Colloid cyst of the third ventricle--a neurological emergency.

Colloid cyst of the third ventricle, although a benign lesion, carries with it high mortality and morbidity if not diagnosed in time. The most common presenting symptom is headache. A 31-year-old man with a history of intermittent, throbbing, unilateral headache and nausea was admitted because of exacerbation of his headache, which responded poorly to medication. A few hours after admission he became comatose. A colloid cyst of the third ventricle causing acute hydrocephaly was diagnosed by computed tomographic scan and removed in toto. Despite an uneventful postoperative course the patient was left with permanent bilateral cerebral damage. In patients with headache not responding to conventional medication, colloid cyst of the third ventricle perhaps should be ruled out, even if the symptoms are suggestive of vascular headache, such as migraine headache.