Introduction: Implantation of DBS electrodes, while patients are awake or under general anesthesia ("asleep") is used, but asleep patient clinical outcomes are not fully documented. In addition, the procedures involved in DBS electrode placement under general anesthesia are not uniform. Our objective was to evaluate the effectiveness of “asleep” standardized GPi surgery with electrophysiological recording in PD patients, by assessing postoperative clinical outcomes and technical accuracy of lead placement through computer mapping.

Methods: A retrospective review of 16 advanced PD patients who underwent bilateral GPi lead placement between 2013-2015 was performed. All patients underwent UPDRS assessment 6-18 months after DBS surgery. Preoperative functional measurements obtained as part of standard clinical care were compared to postoperative data. Post operative DBS system settings, clinical reports of efficacy and side effect profiles, and technical accuracy of lead placement, as measured by the mean radial error, were also analyzed.

Results: Preliminary results include 16 participants (11 males, 5 females) with a mean age of 70.45 years at implantation. Mean time of postoperative testing was 11.26 months. UPDRS motor preoperative mean off-medication score was 53.26. UPDRS motor mean off-medication/on-stimulation UPDRS motor score was 31.43. Mean UPDRS motor on-medication/on-stimulation score was 23.77. Preoperative mean on-medication UPDRS motor score was 28.7. The levodopa equivalent daily dose was reduced on average by 53.338%. There were no adverse events attributable to electrode placement.

Conclusions: GPi leads placed while the patient is under general anesthesia using a standardized technique with electrophysiological recording resulted in improved clinical outcomes, consistent with the level of improvements reported previously for GPi electrode placements under awake conditions. As the study is currently ongoing, the preliminary results are promising and will greatly add to the sparse literature available in regards to DBS targeting GPi while under a general anesthetic.

Patient Care: This retrospective analysis will demonstrate that implanting electrodes in GPi bilaterally in advanced PD patients while under general anesthesia can be safe, more pleasant/tolerable for the patient and clinically efficacious. In addition, UPDRS motor subset scores can be analyzed and concomitantly reviewed with actual electrode placement for further individualization and refinement of DBS therapy.

Learning Objectives: By the conclusion of this session, participants should be able to 1.) appreciate the effectiveness of “asleep” standardized GPi surgery with electrophysiological recording in PD patients 2.) Discuss in small groups surgeon's preference for intraoperative target confirmation strategies

References: Tomlinson et al. 2010, Williams et al. 2014