Which of the following is a sign of elevated sympathetic activity after TBI?

• A. Bradycardia
• B. Hypertension
• C. Diaphoresis
• D. Hypothermia

Answer: (C)

A surge in sympathetic activity after brain injury produces signs of heightened arousal and organ system activation, and sweating is a direct outward marker of that drive. Diaphoresis occurs because eccrine sweat glands are innervated by sympathetic nerves that use acetylcholine; when sympathetic outflow is up, sweating increases. So this option best reflects elevated sympathetic activity.

Bradycardia would suggest reduced sympathetic or increased parasympathetic influence, not a surge. Hypertension can occur with a sympathetic storm but is less specific than visible sweating. Hypothermia indicates impaired thermoregulation or dysautonomia that doesn’t align with sympathetic overdrive.