title: Congenital left temporal large arachnoid cyst causing intraorbital optic nerve damage in the second decade of life.
abstract: OBJECTIVE
  Intracranial sylvian arachnoid cysts are often asymptomatic lesions. We present a 16-year-old female patient with progressive loss of vision together with an unusual visual field defect on the left eye accompanied by headache.
  
  
  METHODS
  A left frontotemporal sylvian arachnoid cyst was known since she was 9 months old, but observed ever since in the asymptomatic patient. Now, ophthalmological examination revealed bi-upper quadrant anopia on the left eye. Magnetic resonance imaging (MRI) and computed tomography showed erosion of the lateral orbital wall associated with intraorbital compression of the optic nerve by the cyst at the entrance into the optic canal. Microsurgical cyst fenestration to the basal cisterns was performed using a temporal mini-craniotomy.
  
  
  RESULTS
  Full improvement of vision and visual field defects was observed in the follow-up. On postoperative MRI, an increase of the tissue surrounding the optic nerve in the conus and better delineation at the entrance of optic canal was noted.
  
  
  CONCLUSIONS
  Long-standing asymptomatic sylvian arachnoid cysts may suddenly produce severe unilateral visual deficits if the cyst erodes the lateral orbital wall. These deficits may rapidly revert to normal if surgical action is not delayed. If surveillance MRIs of sylvian arachnoid cysts show a narrowing of the conus diameter compared to the contralateral side, a yearly ophthalmological surveillance examination seems to be warranted in else wise asymptomatic patients.
authors.affiliation: Department of Neurosurgery, Section of Pediatric Neurosurgery, Eberhard-Karls-University Hospital of Tübingen, Hoppe-Seyler.Str. 3, 72076, Tübingen, Germany. cahitkural@yahoo.com.tr.
authors.forename: Cahit
authors.initials: C
authors.lastname: Kural
authors.affiliation: Department of Neurosurgery, Section of Pediatric Neurosurgery, Eberhard-Karls-University Hospital of Tübingen, Hoppe-Seyler.Str. 3, 72076, Tübingen, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Kullmann
authors.affiliation: Department of Child Neurology, University Children's Hospital, Tübingen, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Weichselbaum
authors.affiliation: Department of Neurosurgery, Section of Pediatric Neurosurgery, Eberhard-Karls-University Hospital of Tübingen, Hoppe-Seyler.Str. 3, 72076, Tübingen, Germany.
authors.forename: Martin U
authors.initials: MU
authors.lastname: Schuhmann
mesh_terms: D000293:Adolescent; D016080:Arachnoid Cysts / Q000150:complications* / Q000151:congenital* / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D020221:Optic Nerve Injuries / Q000209:etiology*; D014057:Tomography, X-Ray Computed; D014786:Vision Disorders / Q000209:etiology
keywords: Cyst fenestration; Intracranial arachnoid cyst; Optic nerve damage; Orbital wall erosion