Of all the interesting manifestations that disordered function of the central nervous system may occasion, abnormal involuntary movements are perhaps the subject of the most intensive investigation and the greatest discussion. When these movements appear in the superficial musculature they naturally attract the attention of the clinician and the patient, but when they occur in less conspicuous muscles they often remain undiscovered, or are ignored and receive less attention than their inherent interest would seem to warrant. To this second group belong the abnormal involuntary movements of muscles, such as those of the palate, pharynx, larynx, diaphragm and other structures.
The syndrome to be described consists of constantly recurrent rhythmic contractions of certain muscles, chief among which are the muscles of the oropharynx. In the patients who manifest the fully developed picture of the disorder there are, in addition to the abnormal involuntary movements, other evidences of disturbed function due