title: A case of Horner syndrome with intermittent mydriasis in a patient with hypoplasia of the internal carotid artery.
abstract: We report a rare case of hypoplasia of the right internal carotid artery (ICA) with ipsilateral congenital Horner syndrome. The etiology and pathogenesis of hypoplasia of the ICA is not well understood. Multiple types of collateral flow have been reported to develop to maintain blood supply to the ipsilateral cerebral hemisphere. Although collateral flow may allow these patients to remain asymptomatic, we postulate that the enlarged posterior communicating artery (PcomA) in our patient caused mass effect on the cisternal segment of cranial nerve III causing intermittent mydriasis apart from Horner syndrome.
authors.affiliation: Department of Radiology, Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Ibrahim
authors.forename: H M
authors.initials: HM
authors.lastname: Branson
authors.forename: J R
authors.initials: JR
authors.lastname: Buncic
authors.forename: M M
authors.initials: MM
authors.lastname: Shroff
mesh_terms: D000293:Adolescent; D002343:Carotid Artery, Internal / Q000002:abnormalities*; D002560:Cerebrovascular Circulation; D002941:Circle of Willis / Q000473:pathology; D003097:Collateral Circulation; D005260:Female; D006732:Horner Syndrome / Q000150:complications* / Q000151:congenital; D006801:Humans; D007498:Iris / Q000002:abnormalities; D018810:Magnetic Resonance Angiography; D015878:Mydriasis / Q000150:complications*; D020769:Posterior Cerebral Artery / Q000473:pathology