Segmented versus Nonsegmented Deep-Brain Stimulation for Essential Tremor Differ in Ataxic Side Effects

BACKGROUND: Directional, deep-brain stimulation may prove beneficial for targets (1) thinner along the lead trajectory, and (2) whose borders are not easily visible by neuroimaging. When targeting the ventral intermediate (VIM) nucleus of the thalamus for essential tremor, even baseline ataxia may be exacerbated by medial spread of current and antidromic stimulation of vestibular-cerebellar-thalamic afferents. CASE REPORT: The present patient with essential tremor developed refractory head tremor leading to implantation of bilateral St. Jude/Abbott segmented leads into the VIM to afford additional programming options. DISCUSSION: Video evidence showed that directional stimulation did not exacerbate ataxia beyond baseline, whereas nondirectional stimulation exacerbated ataxia consistently. We discuss how this programming advantage may help address a common complication from DBS implantation for essential tremor patients.