Intravesical vanilloids and neurogenic incontinence: ten years experience

In this study we critically review our '10-year' experience with intravesical vanilloids (capsaicin and resiniferatoxin) in the treatment of neurogenic incontinence, addressing the issue of their introduction into daily clinical practice.

From July 1992 to June 2001, 54 patients suffering from detrusor hyperreflexia, due to spinal cord injuries, received intravesical instillation of capsaicin, and from January 1995 to June 2001, 47 patients received intravesical instillation of resiniferatoxin (RTX) in order to treat bladder dysfunction and symptoms. All patients presented detrusor hyperreflexia refractory to oral and/or intravesical oxibutynin and they displayed high-voiding pressure associated with frequent urine leakage. Capsaicin was used at a concentration of 10 mM; RTX was tested in two different concentrations: 10 nM and 10 microM. The outcome was considered according to simple parameters: (i) the number of patients who reported an improvement in clinical status (patient dry between clean intermittent catheterization) and urodynamic status (a bladder capacity 50% higher than pretreatment capacity, lasting more than 3 months after the instillation); (ii) the number of patients who continued intravesical therapy; (iii) the number of instillations they received; (iv) the length of the interval between 2 consecutive instillations, and (v) alternative therapies when vanilloids failed.

The topical intravesical instillation of capsaicin produced an improvement in symptoms and urodynamic parameters, in 29 patients (53.7%) after 3 months. In these 29 patients only 7 (24.13%) continued to received capsaicin in June 2001. The mean follow-up was 32.28 +/- 14.20 (range 8-52) months, the mean number of instillations was 6.14 +/- 2.54 (range 2-10) and the mean interval between the 2 consecutive instillations was 7.14 +/- 2.60 (range 4-12) months. The topical intravesical instillation of RTX produced an improvement in symptoms and urodynamic parameters in 73.33% of patients (a total of 45 patients) who received 10 microM. 18 of them (54.54%) continued to received RTX in June 2001. The mean follow-up was 27.88 +/- 10.95 (range 11-49) months, the mean number of instillations was 4.33 +/- 1.60 (range 2-8). The mean interval between 2 consecutive instillations was 9.61 +/- 2.99 (ranged 4-16) months.

The results obtained using RTX seem to be very promising with regard to efficacy and tolerance, particularly in comparison with capsaicin. Even if the number of patients who received capsaicin and RTX remains small, the intravesical vanilloid receptor agonist RTX could offer an attractive alternative to oral medications in the treatment of neurogenic incontinence.