Long-term directional deep brain stimulation: Monopolar review vs. local field potential guided programming.

ABSTRACT

BACKGROUND: Directional subthalamic stimulation in Parkinson's disease can increase stimulation threshold for adverse effects and widen the therapeutic window. However, selection of programming settings is time consuming, requiring a thorough monopolar clinical review. To overcome this, programming may be guided by intraoperatively recording local field potential beta oscillations (13-35 Hz). OBJECTIVES: 1) Evaluate whether the power of beta oscillations recorded intraoperatively can predict the clinically most effective directional contacts; and 2) assess long-term directional stimulation outcomes between patients programmed based on clinical monopolar review and patients programmed based on beta activity. METHODS: We conducted a non-randomized, prospective study with 24 Parkinson's disease patients divided into two groups. In group A (14 patients, 2016-2018), we investigated whether beta activity in the directional contacts correlated with clinical efficacy. Stimulating parameters were selected according to clinical monopolar review and mean follow-up was 27 months. In group B (10 patients, 2018-2019), stimulating parameters were selected according to beta activity and mean follow-up was 13 months. RESULTS: Neurophysiological results showed a strong correlation between clinical efficacy and the low-beta sub-band. Contacts with highest beta peaks increased the therapeutic window by 25%. Selecting the two contacts with highest beta peaks provided an 82% probability of selecting the best clinical contact. Clinical results showed similar improvements in group A (motor score, 72% reduction; levodopa-equivalent daily dose, 65% reduction) and B (72% and 63% reduction, respectively), maintained at long-term follow-up. CONCLUSIONS: Our results validate the long-term efficacy of directional stimulation guided by intraoperative local field potential beta oscillations.