Investigation on the Cortical Communication System

Locked-In Syndrome (LIS) is a neurological condition in which communication is impossible, or profoundly impaired, due to loss of speech and other motor functions, while cognition is intact. The most distressing aspect of LIS is the inability to initiate and sustain communication. Existing assistive technologies (ATs) fall short of a remedy. An effective brain-computer interface (BCI) for communication would dramatically improve quality of life for people with LIS. Electrocorticography (ECoG) with non-penetrating subdural electrodes is a promising implantable approach for BCI. In this study, the "CortiCom system" (which stands for Cortical Communication) wil be used. This system combines an implantable assembly, consisting of four small high-density (HD) ECoG grids on the hand and speech areas of the motor cortex, totalling 128-channels, and a transcutaneous pedestal connector, with an external data acquisition system. With the CortiCom system the overall hypothesis will be tested that broader and more densely spaced ECoG electrodes can better tap into the spatial detail of the organization of the sensorimotor cortex in order to expand BCI function and restore meaningful communication in LIS. Specifically, the CortiCom system will substantially increase the number and density of electrodes recording from the brain to determine whether more sophisticated control and communication can be achieved with more comprehensive and detailed spatial sampling of representations for movements of the hand/arm and of speech articulators. Clinically meaningful outcomes for people with LIS include rapid reestablishment, and stable maintenance of communication, at minimum consisting of a caregiver call-button and menu selections.

Objective:

Primary Objective 1: Demonstrate efficient and stable control of essential BCI functions (initiate BCI, call caregiver, and menu selections). Primary Objective 2: Demonstrate efficient and stable operation of a keyword-based speech BCI.

Intervention:

Participants will be implanted with an assembly consisting of HD-ECoG electrode grids over the sensorimotor cortex and a transcutaneous pedestal connector. The assembly will be connected with an external data acquisition system during recordings. During recordings, feedback about the neural signals is given via a visual display and participants are trained to employ the neural signals for fast brain-based communication. Upon adequate performance, participants can independently (i.e., without researcher involvement) train with and use the system at home for validation of performance and usability. After implantation, participation has a duration of 1 year, with a possibility of extension.

Inclusion criteria

• 18-70 years
• Clinical diagnosis of locked-in state state or likelihood of soon progressing into LIS (within an estimated 2 years), caused by traumatic brain injury, brainstem stroke, neurodegenerative disease, neuromuscular disease or another cause
• • Current or imminent complete or incomplete tetraplegia (quadriplegia) or tetraparesis (quadriparesis)
• • Current or imminent motor-related speech impairment (dysarthria or anarthria)
• Either receiving tracheostomy invasive ventilation, or having a stable and adequate respiratory situation without respiratory support, allowing for safe intubation, mechanical ventilation and detubation during surgery according to the involved clinicians, and, if relevant (e.g., in case of a progressive condition), in combination with a confirmed desire to receive tracheostomy invasive ventilation when that becomes necessary
• Meeting surgical safety criteria, including surgical clearance by the study physicians
• Meeting (neuro)psychological evaluation criteria
• Ability to communicate reliably, such as through eye movement
• Willingness and ability to provide informed consent
• Lives within reasonable distance from University Medical Center Utrecht
• Participant consents to the study and still wishes to participate at the time of the study
• Vision and hearing largely intact

Exclusion criteria

• Performance on formal neuropsychological testing that indicates a significant current or recent psychiatric disorder, cognitive or behavioral 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)
• 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
• Anticipated need for MRI after implantation of the CortiCom assembly