New therapeutic options for refractory neurogenic detrusor overactivity

Current pharmacologic treatment of detrusor overactivity relies on anticholinergic drugs. However, they often have untolerable side effects so that they are administered in doses insufficient to restore urinary continence. Recently, intravesical instillations and injections into the detrusor muscle of new pharmacological agents have been developed. The present study report our own experience in the treatment of detrusor overactivity with intravesical administrations of vanilloid agents and with botulinum-A toxin injections into the detrusor muscle in a group of spinal cord injured patients. In particular, we compared the clinical and urodynamic effects of the 2 drugs in an attempt to find a new and valid therapeutic option in those cases unresponsive to conventional treatment.

Seventy-five patients with spinal cord injury and refractory detrusor overactivity were included in the study: 35 patients received repeated intravesical instillations of resiniferatoxin (RTX) dissolved in normal saline; 40 patients received repeated injections of 300 units botulinum A-toxin diluted in 30 ml normal saline. Clinical assessment and urodynamics were performed at baseline and 6, 12 and 24 months after treatment.

With both treatments there was a significant reduction in mean catheterization and episodes of incontinence and a significant increase in mean first involuntary detrusor contraction and in mean maximum bladder capacity at 6, 12 and 24 months after therapy. We did not detect any local side effects with either treatment. Botulinum-A toxin significantly reduced also the maximum pressure of uninhibited detrusor contractions more than RTX at all follow-up time points.

In patients with spinal cord injury and refractory detrusor overactivity intravesical RTX and botulinum-A toxin injections into the detrusor muscle provided beneficial clinical and urodynamic results with reduction of detrusor overactivity and restoration of urinary continence in most patients. Botulinum-A toxin injection provided better clinical and urodynamic benefits than intravesical RTX.