Mr. Skinner has sustained a C6 spinal cord injury and has developed autonomic dysreflexia. Which of the following is the most common precipitating cause?

Mr. Skinner has sustained a C6 spinal cord injury and has developed autonomic dysreflexia. Which of the following is the most common precipitating cause?

• A. Distended bladder or rectum
• B. Nasal congestion
• C. High dietary fibre
• D. Low blood pressure

Answer: (A)

In autonomic dysreflexia, a noxious stimulus below the level of injury triggers an exaggerated sympathetic response that the damaged spinal cord cannot modulate, leading to a dangerous rise in blood pressure. The most common trigger in someone with a C6 injury is bladder distention or urinary retention, often from a kinked or blocked catheter or incomplete emptying. That distended bladder sends afferent signals that unleash widespread vasoconstriction below the level of injury, while the brain’s ability to dampen this response is lost. Removing the trigger by checking and clearing the catheter and voiding the bladder (and addressing any rectal distention) usually stops the episode. Nasal congestion can occur as a symptom of autonomic dysreflexia, reflecting the vasodilatory flush, but it isn’t the initiating trigger. High dietary fibre and low blood pressure don’t acutely provoke autonomic dysreflexia; the event is driven by a noxious stimulus below the injury and the resultant unchecked sympathetic surge leading to hypertension.

In autonomic dysreflexia, a noxious stimulus below the level of injury triggers an exaggerated sympathetic response that the damaged spinal cord cannot modulate, leading to a dangerous rise in blood pressure. The most common trigger in someone with a C6 injury is bladder distention or urinary retention, often from a kinked or blocked catheter or incomplete emptying. That distended bladder sends afferent signals that unleash widespread vasoconstriction below the level of injury, while the brain’s ability to dampen this response is lost. Removing the trigger by checking and clearing the catheter and voiding the bladder (and addressing any rectal distention) usually stops the episode.

Nasal congestion can occur as a symptom of autonomic dysreflexia, reflecting the vasodilatory flush, but it isn’t the initiating trigger. High dietary fibre and low blood pressure don’t acutely provoke autonomic dysreflexia; the event is driven by a noxious stimulus below the injury and the resultant unchecked sympathetic surge leading to hypertension.