Retained sacral function in children with high level myelodysplasia.

To assess the preservation of sacral function despite denervation higher on the spinal cord in children with myelodysplasia, we examined 151 myelomeningocele patients presenting for urodynamic evaluation from 1980 to 1992 with a lesion at L3 or above on neurological examination. Of the 151 patients 70 (46%) had denervation of the external sphincter on initial evaluation and 81 (54%) had sacral sparing, that is normal or near normal electrical potentials of the external urethral sphincter and/or retained reflexic bladder activity regardless of the presence or absence of sacral reflexes. Of the 81 patients with sacral sparing 57 (70%) had detrusor-sphincter dyssynergia and 21 had synergy or denervation of the sphincter in association with retained detrusor reflexia. Whereas only 18% of children age 1 year or younger with retained sacral function had upper urinary tract deterioration on initial radiological studies (manifested by reflux or hydronephrosis), 57% had deterioration when evaluated after age 1 year. None of the patients without retained sacral function had evidence of upper urinary tract damage at younger than 1 year but 28% of those studied beyond age 1 year had changes. Patients with flaccid lower extremities can retain sacral function, which puts the upper urinary tract at risk of deterioration. Our results show that this risk increases with time.