Does surgical release of secondary spinal cord tethering improve the prognosis of neurogenic bladder in children with myelomeningocele?

PURPOSE

The diagnostic criteria for secondary tethering of the spinal cord in children with prior closure of an open spinal defect are not well defined. Urological, neurological or orthopedic deterioration during followup remains the only strong indicator for the diagnosis of this condition. However, the outcome of untethering surgery cannot always be predicted. The aim of this study was to determine neurourological outcome after secondary untethering surgery in children with myelomeningocele.

MATERIALS AND METHODS

Of 401 children with myelomeningocele followed at our multidisciplinary spina bifida clinic between 1996 and 2005, 56 (14%) were diagnosed with secondary tethering of the spinal cord (median age at diagnosis 4.1 years). The diagnosis was based on urological and neuro-orthopedic deterioration in 58% and 42% of children, respectively. Preoperative urological findings were compared with 6-month postoperative findings.

RESULTS

Febrile urinary tract infection, upper tract dilatation and vesicoureteral reflux were preoperatively documented in 48.2%, 19% and 30% of the 56 children, respectively. At 6 months postoperatively urine cultures were sterile in 34% of patients and upper tract dilatation completely resolved in 45%. For all grades of vesicoureteral reflux complete resolution occurred in 47% of patients. Urodynamic parameters in terms of cystometric bladder capacity and detrusor leak point pressure substantially improved 6 months after untethering surgery (125 vs 170 ml and 69.1 vs 47.5 cm H2O, respectively, p < 0.05). Assessment of urodynamic findings in 19 children at 1 year failed to demonstrate a significant change in these parameters. A subgroup analysis according to patient age at untethering surgery revealed urodynamic improvement was more significant in children who were diagnosed and treated before age 7 years.

CONCLUSIONS

Secondary tethering of the spinal cord is a major risk factor for urological and neurological deterioration in children with myelomeningocele. Close urological surveillance remains the most valuable tool in the early diagnosis. Our study shows that secondary untethering surgery may significantly improve urological outcome.