Thalamic organization in essential tremor patients with neuropathy: implication for functional neurosurgery

BackgroundMechanisms underlying the suboptimal effect of ventral intermediate nucleus deep brain stimulation in patients with essential tremor and co-morbid peripheral neuropathy remain unclear. ObjectivesWe compared disease-related (location and extension of the ventral intermediate nucleus) and surgery-related (targeting, intraoperative testing) factors in essential tremor patients with and without peripheral polyneuropathy treated with deep brain stimulation of the ventral intermediate nucleus, testing whether the overlap between volume of tissue activated and ventral intermediate nucleus (target coverage) was associated with clinical outcomes. MethodsPreoperative diffusion magnetic resonance imaging was used for thalamic segmentation, based on preferential cortical connectivity. The target coverage was estimated using a finite element model. Tremor severity was scored at rest, posture, action, and handwriting at baseline, 6, and 12 months. Tremor improvement 48%). ConclusionsIn essential tremor, co-morbid polyneuropathy may result in suboptimal deep brain stimulation outcomes and lower target coverage, likely related to a reorganization of the ventral thalamic nuclei.