Spasticity following SCI occurs MOST commonly in which types of injuries?

Spasticity following SCI occurs MOST commonly in which types of injuries?

• A. Lumbar and sacral level injuries only
• B. Cervical and upper thoracic level injuries; can occur in both complete and incomplete lesions
• C. Only in incomplete injuries regardless of neurological level
• D. Only in complete injuries at any level

Answer: (B)

Spasticity after spinal cord injury is an upper motor neuron phenomenon caused by loss of supraspinal inhibition of spinal reflexes. When the injury is at the cervical or upper thoracic levels, the descending inhibitory pathways are disrupted over a large portion of the cord, so the reflex circuits below the lesion become hyperexcitable. This makes spasticity more likely in these higher injuries because more of the motor neurons and reflex arcs below the lesion are left intact to be disinhibited. It can occur in both complete and incomplete injuries because the mechanism is the loss of inhibitory input, not the presence of any particular amount of preserved function. Spasticity often emerges after the initial spinal shock phase, weeks to months after injury.

Spasticity after spinal cord injury is an upper motor neuron phenomenon caused by loss of supraspinal inhibition of spinal reflexes. When the injury is at the cervical or upper thoracic levels, the descending inhibitory pathways are disrupted over a large portion of the cord, so the reflex circuits below the lesion become hyperexcitable. This makes spasticity more likely in these higher injuries because more of the motor neurons and reflex arcs below the lesion are left intact to be disinhibited. It can occur in both complete and incomplete injuries because the mechanism is the loss of inhibitory input, not the presence of any particular amount of preserved function. Spasticity often emerges after the initial spinal shock phase, weeks to months after injury.