Short-term Spinal Stimulation Effects in Cerebral Palsy

Children with cerebral palsy (CP) have altered neuromuscular control that impacts gait and participation in daily activities. This research will characterize the acute effects of transcutaneous spinal stimulation (tSCS) on spasticity and gait for individuals with CP using a combined approach of quantitative biomechanical assessment and clinician assessment. Previous research has shown decreases in spasticity after walking with tSCS, but it is unclear whether these changes are due to physical activity or neuromodulation. This research will provide a foundation to characterize changes in spasticity after an acute session of tSCS for individuals with CP.

This research will use the SpineX Spinal Cord Innovation in Pediatrics (SCiP) system. The SCIP system allows for tSCS intensity (mA) at two electrodes to be independently adjusted in 1 mA increments. Other stimulation parameters such as pulse frequency (30 Hz), overlap frequency (10 kHz), pulse width (1 ms), and waveform (biphasic) are constant on the SCiP device. To target sensorimotor function of lower-extremity muscle groups within the spinal cord, the two electrodes are positioned over the spinous process at T11 and L1 with grounding electrodes placed on the pelvis. The tSCS intensity will be set to each individual's maximum tolerable stimulation intensity.

This study will recruit 20 individuals with CP to attend two in-lab visits. One visit will include treadmill walking with tSCS and the other will include treadmill walking without tSCS. The visit order will be pseudo-randomized and balanced across participants. Participants will be consented at the initial visit and will also conduct 3 trials of the 10-Meter Walk Test to evaluate self-selected walking speed. The average speed from these trials will be used to set treadmill speed. At the beginning of each visit, participants will complete a physical exam to characterize range of motion and spasticity via the Modified Tardieu Scale. Participants will complete a 5-minute treadmill familiarization at their self-selected speed to ensure it is comfortable. The tSCS intensity will gradually increase during treadmill familiarization until participants report discomfort. The tSCS intensity will be set at 1 mA below the level of discomfort if the visit calls for tSCS. During the treadmill walking, participants will walk at their self-selected walking speed for 10 - 20 minutes with either (1) no stimulation or (2) tSCS at their maximum tolerable stimulation intensity.

Inclusion criteria

Individuals who:

• have a diagnosis of spastic cerebral palsy or high likelihood of CP diagnosis
• are 4-65 years of age
• have spasticity in lower-extremity muscles
• are at a functional Gross Motor Function Classification System (GMFCS) Level I-III
• can walk for at least 10 minutes with/without support
• can understand and follow simple directions
• have a stable medical condition, as reported by the caregiver/parent

Exclusion criteria

Individuals who:

• who have had lower-extremity surgery or injury in the prior 12 months
• have had botulinum toxin injections in the prior 3 months
• have had selective dorsal rhizotomy (SDR) in the past
• have uncontrolled seizures
• have significant cardiovascular or musculoskeletal disease that would prevent full participation
• are dependent on ventilation support
• have implanted stimulator (e.g. epidural stimulator, vagus nerve stimulator, pacemaker, cochlear implant, etc) or drug delivery device (e.g. baclofen pump)
• have established osteoporosis and taking medication for osteoporosis treatment.
• have rheumatic diseases (rheumatoid arthritis, systemic lupus erythematosus, etc.)
• have active cancer
• have received stem cell injections into the spinal cord