Intravesical capsaicin in patients with detrusor hyper-reflexia--a placebo-controlled cross-over study

The aim of this study was to determine whether intravesical treatment with capsaicin could block detrusor hyper-reflexia (DH) and alter the substance P content, nerve fibres and mucosa of the bladder. Twelve patients with spinal cord disease with DH and urinary incontinence resistant to anticholinergic treatment underwent intravesical administration of 50 ml 2% lignocaine. followed by either 100 ml 1 mmol/l capsaicin or 100 ml physiological saline for 30 min. Cross-over to the alternative treatment took place after 4 weeks. Varying degrees of burning sensation were experienced by all but one patient during the capsaicin treatment and precluded the possibility of conducting studies of this type in a blind manner. No preference for capsaicin treatment was found, and micturition and VAS scores were unchanged after treatment with capsaicin. The mean volume of the contents of the bladder at which DH first appeared was 175 ml after saline and 195 ml after capsaicin (mean difference 20 ml with a 5% confidence interval from -25 to 65). Bladder biopsies taken 2 weeks after treatment with capsaicin showed more pronounced inflammation, superficial haemorrhage, squamous epithelial metaplasia and a more condensed bladder stroma. Immunohistochemical staining for substance P and neuronal cell adhesive molecule revealed the presence of small terminal axons and small nerve bundles in all of the biopsies. Intravesical treatment with capsaicin did not have a beneficial effect on DH or a destructive effect on nerve fibres. It did, however, produce significant reactive changes in the mucosa of the bladder.