Vim thalamic stimulation for tremor.

Chronic stimulation of the ventral intermediate nucleus (Vim) of the thalamus is highly effective for the treatment of tremor. Patients with tremor associated with Parkinson's disease and essential tremor appear to respond best. Patients with cerebellar tremors may also respond but to a lesser extent. Although tremor is improved, Vim DBS does not substantially improve the daily living activities of patients with Parkinson's disease. This is related to the lack of effect on rigidity, bradykinesia, and gait and postural disturbances associated with Parkinson's. For this reason, the majority of patients with Parkinson's disease who require surgery are better treated with interventions in the globus pallidus or subthalamic nucleus, targets that allow improvement in all cardinal features of Parkinson's disease. In contrast, Vim DBS has unequivocal functional benefit in patients with essential tremor, this is likely to remain the major indication of this form of therapy. The mechanism of action of thalamic DBS is not understood and remains a research priority.