We report the 5 year follow-up of a multicenter study of unilateral or bilateral deep brain stimulation (DBS) of the ventralis intermedius (VIM) nucleus of the thalamus in patients with medication-refractory essential tremor (ET).

VIM DBS is an established treatment for disabling ET. Data on long-term efficacy is limited.

127 patients with ET not adequately controlled by medications were implanted with unilateral or bilateral VIM DBS in a prospective, controlled, multicenter study at 12 academic centers. The total and motor clinical tremor rating scale (CTRS) scores at 5 years in the stimulation-on state were compared to baseline and stimulation-off scores. The quality of life in essential tremor questionnaire (QUEST) scale was reported every year up to 5 years.

36 patients were able to complete follow-up at 5 years. Total and motor CTRS scores in the stimulation-on state were improved at 5 years following surgery compared to the stimulation-off state (total -24.7; 95% CI -32.8 to -16.5; p<0.001; motor -16.0; 95% CI -21.6 to -10.4; p<0.001) and baseline (total -33.6; 95% CI -40.5 to -26.6; p<0.001; motor -23.3; 95% CI -28.3 to -18.3; p<0.001). We found significantly improved quality of life as measured by the QUEST summary index at each year of follow-up up to and including 5 years following surgery (-18.4.; 95% CI -26.1 to -10.6; p<0.001).

This is the largest prospective cohort of VIM DBS for ET with long term follow-up. The beneficial effect of VIM DBS in ET for both tremor control and quality of life was persistent over 5 years.