What causes autonomic hyperreflexia?

• A. Stimulation of the parasympathetic nervous system
• B. Decreased sympathetic activity
• C. Stimulation to the sympathetic nervous system
• D. Inhibition of motor pathways

Answer: (C)

Autonomic hyperreflexia is primarily caused by stimulation of the sympathetic nervous system. This condition often occurs in individuals with spinal cord injuries, typically above the T6 level, leading to an exaggerated autonomic response. When there is a noxious stimulus below the level of the injury—such as a full bladder, bowel impaction, or skin irritation—it triggers afferent signals that are transmitted to the spinal cord. These signals can then cause a massive sympathetic discharge, which results in severe hypertension and other autonomic responses, such as facial flushing, headache, and bradycardia.

The sympathetic nervous system's role in this context is crucial because it governs the body's fight-or-flight response. In the case of autonomic hyperreflexia, the disconnection between the brain and the spinal cord leads to unregulated sympathetic activity below the injury site, while above the injury, the body may exhibit a compensatory parasympathetic response. This imbalance contributes to the symptoms associated with the condition.

Understanding the nature of this condition emphasizes the importance of recognizing and managing the underlying triggers to prevent potentially life-threatening complications such as hypertensive crises.