In the past two years we have had occasion to study a series of cases exhibiting remarkable, and in some instances unique, involuntary movements. This report is concerned with these hitherto undescribed cases, and with certain physiologic speculations arising from their analysis.
Involuntary movements have an especial importance because of their relationship to the extrapyramidal system. Ability to interpret and to classify them has developed with understanding of that system, especially of the basal ganglia. We would draw attention to types of dyskinesia, their distribution and accompaniments, and especially to the seeming confirmation in man of observations made on the experimental animal. We present three groups of cases, each with two illustrations. Group 1 demonstrates one rare type of this condition, and a segmental dystonia of unusual localization and limitation; group 2 embraces two cases illustrating unusual types of choreiform movements of the Huntington type, and group 3 illustrates progression