A 55-year-old man presents with a morning headache and vomiting. Over the next hour he develops a blood pressure of 190/110 mmHg, heart rate of 46/min, and an irregular respiratory pattern. This constellation of findings is best explained by:

• A Ischemia of vasomotor centers activating a sympathetic surge ✓
• B Baroreceptor-mediated sympathetic discharge triggered by pain
• C Loss of vagal tone secondary to raised intracranial pressure
• D Reflex tachycardia from cerebral venous congestion

Explanation

The Cushing reflex is a late sign of markedly raised ICP. When ICP approaches arterial pressure, cerebral perfusion falls and medullary ischemia activates the sympathetic vasomotor center, producing hypertension. The resulting hypertension triggers baroreceptor-mediated bradycardia, and brainstem dysfunction gives irregular breathing. The hypertension is driven by central ischemia, not by baroreceptor failure alone, and the bradycardia is reflex rather than primary vagal loss.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.