title: Classification of middle fossa floor dehiscence syndromes.
abstract: OBJECTIVE
  Middle fossa floor dehiscence (MFFD) can present as multiple syndromes depending on dehiscence location, tissue herniation, and dural integrity. The authors propose a classification system for MFFD with the potential to guide clinical decision making.
  
  
  METHODS
  A retrospective analysis of the electronic medical records (years 1995-2012) of patients who had undergone temporal craniotomy for the surgical repair of an MFFD syndrome at a single institution was undertaken. Reviewed data included demographic, operative, presentation, and outcome details. Middle fossa floor dehiscence was classified as follows: Class A, bony dehiscence without herniation of the brain and/or meninges; Class B, herniation of the brain and/or meninges through the middle fossa floor without CSF leakage; Class C, dehiscence with CSF leakage without meningitis; or Class D, dehiscence with meningitis.
  
  
  RESULTS
  Fifty-one patients, 22 males and 29 females, were included in the analysis. The mean age was 48.7 ± 15.5 years, mean body mass index was 32.65 ± 6.86 kg/m(2), and mean symptom duration was 33 ± 42 months. Seven patients underwent repeat surgery for symptomatic recurrence; therefore, there were 58 surgical encounters. Repair included bony reconstruction with hydroxyapatite with or without resection of encephaloceles and/or repair of a dural defect. According to the MFFD classification system described, 15, 8, 27, and 8 cases were categorized as Class A, B, C, and D, respectively. The prevalence of hearing loss was 87%, 63%, and 70% in Classes A, B, and C, respectively. Vestibular symptoms were more prevalent in Class A. Seven patients reported persistent symptoms at the last follow-up. Transient complications were similar in each classification (13%-25%), and a single permanent complication related to anesthesia was observed. There were no mortalities or severe neurological morbidities in the series.
  
  
  CONCLUSIONS
  Middle fossa floor dehiscence has a spectrum of clinical presentations. A classification system may help to clarify the diagnosis and guide therapy. Surgery, the mainstay of treatment, is safe and well tolerated.
authors.affiliation: Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon;
authors.forename: Kunal
authors.initials: K
authors.lastname: Gupta
authors.forename: Hatem A
authors.initials: HA
authors.lastname: Sabry
authors.forename: Aclan
authors.initials: A
authors.lastname: Dogan
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Coppa
authors.forename: Sean
authors.initials: S
authors.lastname: McMenomey
authors.forename: Johnny B
authors.initials: JB
authors.lastname: Delashaw
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Raslan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D035301:Cranial Fossa, Middle / Q000473:pathology*; D004677:Encephalocele / Q000175:diagnosis* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D011183:Postoperative Complications / Q000453:epidemiology / Q000628:therapy; D011184:Postoperative Period; D012008:Recurrence; D012189:Retrospective Studies; D013577:Syndrome; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult
keywords: BMI = body mass index; MFFD = middle fossa floor dehiscence; OHSU = Oregon Health & Science University; Tullio's phenomenon; middle fossa floor dehiscence; surgical outcomes; surgical stratification; surgical technique