Sudden onset of bilateral symmetrical proptosis in acute intracranial hypertension.

A 32-year-old man had the clinical features of progressive increase in intracranial pressure due to a chronic subdural hematoma except for papilledema. Lumbar puncture, however, precipitated acute tentorial coning and severe neurologic signs. The tentorial coning resulted in an acute aggravation of intracranial hypertension and precipitated an increase in the intracranial venous pressure that was transmitted to the orbital veins, causing orbital venous stasis, symmetrical increase in the intraorbital contents, and symmetrical bilateral proptosis.