L-dopa in Parkinsonism and the influence of previous thalamotomy.

A double-blind cross-over trial over 24 weeks (10 weeks on the active remedy, 4 weeks off treatment, and 10 weeks on placebo) of the effect of L-dopa on idiopathic Parkinsonism (paralysis agitans) has shown no difference in the response obtained in patients who had undergone previous stereotaxic ventrolateral thalamotomy and in those who had not. Of the 34 patients (18 men and 16 women) in the trial 18 had been operated on (nine unilateral, nine bilateral operations) and 16 had not. All patients entering the trial were taking anticholinergic drugs in stable dosage and these were continued throughout. The only factor which seemed to limit the response to treatment was pre-existing hypertension. Of 31 patients who completed the 10-week treatment period, 12 showed marked improvement, 15 moderate improvement, and 4 and mild or negligible change. It seems that previous ventrolateral thalamotomy affords some protection against the development of L-dopa-induced involuntary limb movements on the side contralateral to the operation. As found by others, maximum benefit was seen in bradykinesia and rigidity and related features but a significant reduction in tremor was also noted during treatment. Side effects (nausea, hypotension, and involuntary movements) were common but rarely limited the therapeutic response.