Medical Student WesternUniversity COMP-NW, Providence Brain and Spine Institute
Introduction: Deep brain stimulation (DBS) surgery in patients with Parkinson’s under anesthesia, asleep DBS, requires adequate lead placement for optimal symptomatic relief without inducing unwanted motor capsular responses (MCR). There is limited published data on the impact of lead distance to the internal capsule (IC) and MCR production in DBS targeting the globus pallidus internus (GPi). Higher resolution data about the relationship between distance and MCR will help neurosurgeons provide more targeted therapy.
Methods: Demographic and clinical data for adult patients with Parkinson’s who underwent asleep GPi-DBS between January 2018 and March 2022 were collected from medical records. Patients with dystonia, atypical Parkinsonism, drug-induced Parkinsonism, Parkinson’s plus syndrome, dementia, untreated depression, intracranial abnormalities, and brain atrophy were excluded. Stimulation ≤ 8 (volts/mAmps) was run through the DBS electrode to evoke MCR. Distance from IC to lead was measured. A linear mixed-effects regression model was used to assess if MCR had greater odds of occurring when the lead was closer to the IC, adjusting for laterality of lead placement, device type, age at time of procedure and sex. Adjusted odds ratios (AOR) and 95% confidence intervals (95% CI) are reported.
Results: 36/38 patients (95%) had bilateral procedure, 50% were female, and median age at DBS surgery was 66.5 (47-78). 13/38 patients (34%) were stimulated with device A and 25/38 with device B. MCR’s were observed in 15 patients with median distance to IC of 2.0 mm (range 0.2-4.4) and 2.9 mm (range 0.50-5.8) for patients without MCR. Likelihood of MCR decreased with increased distance to IC, OR 0.50 (CI: 0.29-0.86, p=0.01). After adjustments, the OR was 0.43 (CI: 0.22-0.83p=0.01).
Conclusion : The production of MCR was significantly associated with shorter distance of DBS leads to the internal capsule. Other factors like age at surgery, sex, and device used had no significant relationships.
