Objective monitoring of tremor and bradykinesia during DBS surgery for Parkinson disease

Abstract

High-frequency subthalamic nucleus deep brain stimulation (STN-DBS) is an established treatment for patients with advanced Parkinson disease (PD). To date, intraoperative monitoring of parkinsonian symptoms, such as tremor and bradykinesia, is largely based on subjective strategies. We conducted a pilot study to evaluate short-term intraoperative outcomes of unilateral macrostimulation of the STN-DBS in PD patients using a neuromotor symptom registration device (CATSYS 2000 System). We studied 12 consecutive PD patients who received staged unilateral STN-DBS implants and 10 male control subjects free of neurologic deficits using a simple portable system with two sensors: a tremor pen and a touch recording plate. Results revealed excellent test-retest reliability for postural tremor in control subjects. PD patients were evaluated preoperatively during "off" state and intraoperatively for rest, postural tremor intensity, and frequency of finger tapping. Comparisons between premacrostimulation and postmacrostimulation were made using analysis of variance for repeated measures. Electronic rest tremor registration revealed a mean improvement of x 12.5 in tremor intensity measurements in the stimulated/contralateral side (p = 0.002). An overall x 3.8 improvement was registered on the nonstimulated/ipsilateral side. Significant improvements after STN-DBS were also recorded for postural tremor and frequency of finger tapping. Using a noninvasive, simple, and sensitive electronic recording method of intraoperative motor symptom registration, we were able to supplement short-term clinical observation by objectively quantifying the characteristics of tremor and finger tapping in response to subthalamic nucleus deep brain macrostimulation.