title: A boy with arachnoid cyst, a fall, and temporary and reversible visual impairment.
abstract: BACKGROUND
  Temporal arachnoid cysts have been shown to interfere with the function of nervous structures, both cerebral cortex and cranial nerves.
  
  
  RESULTS
  In this case report we describe a boy with a left temporal arachnoid cyst with a sudden onset of visual impairment 4 days after a mild trauma to the head. A perimetry test revealed a complete nasal hemianopia of the left eye, which normalized rapidly after an emergency craniotomy with cyst fenestration 3 hours after the patient experienced the reduced vision.
  
  
  CONCLUSIONS
  The observed, reversible effect on vision is most probably caused by pressure exerted by the medial part of the cyst on the left optic nerve. We believe this is the first time such a case has been described.
authors.affiliation: Elite Mission Hospital & Carewell Clinical Centre, Trichur, Kerala, India.
authors.forename: Ram Kumar
authors.initials: RK
authors.lastname: Menon
authors.affiliation: Department of Clinical Medicine K1, University of Bergen, Bergen, Norway; Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway. Electronic address: kgwe@helse-bergen.no.
authors.forename: Knut G
authors.initials: KG
authors.lastname: Wester
mesh_terms: D000058:Accidental Falls; D000293:Adolescent; D016080:Arachnoid Cysts / Q000150:complications* / Q000601:surgery; D016489:Head Injuries, Closed / Q000150:complications*; D006423:Hemianopsia / Q000209:etiology* / Q000601:surgery; D006801:Humans; D008297:Male; D013702:Temporal Lobe / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome
keywords: arachnoid cyst; minor head trauma; optic nerve; visual impairment