Spinal dysraphism detected by magnetic resonance imaging in patients with anorectal anomalies: incidence and clinical significance.

Though the concept of caudal regression, suggested in 1961 by Duhamel, could explain the association between anorectal anomalies (ARA) and spinal dysraphism (SD), its real incidence may be underestimated and its clinical significance is debatable. From 1988 to 1993, 111 patients with ARA were treated at the authors' institution. Associated anomalies were present in 36% of cases, with the exception of vesicoureteral reflux, which was considered functional rather than anatomical. In view of the late (1 to 2 years after surgical treatment) onset of vesical dysfunction and/or orthopaedic symptoms in some of these patients, a screening protocol was started in 1991, using magnetic resonance imaging (MRI) in all patients with ARA. Fifty patients, 29 boys and 21 girls, underwent a spinal cord MRI, with pathological findings in 25 cases (50%), 13 boys and 12 girls. The authors did not find any significant difference in incidence with respect to high, low, or cloacal malformations. A thickened filum, with or without fibrolipoma, was the most frequent finding, but even tethered cord, syringomyelia, and sac morphological alterations were present. MRI was also able to detect osteoarticular and/or muscular anomalies. Even when a urodynamic study and a neurological and orthopaedic workup were performed in 20 patients undergoing MRI, the clinical significance of these findings remained unclear. However, accurate follow-up of these patients is mandatory in order to detect early neurological symptoms, because currently it is not advisable to refer for neurosurgery all the patients with ARA presenting with anomalies of the spinal cord.