Low-lying spinal cord and tethered cord syndrome in children with anorectal malformations.

Introduction: Anorectal malformations (ARMs) and low-lying spinal cord (LLC) are commonly associated owing to their common embryonic origin. LLC may lead to tethered cord syndromes (TCS), requiring surgery. This study aimed to review the incidence of LLC in children with ARMs using ultrasonography (US) and magnetic resonance (MR) imaging, the incidence of TCS and the surgical outcomes of these patients after detethering.

Methods: We conducted a retrospective study of children who underwent surgery for ARMs in 2002-2009 at KK Women's and Children's Hospital, Singapore.

Results: Out of 101 (16.8%) ARM patients, 17 had LLC, of which 12 (70.6%) were high ARMs. 12 of the 17 (70.6%) patients had abnormal US and MR imaging findings. Five (29.4%) had normal US but abnormal MR imaging results; in these five patients, MR imaging was performed due to new symptoms and equivocal US findings. These 17 patients subsequently underwent surgical detethering. Three out of seven patients with TCS improved after surgery. None of the 17 patients had any complications.

Conclusion: LLC appeared to be associated with high ARMs, although this was not statistically significant. LLC should be investigated for whenever ARM is diagnosed, regardless of its type. Lumbar US is useful for first-line screening for LLC. Abnormal US or onset of new symptoms should subsequently be investigated with MR imaging. Equivocal US findings are also likely to benefit from further MR imaging. Surgery to detether LLC can improve outcome in TCS, while prophylactic detethering for asymptomatic patients with lipoma of the filum terminale has very low surgical risk.