Detrusor overactivity in spina bifida: how long does it need to be treated?

To determine whether a lasting therapeutic effect can be expected from long-term antimuscarinic therapy for neurogenic detrusor overactivity in spina bifida and to answer the question whether detrusor overactivity in spina bifida children with detrusor/sphincter dyssynergia is primarily based on the neuropathy or, in part, can be a secondary detrusor reaction to the functional urethral obstruction.

Fifteen spina bifida patients, aged between 1 and 12 years, all on a regime of clean intermittent catheterisation (CIC) and oxybutynin since shortly after birth, underwent three consecutive urodynamic studies (UDS). One prestudy UDS for treatment control, one UDS after withdrawal of oxybutynin for 3-5 days and one UDS after reinstallment of oxybutynin treatment. Urodynamic results were compared concerning detrusor overactivity, cystometric bladder capacity, and compliance.

Detrusor overactivity was seen in two patients on the prestudy UDS. After several days of withdrawal of oxybutynin overactivity was seen in 11 patients. After oxybutynin withdrawal, bladder compliance was within safe margins for two patients only, after reinstallment, safe vesical pressures were seen in 11 patients.

The functional obstruction due to detrusor/sphincter dyssynergia has been by-passed chronically in all these children by CIC and oxybutynin. Due to the fact that detrusor overactivity recurs immediately after withdrawal of medication after long-term treatment with oxybutynin, one can conclude that there is no long-lasting therapeutic effect of pharmacological suppression. This suggests that in children with detrusor/sphincter dyssynergia, detrusor overactivity is primarily of neuropathic origin.