[A case of cerebral arteriovenous malformation (AVM) with presented remarkable enlargement during 13 years (author's transl)].

A 20-year-old man visited us complaining of head heaviness after he sustained a minor head injury at traffic accident. Although he showed no neurological deficits, the CT--SCAN (Fig. 2) revealed a high density area after contrast enhancement in the left frontal region. Left carotid angiography (Fig. 3) was carried out on admission, revealing a large AVM (3X5X4 cm) in the same area. As he had undergone craniotomy because of chronic subdural hematoma at the age of seven, the left carotid angiogram (Fig. 1) taken at that time was re-examined. It revealed no abnormal shadows suggesting the presence of the AVM. Since AVM is a congenital disease, the present large AVM is considered to have grown in size from the cryptic type for the past 13 years, escaping detection by the initial angiogram.