In spinal cord injury at or above T6, autonomic dysreflexia can occur. Which of the following is a common trigger?

• A. Dehydration
• B. Bladder or rectum distention.
• C. Overhydration
• D. Hypothermia

Answer: (B)

In spinal cord injury at or above T6, autonomic dysreflexia happens when a noxious stimulus below the injury triggers a massive, unregulated sympathetic response. The most common trigger is bladder or rectal distention—such as a full bladder from urinary retention or stool impaction—which sends signals that cannot be moderated by brain input due to the disruption of descending pathways. This leads to sudden vasoconstriction below the level of injury and a dangerous rise in blood pressure, often with headache, flushing above the injury, and bradycardia below or near normal heart rate above the injury. Dehydration or overhydration aren’t typical triggers of autonomic dysreflexia, and hypothermia isn’t the classic precipitating stimulus, making bladder or rectal distention the best answer.