The incidence of occult spinal dysraphism and the onset of neurovesical dysfunction in children with anorectal anomalies

The urological malformations associated with anorectal anomalies (ARA) are not only anatomical, but also functional, the latter being related to congenital neurovesical dysfunction (NVD). The true incidence of spinal dysraphism (SD) in these children is still unclear and is probably underestimated. The concept of caudal regression could explain its association with the anorectal anomalies. Because of awareness of the late onset of neurovesical dysfunction and/or orthopaedic symptoms in some of our patients, in 1991 we started to screen with magnetic resonance imaging (MRI) the spinal cord of all patients with ARA. Eighteen (44%) out of 41 patients without neurological or orthopaedic symptoms and 7 (78%) of 9 children with neurological or orthopaedics symptoms screened by MRI showed pathological findings. The overall incidence of spinal dysraphism in ARA was 50%, without any great difference with respect to the type of the anomaly (high, low, cloacal). The pathological MRI findings encountered were: fibrinolipoma (with or without a thickend filum terminale), tethering of the cord and syringomyelia, and sac anomalies. In order to check the onset of NVD in these children, we performed urodynamic studies with external sphincter electromyography in 24. Grouped by age: 14 were between 5 and 18 months and ten were 4 to 13 years old. Ten patients (71%) out of the first group and 3 (30%) out of the second had a normal urodynamic pattern. A total of 11 children had pathological findings; of these, 4 infants had a hyperreflexic bladder (one with detrusor-sphincter dyssynergia) suggesting upper motor neuron (UMN) lesion. Of the 7 older patients, two had UMN and 3 lower motor neuron (LMN) lesion. Two of the remaining children (without spinal dysraphism) had Down syndrome and their urodynamic pattern (detrusor-sphincter incoordination) was not conclusive for NVD. The incidence of spinal dysraphism in children with anorectal anomalies is high and screening with morphological studies of the spinal cord are mandatory. Neurovesical dysfunction should be suspected in all these children and it is likely to be congenital in nature. Early and repeated urodynamic studies are recommended to detect neurogenic bladder dysfunction before the onset of symptoms.