A spinal cord injury (SCI) is damage to the nerves that send signals between the brain and the body. This can disrupt control over the legs, leading to changes in sensation and movement. The extent of recovery varies, but for many, regaining some degree of leg function is an attainable goal through dedicated rehabilitation and technological support.
The Spinal Cord’s Role in Leg Movement
A spinal cord injury disrupts the communication pathway between the brain and the body. The nature of this disruption is defined by whether the injury is “complete” or “incomplete.” A complete injury involves a total loss of motor and sensory function below the level of the injury. An incomplete injury means some nerve pathways remain intact, allowing for a degree of communication.
Individuals with incomplete injuries have a better chance of regaining leg movement. This potential is rooted in neuroplasticity, the brain and spinal cord’s ability to reorganize and form new neural connections. Following an injury, the nervous system can sometimes find new ways to send signals around the damaged area, a process guided by targeted rehabilitation.
The spinal cord also contains neural circuits known as central pattern generators (CPGs). These networks can produce the basic rhythmic muscle patterns for walking, independent of direct commands from the brain. After an injury, these CPGs can lie dormant, but specific therapies use repetitive movements to stimulate the spinal cord and encourage it to relearn walking motions.
Types of Post-Injury Leg Movement
After a spinal cord injury, it is helpful to understand the difference between involuntary and voluntary movements. A common involuntary movement is spasticity—tightness or sudden, uncontrolled muscle contractions in the legs. These movements are not controlled by the brain but are reflexes managed by the spinal cord below the injury, and do not represent a return of voluntary control.
Spasms occur because the injury interrupts the brain’s signals that would normally moderate reflex activity, causing the spinal cord to become hyperexcitable. This leads to exaggerated responses to stimuli like touch or stretching. Managing spasticity is often part of the rehabilitation process, as it can interfere with therapy.
In contrast, voluntary movement is any motion that is consciously controlled, no matter how small, such as a slight tightening of a thigh muscle or a wiggle of a toe. The presence of any voluntary movement is a significant indicator of an incomplete injury. It suggests that some neural pathways connecting the brain to the leg muscles have survived, which is a positive sign for therapy.
Rehabilitative Therapies for Leg Recovery
Physical therapy (PT) is one of the first and most continuous interventions. PT focuses on maintaining the physical health of the legs through stretching to preserve range of motion and prevent joint stiffness. Therapists also work on strengthening any muscles that still have voluntary activation, using targeted exercises.
Occupational therapy (OT) plays a complementary role by helping individuals adapt their movements to perform daily life activities. An occupational therapist might teach new techniques for safely transferring from a wheelchair to a bed or for using their legs to maintain balance. This practical application helps integrate any recovered function into a person’s routine.
A highly effective approach for promoting walking is activity-based therapy, such as locomotor training. This therapy often involves supporting a patient in a harness over a treadmill while physical therapists manually guide their legs through walking motions. This repetitive practice is designed to stimulate the central pattern generators in the spinal cord and promote neuroplasticity, encouraging the nervous system to strengthen the circuits for gait.
Technological Aids and Advanced Interventions
Technology and advanced interventions offer powerful tools to assist in both daily function and rehabilitation.
- Functional Electrical Stimulation (FES) is a technology that applies small electrical pulses to weakened muscles, causing them to contract. This can be synchronized to allow for activities like cycling on a stationary FES bike, which helps maintain muscle mass and improves circulation.
- Wearable robotic exoskeletons can provide the support needed to stand and walk. These powered suits are strapped to the legs and torso and use motors to move the user’s joints, serving as both an assistive device and a tool for robotic-assisted gait training.
- Epidural stimulation is an advanced intervention involving a surgically implanted device that delivers a continuous electrical current to the lower spinal cord. This stimulation raises the excitability of spinal circuits, making them more responsive to weak signals from the brain.
- Stem cell therapies represent a future treatment direction, with research exploring their use to repair the damaged spinal cord or create a “bridge” for nerve signals. It is important to note that these treatments are still in the experimental phase.