Cortical Blindness Following Coil Embolization of Intracranial Aneurysm

Abstract

Abstract: : Purpose: To report the occurrence of cortical blindness in patients who had undergone endovascular coil embolization for the treatment of intracranial aneurysm. The development of transient cortical blindness is a rare but known complication after administration of angiographic contrast agent. The incidence is reported to range from 0.3%– 1% with non–ionic dyes and as high as 4% when hyperosmolar iodinated agents are administered. Contrast agent–induced disruption of the blood–brain barrier with a direct neurotoxic effect has been postulated; however, the exact mechanism is not precisely known. Methods: An observational case report of patients undergoing embolization procedures for intracranial aneurysm during the 6–year interval 1999 through 2004. Results: We found four (4) patients (three male and one female) that developed transient cortical blindness after posterior circulation interventional procedures for aneurysms. The patients mean age was 47 years (range, 41–54). All patients underwent endovascular occlusion of intracranial aneurysms. Arteriography was performed with iopromide, a nonionic water soluble contrast agent. The number of injections per procedure varied per patient. The total delivered volume ranged between 120 – 220 cc of contrast agent injected into the posterior cerebral circulation. All patients subsequently developed visual deficits within several hours to one day after the procedure. Three patients developed a right homonymous hemianopia while one patient had a decrease in visual acuity to light perception. Imaging studies revealed no evidence of an vaso–occlusive or embolic process. All four patients had complete resolution of visual deficits. In three cases the resolution of deficits occurred within several days while in one patient complete resolution occurred by one month. This problem was not seen in any patients treated for anterior circulation aneurysms. Conclusions: Transient cortical blindness secondary to administration of a non–ionic low osmolar contrast agent is a rare, self limited complication. It is characterized by a decrease in vision with binocular field deficits, normal pupillary reflexes and fundus examination. The prognosis is favorable with full recovery in most cases. It must be differentiated from an embolic or vaso–occlusive phenomenon which may present very similarly. Though rare, endovascular neurosurgeons, neuro–intensivists and ophthalmologists must be aware of this complication.

Keywords: neuro-ophthalmology: cortical function/rehabilitation • visual impairment: neuro-ophthalmological disease • visual fields