title: Retro-odontoid soft tissue mass associated with atlantoaxial subluxation in an elderly patient: a case report.
abstract: BACKGROUND
  We present the case of an elderly patient with a retro-odontoid soft tissue mass associated with atlanto-axial subluxation.
  
  
  METHODS
  A 74-year-old man was admitted to our hospital with progressive motor weakness in his right arm and neck pain. Radiological examinations revealed atlantoaxial subluxation and diffuse degenerative changes. Cervical MRI revealed a syrinx at the C1 level and a retro-odontoid soft tissue mass that severely compressed the spinal cord. The mass was of low signal intensity on both T1- and T2-weighted images. Conservative therapy could not stop the progression of his symptoms, so posterior decompression via a laminectomy of C1 and occipitocervical fixation was performed. These procedures resulted in an improvement of his neurological condition and in reduction of the mass and the compression of the spinal cord.
  
  
  CONCLUSIONS
  The patient lacked any specific conditions that might have caused chronic atlantoaxial subluxation. The degenerative changes alone might have provoked chronic atlantoaxial subluxation and a subsequent retro-odontoid soft tissue mass. In patients with this condition, posterior fixation without direct removal of the mass should be the first choice for surgical intervention.
authors.affiliation: Department of Neurosurgery, Oita Medical University, Oita, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Isono
authors.forename: K
authors.initials: K
authors.lastname: Ishii
authors.forename: T
authors.initials: T
authors.lastname: Kamida
authors.forename: M
authors.initials: M
authors.lastname: Fujiki
authors.forename: M
authors.initials: M
authors.lastname: Goda
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
mesh_terms: D000368:Aged; D001268:Atlanto-Axial Joint; D019299:Decompression, Surgical; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology*; D007796:Laminectomy; D008279:Magnetic Resonance Imaging; D008297:Male; D009809:Odontoid Process; D011859:Radiography; D012983:Soft Tissue Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000000981:diagnostic imaging; D013117:Spinal Cord Compression / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000209:etiology