Cavernous malformations of the optic chiasma.

Two cases of cavernous malformation of the optic chiasm are reported, and 12 previously reported cases are reviewed. The first patient presented with gradually progressive and the second patient with a subacute chiasmal syndrome. Total excision was performed in both cases. Visual function improved slightly after surgery in the first patient while the other showed marked improvement. Although cavernous malformations are angiographically occult, pre-operative diagnosis has become possible based on the characteristic features such as repeated haemorrhages in multiple sinusoidal structures as revealed by magnetic resonance imaging (MRI). A gliotic interspace between the malformation and normal neural tissue provides a plane of cleavage for dissection which permits total excision without causing new deficits. Review of previously reported cases revealed that chiasmal cavernous malformations haemorrhage more frequently than those in the brain. Early diagnosis with total excision is the treatment of choice for cavernous malformations of the optic chiasma.