HIGH-FREQUENCY STIMULATION OF THE SUBTHALAMIC NUCLEUS SUPPRESSES EXPERIMENTAL RESTING TREMOR IN THE MONKEY

The effect of high-frequency stimulation of the subthalamic nucleus on parkinsonian-like resting tremor was investigated in two monkeys (Mac aca fascicularis). Unilateral tremor of the arm and leg was induced by electrical coagulation of the brainstem area including the substantia nigra and the red nucleus. The tremor was only seen at rest condition with a very stable frequency of 4.46+/-0.59 Hz (mean +/- S.D.). Apomo rphine (0.1-0.4 mg/kg, s.c.) completely blocked the tremor, suggesting that it was a dopaminergic-dependent symptom just like the parkinsoni an tremor. When the stimulating frequency varied from 20 to 1000 Hz, b oth mono- and bipolar stimulation (square pulses, 0-5 mA, 0.06 ms) of the subthalamic nucleus suppressed resting tremor in a frequency-depen dent manner but monopolar stimulation was more effective. These effect s remained stable for more than two years. The present results suggest that the subthalamic nucleus is involved in the control and mechanism of resting tremor and that the high-frequency stimulation of the subt halamic nucleus can be used as an alternative therapy in parkinsonian patients with akinesia, rigidity and resting tremor. (C) 1998 IBRO. Pu blished by Elsevier Science Ltd.