Objective: To determine post-surgical cognitive changes and their predictive factors after bilateral ventral intermediate nucleus (VIM) thalamic Deep Brain Stimulation (DBS) in people with essential tremor (ET) through retrospective analysis of a prospectively collected cohort at a single academic center.

Background: ET is a very prevalent adult-onset movement disorder. DBS is an effective therapeutic option for medication refractory tremor. Cognitive impairments in ET are recognized but less is known about post-surgical cognitive changes after bilateral VIM DBS. While some studies have shown general cognitive stability months to years after surgery, clinically modest changes in various domains have been noted.

Method: People with ET undergoing neuropsychological evaluation before and approximately one year after bilateral VIM DBS at our center were included. Tests analyzed included WAIS-IV: Arithmetic and Digit Span Backwards, DKEFS: Verbal Fluency and Color-Word Interference Test: Inhibition (CWI), HVLT-R Retention, and Trail Making Test B. Tests were selected from a broader assessment battery based on relevance to daily functioning and vulnerability to decline reported in the literature. Paired samples t-tests were used to compare scores pre and post-DBS. For variables which included time between assessments, age, gender, education, tremor severity or baseline performance, that were found to significantly differ, multiple regressions with difference scores were used to evaluate potentially associated variables.

Results: 40 people with ET (65% male, 100% Caucasian, Mean Age 69.25) met criteria. There was significant worsening on WAIS-IV Arithmetic (F_(1,35)=3,46; p=0.01) and CWI (F_(1,38)=2.1; p=0.041) one year post-DBS. Decline in mental arithmetic was predicted by baseline arithmetic performance (p=0.027) and in a smaller subset with TETRAS scores (n=17), tremor severity (p=.002). Decline in CWI was not predicted by any variable.

Conclusion: Significant declines in measures of working memory and executive function were noted in this ET cohort approximately one year after bilateral VIM DBS. This is the first study to note decline in working memory measured by mental arithmetic and the decline was predicted by baseline arithmetic performance and tremor severity. These results could guide participant selection for VIM DBS if validated in larger cohorts. Future studies exploring mechanisms underlying this cognitive decline are needed.

References: 1. Dhima K, Biars J, Kondylis E, Nagel S, Yu XX, Floden DP. Neuropsychological outcomes after thalamic deep brain stimulation for essential tremor. Parkinsonism Relat Disord. 2021 Nov;92:88-93.
2. Jones JD, Orozco T, Bowers D, Hu W, Jabarkheel Z, Chiu S, Ramirez-Zamora A, Foote K, Okun MS and Wagle Shukla A (2020). Cognitive Outcomes for Essential Tremor Patients Selected for Thalamic Deep Brain Stimulation Surgery Through Interdisciplinary Evaluations. Front. Hum. Neurosci. 14:578348.
3. Cernera S, Okun MS and Gunduz A (2019) A Review of Cognitive Outcomes Across Movement Disorder Patients Undergoing Deep Brain Stimulation. Front. Neurol. 10:419

« Back to 2025 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-changes-after-bilateral-thalamic-vim-dbs-a-single-center-experience/