Rare and treatable cause of progressive visual loss

Abstract

A 58-year-old woman presented with a 6-month history of progressive left blurred vision without headaches or orbital pain. The neuro-ophthalmologic examination revealed reduced visual acuity (20/60) and inferior nasal field defect in the left eye. Visual field and acuity in the right eye was normal. There was no papillary defect but the fundus of the left optic nerve seemed slightly pale. MRI demonstrated a multilocular lesion at the left optic nerve to the optic chiasm with mixed intense signals (figure 1). Result of 3D CT angiography was normal. The patient underwent a left pterional craniotomy, which exposed subpial multiphasic hematoma at the right optic nerve to the optic chiasm. Sharp incision of the optic pia mater disclosed mulberry-like vascular malformation with partially thrombosed small vessels. A gliotic interphase between the malformation and normal neural tissue provided a plane of cleavage for total excision (figure 2). Histopathologic examination was consistent with cavernous malformation. The postoperative course was uneventful. Visual acuity improved to 20/40 in the left eye with resolution of visual field defect.