Is Awake Deep Brain Stimulation Surgery Outdated? On the Importance of Intraoperative Microelectrode Recording and Macrostimulation

Aim: Deep brain stimulation (DBS) has become an established treatment for diverse neurological diseases. Nevertheless, the technique of lead implantation differs widely among functional neurosurgeons. During recent years, classical aids such as intraoperative microelectrode recording (MER) and macrostimulation (MS) in the awake patient were challenged. Our aim was to investigate the relevance of these techniques according to lead trajectory adjustment rates and comparing intraoperative response to stimulation between anatomically planned (PSP) and definite stimulation points (DSP), along with follow-up outcome.

Methods: We conducted a retrospective analysis of prospectively collected datasets of Parkinson’s disease (PD) patients that had bilateral lead placement in the subthalamic nucleus for DBS. The implantation was performed awake with MER and MS in all patients. Intraoperative motor outcomes between the stimulation sites were compared along with the lead trajectory adjustment rate. The outcome at 6 months according to the Unified PD Rating Scale-III (UPDRS-III), levodopa equivalent daily dose (LEDD), and DBS-related adverse events (AE) was analyzed.

Results: In 47 of 101 patients and 59 of 202 leads intraoperative lead adjustment was performed respectively. Twenty-nine percent of the leads were adjusted due to MS but only 3% solely due to MER results. The mean response to MS improved significantly between PSP and DSP (37.07 ± 2.18% vs 41.38 ± 2.15%, p < 0.001) with a more pronounced effect in initially poor responding electrodes (18.08 ± 3.78% vs 31.47 ± 2.78%, p < 0.001), leading to a number needed to treat of 9.6 per electrode. After 6 months, follow-up UPDRS-III (23.3 ± 1.1 vs 15.6 ± 0.8, p < 0.001) and LEDD (1262.3 ± 60.9 mg/d vs 487.7 ± 39.2 mg/d, p < 0.001) showed significant improvement. The optimal intraoperative stimulation site covered the active electrode contact in 87% of leads. Fifteen stimulation- or surgery-related AE occurred.

Conclusion: The use of MER and MS has an important influence on the intraoperative lead placement. The intraoperatively identified stimulation site corresponds to the chronically active contact. Poor DBS outcome is prevented in a subgroup of leads. Follow-up UPDRS-III results, LEDD reductions, and DBS-related AE correspond to previously published data.