Long-Term Effects of Deep Brain Stimulation for Essential Tremor with Subjective and Objective Quantification via Mailed-In Questionnaires

Abstract

Background: Deep brain stimulation (DBS) is a standard treatment for patients with disabling essential tremor. The short-term efficacy rate is well established. Objectives: To assess the long-term effects of DBS in our series and evaluate the durability of the effects over time. Methods: Eighty-four patients implanted with unilateral or bilateral DBS for essential tremor were asked to complete three mailed-in questionnaires to assess DBS efficacy objectively and subjectively. Results: Twenty-six patients responded, with a median follow-up of 41 months. Approximately half of the patients had more than 48 months of follow-up. At the time of follow-up, the Tremor Rating Scale was reduced from a mean score of 7 (5–8) to 3 (2–3) with DBS OFF and ON, respectively. Quality of life, measured with a subset of items of the ADL Taxonomy, improved from a mean of 26 (23–33) to 12 (12–14), comparing DBS OFF and ON. No significant differences were seen when comparing efficacy at short- (<12 months), middle- (12–48 months) or long-term (>48 months) follow-ups. Conclusion: DBS has long-term efficacy for tremor control. This is associated with sustained benefits in quality of life. The duration of the follow-up was not associated with any significant difference in efficacy.