title: Arachnoid cyst confined to the internal auditory canal-endoscope-assisted resection: case report and review of the literature.
abstract: BACKGROUND
  An arachnoid cyst confined to the internal auditory canal is a rare condition. Different pathogeneses are discussed, and a progressive enlargement of the cysts has been reported. This case illustrates the beneficial aspect of endoscopic assistance in microsurgical resection of this lesion.
  
  
  METHODS
  A slowly progressive hearing loss developed in a 35-year-old woman over 2 years; she reported experiencing tinnitus for 7 years. Magnetic resonance imaging revealed a cystic lesion in the internal auditory canal appearing hypointense on T1-weighted images and hyperintense on T2-weighted images, suggesting an arachnoid cyst.
  
  
  METHODS
  The cyst wall was fenestrated and partially resected in an endoscope-assisted microsurgical technique. Adherent vestibular nerve fibers in the cyst wall prevented total removal of the cyst. The histological examination confirmed the diagnosis of an arachnoid cyst.
  
  
  CONCLUSIONS
  The endoscope-assisted microsurgical technique enables a safe cyst resection with good visualization of important neurovascular structures within the internal auditory canal. Small remnants of the capsule that are firmly attached to important neurovascular structures should be left in place rather than risk neurological deficits.
authors.affiliation: Department of Neurosurgery, Ernst Moritz Arndt University, Greifswald, Germany. sfleck@uni-greifswald.de
authors.forename: Steffen Kristian
authors.initials: SK
authors.lastname: Fleck
authors.forename: Jörg
authors.initials: J
authors.lastname: Baldauf
authors.forename: Soenke
authors.initials: S
authors.lastname: Langner
authors.forename: Silke
authors.initials: S
authors.lastname: Vogelgesang
authors.forename: Henry Werner
authors.initials: HW
authors.lastname: Siegfried Schroeder
mesh_terms: D000328:Adult; D016080:Arachnoid Cysts / Q000150:complications / Q000473:pathology / Q000601:surgery*; D007758:Ear, Inner / Q000473:pathology / Q000601:surgery*; D004724:Endoscopy / Q000379:methods*; D005260:Female; D034381:Hearing Loss / Q000209:etiology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D013506:Otologic Surgical Procedures / Q000379:methods*; D014012:Tinnitus / Q000209:etiology / Q000601:surgery