Key Points

• People with SCI may have no sensation or movement in their legs, while some maintain the ability to move their legs, feel pain, and some are able to walk. Though the rehabilitation of lower extremity walking may not be possible (e.g., in someone with complete tetraplegia), some forms of exercise and rehabilitation for lower limbs can be used to maintain muscle health as well as minimize other complications, such as osteoporosis, spasticity, pain, or wounds.
• Generally speaking, those with lower levels of injuries and incomplete SCI (i.e., the spinal cord is not completely severed) will be more likely to walk post-SCI. There has been some research on predicting who will or will not be able to walk after SCI, looking at factors like age, injury level and severity, and voluntary movement or strength in certain muscle groups. Hicks et al. (2017) (https://www.ambulation.ca/) states that walking ability can be predicted with relatively high accuracy with 3 variables: age, L3 motor score at admission, and S1 light touch sensory score at admission.
• Rehabilitation strategies for enhancing lower limb function after SCI typically have focused on range of motion (ROM) and stretching, building strength, attempting functional tasks, and pairing electrical stimulation (ES) to strengthen or help activate functioning musculature. Standing and overground ambulation training are also important components of conventional rehabilitation, either with or without bracing or assistive devices.
• In the last several years, we have seen increasing emphasis on providing task-specific training of functional movements, such as walking, with the help of body weight support treadmills (BWST). We have also seen technological applications for assisting walking rehabilitation, such as robotic devices or exoskeletons, virtual reality, and different neuromodulation strategies.

Overground Training

• Overground gait training (OGT) has been the predominant approach for regaining walking function, until recent years when the emphasis shifted to other forms of locomotor training (LT).
• Overground walking training (OWT) does not require expensive devices, and it more closely resembles conditions in daily life compared to walking on a treadmill.
• Walking training that is progressively challenging, over different surfaces, and includes motor skills training (MST), as well as strength/weight-bearing training and range of motion (ROM) stretching may result in long-lasting benefits in people with incomplete and complete SCI.

Body-Weight Supported Treadmill Training (BWSTT)

• Body-weight supported treadmill training (BWSTT) is a rehabilitation technique that uses a system of harness/straps connected to an overhead suspension system, supporting a portion of the person’s weight as they walk on a motorized treadmill.
• For people in the acute/subacute phase of SCI (i.e., less than 12 months post-SCI), body-weight supported treadmill training (BWSTT) may be as effective on walking ability as overground mobility training of similar intensity.
• Body weight-support training can improve gait outcomes in patients with chronic and incomplete SCI, but there is no clear evidence that one specific strategy is superior to another (i.e., overground, treadmill training, robotic-assisted treadmill training, exoskeleton-assisted walking [EAW]; with/without functional electrical stimulation [FES]).
• Longer durations of BWSTT sessions are encouraged, if possible, to move beyond strength and stability to provide improvements in functional walking (i.e., walking at home or in the community).

Orthoses/Braces

• Ankle-foot-orthosis (AFO) can enhance walking function in patients with incomplete SCI who have drop-foot.
• Knee-ankle-foot orthosis (KAFO) can enable slow walking with elbow crutches or a walker in people with motor complete and low thoracic lesions, but usually not at speeds sufficient for community ambulation.

Wearable Powered Exoskeletons (WPEs)

• A wearable exoskeleton can enable safe walking training and improvements in strength outcomes in most patients with SCI.
• There are several limitations to exoskeleton use as a rehabilitation therapy tool such as device safety, set-up requirements, high cost, and limited accessibility and availability for gait rehabilitation.
• There is insufficient evidence regarding whether wearable exoskeleton-assisted training provides better walking function compared with other approaches to walking training in patients with SCI.
• There is little consensus with regards to training regimens and which exoskeleton models to use.

Neuromodulation

Neuroplasticity refers to the capacity of the nervous system to modify its structural and functional organization, adjusting itself to changing demands and environment; neuromodulation can be defined as the induction of neuroplastic changes via local application of electrical, magnetic, acoustic, optic, tactile, or pharmacological stimuli. The SCIRE YouTube channel demonstrates neuromodulation a number of ways, including chemically (intrathecal baclofen), via electrical stimuli (FES and epidural stimulation), and magnetic fields (transcranial magnetic stimulation [TMS]).

Neuromodulation can be applied to three main areas of the body: the brain, the spinal cord, and the peripheral nerves, through invasive and/or non-invasive approaches.

In recent years, the combination of walking or strength training with neuromodulation of the brain or the spinal cord has been investigated as a means to enhance the excitability of motor circuits and to increase training efficacy, promoting motor recovery.

• Functional Electrical Stimulation (FES) – electrical stimulation is applied to peripheral muscles and the nerves located outside the spinal cord and brain. This stimulation causes the muscles to contract and can assist with purposeful or functional movement in weak or paralyzed muscles. FES is delivered using a variety of handheld or specialized commercial electrical therapy machines connected to electrodes that are placed on the skin’s surface.
• Studies in SCI typically show that FES paired with exercise or walking training leads to better improvements in walking or strength than the exercise alone. This is often because a muscle is activated by the stimulation that normally cannot be voluntarily activated by the person with SCI.
• Of greater interest are the carryover effects found after FES training. Several investigators have reported that improvements in walking have (e.g., overground walking speed and distance, step length) been present even when the stimulator was turned off, suggesting that neuroplastic changes have taken place in response to regular use of FES and walking training.
• Other types of transcutaneous stimulation, like repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), or transcutaneous spinal current stimulation (tSCS), attempt to stimulate the brain and the spinal cord non-invasively (i.e., from outside of the body). Pairing this kind of electrical stimulation with exercise has been studied much less than FES, though some evidence exists that tSCS is useful for improving standing training and walking in people with SCI.
• There are also implantable types of stimulation that attempt to replace the electricity directly in the spinal cord. Epidural spinal cord stimulation has been completed successfully and had some effects on recipients and their walking abilities. This procedure, however, has yet to be approved in many countries including Canada and the USA.

Biofeedback and Virtual Reality

• Biofeedback is a process where instruments measure physiological activity and ‘feed back’ information to the user, as in electromyography, mirror therapy, or force sensors.
• Virtual Reality (VR) is a technology in which users interact in a computer-generated environment, allowing the practice of rehabilitation exercises in a safe and controlled manner; it can be low-tech and semi-immersive (e.g., video game consoles with cameras) or high-tech and fully immersive (e.g., VR goggles, VR caves).
• Because people with SCI lack sensation/sensory input below their level of injury, biofeedback and VR can compensate and provide visual feedback on body position, cue stepping and standing, enhance movement practice, as well as increasing adherence to home-based rehabilitation or telerehabilitation.

Several studies have been conducted including people with chronic SCI, who performed standing and walking programs coupled with virtual reality (VR) or biofeedback with promising results that VR/biofeedback enhances walking more than walking training alone.