Do the effects measured by intraoperative and postoperative STN macrostimulation in Parkinson's disease match?

The aim of our study was to compare the results obtained by intraoperative and postoperative subthalamic nucleus (STN) macrostimulation in Parkinson's disease (PD). One hundred three PD patients implanted with bilateral STN stimulation were included. The thresholds for efficacy and side effects (motor contraction; paresthesias; oculomotor signs) observed on the same trajectory and at the same depth during the intraoperative evaluation and the first postoperative setting of STN stimulation parameters were collected. The level of improvement was divided into four categories depending on the degree of rigidity reduction: 0: no effect, A (mediocre efficacy): 20-50%, B (good efficacy): 60-100%, LL: lesion-like effect (disappearance of rigidity after implantation). Efficacy of STN stimulation was analyzed in 83 patients for a total of 664 contacts. For the best effects (B, LL), the results obtained in the operative room were concordant with those of the postoperative evaluation for 81% of the contacts. For the mediocre effects (A) and absence of efficacy, the results were only concordant in 20%. Side effects were analyzed in 103 patients for a total of 824 contacts. In 35% of the tested contacts paresthesias that were absent during surgery were observed postoperatively. This discrepancy was of 17% for the motor and of 10% for oculomotor side effects. Differences between the type of electrodes used, the stimulation parameters employed and the conditions of the assessment could explain these discrepancies.