title: Factors influencing on retro-odontoid soft-tissue thickness: analysis by magnetic resonance imaging.
abstract: METHODS
  A retrospective, consecutive case series.
  
  
  OBJECTIVE
  To analyze the relationship between retro-odontoid soft-tissue thickness and patients' age, sex, and degenerative changes of cervical spine and to investigate the effect these factors have on retro-odontoid soft-tissue thickness.
  
  
  BACKGROUND
  Thickening of the soft tissue posterior to the odontoid process can form a retro-odontoid pseudotumor causing symptoms of spinal cord compression. Rheumatoid arthritis and long-term dialysis have been reported as possible causes for this. However, there have been reports of retro-odontoid pseudotumors without coexisting diseases.
  
  
  METHODS
  Findings from a total of 503 cases of cervical spine magnetic resonance images were reviewed, and retro-odontoid soft-tissue thickness was measured. The values were matched for age, sex, presence of degenerative changes, rheumatoid arthritis, and dialysis and were analyzed for significance.
  
  
  RESULTS
  Retro-odontoid soft tissue thickened with age, and this was also seen in male patients and patients with degenerative changes. Significant increase in thickness was also observed in patients undergoing dialysis and further increased with prolonged dialysis. There was no significant association with presence of rheumatoid arthritis.
  
  
  CONCLUSIONS
  There is association between age, sex, degenerative cervical spine changes, and dialysis with retro-odontoid soft-tissue thickness. With dialysis, retro-odontoid soft-tissue thickness increases with increasing duration. Thus, reviewing magnetic resonance image from daily practice indicates that cervical spine degeneration is associated with the development of retro-odontoid pseudotumors.
authors: From the Department of Radiology, The Jikei University School of Medicine, Tokyo, Japan. s_tojo@mbd.nifty.com
authors: Shinjiro
authors: S
authors: Tojo
authors: Reina
authors: R
authors: Kawakami
authors: Takenori
authors: T
authors: Yonenaga
authors: Daichi
authors: D
authors: Hayashi
authors: Kunihiko
authors: K
authors: Fukuda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000150:complications; D002648:Child; D005260:Female; D051445:Fibrocartilage / Q000473:pathology; D006801:Humans; D008022:Ligaments / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009809:Odontoid Process / Q000473:pathology*; D006435:Renal Dialysis / Q000009:adverse effects; D012189:Retrospective Studies; D012307:Risk Factors; D013117:Spinal Cord Compression / Q000209:etiology / Q000473:pathology*; D013122:Spinal Diseases / Q000150:complications / Q000473:pathology*; D013583:Synovial Membrane / Q000473:pathology; D013680:Tectorial Membrane / Q000473:pathology; D055815:Young Adult