Which statement is FALSE regarding autonomic hyperreflexia?

Which statement is FALSE regarding autonomic hyperreflexia?

• A. Distention of a hollow viscus below the level of transection can elicit autonomic hyperreflexia
• B. Up to 85% of patients with a transection above T6 will exhibit autonomic hyperreflexia under general anesthesia
• C. Propranolol is effective in treating hypertension associated with autonomic hyperreflexia
• D. Spinal anesthesia is effective in preventing autonomic hyperreflexia

Answer: (C)

Autonomic hyperreflexia occurs in people with spinal cord injuries above roughly T6. A noxious stimulus below the level of injury—such as bladder distention or rectal stimulation—triggers a massive sympathetic discharge below the lesion because supraspinal control is interrupted. The result is a dangerous rise in blood pressure, often with headache and flushing above the injury and pallor or coolness below it. The critical steps in management are to remove or alleviate the trigger, place the patient upright to help lower BP, and use rapid-acting vasodilators if the hypertension persists. Propranolol, a nonselective beta-blocker, is not effective for treating this hypertensive crisis. It does not address the underlying vasoconstrictive surge driven by sympathetic outflow below the injury and can even be problematic by allowing unopposed alpha-adrenergic activity, potentially worsening hypertension and masking compensatory signs. In contrast, first-line pharmacologic measures include fast-acting vasodilators such as nitroglycerin, nitroprusside, nifedipine, or hydralazine, and in some settings agents with both alpha and beta blockade like labetalol may be used. Spinal or regional anesthesia can prevent the reflex by blocking afferent signaling, but relying on propranolol is not appropriate.

Autonomic hyperreflexia occurs in people with spinal cord injuries above roughly T6. A noxious stimulus below the level of injury—such as bladder distention or rectal stimulation—triggers a massive sympathetic discharge below the lesion because supraspinal control is interrupted. The result is a dangerous rise in blood pressure, often with headache and flushing above the injury and pallor or coolness below it. The critical steps in management are to remove or alleviate the trigger, place the patient upright to help lower BP, and use rapid-acting vasodilators if the hypertension persists.

Propranolol, a nonselective beta-blocker, is not effective for treating this hypertensive crisis. It does not address the underlying vasoconstrictive surge driven by sympathetic outflow below the injury and can even be problematic by allowing unopposed alpha-adrenergic activity, potentially worsening hypertension and masking compensatory signs. In contrast, first-line pharmacologic measures include fast-acting vasodilators such as nitroglycerin, nitroprusside, nifedipine, or hydralazine, and in some settings agents with both alpha and beta blockade like labetalol may be used. Spinal or regional anesthesia can prevent the reflex by blocking afferent signaling, but relying on propranolol is not appropriate.