INTRAMEDULLARY ANGIOGRAPHICALLY OCCULT VASCULAR MALFORMATIONS OF THE SPINAL-CORD

OBJECTIVE: This study was performed to elucidate the differences betwe en angiographically occult vascular malformations of the spinal cord a nd the histological subtypes. METHODS: The cases of six patients with spinal intramedullary angiographically occult vascular malformations e ncountered during the past 10 years were examined regarding clinical c ourse, neuroradiological manifestations, and surgical consideration. R ESULTS: There were four cavernous malformations and two arteriovenous malformations. The cervical section of the spinal cord was involved in four cases, and the thoracic section of the spinal cord was involved in two. All of the patients had presented with motor weakness and sens ory disturbance below the level of the lesion. Two distinct clinical c ourses were observed; they were neurological decline with repeated epi sodes of relapse and remission (four patients) and continuing neurolog ical decline (two patients). Although a mixed-intensity core surrounde d by a low-intensity rim is thought to be characteristic of cavernous malformations, we were not able to differentiate the histological type s on the basis of magnetic resonance imaging findings alone. CONCLUSIO N: In cases of spinal intramedullary angiographically occult vascular malformations, even if clinical course and magnetic resonance imaging findings are consistent with cavernous malformation, other histologica l subtypes need to be considered. Surgery should be considered for sym ptomatic patients, because symptoms and signs that are probably caused by bleeding tend to worsen rather than stabilize.