Role of C afferent fibers and monitoring of intravesical resiniferatoxin therapy for patients with idiopathic detrusor overactivity.

Purpose: Resiniferatoxin (RTX) is a specific C fiber neurotoxin which produces desensitization. In this study we performed intravesical RTX therapy in patients with idiopathic detrusor overactivity. In addition we measured the current perception threshold of C and A delta fibers before and after treatment to evaluate clinical significance.

Materials And Methods: The protocol involved an RTX solution (100 ml of 50 nM) instilled in the bladder for 30 minutes. Four men and 6 women 59 to 75 years old were treated. Effects on bladder function were evaluated before and 30 days after treatment by cystometry and Neurometer (Neurotron, Inc., Baltimore, Maryland). Subjective and objective measures included bladder diaries and quality of life before treatment, and 7, 30 and 90 days subsequently.

Results: Of the 10 patients 5 noted improvement and 2 of them became dry. The other 5 patients were considered to have stationary symptoms. Mean maximal cystometric capacity +/- SD increased from 229 +/- 108 ml at baseline to 271 +/- 99.5 ml at 30 days (p = 0.04). The mean number of daily episodes of urinary incontinence decreased from 3.5 +/- 2.2 to 2.0 +/- 1.6 (p = 0.008) at 7 days, to 1.9 +/- 1.6 (p = 0.018) at 30 days and to 2.5 +/- 1.7 (p = 0.018) at 90 days. Mean current perception threshold values of C and A delta fibers did not change significantly, from 46.9 +/- 35.2 to 56.4 +/- 32.1 (p = 0.161) and from 66.9 +/- 31.7 to 66.4 +/- 25.2 (p = 0.952), respectively. However, values of C fibers increased in all patients who showed improvement from 46.2 +/- 33.2 to 64.0 +/- 36.8 (p = 0.043).

Conclusions: Intravesical RTX improved bladder capacity and leak episodes in patients with idiopathic detrusor overactivity. Intravesical RTX is a promising treatment for this condition.