title: Interdural Spinal Cyst: A Rare Clinical Entity.
abstract: BACKGROUND
  For more than 2 decades, dural spinal cysts have been broadly classified as extradural and intradural.
  
  
  METHODS
  A 40-year-old woman presented with radicular thoracic pain. Intraoperative findings showed the cyst to be present within the dura itself.
  
  
  CONCLUSIONS
  We suggest a revised classification of spinal dural cysts. This case highlights that, during surgery for spinal meningeal cysts, surgeons should bear in mind the possibility of an interdural cyst. This may help avoid inadvertent tears in the deep layers of such cysts, thus maintaining dural patency.
authors.affiliation: Department of Neurosurgery, Cork University Hospital, Cork, Ireland. Electronic address: jahangirsajjad@rcsi.ie.
authors.forename: Jahangir
authors.initials: J
authors.lastname: Sajjad
authors.affiliation: Department of Neurosurgery, Cork University Hospital, Cork, Ireland.
authors.forename: Irfan
authors.initials: I
authors.lastname: Yousaf
authors.affiliation: Department of Neuropathology, Cork University Hospital, Cork, Ireland.
authors.forename: Niamh
authors.initials: N
authors.lastname: Bermingham
authors.affiliation: Department of Neurosurgery, Cork University Hospital, Cork, Ireland.
authors.forename: George
authors.initials: G
authors.lastname: Kaar
mesh_terms: D000328:Adult; D020863:Central Nervous System Cysts / Q000473:pathology* / Q000601:surgery*; D004388:Dura Mater / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008866:Microsurgery / Q000379:methods; D019635:Neurosurgical Procedures / Q000379:methods*; D035583:Rare Diseases / Q000473:pathology / Q000601:surgery; D013120:Spinal Cord Neoplasms / Q000473:pathology* / Q000601:surgery*; D016896:Treatment Outcome
keywords: Interdural cyst; Meningeal cysts; Spine