Which statement is TRUE regarding spasticity in SCI with respect to injury completeness?

Which statement is TRUE regarding spasticity in SCI with respect to injury completeness?

• A. It cannot occur in complete injuries
• B. It occurs only in incomplete injuries
• C. It can occur in both complete and incomplete injuries
• D. It only occurs during spinal shock and then disappears

Answer: (C)

Spasticity after spinal cord injury comes from loss of inhibitory input from the brain to the spinal reflex circuits below the injury. When this supraspinal control is disrupted, the stretch reflexes can become hyperactive, producing the velocity-dependent resistance to passive movement that defines spasticity. This can happen whether the injury is complete or incomplete because the essential issue is the disruption of descending inhibition, not the presence of some preserved function at the lesion site. Spinal shock is a transient phase with flaccidity and absent reflexes that typically improves over weeks; spasticity that develops after this period is due to the disinhibited reflex pathways, not a continuation of spinal shock. Therefore, spasticity can occur in both complete and incomplete injuries, with timing and severity varying between individuals.

Spasticity after spinal cord injury comes from loss of inhibitory input from the brain to the spinal reflex circuits below the injury. When this supraspinal control is disrupted, the stretch reflexes can become hyperactive, producing the velocity-dependent resistance to passive movement that defines spasticity. This can happen whether the injury is complete or incomplete because the essential issue is the disruption of descending inhibition, not the presence of some preserved function at the lesion site. Spinal shock is a transient phase with flaccidity and absent reflexes that typically improves over weeks; spasticity that develops after this period is due to the disinhibited reflex pathways, not a continuation of spinal shock. Therefore, spasticity can occur in both complete and incomplete injuries, with timing and severity varying between individuals.