Deep Brain Stimulation for Essential Tremor: A Comparison of Targets

Abstract

Background: Deep brain stimulation (DBS) is an established treatment for refractory essential tremor (ET). Initially, the target of choice was the thalamic ventralis intermedius nucleus (VIM). However, the zona incerta (ZI) has been suggested as a superior target. Both targets are considered safe and effective, but a direct comparison between these targets is lacking.

Methods: We analyzed a single-center cohort of 44 patients with ET treated with DBS between 1998 and 2017, targeting the VIM and/or ZI. Patient-reported outcome on the Washington Heights-Inwood Genetic Study of Essential Tremor rating scale, adverse events, and stimulation-induced side effects were assessed.

Results: Patient-reported outcome of ZI DBS (-2.2 ± 1.2; 18 patients with 28 electrodes) was superior to VIM DBS (-1.2 ± 1.4; 10 patients with 19 electrodes) (P < 0.01). There was no difference in adverse events between implantations in VIM (45%) and ZI (46%). Dysarthria stimulation-induced side effects were significantly more often reported after VIM DBS (P = 0.01), whereas visual stimulation-induced side effects occurred more often after ZI DBS (P = 0.04).

Conclusions: In this study, ZI DBS was superior to VIM DBS in terms of patient-reported effectiveness. There was a comparable number of complications between both targets. This finding further supports ZI over VIM as the principal DBS target in essential tremor.

Keywords: Deep brain stimulation; Essential tremor; Ventralis intermedius nucleus; Zona incerta.