How does the level of spinal injury relate to motor and sensory deficits?

• A. Injury level determines only motor function, with sensory unaffected.
• B. Incomplete injuries show no deficits.
• C. Injury level correlates with distribution of paralysis and sensory loss; complete injuries have total loss below the level; incomplete injuries vary by tract involvement.
• D. There is no relationship between injury level and deficits.

Answer: (C)

The level of spinal injury determines which pathways are disrupted, so motor and sensory deficits map to the nerves and tracts below that level. The motor system travels in the corticospinal tract, and sensation travels through the dorsal columns and the spinothalamic tracts, all organized to specific spinal segments. So when an injury occurs, what’s lost below the lesion mirrors the segmental distribution of those pathways.

If the injury is complete, every tract below the lesion is interrupted, producing total loss of motor function and sensory perception beneath that point. If the injury is incomplete, some tracts remain intact, so the pattern of paralysis and sensory loss varies depending on which pathways are spared. This explains why deficits follow the level of injury and why incomplete injuries show a range of presentations rather than a uniform deficit.

That’s why the best description is that the injury level correlates with the distribution of paralysis and sensory loss, with complete injuries causing a total loss below the level and incomplete injuries showing variable deficits based on tract involvement.