Tethered Cord Syndrome in Occult Spinal Dysraphism: Timing and Outcome of Surgical Release

Objective: To investigate the influence of neurosurgical intervention on the appearance of upper motor neuron (UMN) signs in newborns diagnosed with occult spinal dysraphism and tethered cord (TC) during the first month of life.

Methods: A prospective study (1990 to 1996) of 22 consecutive newborns with occult spinal dysraphism monitored for the appearance of UMN signs. Untethering was performed when neurologic or urodynamic investigation indicated the presence of UMN dysfunction.

Results: Of 22 patients, 10 remained free of UMN symptoms during follow-up (mean, 67+/-22 months). Untethering was performed in 12 of 22 patients because of the presence of UMN symptoms. In 7 of these 12 patients, there was a documented asymptomatic period of 13+/-11 months before the onset of UMN symptoms. Untethering at a mean age of 18+/-17 months restored normal neurologic and urinary function in all patients (mean postoperative follow-up, 25+/-16 months). Of the 12 children, 5 presented with UMN signs at birth. In these children, untethering was performed at a mean age of 9+/-5 months. In two of these five patients, UMN symptoms did not resolve after surgery, and ongoing conservative bladder treatment was required (mean follow-up, 37+/-14 months). In none of the 12 operated children did signs of retethering occur.

Conclusions: A significant number (10/22) of children born with occult spinal dysraphism and TC did not develop UMN symptoms during follow-up; neurosurgical correction after the appearance of an UMN sign restored normal neurologic and urinary function in all children; and untethering in children presenting at birth with UMN symptoms resulted in poorer outcome.