To report long-term outcomes of bilateral thalamic ventral intermediate nucleus (Vim) deep brain stimulation in three patients with refractory orthostatic tremor.

OT is a rare and debilitating tremor, often more prevalent in women in the sixth decade(Boogers et al., 2022). Examinations often appear normal, resulting in delayed diagnosis. Presenting symptoms are subtle such as unsteadiness, and weakness when standing (Benito-León & Domingo-Santos, 2016). Medications remain first-line treatment; however, DBS has emerged as a potential option for refractory cases. While prior studies have indicated short-term improvements in stance time post-DBS, there is a need for further long-term evaluations(Boogers et al., 2022).

We retrospectively screened medical records identifying patients diagnosed with OT clinically who underwent DBS. Data were collected through chart reviews and long-term follow-ups via phone interviews.

Three female patients with medication-refractory OT and a mean symptom duration of 8 years underwent bilateral Vim thalamic DBS. All reported significant disability in stance time and gait, with a modified Rankin Scale (mRS) score of 3 at baseline. Initial improvement was noted as early as one month in one case, with maximum improvement achieved within 1.5 to 30 months. Adverse events were transient, including dysarthria and memory impairment, with one patient requiring a revision of DBS. Self-reported improvements in stance duration were estimated at 70-80% for all patients. Follow-up periods ranged from 24 to 120 months, with mRS scores improving to 1 in two patients, while the third patient maintained an mRS of 3, necessitating an assisted gait device. All patients reported improvements in quality of life and activities of daily living.

Bilateral Vim DBS can be a viable option for patients with disabling OT unresponsive to medical therapy. While all cases demonstrated increased standing time, individual functional outcomes varied, emphasizing the importance of setting realistic expectations with patients.