Neurological side-effects in a series of operations on the basal ganglia.

T HIS is a s tudy of the neurological sideeffects of operations on the basal ganglia. I t is based on the correlation of clinical and radiological data obtained in a series of 650 basal ganglia operations for Parkinson 's disease. The medical l i terature shows particular concern with the optimal location of the lesion which will result in relief of rigidity and tremor. There is now almost complete agreemen t tha t the best therapeutic effects are achieved by lesions located in the area of the ventral thalamus al though the exact coordinates va ry somewhat from one author to another.l,4,5,s Hemiballismus and hemiplegia are two impor tan t complications following basal ganglia surgery. 7'9 Menta l changes following bilateral operations have also been mentioned especially by the Riechert school. 6 Informat ion regarding other neurological phenomena occasionally seen following basal ganglia stereotactic surgery is scarce. The symptoms include dystonic movements and postures, dysarthria , sensory changes and "thalamic pain ." One also gathers the impression that postoperat ive problems such as hemiplegia and mental changes are primarily due to true surgical complications, especially vascular softening and hemorrhages2 I t is our purpose to analyze our own series in order to discover the correlation, if any, between the radiological location of the lesions and the most common neurological side-effects. We will not concern ourselves with clinical results in terms of alleviation of t remor and rigidity except for comparison and we have eliminated those cases where the undesirable effects were the result of purely surgical complications, such as hemorrhage. This work follows closely the paper first published in 1960 by Cooper and one of