STN stimulation in general anaesthesia: evidence beyond 'evidence-based medicine'

Awake surgery is regarded mandatory for optimal electrode implantation into the subthalamic nucleus (STN) for deep brain stimulation (DBS) in Parkinson's disease (PD). However, this is questionable since general anaesthesia (GA) does not preclude intraoperative microrecordings and clinical evaluation of, for example, current spread to the corticospinal tract. In addition, even in the awake state, clinical testing is not without limitations. We report on intra- and postoperative findings in 11 patients suffering from advanced PD who were operated under GA (propofol/remifentanil). The activity of STN neurons under GA was characterized by excessive burst discharges that differed fundamentally from the irregular tonic patterns observed in the STN of awake patients. In all patients, we obtained improved motor symptoms and reduced levodopa-induced dyskinesias and motor fluctuations, which was associated with a reduction in the levodopa equivalent daily dose. Therapeutic DBS was not limited by current spread to the corticospinal tract in any of the patients. The trajectories chosen for electrode implantation in GA compared well to awake surgery. Our results indicate that STN surgery in GA can be performed in a safe manner. It can be offered to anxious patients, and represents a viable option when awake surgery bears a risk for the patient.