Operant Conditioning of the Wrist Extensor Motor Evoked Potential to Target Corticospinal Plasticity and Upper Limb Motor Recovery After Cervical Spinal Cord Injury
Trial Snapshot
- Phase
- Phase 1
- Status
- Recruiting
- Enrollment
- 11
- Locations
- 1
- Primary Endpoint
- Extensor Carpi Radialis (ECR) Motor Evoked Potential (MEP) amplitude
Study Overview
Brief Summary
Individuals with chronic cervical spinal cord injury will complete a 10-week training protocol where participants receive non-invasive brain stimulation and feedback on the size of the corresponding muscle response (wrist extensor).
Investigators will assess the impact of the brain stimulation training on 1) the brain-to-spinal cord-to-muscle connection and 2) motor functions of the arm and hand. Also, brain and spine magnetic resonance imaging will be collected before and after the training. The imaging measurements will tell investigators about how spinal damage, brain function, and brain structure relate to motor presentation and the response to the training.
Detailed Description
Corticospinal function is essential in generating and controlling voluntary movements. Cervical spinal cord injury (SCI) disrupts corticospinal connections, therefore, often results in weak voluntary activation of muscles and impaired motor control in the upper limb (UL). An intervention that improves corticospinal function could enhance motor function recovery; however, such interventions are not currently readily available to people with incomplete SCI. Operant up-conditioning of a motor evoked potential (MEP) to transcranial magnetic stimulation (non- invasive brain stimulation) that can increase corticospinal excitability for the targeted muscle may be able to fill this gap. The overarching hypothesis is that targeting beneficial plasticity to the corticospinal pathway can change the brain and spinal cord and improve upper limb motor function in people with chronic cervical SCI. As initial steps towards testing this, the proposed project aims to apply MEP operant up-conditioning in the wrist extensor of the affected UL, improve corticospinal activation of the wrist extensor, and thereby improve motor functions in which the wrist is involved in individuals with cervical SCI. Recent studies suggest that MEP up- conditioning is feasible and can increase MEP size that reflects corticospinal excitability. Building on those studies, this project will examine the effects of wrist extensor MEP operant up-conditioning in people with chronic cervical SCI. Individuals with weak wrist extension due to incomplete cervical SCI will undergo a standard MEP up-conditioning protocol (6 baseline and 24 up-conditioning sessions over 10 weeks). Before and after the intervention period, neurophysiological measurements, clinical and functional assessments, neuroimaging of the spinal cord and brain will be performed. The results will facilitate development and clinical translation of MEP operant conditioning as a novel non-invasive therapy that may complement other therapies and further enhance motor function recovery in people with SCI or other disorders.
Study Design
- Study Type
- Interventional
- Allocation
- Na
- Intervention Model
- Single Group
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •Adult (≥18 yrs old)
- •A history of injury to spinal cord at or above C6
- •>6 months post SCI
- •Weak wrist extension at least unilaterally
- •Expectation that current medication will be maintained without change for at least 3 months. Stable use of anti-spasticity medication (e.g., baclofen, diazepam, tizanidine) is accepted.
Exclusion Criteria
- •Motoneuron injury
- •Medically unstable condition
- •Cognitive impairment
- •A history of epileptic seizures
- •Metal implants in the cranium
- •Implanted biomedical device in or above the chest (e.g., a cardiac pacemaker, cochlear implant)
- •Extensive use of functional electrical stimulation to the arm on a daily basis
- •Pregnancy (due to changes in posture and potential medical instability)
- •Contraindications to MRI
- •No measurable MEP elicited in the ECR
- •Unable to produce any voluntary ECR EMG activity
Arms & Interventions
Operant Up-Conditioning of the Motor Evoked Potential
The intervention consists of approximately 6 baseline sessions and 24 conditioning sessions at a pace of 3 sessions/week, 1-2 hour duration, over 10 weeks. At the beginning of each session, electromyographic (EMG) recording and nerve stimulating electrodes are placed over the arm. In all sessions, motor evoked potentials (MEPs) will be measured while the sitting subject provides a pre-set level of background muscle EMG with joint angles fixed. In 225 control trials of each baseline sessions and the first 20 trials of conditioning sessions the subject will receive no feedback as to MEP size (i.e., control MEPs). In 225 conditioning trials of each conditioning session, the subject will be encouraged to increase the target muscle MEP, and will receive immediate feedback as to whether MEP size was above a criterion (i.e., whether the trial was a success).
Intervention: Up-conditioning of the wrist extensor motor evoked potential (Behavioral)
Outcomes
Primary Outcomes
Extensor Carpi Radialis (ECR) Motor Evoked Potential (MEP) amplitude
Time Frame: Reported as an average of the 6 baseline sessions (over weeks 1-2) and average of the last 6 conditioning sessions (over weeks 8-10)
Size of MEP elicited at the fixed stimulus intensity (e.g., \~ 10-15% maximum stimulator output) of transcranial magnetic stimulation (TMS) above motor threshold) (in %M wave maximum amplitude)
Secondary Outcomes
- Maximum Voluntary Contraction - ECR(Reported as an average of the 6 baseline sessions (over weeks 1-2) and average of the last 6 conditioning sessions (over weeks 8-10))
- Capabilities Upper Extremity Test (CUE-T)(Baseline, after the 24th conditioning session (typically within 1 week), 1 month and 3 months post)
- Graded and Redefined Assessment of Strength, Sensibility, and Prehension (GRASSP)(Baseline, after the 24th conditioning session (typically within 1 week), 1 month and 3 months post)
- Spinal Cord Independence Measure (SCIM III)(Baseline, after the 24th conditioning session (typically within 1 week), 1 month and 3 months post)
- Life Situation Questionnaire Revised (LSQ-R)(Baseline, after the 24th conditioning session (typically within 1 week), 1 month and 3 months post)
Investigators
Allison Lewis
Post-doctoral Scholar, Principal Investigator
Medical University of South Carolina