The goal of this study is to test the effects of non-invasive electrical stimulation of the spinal cord (called transcutaneous spinal cord stimulation, or tSCS) on arm and hand movement in people with motor impairments after a traumatic brain injury (TBI). Specifically, tSCS will be delivered using adhesive electrode pads placed on the skin over the upper back. The research team will measure how tSCS affects strength, movement control and muscle spasticity using different tests. Results of this study will help develop future treatments using an implanted (invasive) form of spinal cord stimulation to improve arm and hand function, helping people with TBI become more independent and improve their quality of life.
The main goal of this study is to assess the immediate effects of cervical transcutaneous spinal cord stimulation (tSCS) on arm and hand motor functions after traumatic brain injury (TBI). Specifically, the investigators will assess the immediate effects of tSCS across four different axes: arm and hand strength, arm motor control, joint synergies and spasticity. The study hypothesis is that tSCS can immediately facilitate voluntary motor output of upper limb muscles by modulating residual descending drive to spinal motoneurons in TBI individuals. In this approach, tSCS targets large-diameter sensory fibers projecting onto motor neuron pools of upper limb muscles. Thus, by modulating the activity of these sensory fibers, the investigators hypothesize that tSCS can immediately increase the excitability of motoneurons receiving residual supraspinal input during movement execution. Upon completion of this study, the investigators expect to build foundational evidence supporting the use of invasive (e.g. epidural spinal cord stimulation) and non-invasive SCS (tSCS) to improve upper limb motor function in individuals affected by chronic motor impairments after TBI. These results will lay the groundwork for future studies aimed at developing SCS neuroprosthetic devices.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
14
All participants enrolled in this group will receive non-invasive transcutaneous electrical stimulation of the cervical spinal cord (tSCS) while performing strength, spasticity and motor control assessment tasks. Researchers will assess the immediate effects of tSCS (within the same experimental session) on arm and hand movements in individuals with motor impairments caused by traumatic brain injury.
University of Pittsburgh
Pittsburgh, Pennsylvania, United States
Strength
Isometric maximum voluntary contraction (MVC) force of shoulder flexion, shoulder extension, elbow flexion, elbow extension, and hand grip under transcutaneous spinal cord stimulation ON and OFF conditions. MVC force will be compared across transcutaneous spinal cord stimulation ON and OFF conditions within the same experimental session.
Time frame: Immediate (tSCS ON vs tSCS OFF condition within the same experimental session)
Spasticity
Spasticity will be measured using the Modified Ashworth Scale (MAS) for the following muscle groups under transcutaneous spinal cord stimulation ON and OFF conditions: shoulder flexors, shoulder extensors, shoulder abductors, shoulder adductors, elbow flexors, elbow extensors, wrist pronators, wrist supinators, wrist flexors, wrist extensors, and finger flexors/extensors. The MAS is a 0-4 ordinal scale that quantifies resistance to passive stretch as a measure of spasticity, with lower scores indicating minimal spasticity and higher scores indicating marked spasticity. The MAS scores will be summed across all muscle groups to create an overall metric quantifying spasticity. MAS scores will be compared across transcutaneous spinal cord stimulation ON and OFF conditions within the same experimental session.
Time frame: Immediate (tSCS ON vs tSCS OFF condition within the same experimental session)
Movement smoothness
An exoskeleton robot (KINARM) will be used to assess arm movement smoothness during two-dimensional (2D) reaching tasks under transcutaneous spinal cord stimulation ON and OFF conditions. Movement smoothness will be quantified using log-dimensionless jerk of the hand velocity. Log-dimensionless jerk will be compared across transcutaneous spinal cord stimulation ON and OFF conditions within the same experimental session.
Time frame: Immediate (tSCS ON vs tSCS OFF condition within the same experimental session)
Joint velocity
An exoskeleton robot (KINARM) will be used to assess arm joint velocity during two-dimensional (2D) reaching tasks under transcutaneous spinal cord stimulation ON and OFF conditions. Arm joint velocity will be quantified as the ratio between the time required to move the arm from an initial position to a final target and the distance between the positions (m/s). Arm joint velocity will be compared across transcutaneous spinal cord stimulation ON and OFF conditions within the same experimental session.
Time frame: Immediate (tSCS ON vs tSCS OFF condition within the same experimental session)
Discomfort/Pain
Discomfort and/or pain experienced by participants during transcutaneous spinal cord stimulation will be assessed using a self-reported 0-10 scale, where low values indicate low discomfort/pain, and high values indicate high discomfort/pain.
Time frame: Immediate (while tSCS is ON)
Join Synergies
The "movement combining synergies" and "movement out-of-synergies" subcomponents of the Fugl-Meyer Assessment (FMA) for upper extremity motor function will be used to quantify joint synergies under transcutaneous spinal cord stimulation ON and OFF conditions. The Fugl-Meyer Assessment (FMA) is a performance-based impairment index designed to evaluate upper extremity motor function in individuals with post-stroke hemiparesis. The FMA for upper extremity motor function consists of 33 items, each scored with 0-2 points (0 = cannot perform task, 2 = fully performs task), resulting a maximum score of 66 points . For this study, the subscores from the 'movement combining synergies' and 'movement out-of-synergies' components will be summed to quantify changes in joint synergies. FMA subscores will be compared across transcutaneous spinal cord stimulation ON and OFF conditions within the same experimental session.
Time frame: Immediate (tSCS ON vs tSCS OFF condition within the same experimental session)
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