An exoskeleton controlled by an epidural wireless brain-machine interface in a tetraplegic patient: a proof-of-concept demonstration.

BACKGROUND: Approximately 20% of traumatic cervical spinal cord injuries result in tetraplegia. Neuroprosthetics are being developed to manage this condition and thus improve the lives of patients. We aimed to test the feasibility of a semi-invasive technique that uses brain signals to drive an exoskeleton. METHODS: We recruited two participants at Clinatec research centre, associated with Grenoble University Hospital, Grenoble, France, into our ongoing clinical trial. Inclusion criteria were age 18-45 years, stability of neurological deficits, a need for additional mobility expressed by the patient, ambulatory or hospitalised monitoring, registration in the French social security system, and signed informed consent. The exclusion criteria were previous brain surgery, anticoagulant treatments, neuropsychological sequelae, depression, substance dependence or misuse, and contraindications to magnetoencephalography (MEG), EEG, or MRI. One participant was excluded because of a technical problem with the implants. The remaining participant was a 28-year-old man, who had tetraplegia following a C4-C5 spinal cord injury. Two bilateral wireless epidural recorders, each with 64 electrodes, were implanted over the upper limb sensorimotor areas of the brain. Epidural electrocorticographic (ECoG) signals were processed online by an adaptive decoding algorithm to send commands to effectors (virtual avatar or exoskeleton). Throughout the 24 months of the study, the patient did various mental tasks to progressively increase the number of degrees of freedom. FINDINGS: Between June 12, 2017, and July 21, 2019, the patient cortically controlled a programme that simulated walking and made bimanual, multi-joint, upper-limb movements with eight degrees of freedom during various reach-and-touch tasks and wrist rotations, using a virtual avatar at home (64·0% [SD 5·1] success) or an exoskeleton in the laboratory (70·9% [11·6] success). Compared with microelectrodes, epidural ECoG is semi-invasive and has similar efficiency. The decoding models were reusable for up to approximately 7 weeks without recalibration. INTERPRETATION: These results showed long-term (24-month) activation of a four-limb neuroprosthetic exoskeleton by a complete brain-machine interface system using continuous, online epidural ECoG to decode brain activity in a tetraplegic patient. Up to eight degrees of freedom could be simultaneously controlled using a unique model, which was reusable without recalibration for up to about 7 weeks. FUNDING: French Atomic Energy Commission, French Ministry of Health, Edmond J Safra Philanthropic Foundation, Fondation Motrice, Fondation Nanosciences, Institut Carnot, Fonds de Dotation Clinatec.

Do patients still require admission to an intensive care unit after elective craniotomy for brain surgery?

BACKGROUND: After elective craniotomy for brain surgery, patients are usually admitted to an intensive care unit (ICU). We sought to identify predictors of postoperative complications to define perioperative conditions that would safely allow ICU bypass. METHODS: This observational cohort study enrolled 358 patients admitted to neuro-ICU after elective intracranial procedures. Postoperative complications were defined as unexpected events occurring within 24 hours of surgery that required imaging or treatment for neurologic deterioration. RESULTS: Fifty-two patients were transferred postoperatively to neuro-ICU with sedation and mechanical ventilation. Of the remaining 306 patients subjected to an attempt to awake and extubate in the operating room, 26 (8%) developed 1 postoperative complication, primarily a new motor deficit, unexpected awakening delay, or subsequent deterioration in consciousness. Four intracerebral hematomas required surgical evacuation and each of these was detected within 2 hours after surgery. Predictors of postoperative complications included failure to extubate the trachea in operating room [odds ratio 61.8; 95% confidence interval (CI) 12.2-312.5], and, to a lesser extent, a duration of surgery of more than 4 hours (odds ratio 3.3; 95% CI 1.4-7.8), and lateral positioning of the patient during the procedure (odds ratio 2.8, 95% CI 1.2-6.4). CONCLUSIONS: Our results encourage prospectively testing the hypothesis that patients with immediate, successful tracheal extubation after elective craniotomy for brain surgery, with a surgical duration of less than 4 hours in a nonlateral position could be monitored safely in the postanesthesia care unit before being discharged to a neurosurgical ward.