Inclusion Criteria:
1. Age between 22 and 65 years of age.
2. Tetraplegia due to a static identified disease process (spinal cord injury or stroke) that prevents functional activity of the upper extremity.
3. Onset of tetraplegia at least 12 months prior to enrollment, with stability of weakness for at least 3 months.
4. Must have sufficiently intact cortical motor structures and stable medical prognoses to be able to perform the BCI control tasks for at least one year. .
5. Ability to speak understandably or, if unable to speak understandably, a reliable means of yes/no communication.
6. Life expectancy greater than 13 months.
7. Chronic care environment within a three-hour drive of the study site or the ability to temporarily relocate to a residence within a three-hour drive of the study site.
8. Willingness to remain available (geographically stable) for at least 13 months after enrollment, including maintenance of the evaluation schedule, frequent visits to the Investigator's office, and visits of Sponsor personnel to the subject's chronic care environment.
9. Willingness to allow videotape recordings to be made of the surgical procedure (for training purposes) and portions of the Feasibility Evaluations.
10. A stable psychosocial support system.
11. Scalp devoid of any lesions or skin breakdown precluding surgery.
12. Ability to provide voluntarily informed consent in accordance with Site institutional policies and willingness to release of Personal Health Information from the date of the injury or disease onset through the completion of the clinical Study.
13. Availability of caregivers capable of providing the necessary daily care of the subject's skin and electrode externalization sites.
Exclusion Criteria:
1. Presence of an implanted stimulator such as a pacemaker, spinal cord stimulator, cochlear implant, deep brain stimulator, vagus nerve stimulator, or defibrillator. (Implanted intrathecal pumps for pain or spasticity, cough implants, or diaphragmatic pacers are not excluded.)
2. Any active infection(s) or unexplained fever.
3. Active cancer within the one year prior to enrollment (other than adequately treated basal or squamous cell skin cancer).
4. Uncontrolled insulin-dependent diabetes mellitus.
5. Hydrocephalus requiring diversion of cerebrospinal fluid.
6. Autonomic dysreflexia within three months prior to enrollment that required urgent evaluation and pharmacologic intervention prescribed by a physician.
7. Seizure within 3 months prior to enrollment.
8. Any medical condition expected to require routine MRI imaging or subjects with contraindication(s) to MRI.
9. History of osteomyelitis or skin disorder that causes excessive skin sloughing, lesions or breakdown of the scalp.
10. Chronic use of medications such as sedatives that may significantly retard motor coordination and cognitive ability.
11. Chronic use of anticoagulant medications. (Subjects receiving prophylactic anticoagulation solely for the prevention of deep venous thrombosis are not excluded, but must be able to have their prophylactic anticoagulation suspended temporarily for the surgical procedure and immediate post-operative period.)
12. Chronic use of steroids or immunosuppressant therapy.
13. Active treatment for another serious medical, neurological or psychiatric disease or disorder that could seriously affect the subject's ability to undergo surgical implantation of the electrodes or participate in the testing sessions.
14. Pregnant, lactating, or of childbearing age and not using adequate birth control.
15. Active consumption of more than 1 alcoholic beverage per day.
16. Suicide attempt within 12 months prior to enrollment.
17. History of myocardial infarction or unstable cardiac arrhythmia.
18. Enrollment in any other investigational study that may interfere with the time commitments required of this study.
19. Subjects who are immunocompromised.
20. Subjects who require ongoing diathermy or ultrasound treatments.
21. Subjects with severe upper extremity joint contractures or Ashworth spasticity scores of 4 that would limit functional movements.
22. Subjects who have contraindication(s) to CT.
23. Subjects who are ventilator dependent. Subjects who are sometimes ventilator-assisted (for example, while sleeping) are not excluded.
