title: Cyst formation following radiosurgery for AVMs: report of 3 cases.
abstract: BACKGROUND
  Stereotactically-focused radiosurgery (SRS) for the treatment of arteriovenous malformations (AVM) has been in widespread use for over two decades. Over this timeframe the indications for treatment, standardization of radiation dosage, and the results expected from treatment have been elaborated. Less well known are the long-term complications associated with SRS. We report three patients who had SRS for the treatment of AVM who developed a cyst at the site of treatment as a late complication.
  
  
  METHODS
  From 201 patients treated by SRS for an AVM, three developed a cyst at the treatment site. Their clinical presentation, the characteristics of the AVMs and the treatment were reviewed, as well as similar cases gleaned from the literature.
  
  
  RESULTS
  Three women, aged 28-43 years, had an AVM treated by: craniotomy and clipping of arterial feeders followed by SRS, by craniotomy for resection followed by SRS or by endovascular embolization and SRS. The patients did well following treatment but two of them developed a symptomatic and the other an asymptomatic cyst at the treatment site 3-19 years later. The symptomatic patients underwent marsupialization of the cyst and the other is under observation.
  
  
  CONCLUSIONS
  Stereotactic radiosurgery is an established and safe treatment for patients with AVMs. Delayed cyst formation can occur many years after treatment and long term follow-up is indicated in patients whose AVM has been treated with SRS.
authors.affiliation: Department of Neurosurgery, McGill University Health Centre, Montreal, Quebec, Canada.
authors.forename: Q
authors.initials: Q
authors.lastname: Al Hinai
authors.forename: D
authors.initials: D
authors.lastname: Tampieri
authors.forename: L
authors.initials: L
authors.lastname: Souhami
authors.forename: A
authors.initials: A
authors.lastname: Sadikot
authors.forename: D
authors.initials: D
authors.lastname: Sinclair
authors.forename: R
authors.initials: R
authors.lastname: Leblanc
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D001165:Arteriovenous Malformations / Q000601:surgery; D003560:Cysts / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D006801:Humans; D011183:Postoperative Complications / Q000503:physiopathology*; D016634:Radiosurgery / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed