Autonomic dysreflexia can be triggered by which of the following?

• A. Nausea
• B. Full bladder
• C. Loud noise
• D. Sleep deprivation

Answer: (B)

Autonomic dysreflexia happens when a stimulus below a spinal cord injury, typically above the T6 level, triggers an unregulated sympathetic response. Because descending inhibitory signals can’t cross the injured cord, the result is widespread vasoconstriction below the injury with a dangerous rise in blood pressure, often accompanied by headache, sweating, and other autonomic signs above the level of injury.

A full bladder is the classic trigger because bladder distension provides a strong visceral stimulus that sends afferent signals into the spinal cord below the lesion, sparking that massive sympathetic outflow. The injury prevents the brain from damping this response, so the hypertension can be rapid and severe.

Nausea, loud noise, and sleep deprivation can cause stress or autonomic arousal in other contexts, but they do not routinely provoke the specific reflex vasoconstriction below a high spinal lesion that defines autonomic dysreflexia.