Isolated filar cyst on lumbar spine sonography in infants: a case-control study.

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.

MATERIALS AND

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.

CONCLUSION

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.