Activating Spinal Circuits to Improve Walking, Balance, Strength, and Reduce Spasticity

SCIMS Site Specific Project: Activating Spinal Circuits to Improve Walking, Balance, Strength, and Reduce Spasticity

For many people with spinal cord injury (SCI), the goal of walking is a high priority. There are many approaches available to restore walking function after SCI; however, these approaches often involve extensive rehabilitation training and access to facilities, qualified staff, and advanced technology that make practicing walking at home difficult. For this reason, developing training approaches that could be easily performed in the home would be of great value. In addition, non-invasive spinal stimulation has the potential to increase the effectiveness of communication between the brain and spinal cord. Combining motor skill training (MST) with transcutaneous spinal stimulation (TSS) may further enhance the restoration of function in persons with SCI. Therefore, the purpose of this study is to determine if moderate-intensity, MST can improve walking-related outcomes among persons with SCI and to determine if the addition of non-invasive TSS will result in greater improvements in function compared to training alone.

Individuals with SCI will be asked to participate in this study over a four-week period. During the first 2 weeks (wash-in phase), individuals will participate in 6 aerobic and exercise training sessions as part of either an existing outpatient clinical program or by completing a personalized exercise plan. During the intervention phase (last 2 weeks), participants will be randomized to complete 6 training sessions of: 1) motor skill training combined with TSS (MST+TSS group), or 2) motor skill training combined with shamTSS (MST+shamTSS), or 3) cyclic aerobic exercise combined with TSS (CAX+TSS). All participants will complete 3 testing sessions: baseline testing 1 (prior the wash-in phase), testing 2 (after the completion of the wash-in phase and prior the intervention phase), and testing 3 (after the completion of the intervention phase) to assess their walking ability, balance, strength, and spasticity. During the intervention phase and to monitor within-session changes, participants will also complete a short version of walking function and balance assessments prior to and after each training session.

spinal, cord, incomplete, motor, skill, training, transcutaneous, stimulation, TSS, tSCS, electrophysiology

During MST participants will perform a series of 6 motor skill exercises designed to challenge balance, lower extremity coordination, agility, and speed. Five of these activities will be performed while standing to promote upright control and one activity will be performed while seated (alternating toe-tapping) to provide opportunity for active recovery. Participants will perform each exercise for one minute each, until 4 cycles of the circuit have been completed (approximately 45 minutes total). Motor training activities will be performed at an intensity of 40-59% of heart rate reserve (HRR). During MST, participants will wear a chest-worn heart rate monitor to ensure that the optimal HRR range is achieved. HRR will be calculated from resting and peak heart rate measures obtained during baseline testing via administration of a graded-exercise test.

TSS will be delivered using a commercially available neuromuscular electrical stimulator. The active electrode will be positioned directly over the spine at the T11/T12 spinous interspace, and the reference electrode will be positioned over the umbilicus. Stimulation intensity will be gradually increased until paresthesia of the lower legs and feet is achieved or to the highest level each participant can tolerate. Stimulation will be delivered for a total duration of 30 min after paresthesia/ maximum tolerability is reached.

Participants will complete 35 minutes of seated elliptical exercise (5min warm up + 30 min of training) and will be asked to maintain a constant step rate for the duration of the intervention. This training may take up to 45 minutes if rest breaks are necessary. During CAX, participants will wear a chest-worn heart rate monitor to ensure that a HRR range of 40-59% is maintained. Resistance level will be adjusted to ensure the optimal target heart rate is achieved.

Walking speed (as determined by the 10MWT) is the primary outcome measure for assessing walking function. Participants will complete 3 10MWT trials at each testing session, separated by 2 minutes of seated rest. The average walking speed of the 3 walks will be calculated and used in the analyses.

Testing 1(Day 1), Testing 2 (Day 12), Pre/Post Training 1-6 (Days 15, 17, 19, 22, 24, 26), Testing 3 (Day 27)

Gait quality will be assessed from spatiotemporal gait characteristics (cadence [strides/min], stride length [cm] of the weaker and stronger limbs, and step length symmetry) collected via instrumented walkway as participants completed three, 10MWT trials at each testing session. The average cadence across three walks will be used in the analysis.

Testing 1(Day 1), Testing 2 (Day 12), Pre/Post Training 1-6 (Days 15, 17, 19, 22, 24, 26), Testing 3 (Day 27)

Gait quality will be assessed from spatiotemporal gait characteristics (cadence [strides/min], stride length [cm] of the weaker and stronger limbs, and step length symmetry) collected via instrumented walkway as participants completed three, 10MWT trials at each testing session. The average stride length across three walks will be used in the analysis.

Testing 1(Day 1), Testing 2 (Day 12), Pre/Post Training 1-6 (Days 15, 17, 19, 22, 24, 26), Testing 3 (Day 27)

Gait quality will be assessed from spatiotemporal gait characteristics (cadence [strides/min], stride length [cm] of the weaker and stronger limbs, and step length symmetry) collected via instrumented walkway as participants completed three, 10MWT trials at each testing session. The average step length for each leg across three walks will be used to compute the symmetry index (%).

Balance will be measured using the BBS. The BBS total score will be calculated for each participant at each testing session. The total range of scores for the BBS equals 0-56, with higher scores from baseline indicating greater balance performance and lower scores from baseline indicating worsened balance performance. A subset of the BBS will be assess before and after each training session.

Testing 1 (Day 1), Testing 2 (Day 12), Pre/Post Training 1-6 (Days 15, 17, 19, 22, 24, 26), Testing 3 (Day 27)

The FES-I total score will be calculated for each participant at each testing session to measure fear of falling. The total range of scores for the FES-I equals 16-64, with lower scores indicating decreased fear of falling.

The SCATS will be used to assess spasticity. The total range of scores possible for the SCATS is 0-18, with a total score of 0 indicating no lower limb spasticity and higher total scores indicating greater spasticity severity.

The modified 5-times sit-to-stand test will be used as a measure of functional lower extremity strength. The average time to complete the test will be calculated at each testing session.

Functional walking capacity will be measured based on the 2MWT distance. Total distance walked in 2-minutes will be recorded for each participant at each testing session.

Knee extensor (quadriceps) and ankle plantar flexors (gastrocnemius and soleus) strength will be measured using an isokinetic dynamometer. Maximum knee extensor force will be analyzed based on the maximum force produced over three attempts.

Torque vs speed production will be using an isokinetic dynamometer. Maximum rate of torque production will be calculated based on the highest rate measured over three attempts.

The modified SCI-SET is a subjective measure used to assess the effects of spasticity on daily life in people with SCI. It requires participants to recall their past 7 days when rating the impact of spasticity. The scale uses a range of -2 (very problematic) to +1 (helpful).

Inclusion Criteria: Be 18-70 years of age Have a spinal cord injury (neurological level C3-T12) that occurred ≥3 months (sub-acute to chronic) prior to enrollment Have ISNCSCI severity classification C or D Able to stand for at least 5 minutes (with or without the aid of an assistive device) Able to move each leg independently for at least 3 steps (with or without the aid of an assistive device) Able to rise from sit to stand with moderate assistance from one person Use of prescription medication(s) for control of spasticity if the dosage has not changed in the last 2 weeks and you notify the study staff if your medication(s) change during study participation Ability and willingness to consent and authorize use of personal health information Ability to follow multiple instructions and communicate pain or discomfort Exclusion Criteria: Progressive spinal lesions including degenerative, or progressive vascular disorders of the spine and/or spinal cord Injuries below the neurological spinal level of T12 Pregnant, or if you have reason to believe you are or may become pregnant due to unknown risks to the fetus associated with TSS History of cardiovascular irregularities Presence of orthopedic conditions that would adversely affect participation in exercise Implanted stimulators of any type will be excluded due to unknown potential of electrical stimulation effects (e.g., baclofen pump, epidural spinal stimulator, implanted cardiac defibrillator, diaphragmatic pacemaker) Any cuts or sensitivity of the skin near the level of stimulation Active cancer or history of cancer Inability and unwillingness to consent and authorize use of personal health information