Engaging Reticulospinal Inputs to Improve Walking Ability in Humans With Spinal Cord Injury
Shirley Ryan AbilityLab
Summary
Locomotor recovery is one of the most important goals of individuals with spinal cord injury (SCI). Ambulatory deficits severely impact daily functions resulting in lower quality of life for people living with paralysis due to SCI. Although studies have shown that locomotor training improves locomotor function in people with chronic SCI, the benefits remain limited. Our overall hypothesis is that we can engage additional descending motor pathways, such as the reticulospinal tract (RST), to improve locomotor function in humans with chronic incomplete SCI. In this study we propose to test the effects of a novel intervention that uses repeated paired loud auditory and electrical stimulation of muscle afferents combined with locomotor training on walking speed and voluntary muscle strength.
Description
Individuals with chronic incomplete SCI will be randomly assigned to a group that will receive 10 sessions of a startle stimulus (a very brief, loud sound) and electrical stimulation combined with locomotor training or 10 sessions of a non-startle stimulus (a very brief, soft sound) combined with locomotor training.
Eligibility
- Age range
- 18–75 years
- Sex
- All
- Healthy volunteers
- No
Inclusion Criteria: * History of traumatic or non-traumatic SCI ≥ 6 months * International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) level at and above T10. * American Spinal Injury Association AIS Grade C, or D * Weakness in ankle dorsiflexors (LEMS\<=3) with the ability to perform a small voluntary ankle dorsiflexion (as detected by presence of voluntary EMG activity in the tibialis anterior) with at least one leg. * Ability to tolerate standing position. * Ability to walk at a minimum speed of 0.1 mile/hour on a treadmill with less than 70% body weight suppo…
Interventions
- DevicePaired Associative Stimulation
This new intervention consists of locomotor training in combination with paired low-intensity electrical stimulation and stimulation of the reticulospinal tract through loud sounds. Participants will receive auditory stimulation (LAS, 110dB, 500Hz, 50ms) through headphones and electrical stimulation through a pair of electrodes with 2cm inter-electrode distance positioned on the motor point over the quadriceps and the tibialis anterior muscles bilaterally. The motor point will be identified as the position of the electrodes that elicits a small visible muscle twitch or muscle contraction upon palpation over the tendon with the minimum stimulation intensity. Stimuli will be delivered with a pulse duration of 200 microseconds and will be timed to arrive at the level of the brainstem \~7ms before auditory signals.
- BehavioralLocomotor Training
Participants will walk on a treadmill with body-weight support (ZeroG, Aretech) in the range 0-70% as needed to prevent excessive knee flexion during stance phase or toe dragging during swing phase (Finch et al. 1991). Each session will last approximately 60-min and the duration of the treadmill training will be timed to be 30 min. Subjects will be encouraged to walk at a self-selected speed at or above 0.1m/s. Speed and body-weight support will be adjusted to achieve a perceived exertion score of 4-5 (Moderate) in the Borg scale (Borg 1982). Subjects will be allowed to rest as needed during the training sessions.
- DeviceSham stimulation
Participants will receive brief low-intensity auditory clicks (80dB, 500Hz, 50ms) through headphones and electrical stimulation through a pair of electrodes with 2cm inter-electrode distance positioned on the motor point over the quadriceps and the tibialis anterior muscles bilaterally. The motor point will be identified as the position of the electrodes that elicits a small visible muscle twitch or muscle contraction upon palpation over the tendon with the minimum stimulation intensity. Stimuli will be delivered with a pulse duration of 200 microseconds and will be timed to arrive at the level of the brainstem \~7ms before auditory signals.
Location
- Shirley Ryan AbilityLabChicago, Illinois