INHIBITION OF LEVODOPA EFFECTS BY INTERNAL PALLIDAL STIMULATION

We report three patients with bilateral GPi stimulation for stage 4 Pa rkinson's disease (PD) with severe levodopa-induced dyskinesias (LID). In all three it was possible to completely inhibit LID using high-sti mulation parameters. Parallel to complete inhibition of LID, an inhibi tion of the anti-akinetic effect of levodopa was observed, whereas, at the same time, rigidity was markedly improved. GPi stimulation is ada ptable over time, and stimulation parameters have to be programmed acc ording to off- and on-period motor symptoms. The main interest of stim ulation is the possibility of finding a compromise between LID allevia tion in on-phase without loss of the beneficial motor effects and impr ovement in parkinsonism in off-phase. In some patients, residual dyski nesias have to be accepted so as not to aggravate on-period motor symp toms by a presumed overinhibition of basal ganglia outflow.