Rescue deep brain stimulation for recurrent essential tremor after ventral intermediate nucleus thalamotomy: illustrative cases

BACKGROUND: Medication-refractory essential tremor (ET) patients who undergo MR-guided focused ultrasound or Gamma Knife thalamotomy may experience tremor recurrence, prompting rescue deep brain stimulation (DBS). Yet, the impact of prior ventral intermediate nucleus (VIM) lesioning on DBS targeting, microelectrode recording (MER), and stimulation programming remains uncertain. OBSERVATIONS: The authors present 3 ET patients undergoing bilateral DBS for tremor recurrence after thalamotomy. Thalamotomy lesions showed depressed electrophysiological activity versus nonlesioned VIM on MER (p = 0.0397) and required smaller DBS charge density increases for tremor control, suggesting irreversible lesion effects despite tremor recurrence. Tremor recurrence correlated with lesion mislocation; specifically, ablations missed the central VIM (mean 1.8 mm) and decussating dentato-rubro-thalamic tract. For rescue DBS, ventral VIM stimulation yields the greatest tremor reduction, while central VIM stimulation balanced tremor control with adverse effects. LESSONS: DBS is a safe, effective rescue treatment for failed thalamotomy without needing to retarget the prior lesion site. The authors advocate for prospective studies of initial DBS targeting 2 mm anterior to standard VIM coordinates, reducing intraoperative readjustment for central VIM stimulation; and initial thalamotomy targeting 1 mm anterior and 1.2-1.5 mm superior to standard coordinates for durable tremor control through ablation of both central and ventral VIM. https://thejns.org/doi/10.3171/CASE25955.