To report outcomes of MRI guided focused ultrasound (MRgFUS) unilateral ventral intermediate nucleus (VIM) thalamotomy in essential tremor (ET) patients at a single institution.

MRgFUS VIM thalamotomy is an approved non-invasive treatment for ET. In select ET patients unilateral MRgFUS VIM thalamotomy is an increasingly utilized surgical option for treatment of medication refractory tremor.

Patients with medication refractory ET underwent unilateral MRgFUS VIM thalamotomy at a single institution. The Essential Tremor Rating Assessment Scale (TETRAS) activities of daily living (ADL) and performance subscales, global improvement scales and adverse effects were obtained at baseline and subsequent follow-up visits ranging from 1.5-16.5 months.

46 patients (24 female) underwent MRgFUS VIM thalamotomy (40 left VIM). Mean age at time of surgery was 75.0 ± 10.2 years (41.0-95.3) and disease duration was 25.9 ± 17.9 years (3.5-72.3). Mean follow-up was 7.3 ± 4.6 months. TETRAS ADL subscale improved from 26.2 at baseline to 10.8 at last follow-up (59%, p<0.001) and TETRAS performance subscale improved from 26.0 at baseline to 15.5 at last follow-up (40.4%, p<0.001). At last follow-up, 34/46 (74%) patients reported marked global improvement, 6/46 (13%) had moderate improvement and 3/46 (6.5%) had mild improvement. No change was reported by 3/46 (6.5%).

Common adverse effects included gait imbalance and speech/swallowing difficulties immediately after surgery which in the majority of patients improved and resolved back to baseline at subsequent follow-up visits. One patient had poor outcome and had subsequent deep brain stimulation. Two patients had repeated MRgFUS to improve outcome and 2 had unrelated deaths greater than 4 months after surgery.

Unilateral MRgFUS thalamotomy is a safe and effective treatment for patients with medication refractory ET. Adverse effects of speech, swallowing and gait difficulties occur related to the surgery, but in the majority of patients these adverse effects resolve over time.