A 58-year-old man with a large left basal ganglia hemorrhage suddenly develops blood pressure of 220/115 mmHg, heart rate of 44/min, and irregular breathing. Which mechanism best explains this combination of findings?
- A Baroreceptor-mediated reflex bradycardia from the elevated blood pressure
- B Compression of the medullary vasomotor center causing an ischemic pressor response ✓
- C Neurogenic pulmonary edema triggering sympathetic discharge
- D Seizure-related autonomic instability
Correct answer: B. Compression of the medullary vasomotor center causing an ischemic pressor response
Explanation
The triad of hypertension, bradycardia, and irregular respiration is the Cushing reflex. Raised ICP reduces medullary perfusion, and the resulting medullary ischemia drives intense sympathetic vasoconstriction that raises arterial pressure to restore brain perfusion. The hypertension then activates carotid baroreceptors, producing the bradycardia. Option A reverses the causality: the bradycardia is secondary to the ischemia-driven hypertension, not the primary event.
Reference: Ganong's Review of Medical Physiology, 26th ed.
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