title: Complete labyrinthine aplasia: clinical and radiologic findings with review of the literature.
abstract: OBJECTIVE
  Complete labyrinthine aplasia (CLA), also referred to as Michel aplasia, is a severe congenital anomaly of the inner ear, defined by the complete absence of inner ear structures. The purpose of this study was to document the imaging findings in a series of patients with CLA, with review of the literature, to better understand this anomaly.
  
  
  METHODS
  The CT and MR imaging findings of 9 patients (14 ears with CLA) were retrospectively evaluated. The audiologic tests and patient charts were also retrospectively reviewed.
  
  
  RESULTS
  CLA was bilateral in 5 and unilateral in 4 patients. The petrous bone was hypoplastic in all 14 ears, but the otic capsule was aplastic in only 5. The middle ear and mastoid volumes were decreased in most of the ears. The stapes was aplastic in 1 ear and was dysplastic in 5 ears. The internal acoustic canal was aplastic in 4 ears and markedly narrowed in 10 ears. The facial nerve canal showed a variety of anomalies and aberrant courses in 11/14 ears. The bony covering of the jugular bulb was defective in 9 ears. Tegmen tympani defects were seen in 3 patients, and there were several accompanying skull base and posterior fossa anomalies.
  
  
  CONCLUSIONS
  Although CLA is a rare developmental anomaly, its accurate diagnosis and its differential diagnosis from labyrinthine ossificans is crucial. Proper guidance of these patients for brain stem implantation in the critical period of brain development depends on the recognition of the characteristic imaging findings of CLA.
authors.affiliation: Department of Radiology, Hacettepe University, Ankara, Turkey. burce@hacettepe.edu.tr
authors.forename: B
authors.initials: B
authors.lastname: Ozgen
authors.forename: K K
authors.initials: KK
authors.lastname: Oguz
authors.forename: A
authors.initials: A
authors.lastname: Atas
authors.forename: L
authors.initials: L
authors.lastname: Sennaroglu
mesh_terms: D000293:Adolescent; D001298:Audiology; D002648:Child; D002675:Child, Preschool; D007758:Ear, Inner / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D007759:Labyrinth Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed