Innovative Brain-Computer Interface for People With Spinal Cord Injury

Spinal Cord Injury (SCI) results in motor impairments in body parts innervated by the spinal cord below the site of the lesion. In addition to loss of leg movements, individuals with high cervical SCI experience significant impairments in arm and hand function (tetraplegia), impacting their access to digital devices, with obvious consequences for their ability to communicate, participate in society and the workforce, autonomously manage their life, and benefit from the entertainment options digital devices offer these days. Current assistive technologies (AT) for control over digital devices, such as voice control, eye-tracking, and head- or mouth-controlled devices, are often unintuitive, slow, limited in functionality, aesthetically unattractive, and they often interfere with regular movement or speech. An effective Brain-Computer Interface (BCI) would enable individuals with SCI to use movement-related neural signals to directly control digital devices, taking away the disadvantages of current AT. This would dramatically improve their quality of life.

The Brain InterChange from CorTec is an active implantable medical device for measurement of neuronal activity and electrical stimulation of the human nervous system, comprising an internal and an external unit. The internal unit consists of a small high-density ECoG grid with 32 contacts placed subdurally and a connected implantable amplifier/transmitter device that is placed subcutaneously. The external unit comprises a headpiece, for power transmission to the internal unit, a communication unit, that receives the data transmitted from the internal unit and controls the power transmission, and a USB cable, that connects the communication unit to the computer that has software to process and translate the brain data to a means of digital device control for SCI patients with custom in-house software developed during this study.

The BCI system also allows to provide users with somatosensory feedback about their motor attempts (in addition to the visual feedback), by delivering electrocortical stimulation (ECS) to the somatosensory regions of the brain. As such, the aim is to generate a more natural relation between intent (movement attempt of a body part) and effect (sensation in the same body part), which is expected to lead to fast training and accurate BCI performance.

Inclusion criteria

• Clinical diagnosis of SCI at the cervical level C4 or higher (C1-C4)
• Complete or incomplete tetraplegia (quadriplegia) or tetraparesis (quadriparesis), i.e., level A or B at the American Spinal Injury Association (ASIA) Impairment Scale
• Meeting surgical safety criteria, including surgical clearance by the study physicians
• Meeting (neuro)psychological evaluation criteria
• Ability to communicate reliably, via speech or other means
• Willingness and ability to provide informed consent.
• Lives within reasonable distance from UMC Utrecht
• Participant consents to the study and still wishes to participate at the time of the study.
• Vision and hearing largely intact.
• For candidates who are not currently receiving invasive ventilation, and who have current respiratory problems (e.g., at night), there should be a clear and confirmed desire to proceed with tracheostomy ventilation whenever that would become necessary.

Exclusion criteria

• Having a spinal cord injury with a degenerative or progressive etiology.
• Having evident swallowing problems.
• Having a significant current or recent anxiety disorder or depression or cognitive impairment that would interfere with obtaining informed consent or fully participating in study activities.
• Medical conditions contraindicating surgery of a chronically implanted device or that could interfere with study participation (for example active infections, unexplained fever, existing scalp lesions or skin breakdown, osteomyelitis, hepatitis, any autoimmune disease/disorder, epilepsy, skin disorders causing excessive skin sloughing or poor wound healing, cranioplasty, significant cardiovascular, metabolic, or renal impairments, chronic oral or intravenous use of steroids or immunosuppressive therapy, active cancer within the past year or requires chemotherapy, uncontrolled autonomic dysreflexia within the past 3 months, hydrocephalus with or without an implanted ventricular shunt or a medical contraindication to stop anti-coagulant medications during surgery, or a catabolic state, or strong and frequent spasms)
• Presence of pre-surgical findings in anatomical, functional, and/or vascular neuroimaging that makes achieving implant locations too challenging or incompatible with desired risk levels.
• Inability to undergo MRI for pre-implantation evaluation, for example due to the presence of implanted devices that are incompatible with MRI, which may include pacemakers, cardiac defibrillators, spinal cord or vagal nerve stimulators, deep brain stimulators, and cochlear implants or devices that deliver diaphragm pacing.
• Anticipated need for MRI after implantation of the Brain InterChange system.