Autonomic dysreflexia most commonly occurs with spinal cord injuries at or above which vertebral level?

Autonomic dysreflexia most commonly occurs with spinal cord injuries at or above which vertebral level?

• A. T6
• B. C4
• C. L1
• D. T12

Answer: (A)

Autonomic dysreflexia happens when a spinal cord injury blocks the brain’s ability to dampen reflexes, so a stimulus below the injury triggers a large, unopposed sympathetic response. The level most commonly linked to this is around the thoracic level of T6. The major sympathetic supply to the abdominal organs (the splanchnic vascular bed) comes from roughly T5 to T9. If the injury is at or above T6, descending inhibitory pathways can’t modulate those below-injury nerves, so a noxious stimulus such as bladder distension or stool impaction drives a massive vasoconstrictive surge below the level of injury. The brain may respond by increasing parasympathetic activity above the lesion (causing bradycardia and flushing above the injury), but it cannot reverse the intense hypertension below the injury. That’s why injuries at or above T6 are the ones most associated with autonomic dysreflexia.

Autonomic dysreflexia happens when a spinal cord injury blocks the brain’s ability to dampen reflexes, so a stimulus below the injury triggers a large, unopposed sympathetic response. The level most commonly linked to this is around the thoracic level of T6. The major sympathetic supply to the abdominal organs (the splanchnic vascular bed) comes from roughly T5 to T9. If the injury is at or above T6, descending inhibitory pathways can’t modulate those below-injury nerves, so a noxious stimulus such as bladder distension or stool impaction drives a massive vasoconstrictive surge below the level of injury. The brain may respond by increasing parasympathetic activity above the lesion (causing bradycardia and flushing above the injury), but it cannot reverse the intense hypertension below the injury. That’s why injuries at or above T6 are the ones most associated with autonomic dysreflexia.