[Recurrence of AVM after disappearing on postoperative angiography--report of two cases]

We reported two cases of recurrent arteriovenous malformation (AVM), which had been operated on before and these AVMs disappeared on postoperative angiography. The first case was a 13-year-old boy who had suffered from intracerebral hematoma at the age of nine years. The first angiography showed AVM located in the left central region, fed by peripheral branches of the anterior and middle cerebral arteries. Sixteen days after the onset, removal of the AVM was carried out. Postoperative course was uneventful and angiography showed that the AVM had disappeared. However, 4 years later, follow-up digital subtraction angiography showed that the AVM had reappeared in the operated region. Extirpation of the recurrent AVM was repeated. The second case was a 28-year-old woman who had presented intracerebral hematoma at the age of 23 years. Angiography revealed AVM located in the right posterotemporal region, fed by a temporal branch of the middle cerebral artery. Removal of the AVM was carried out one month after the onset. Postoperative neurological status was good and angiography showed no residual AVM. Five years later, enhanced CT scan demonstrated a linear enhanced area in the operated region. This led us to suspect recurrence of the AVM. Conventional angiography presented reappearance of the AVM, and reoperation was performed. Reported cases of AVM, which recurred after disappearing on postoperative angiography, were very rare. Small abnormal vascular channels located in the surrounding area of the main nidus may be left after the initial operation, and they may have grown to nidus some years later.(ABSTRACT TRUNCATED AT 250 WORDS)