Brain-controlled Spinal Cord Stimulation in Patients With Spinal Cord Injury

In a current first-in-human study, called Stimulation Movement Overground (STIMO, NCT02936453), Epidural Electrical Stimulation (EES) of the spinal cord is applied to enable individuals with chronic severe spinal cord injury (SCI) to complete intensive locomotor neurorehabilitation training. In this clinical feasibility study, it was demonstrated that EES results in an immediate enhancement of walking function, and that when applied repeatedly as part of a neurorehabilitation program, EES can improve leg motor control and trigger neurological recovery in individuals with severe SCI to a certain extent (Wagner et al. 2018). Preclinical studies showed that linking brain activity to the onset and modulation of spinal cord stimulation protocols not only improves the usability of the stimulation, but also augments neurological recovery. Indeed, rats rapidly learned to modulate their cortical activity in order to adjust the amplitude of spinal cord stimulation protocols. This brain-spine interface allowed them to increase the amplitude of the movement of their otherwise paralyzed legs to climb up a staircase (Bonizzato et al. 2018). Moreover, gait rehabilitation enabled by this brain-spine interface (BSI) augmented plasticity and neurological recovery. When EES was correlated with cortical neuron activity during training, rats showed better recovery than when training was only supported by continuous stimulation (Bonizzato et al. 2018). This concept of brain spine-interface was validated in non-human primates (Capogrosso et al. 2016). Clinatec (Grenoble, France) has developed a fully implantable electrocorticogram (ECoG) recording device with a 64-channel epidural electrode array capable of recording electrical signals from the motor cortex for an extended period of time and with a high signal to noise ratio the electrical signals from the motor cortex. This ECoG-based system allowed tetraplegic patients to control an exoskeleton (ClinicalTrials.gov, NCT02550522) with up to 8 degrees of freedom for the upper limb control (Benabid et al. 2019). This device was implanted in 2 individuals so far; one of them has been using this system both at the hospital and at home for more than 3 years. We hypothesize that ECoG-controlled EES in individuals with SCI will establish a direct bridge between the patient's motor intention and the spinal cord below the lesion, which will not only improve or restore voluntary control of leg movements, but will also boost neuroplasticity and neurological recovery when combined with neurorehabilitation.