Neurosurgical Treatment of Parkinsonism and Allied Disorders of Involuntary Movement (Dyskinesiæ)

SURGICAL attempts to relieve disorders of involuntary movement (dyskinesih) date from the excisions of cerebral cortex first practised in 1890 by Sir Victor Horsley. His three patients, suffering from choreoathetosis, had gratifying results which, however, were not easily reproduced by other surgeons of the period. The development of ancillary neurological investigative methods later permitted more accurate excision of motor and premotor areas of the cerebral cortex with relief of Parkinsonian tremor and choreoathetotic movements (Bucy and Case, 1939), but at the expense of contralateral hemiparesis and usually without relief of rigidity. Operations on the internal capsule, cerebral peduncle and spinal cord have the same drawback and none have gained wide acceptance. Recently operations have been evolved in which lesions are produced in certain parts of the basal ganglia or their efferent fibres. Abolition or relief of involuntary movements, tremor, and rigidity has been obtained without coincident hemiparesis. Such operations are now in routine use in a few clinics in Europe and North America. Their development must be considered relative to the anatomy, physiology, and patho-physiology of the subcortical nuclei making up the basal ganglia. To the anatomist the basal ganglia comprise the caudate nucleus, putamen, globus pallidus, and amygdaloid nucleus. The caudate and putamen, having identical histology and close anatomical connections, are sometimes considered a single organ and are together named the striatum because of their striated appearance on section. The globus pallidus and the putamen are described together on naked eye structure as the lentiform nucleus, but it should be emphasized that the globus pallidus has a very different microscopic structure and is more closely allied to the subthalamus. Neurophysiologists, as a result of recent work, have added to the anatomical classification several other important structures to form a functional group. These additions are the subthalamic nucleus (corpus Luysii), the red nucleus and substantia nigra in the upper mid brain, and certain cerebellar connections, notably the dentate nucleus and brachium conjunctivum. What we are dealing with, then, is that group of structures concerned with motor function exclusive of the conventional pyramidal system.