Involuntary Movements and Neurotransmitters

Abstract

The clinical study of involuntary movements is helped by neurophysiological and neuropharmacological methods which are very useful for defining the different components of complex movements. Two main groups of involuntary movements can be contrasted according to whether or not they display a rhythm. The defect of a neurotransmitter or the hypersensitivity of the receptors are considered for the different types of movements.

The study of Involuntary Movements has now entered a new period, the period of neurochemistry. It would be dangerous, however, to forget the two preceding stages, the clinical and the neurophysiological ones, and to carry out complex chemical studies without defining the abnormal movements we are dealing with. Therefore, clinical examination with the help of neurophysiological methods is still the first stage of the diagnostic process.
This could seem self-evident but a perusal of the literature shows that many publications lack the most elementary details and use terms without proper justifications.
In this review of Involuntary Movements (I. M.), the type and the characteristics of the I. M. will be mentioned while the state of the art concerning the neurotransmitters will be indicated.
A new approach to the study of I. M. has been opened by the neuro-immunological methods which have proved promising in the case of Huntington disease and perhaps even in that of Parkinson's disease. These methods have appeared at a time when neuro-transmitter studies had proved disappointing in spite of the initial hopes they had raised.
Two main groups of abnormal movements can be contrasted according to whether or not they display a rhythm. The presence of a rhythm implies a synchronizing mechanism for the discharges of motor units. Such a mechanism is specific enough to justify the distinction between rhythmic and arrhythmic I. M.

Key words

Involuntary movements - Neurotransmitters - Tremor - Chorea