What is autonomic dysreflexia and which patients are at risk?

• A. Low blood pressure after spinal cord injury
• B. An exaggerated autonomic response causing severe hypertension due to noxious stimuli in patients with SCI at or above T6
• C. Overactive bladder causing urge incontinence in lower lumbar injuries
• D. Hypersensitivity reaction causing bradycardia in cervical injuries

Answer: (B)

Autonomic dysreflexia is an emergency reaction of the autonomic nervous system that occurs in people with spinal cord injuries at or above the T6 level. A noxious stimulus below the level of injury—such as a full bladder, catheter problems, bowel impaction, or a skin ulcer—triggers a massive sympathetic response. Because the injury disrupts signals from the brain, this sympathetic surge is not properly modulated, so vasoconstriction below the injury drives a sudden, dangerous rise in blood pressure. The brain may respond with reflex bradycardia, and there can be sweating or flushing above the level of injury.

The risk is highest when the injury is at or above T6 because the sympathetic outflow to the major vascular beds (especially the splanchnic circulation) is disrupted from above, allowing unchecked sympathetic activity in response to below-level stimuli. Recognizing and managing triggers promptly is crucial: sit the patient up to help lower blood pressure, locate and remove the triggering stimulus (for example, empty or fix the bladder, relieve bowel impaction, remove tight clothing), and monitor blood pressure closely. This is a medical emergency requiring rapid assessment and intervention.