Abstract Details

Title Evidence of Improved Verbal Fluency Following Unilateral Right Hemisphere Subthalamic Nucleus Deep Brain Stimulation for Parkinson’s Disease

Topic Movement Disorders

Presentation(s) S51 - Movement Disorders: Tremor, Parkinsonism, and Non-motor Symptoms (4:42 PM-4:54 PM)

Poster/Presentation
Number 007

Background STN-DBS is safe and effective for motor symptoms, but a widely replicated cognitive outcome following bilateral STN-DBS is verbal fluency decline. Since non-motor symptoms, including mild cognitive impairment and dementia are a significant cause of disability in Parkinson’s disease (PD), reducing the risk of DBS-related cognitive decline is important. Compared to bilateral STN-DBS, little is known about unilateral STN-DBS effects on verbal fluency

Objective To investigate verbal fluency following unilateral subthalamic nucleus deep brain stimulation (STN-DBS).

Design/Methods We enrolled 31 PD patients who underwent unilateral STN-DBS in a randomized, cross-over, double-blind study (SUNDIAL). Targets were based on treatment of the most symptomatic side (n = 17 left STN-DBS; 14 right STN-DBS). At 2-, 4-, and 6-months post-surgery, all participants completed a verbal fluency measure (FAS/CFL), and stimulation type (directional versus ring) was randomized. Welch’s two-sample t-test was used to compare verbal fluency baseline scores and the effects of hemisphere and stimulation on cognition were analyzed using linear mixed effects models. Covariates included age, education, and levodopa equivalents at each time point.

Results

Left STN-DBS patients scored lower on a verbal fluency task than right STN-DBS patients (t(20.66) = -2.49, p = 0.02) at baseline. Following DBS surgery, we observed declines in verbal fluency over the study duration only in the left STN-DBS group (p = 0.02), while the right STN-DBS group improved (p<.001). Stimulation type was not associated with verbal fluency performance.

Conclusions After adjusting for age, education, and levodopa equivalent dose, we found group-level verbal fluency declines following unilateral left STN-DBS and improved verbal fluency following unilateral right STN-DBS. In contrast with bilateral STN-DBS where verbal fluency declines are often reported, it is possible that selecting unilateral right STN-DBS to control left-sided symptoms may be a modifiable risk factor to potentially reduce the likelihood of verbal fluency declines in patients with PD.

Authors/Disclosures
Victor A. Del Bene, PhD (The University of Alabama at Birmingham) PRESENTER	Dr. Del Bene has nothing to disclose.
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Kelly A. Mills, MD (Johns Hopkins University)	Dr. Mills has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Tilosia. The institution of Dr. Mills has received research support from NINDS. The institution of Dr. Mills has received research support from MJFF. The institution of Dr. Mills has received research support from GKC.
	No disclosure on file
Nicole Bentley (University of Alabama Birmingham)	No disclosure on file
Harrison C. Walker III, MD (University of Alabama at Birmingham)	Dr. Walker has nothing to disclose.