Influence of Anesthesia and Clinical Variables on the Firing Rate, Coefficient of Variation and Multi-Unit Activity of the Subthalamic Nucleus in Patients with Parkinson’s Disease

Abstract

Background: Microelectrode recordings (MER) are used to optimize lead placement during subthalamic nucleus deep brain stimulation (STN-DBS). To obtain reliable MER, surgery is usually performed while patients are awake. Procedural sedation and analgesia (PSA) is often desirable to improve patient comfort, anxiolysis and pain relief. The effect of these agents on MER are largely unknown. The objective of this study was to determine the effects of commonly used PSA agents, dexmedetomidine, clonidine and remifentanil and patient characteristics on MER during DBS surgery. Methods: Data from 78 patients with Parkinson’s disease (PD) who underwent STN-DBS surgery were retrospectively reviewed. The procedures were performed under local anesthesia or under PSA with dexmedetomidine, clonidine or remifentanil. In total, 4082 sites with multi-unit activity (MUA) and 588 with single units were acquired. Single unit firing rates and coefficient of variation (CV), and MUA total power were compared between patient groups. Results: We observed a significant reduction in MUA, an increase of the CV and a trend for reduced firing rate by dexmedetomidine. The effect of dexmedetomidine was dose-dependent for all measures. Remifentanil had no effect on the firing rate but was associated with a significant increase in CV and a decrease in MUA. Clonidine showed no significant effect on firing rate, CV or MUA. In addition to anesthetic effects, MUA and CV were also influenced by patient-dependent variables. Conclusion: Our results showed that PSA influenced neuronal properties in the STN and the dexmedetomidine (DEX) effect was dose-dependent. In addition, patient-dependent characteristics also influenced MER.

Impact of Procedural Sedation on the Clinical Outcome of Microelectrode Recording Guided Deep Brain Stimulation in Patients with Parkinson’s Disease

“…Many centers employing MER-based DBS surgery prefer to perform the procedure under awake conditions to obtain reliable neurophysiological mapping and enable intraoperative test stimulation to observe the motor improvement and potential side-effects. In our recent work we have shown that anesthetic agents alter the firing characteristics of the STN, which is consistent with data obtained from previous studies [ 10 , 11 , 12 , 13 , 14 , 15 ]. These findings provide important arguments to avoid the use of anesthetic drugs during DBS surgery.…”

“…Dexmedetomidine and clonidine produce dose-dependent sedation, analgesia, and anxiolysis [ 33 , 34 ]. Contrary to most sedatives, α 2 agonists do not have a direct gamma-aminobutyric acid (GABA)-ergic effect and so have a less profound effect on MER compared to the GABA-ergic drugs [ 10 , 32 ]. Remifentanil, acting mainly on the mu opioid receptor agonist, has limited effects on STN neuronal activity at low doses, though a recently published report showed a significant reduction in STN neuronal activity with doses above 0.1 µg/kg/min [ 10 , 15 ].…”

“…Intraoperative localization of the dorsolateral STN can be achieved by MER. In a previous study, we examined the effect of PSA with dexmedetomidine, clonidine, and remifentanil on neuronal activity during STN DBS [ 10 ]. We observed a dose-dependent decrease in multi-unit activity associated with dexmedetomidine.…”

“…MER was sampled for around 30 s at each depth. We defined the position of the dorsal border of the STN as the point at which a sudden increase in baseline activity and increase in discharge rate with a rhythmic burst activity was detected [ 10 ]. The electrode signals were sampled at 20 or 25 kHz, bandpass-filtered online (V3.15; Inomed Medizintechnik GnmH, Emmendingen, Germany), and saved for offline analysis.…”

Special Issue: Trends in Clinical Deep Brain Stimulation

“…Their literature review forms the basis to initiate non-inferiority studies to confirm the safety and efficacy of DBS surgeries under general anesthesia. In our electrophysiology study, we studied the effects of procedural sedation and analgesia (PSA) on MER [ 9 ]. One of our main findings was that dexmedetomidine reduces the power of the multi-unit activity (MUA) in a dose-dependent matter.…”