Bilateral Ventral Intermediate Nucleus Thalamic Deep Brain Stimulation in Orthostatic Tremor.

ABSTRACT

BACKGROUND: Orthostatic tremor (OT) is characterized by high-frequency leg tremor when standing still, resulting in a sense of imbalance, with limited treatment options. Ventral intermediate (Vim) nucleus thalamic deep brain stimulation (DBS) has been reported as beneficial in a few cases. OBJECTIVE: To report clinical outcomes, lead locations, and stimulation parameters in 2 patients with severe medication-refractory OT treated with Vim DBS. METHODS: The patients underwent surface electromyography (EMG) to confirm the OT diagnosis. Outcomes were measured as change in tolerated standing time at the last follow-up. Lead locations were quantified using postoperative MRI. RESULTS: Vim DBS was well tolerated and resulted in improvement in standing time (patient 1 50 s at baseline to 15 min 16 months after surgery; patient 2 34 s at baseline to 4.2 min 7 months after surgery). Postoperative surface EMG for patient 1 demonstrated a delayed onset of tremor, lower-amplitude tremor, and periods of quiescence, but an unchanged tremor frequency. CONCLUSION: These cases provide further support for Vim DBS to improve standing time in severe medication-refractory OT. The location of the effective thalamic target for OT does not differ from the effective target for essential tremor.