Intracranial Arterial Compression of the Anterior Visual Pathway

Compression of anterior visual pathway (AVP) structures by intracranial arteries is observed not infrequently on neuroimaging. Whether or not such compression results in damage to these structures, however, remains unclear. This information is important to define as AVP compression by intracranial arteries may be a causative factor in patients with otherwise unexplained visual dysfunction. In a single centre, 37 patients with evidence of intracranial artery AVP compression demonstrated on magnetic resonance imaging were identified by retrospective review of case records over the period 2011-2017. Variables were collected, including patient demographics, visual acuity, visual fields, pupillary reactions and optic disc appearance for patients in the case series. Visual field deficits correlated with compression sites in the 37 patients examined. Internal carotid artery-optic nerve compression was the most frequent (unilateral compression n = 9, bilateral compression n = 14), followed by chiasmal compression by the anterior cerebral artery (n = 8) and a combination of optic nerve and chiasmal compression (n = 5). Visual acuity and visual fields were stable on follow-up (mean 4 years) in 24 of 26 cases (93%). We conclude that AVP compression by intracranial arteries may be a causative factor in unexplained visual dysfunction. The visual defects are largely non-progressive.