The purpose of this study is to examine how injection of botulinum toxin in the bladder affects bladder function. The trial is carried out in children born with malformation of the spinal cord and subsequent overactive bladders. The purpose of treating the bladder (with different drugs) is to prevent damage to the kidneys and renal function. The aim of this study is to compare a conventionally used drug (oxybutynin) with botulinum toxin. The hypothesis of the study is that botulinum toxin is equal to oxybutynin in the treatment of overactive bladder.

Neurogenic bladder is often seen in children with myelomeningocele, tumors in the spinal canal, or a traumatized spinal cord. The majority of the patients have high pressure bladders which can lead to reflux and frequent infections in the urinary tract. Although children experience insufficient bladder emptying, many of them also experience urinary incontinence and have to perform clean intermittent catheterization (CIC). If no intervention is made, the children are at high risk of renal deterioration.

Inclusion Criteria:

• Myelomeningocele
• Neurogenic bladder with untreated leak point pressures > 40 mmH2O
• Treated with oxybutynin or other parasympatholytics

Exclusion Criteria:

• Acute urinary tract infection
• Compromised neuromuscular transmission