Precise stimulation location optimizes speech outcomes in essential tremor. (November 2016)

• Record Type: Journal Article
• Authors: Matsumoto, Joseph Y.; Fossett, Tepanta; Kim, Minsoo; Duffy, Joseph R.; Strand, Edythe; McKeon, Andrew; Lee, Kendall H.; Stead, Matt; Burnett, Melinda; Adams, Andrea C.; Klassen, Bryan T.
• Is Part Of: Parkinsonism & related disorders. Volume 32(2016)
• Page Start: 60
• Page End: 65
• Publication Date: 2016-11
• Subjects: Essential tremor -- Deep brain stimulation -- Speech -- Dysarthria; Parkinson's disease -- Periodicals; Movement disorders -- Periodicals; Movement Disorders -- Periodicals; Nerve Degeneration -- Periodicals; Nervous System Diseases -- Periodicals; Parkinson Disease -- Periodicals; Tremor -- Periodicals; Parkinson, Maladie de -- Périodiques; Parkinson's disease; 616.833
• DOI: 10.1016/j.parkreldis.2016.08.017
• Languages: English
• ISSNs: 1353-8020

Abstract

Abstract: Background: Deep brain stimulation for essential arm tremor is often complicated by dysarthria and persistent voice tremor. Objective: To determine the relationship of stimulation location to speech outcomes following bilateral thalamic deep brain stimulation (DBS) for essential tremor (ET). Methods: Eighteen patients undergoing bilateral DBS for ET were prospectively studied. Speech pathologists grouped patients by final speech outcome (normal speech, voice tremor, or dysarthria). Locations of the active leads were calculated by normalizing the segmented thalamic volumes to those in the Morel atlas. Stimulation volumes within thalamic nuclei, error distances from target, and measures of accuracy were calculated and differences in measures between outcome groups tested. Results: At optimal stimulation, 8 patients had normal speech, 6 had voice tremor, and 4 had mild dysarthria. Stimulation volumes were statistically concentrated within the ventral lateral posterior nucleus (VLp). The percentage of stimulation volume outside the VLp was higher in patients with dysarthria (60% vs. 24%, p = 0.02) or voice tremor (55% vs. 24%, p = 0.03) compared to patients with normal speech outcomes. The error distance from the center of VLp was greater for patients with dysarthria than those with normal speech (12.6 vs. 7.6 mm, p = 0.02). Electrodes with lower efficiency for VLp stimulation were more frequent with poor speech outcomes and in patients with persistent voice tremor. Conclusions: Following bilateral DBS for ET, 22% of patients develop a non-disabling dysarthria. Optimal speech outcomes were achieved in 44% of patients and correlated with precise stimulation location within and not outside of the VLp. Highlights: The effects of bilateral DBS for essential tremor on speech was studied in 18 patients. 22% of patients developed a mild to moderate dysarthria after surgery. Only 44% of patients had an optimal speech outcome without dysarthria or tremor. Dysarthria patients had less precise placement of electrodes in the VLP nucleus. Optimal speech outcomes correlated with precise stimulation location.