• Marisa DiMarzio, Radhika Madhavan, Ileana Hancu, Eric Fiveland, Julia Prusik, Suresh Joel, Michael Gillogly, Ilknur Telkes, Michael D Staudt, Jennifer Durphy, Damian Shin, and Julie G Pilitsis.
• Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York.
• Neurosurgery. 2021 Jan 13; 88 (2): 356-365.

BackgroundModels have been developed for predicting ideal contact and amplitude for subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson disease (PD). Pulse-width is generally varied to modulate the size of the energy field produced. Effects of varying frequency in humans have not been systematically evaluated.ObjectiveTo examine how altered frequencies affect blood oxygen level-dependent activation in PD.MethodsPD subjects with optimized DBS programming underwent functional magnetic resonance imaging (fMRI). Frequency was altered and fMRI scans/Unified Parkinson Disease Rating Scale motor subunit (UPDRS-III) scores were obtained. Analysis using DBS-OFF data was used to determine which regions were activated during DBS-ON. Peak activity utilizing T-values was obtained and compared.ResultsAt clinically optimized settings (n = 14 subjects), thalamic, globus pallidum externa (GPe), and posterior cerebellum activation were present. Activation levels significantly decreased in the thalamus, anterior cerebellum, and the GPe when frequency was decreased (P < .001). Primary somatosensory cortex activation levels significantly decreased when frequency was increased by 30 Hz, but not 60 Hz. Sex, age, disease/DBS duration, and bilaterality did not significantly affect the data. Retrospective analysis of fMRI activation patterns predicted optimal frequency in 11/14 subjects.ConclusionWe show the first data with fMRI of STN DBS-ON while synchronizing cycling with magnetic resonance scanning. At clinically optimized settings, an fMRI signature of thalamic, GPe, and posterior cerebellum activation was seen. Reducing frequency significantly decreased thalamic, GPe, and anterior cerebellum activation. Current standard-of-care programming can take up to 6 mo using UPDRS-III testing alone. We provide preliminary evidence that using fMRI signature of frequency may have clinical utility and feasibility.Copyright © 2020 by the Congress of Neurological Surgeons.

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