title: Isolated filar cyst on lumbar spine sonography in infants: a case-control study.
abstract: BACKGROUND
  Simple cysts found within the filum terminale of infants on lumbar spine sonography are relatively common, but no study has established their clinical significance.
  
  
  OBJECTIVE
  To obtain information on the sonographic features of isolated filar cysts and determine their clinical significance in comparison with age- and sex-matched controls.
  
  
  METHODS
  We performed a retrospective review of 644 consecutive spine sonograms in patients younger than 8 months. Gestational age- and sex-matched controls with normal lumbar sonograms were taken from the same period. We obtained short-term clinical follow-up of motor milestones for each group.
  
  
  RESULTS
  The incidence of filar cyst was 78 of the 644 (11.8%) and was inversely related to age. Developmental follow-up of the study patients compared with control population showed no statistically significant difference in the ages at which the infants were able to turn over, crawl and walk. Follow-up MR imaging of 13 study patients (19%) failed to demonstrate filar cysts previously identified on sonography.
  
  
  CONCLUSIONS
  No significant difference was found in the short-term outcome of infants with isolated filar cysts on lumbar sonography compared with that of a control population. Filar cysts should be considered a normal variant when found in isolation on lumbar sonography.
authors.affiliation: Department of Diagnostic Radiology, Allegheny General Hospital, Pittsburgh, PA, USA.
authors.forename: Neville
authors.initials: N
authors.lastname: Irani
authors.forename: Asha R
authors.initials: AR
authors.lastname: Goud
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Lowe
mesh_terms: D000367:Age Factors; D016022:Case-Control Studies; D002420:Cauda Equina / Q000000981:diagnostic imaging* / Q000473:pathology; D002657:Child Development; D003560:Cysts / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D015588:Observer Variation; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000453:epidemiology; D012189:Retrospective Studies; D014463:Ultrasonography