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

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.