Experience and safety of intraoperative Neuropixels: a case series of 56 patients

The Neuropixels probe, a high-density silicon microelectrode array, has been a transformative tool for extracellular recording of large numbers of single neurons across animal models. Traditional tungsten microelectrodes available for clinical neurophysiology typically only record 1-2 neurons at a given time. Human intraoperative Neuropixels recording increases access to single-neuron spiking by an order of magnitude and is poised for rapid adoption. The authors' objective was to determine the safety and yield of intraoperative Neuropixels for large-scale simultaneous neuronal recordings.

This study examined safety and the success rate from the authors' case series of 56 consecutive patients who participated in Neuropixels intraoperative recording at the authors' institution. All participants were undergoing craniotomy for resection for various pathologies (intractable epilepsy [n = 33], tumor [n = 19], and vascular lesion [n = 4]). Among these craniotomies for resection, the vast majority were done under monitored anesthesia care with awake mapping (50/56). In all cases, a Neuropixels probe was placed into tissue that was resected, allowing histology to be recovered from a subset of cases. All intraoperative probe fractures, cases that did not yield any putative single-neuron recordings, and postoperative complications are reported here.

No medical or neurological complications, surgical complications, 30-day readmissions, or deaths were observed. Overall, probe fractures were rare (n = 3) and all occurred within the first 6 cases. All fractures occurred at the base of the probe shank and were easily recovered. In recovered acute histology from 1 case, the histological evidence of insertion was minimal and proportional to the 70 mm × 132 mm cross-sectional area. In terms of yield, most cases had good neuronal yield, with only 9 (16.1%) cases that did not result in at least 1 putative single-neuron recording, with the etiology of failure being attributable to either electrical noise (6/9) or there being no detectable spikes (3/9). All cases that did not result in at least 1 putative single-neuron recording occurred within the first 20 cases, suggesting significant improvements in the learning curve and techniques for high-yield and safe intraoperative recordings.

Intraoperative Neuropixels recordings can be done safely for large-scale neuronal recordings. Over time, the authors experienced no probe fractures and improved success rate of microelectrode recording. Further measures to float the electrodes, limit forces on the probe, and prevent probe fracture during insertion may improve the yield. Neuropixels has tremendous potential for future applications in clinical functional mapping over traditional microelectrodes.