Association of imperforate anus with occult spinal dysraphism

Abstract

Neurological deficits may occur in some children with imperforate anus produced by unrecognized spinal cord anomalies amenable to neurosurgical correction. Although this association has been well described, its frequency has not been defined. The authors prospectively studied 45 infants with imperforate anus from 1985 to 1992 to establish the frequency of this association. Eighteen infants (40%) had high imperforate anus, 24 had low imperforate anus (53%), and 3 had anal stenosis (7%). All underwent radiographic spinal cord imaging in early infancy, which consisted of radiographs (45), ultrasound (26), magnetic resonance imaging (29), computed tomography (1), and myelography (1). Thirty-three percent of the patients with imperforate anus had bony sacral abnormalities. Eight infants were discovered to have spinal cord abnormalities. Two of those infants had obvious myelomeningocele at birth, and 6 infants (14%) had occult spinal dysraphism consisting of tethered cord with or without associated lipoma of the cord. There was no correlation between the presence of tethered cord and the gender of the infants, the type of malformation (high versus low imperforate anus), or the presence of sacral dysplasia (Fisher's exact test). Five of the infants who were found to have tethered cord underwent neurosurgical intervention and repair of the defect, and 1 infant was followed up clinically. The mean follow-up time of all the infants was 2.5 ± 0.9 (±SD) years. No neurological sequelae occurred in the infants who had surgical correction. The frequency of occult spinal dysraphism with imperforate anus was 14%. It was independent of the type of imperforate anus or the coexistence of bony sacral anomalies. Therefore all children with imperforate anus should be screened for the presence of tethered cord in early infancy, either by ultrasound or MRI, because early neurosurgical correction can prevent the development of delayed neurological sequelae.