Interfacing With NeuroTechnology to Expand Neural Throughput (INTENT)

The goal of this clinical trial is to evaluate the safety and preliminary efficacy of an implantable device that records and stimulates different areas of the brain to allow adults affected by disabling paralysis (see Eligibility for more details) to control and receive feedback from assistive devices.

Inclusion Criteria: * Complete or incomplete tetraplegia (quadriplegia), tetraparesis (quadriparesis), severe ataxia, or disabling motor impairments in both upper limbs, based on neurological exam. In addition, these motor impairments may be combined with severe motor-related speech impairment (dysarthria or anarthria), as in Locked In Syndrome (LIS) and amyotrophic lateral sclerosis (ALS), including the bulbar variant of ALS. * Clinical diagnosis must be established for the etiology of motor impairments, including brainstem stroke\*, traumatic spinal cord injury (SCI), or progressive and irreversible neuromuscular disease, including muscular dystrophy and motor neuron disease, including amyotrophic lateral sclerosis (ALS). \*Brain stem stroke is defined as an acute onset of neurological deficit with clinical features of brain stem or cerebellar dysfunction lasting more than 24 hours together with computed tomography (CT) or magnetic resonance imaging (MRI) evidence of ischemic infarction or parenchymal hemorrhage. * Candidates with traumatic spinal cord injury must have a complete or incomplete tetraplegia or tetraparesis (ASIA Impairment Scale A, B, C) with an injury level of C6 or higher. * Candidates with tetraplegia or tetraparesis from traumatic SCI and other non-progressive neurological disorders must have an upper extremity motor score (UEMS, ISNCSCI) of 7 or less in each of the upper extremities. Candidate must also have less than antigravity strength (\< 3) throughout the lower limbs. * Candidates with progressive conditions with shortened life expectancy, such as ALS, must have less than antigravity strength (\