Objective: Explore potential biomarkers in dystonia patients implanted with Medtronic Percept™.

Background: Though highly variable in presentation and underlying cause, individuals with dystonia present with excessive muscle tone leading to muscle spasms, abnormal posturing, and tremors. In medically refractory cases, deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been shown to be an effective treatment. However, dystonic symptoms generally improve over weeks to months following DBS programming, making it difficult to predict optimal parameters. Previous studies have demonstrated low frequency pallidal oscillations (e.g., theta band, 4-10 Hz) to correlate with dystonic muscle activity and clinical severity. Yet, little is known about acute/chronic changes of this oscillatory activity with continuous stimulation.

Method: We collected LFP activity from the GPi of 2 dystonia patients implanted with Medtronic SenSight/Percept™ during standard of care management (intraoperatively and outpatient). Patient 1 (P1) was implanted in the right GPi for hemidystonia of the left hemibody. Patient 2 (P2) was implanted with bilateral GPi leads for cervical dystonia with head tremor.

Results: P1 had a prominent theta peak (6.3 Hz) intraoperatively which was also present at initial programming visit (6.8 Hz; 1 month postop). The electrode contacts clinically deemed to be ideal for chronic stimulation coincided with those with theta peak power observed at the initial programming session. P2 had prominent theta peaks intraoperatively for each lead implantation (1 month apart; Left GPi: 6.8 Hz; Right GPi: 4.8 Hz), which were also present during initial programming visit (Left and Right GPi: 6.8 Hz; 1 month post 2^nd side). Additionally, P2 experienced an acute improvement to head tremor when stimulation was turned on (vs off stim).

Conclusion: In 2 individuals with dystonia, theta peaks (4-10 Hz) were identified intraoperatively and during outpatient physiological monitoring along with clinical benefit from GPi-DBS. Additionally, P2 had an acute benefit of mobile dystonia, providing further evidence that GPi-DBS can produce acute effects on dystonic symptoms. Identifying the relationship of physiological biomarker activity to dystonic signs will provide the rationale for optimizing DBS and development of programming strategies to expedite outcome improvement in dystonia patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tracking-physiological-biomarker-activity-in-the-globus-pallidus-internus-in-two-dystonia-patients-implanted-with-medtronic-percept/