Urodynamic findings in children with myelomeningocele after untethering of the spinal cord.

PURPOSE: The effect on bladder function of tethered spinal cord release in individuals with myelomeningocele differs in published studies, and the benefit has been the subject of debate. We studied the urodynamic findings in a consecutively treated population.
MATERIALS AND METHODS: Of 120 children born with myelomeningocele between 1986 and 1999, 20 underwent surgery for the tethered cord syndrome at a median age of 8 years (range 2 to 13). Time points for cystometry used for comparison were before symptoms at a median age of 20 months (range 9 to 106), a median of 5 months preoperatively (1 to 33) and at 12 months postoperatively (6 to 19). Severe bladder dysfunction was defined as basal pressure more than 40 and/or overactivity greater than 60 cm H2O, moderate dysfunction as basal pressure 20 to 40 and/or overactivity 20 to 60 cm H2O, and mild dysfunction as basal pressure less than 20 cm H2O.
RESULTS: Of the 20 patients who underwent untethering 7 had improvement to a milder dysfunctional level, while 1 deteriorated postoperatively. Six patients experienced deterioration in bladder dysfunction level before untethering, and all returned to a milder level afterward. A total of 10 patients had unchanged bladder dysfunction before symptoms and preoperatively. Of these patients 9 (90%) continued unchanged after untethering, while 1 deteriorated.
CONCLUSIONS: After untethering secondary to myelomeningocele 35% of the patients experienced improved bladder function and 5% deteriorated. All of the patients who deteriorated before untethering improved afterward, and 90% of those who were stable preoperatively continued to be stable postoperatively. Therefore, regular evaluation of bladder function in children with myelomeningocele should be performed.