THE SUBTHALAMIC NUCLEUS AND TREMOR IN PARKINSONS-DISEASE

The role of the subthalamic nucleus (STN) in the origin of parkinsonia n tremor is discussed. Previous studies in monkeys made parkinsonian b y MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) administration s uggested a direct participation of the STN in the pathophysiology of t remor. We recorded tremor-related activity in the STN in 12 patients w ith Parkinson's disease (PD) and found that microstimulation of the se nsorimotor region of the nucleus, where these neurons are present, sto pped the tremor with a very short latency. Longterm treatment by means of bilateral deep-brain stimulation (DBS) in the same 12 patients led to a significant reduction of tremor as well as other cardinal featur es of PD. This effect was blindly assessed at 3 months after implantat ion. In another group of seven patients, a unilateral lesion of the ST N was performed. Both postural and resting tremor were significantly i mproved on the limbs contralateral to the lesion side. In three patien ts, tremor disappeared completely after 12 months of follow up. The el ectrophysiologic data and therapeutic effect of inactivating the STN s trongly indicated that this structure is directly involved in the orig in of parkinsonian tremor, as suggested by the MPTP model.