Neuropathological effects of chronically implanted, intracortical microelectrodes in a tetraplegic patient

Abstract Objective. Intracortical microelectrode arrays (MEA) can be used as part of a brain–machine interface system to provide sensory feedback control an artificial limb assist persons with tetraplegia. Variability in functionality electrodes has been reported but few studies humans have examined the impact chronic brain tissue responses revealed postmortem on electrode performance vivo. Approach. In tetraplegic man, recording MEAs were implanted into anterior intraparietal area and Brodmann’s 5 (BA5) posterior parietal cortex stimulation array was BA1 primary somatosensory (S1). The participant expired from unrelated causes seven months after MEA implantation. underlying two three devices processed for histology electrophysiological recordings assessed. Main results. Recordings neuronal activity obtained all despite meningeal encapsulation. However, S1 had greater encapsulation, yielded lower signal quality than other failed elicit percepts electrical stimulation. Histological examination tissues BA5 implant sites localized leptomeningeal proliferation fibrosis, lymphocytic infiltrates, astrogliosis, foreign body reaction around electrodes. site showed focal cerebral microhemorrhages vascular ectasia. damage including recanalization, loss, extensive subcortical white matter necrosis. response at included hemorrhagic-induced injury suggesting likely mechanism reduced function implant. Significance. Our findings are similar those animal intracortical implants suggest that disruption microhemorrhage during device implantation important contributors overall individual should topic future development mitigate responses. Neurosurgical considerations also discussed.