Bilateral high-frequency stimulation of the internal globus pallidus in advanced Parkinson's disease

We report here the results of an open prospective study in 9 patients suffe ring from severe Parkinson's disease with on/off fluctuations and restricte d off-period mobility, who underwent bilateral implantation of stimulating electrodes in the internal pallidum. At S-month follow-up, the total Unifie d Parkinson's Disease Rating Scale (UPDRS) motor score in the medication-of f state was reduced from 54.1 +/- 14.8 to 23.9 +/- 11.7 (44.2%) when stimul ation was turned on. Comparison of UPDRS subscores revealed significant imp rovements for tremor, rigidity, bradykinesia, gait and posture, and dyskine sias. The results of the clinical scoring could be confirmed by significant changes in the quantitative assessment of hand function and walking. Bilat eral pallidal stimulation reduced the amount and severity of on/off fluctua tions. Additional follow-up at 6 months (n = 6), 9 months (n = 6), and 12 m onths (n = 4) did not show a decline in effectiveness of stimulation. There was no permanent morbidity associated with the procedure. A subtle reducti on of verbal fluency, which was not evident to the patients, was the only c ognitive side effect of the procedure in neuropsychological testing. Chroni c bilateral high-frequency stimulation of the internal pallidum seems to be a neurologically safe and highly effective treatment for "off" symptoms, d yskinesias, and motor fluctuations in advanced stages of Parkinson's diseas e.