Voice and Speech in Deep Brain Stimulation in Dystonia: A Retrospective Study, Systematic Review, and Meta‐Analysis

BACKGROUND: Relatively little is known about voice and speech abnormalities and their changes after deep brain stimulation (DBS) in patients with dystonia. OBJECTIVE: The aim was to determine the incidence of speech abnormalities, including laryngeal dystonia, among patients with dystonia receiving DBS and to characterize their response to this neurosurgical neuromodulation. METHODS: A three-part study, including a retrospective analysis, systematic literature review, and meta-analysis, was completed. Patients with dystonia receiving DBS at Massachusetts General Hospital and the University of California San Francisco between 2004 and 2024 were included in the retrospective study. Those with preoperative voice and speech abnormalities were grouped by type of alterations and response to DBS and evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) speech and swallowing subscores. A systematic literature review was conducted for studies of voice and speech outcomes in DBS for dystonia. A meta-analysis of studies reporting BFM speech and swallowing subscores pre- and post-DBS was performed. RESULTS: One hundred eighty-three participants received DBS for dystonia, and 34 (18.6%) had baseline voice and speech abnormalities. BFMDRS speech and swallowing subscores improved with DBS in isolated (but not combined) dystonia, driven primarily by two subgroups. Twenty studies were included in the systematic literature review. A majority of included speech measures were unchanged with DBS; a smaller number showed improvement or worsening. Nine studies reporting pre- and post-DBS BFMDRS speech and swallowing subscores were included in the meta-analysis, which showed improvement with DBS. CONCLUSIONS: Data are mixed on response of speech to DBS in dystonia, though worsening of speech appears rare.