myasthenia gravis

OBJECTIVE To evaluate dysphagia at the oropharyngeal stage of swallowing and to determine the pathophysiological mechanisms of dysphagia in patients with myasthenia gravis. METHODS Fifteen patients with myasthenia gravis with dysphagia and 10 patients without dysphagia were investigated by a combined electrophysiological and mechanical method described previously. Laryngeal movements were detected by a piezoelectric transducer and the related submental EMG (SM-EMG) and sometimes the EMG of cricopharyngeal muscle of the upper esophageal sphincter (CP-EMG) were recorded during dry or wet swallowing. The results of these electrophysiological variables were compared with those of normal age matched control subjects. RESULTS In patients with myasthenia gravis with dysphagia, it was found that the time necessary for the larynx to remain in its superior position during swallowing and swallowing variability in successive swallows increased significantly compared with normal subjects and with patients with myasthenia gravis without dysphagia. The total duration of SM-EMG activity was also prolonged in both groups but more severely in the dysphagic patients. Electromyographic activity of the CP sphincter was found to be normal in the dysphagic patients investigated. All the patients with myasthenia gravis with dysphagia had pathological dysphagia limits (<20 ml water) whereas other patients except two, were within normal limits. CONCLUSIONS Because the electrophysiological variables related to oropharyngeal swallowing were prolonged even in patients with myasthenia gravis without dysphagia, it is concluded that the submental and laryngeal elevators are involved subclinically in myasthenia gravis and, because of compensating mechanisms, the patient may not be dysphagic. As the CP-EMG behaviour was found to be normal, a coordination disorder between normal CP sphincter muscle and the affected striated muscles of the laryngeal elevators may be one of the reasons for dysphagia in myasthenia gravis. This method also made it possible to investigate the myasthenic involvement in the laryngeal elevators that cannot be evaluated by other electrophysiological methods in myasthenia gravis.

[1]  R. Carpenter,et al.  The otolaryngologic presentation of myasthenia gravis , 1979, The Laryngoscope.

[2]  D. Cerenko,et al.  Timing of major events of pharyngeal swallowing. , 1988, Archives of otolaryngology--head & neck surgery.

[3]  H. Wit,et al.  Simultaneous manometry and electromyography in the pharyngoesophageal segment , 1985, The Laryngoscope.

[4]  Cumhur Ertekin,et al.  An electrophysiological investigation of deglutition in man , 1995, Muscle & nerve.

[5]  I. Aydogdu,et al.  Piecemeal deglutition and dysphagia limit in normal subjects and in patients with swallowing disorders. , 1996, Journal of neurology, neurosurgery, and psychiatry.

[6]  R. Goyal,et al.  Disorders of pharyngeal and upper esophageal sphincter motor function. , 1976, Archives of internal medicine.

[7]  W. B. Seamen.  Pharyngeal and upper esophageal dysphagia. , 1976, JAMA.

[8]  Jo Shapiro,et al.  Evaluation and treatment of swallowing disorders , 1992, Comprehensive therapy.

[9]  D. Grob,et al.  The Course of Myasthenia Gravis and Therapies Affecting Outcome a , 1987, Annals of the New York Academy of Sciences.

[10]  K. King,et al.  Esophageal manometric studies in patients with myasthenia gravis. , 1988, The Journal of thoracic and cardiovascular surgery.

[11]  H. Chiu.  [Single fiber electromyography in myasthenia gravis]. , 1988, Taiwan yi xue hui za zhi. Journal of the Formosan Medical Association.

[12]  T. Shipp,et al.  Pharyngoesophageal muscle activity during swallowing in man , 1970, The Laryngoscope.

[13]  I. Aydogdu,et al.  Effects of bolus volume on oropharyngeal swallowing: an electrophysiologic study in man. , 1997, The American journal of gastroenterology.

[14]  M. Silbiger,et al.  Neuromuscular disorders affecting the pharynx. Cineradiographic analysis. , 1967, Investigative radiology.

[15]  Donner Mw,et al.  Cinefluorographic analysis of pharyngeal swallowing in neuromuscular disorders. , 1966 .

[16]  E T Stewart,et al.  Physiology and radiology of the normal oral and pharyngeal phases of swallowing. , 1990, AJR. American journal of roentgenology.

[17]  M. Bromberg,et al.  Dysphagia in elderly men with myasthenia gravis , 1996, Journal of the Neurological Sciences.

[18]  J. Logemann,et al.  Evaluation and treatment of swallowing disorders , 1983 .

[19]  M. Mahon,et al.  A histological and histochemical study of the cricopharyngeus muscle in man. , 1988, Journal of anatomy.

[20]  Khan Oa,et al.  Myasthenia gravis presenting as dysphagia: clinical considerations. , 1994 .

[21]  W. Seaman.  Pharyngeal and Upper Esophageal Dysphagia , 1976 .

[22]  I. Cook.  Normal and disordered swallowing: new insights. , 1991, Bailliere's clinical gastroenterology.

[23]  D B Sanders,et al.  AAEE Minimonograph #25: Single‐fiber electromyography in myasthenia gravis , 1986, Muscle & nerve.

[24]  M. Shochina,et al.  Manometry and electromyography of the pharyngeal muscles in patients with dysphagia. , 1990, Archives of otolaryngology--head & neck surgery.

[25]  M. Silbiger,et al.  Cinefluorographic analysis of pharyngeal swallowing in neuromuscular disorders. , 1966, The American journal of the medical sciences.