Fusiform aneurysms (dolichoectasia) of the internal carotid artery as cause of optic nerve damage

Abstract

Dolichoectasia of cerebral vessels most often occurs in middle-aged or elderly patients, also occasionally in children and in subjects with neurofibromatosis type NF-i. It seems that less atherosclerosis but severe deficiency of reticular fibers in the media associated with extensive defects in the elastic lamina represents the main factor in the pathogenesis of these ectasias. In contrast to saccular aneurysms, the fusiform aneurysms never cause subarachnoid hemorrhage. Those originating from the internal carotid artery produce damage to the optic nerve by direct pressure or by impairment of the circulation of nutrient vessels. Visual loss may be slowly progressive or acute, affecting one eye weeks or years before the other. Visual field defects are not specific: altitudinal, temporal, constriction, central or cecocentral scotomas. Progressive optic atrophy on the affected side is the rule; sometimes papilledema on the other side can mimick a Foster-Kennedy syndrome. The treatment possibilities are discussed: for example, surgical excision of the ectatic vessel region, decompression of the optic nerve by separation from the ectatic vessel (interposition of muscle tissue), or unroofing the optic canal and subsequent cutting of the dural fold and the dural sheath of the optic nerve.

Key Words:

• Fusiform aneurysms (dolichoectasias)
• ectasias of the internal carotid artery
• compression of optic nerves
• optic atrophy
• MRI angiography
• microsurgical decompression of optic nerves