Surgical aspects and outcome of delayed tethered cord release.

Out of a total of 550 children followed up at our spina bifida center, we report on 81 patients who were reoperated upon for secondary tethered cord syndrome between 1993 and 2000. In four cases with preceding severe progressive scoliosis, untethering was followed by surgical correction and stabilization of curvatures. In 77 patients, the indication for surgery was based on late progressive neurological deterioration. The current clinical relevance of competing etiologic factors such as symptomatic Chiari malformation, hydromyelia, and shunt dysfunction, requiring different clinical management, had been previously carefully excluded. The children underwent magnetic resonance imaging (MRI) or myelo-computed tomography (m-CT) to identify the morphologic extent of tethering and any associated spinal malformations such as dermoid tumors (19 cases) or diastematomyelia (9 cases). Surgery became faster and safer through bilateral dural incision, undercutting arachnoid adhesions along the tethered area, although this procedure increased the need for dural grafting. Complete release of the conus medullaris and cauda equina was achieved in a total of 75 cases (93 %) including those who had undergone prophylactic surgery. A mean follow-up of 4.8 years in 77 patients operated upon for late progressive neurological deterioration confirmed stabilization of presenting symptoms in 65 cases (84 %) with 20 of them (26 %) even showing significant improvement. In 12 patients (16 %), including all cases of incomplete untethering (n = 4), there was further deterioration.