Objective: This study aimed to assess the clinical efficacy of each contact and the correlation between the clinical best contacts and radiologically defined optimal contacts.

Background: Subthalamic nucleus deep brain stimulation (STN-DBS) is effective in patients with Parkinson’s Disease (PD) and medication refractory motor symptoms. The dorsolateral STN is generally considered the preferred target for DBS, nevertheless, studies of anatomical location and active contacts have found discordant results. The optimal site for best stimulation effect remains ambiguous and no blinded acute stimulation studies in STN DBS have been performed.

Methods: 7 patients with STN-DBS more than 6 months for PD (contacts, n=48), after overnight withdrawal of PD medications, underwent a randomised blinded acute assessment of clinical contact efficacy based on the threshold and maximum reduction in UPDRS-III rigidity score and the corresponding voltage required. The euclidian distance of each contact from the ideal target position on the fused preoperative MRI and postoperative CT were evaluated by a blinded rater. The contacts were ranked clinically based on clinical efficacy and radiologically based on respective distance from the ideal location and compared for correlation.

Results: The clinical effectiveness of stimulation was significantly different between the four contacts (ANOVA F=3.5, p<0.05) and the best contacts were significantly superior to worst contacts (p=0.03). Moreover, all four contacts were ranked significantly different in the clinical (F=6.60, p=0.008) and radiological ranking (F=10.5, p=0.0000). Contact 1, with the mean AC-PC coordinates 12.0±1.3mm lateral, 2.9±1.9mm posterior and 3.4±1.2mm inferior, was ranked equally as best contact in clinical and radiological ranking (p>0.05). There was a correlation between position of the clinical and radiological best contacts (P<0.05) but not the worst contacts (p>0.05).

Conclusions: Best contacts determined in blinded acute stimulation correlate well with the anatomical best contact predicted from imaging in dorsolateral STN, However, radiological prediction of worst contact appears unreliable. The results emphasise the importance of clinical contact screening in PD patients with STN DBS in determining the most and least effective stimulation parameters.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/blinded-acute-assessment-of-electrode-contact-efficacy-compared-with-contact-location-for-subthalamic-nucleus-deep-brain-stimulation-in-parkinsons-disease/