title: Congenital Horner's syndrome resulting from agenesis of the internal carotid artery.
abstract: OBJECTIVE
  To report a patient with agenesis of the right internal carotid artery associated with ipsilateral, congenital Homer's syndrome.
  
  
  METHODS
  Case report.
  
  
  METHODS
  A 30-year-old woman, with a past history of migraine headaches, underwent neuro-ophthalmologic and neuroradiologic evaluation for transient visual obscurations and congenital Horner's syndrome.
  
  
  RESULTS
  A right, third-order neuron Horner's syndrome was confirmed with 1% hydroxyamphetamine topical drops. Cranial magnetic resonance imaging revealed an absent right internal carotid artery flow void, computed tomography demonstrated absence of the right carotid canal, and cerebral angiography confirmed absence of the right internal carotid artery. No atheromatous lesions were found and the results of coagulation studies were normal.
  
  
  CONCLUSIONS
  Agenesis of the internal carotid artery is a rare cause of congenital Horner's syndrome. The cause of transient visual blurring in the current patient remains unproven.
authors.affiliation: Department of Neurology, University of Alabama School of Medicine, Birmingham, USA.
authors.forename: F H
authors.initials: FH
authors.lastname: Ryan
authors.forename: L B
authors.initials: LB
authors.lastname: Kline
authors.forename: C
authors.initials: C
authors.lastname: Gomez
mesh_terms: D000328:Adult; D002340:Carotid Artery Diseases / Q000151:congenital* / Q000175:diagnosis; D002343:Carotid Artery, Internal / Q000002:abnormalities* / Q000000981:diagnostic imaging; D002533:Cerebral Angiography; D005260:Female; D006732:Horner Syndrome / Q000151:congenital* / Q000175:diagnosis; D006801:Humans; D018810:Magnetic Resonance Angiography; D014057:Tomography, X-Ray Computed