Objective
The aim of this study was to investigate the efficacy of capsaicin, a neurotoxin for C-fiber afferents, applied intravesically in the treatment of neurogenic bladder with detrusor hyperreflexia (DH).

Method
Six subjects, three women and three men with traumatic spinal cord injury who had neurogenic bladder manifested with DH and urinary incontinence resistant to oral and intravesical anticholinergic instillation treatment were tried with intravesical administration of capsaicin (1 mmol/l 100 ml) for 30 minutes. Single instillation was given in five subjects and two instillations in one. Maximal detrusor pressure and maximal bladder volume were monitored by the portable cystometer. Follow-up monitor of pressure and volume was recorded after 1 week and every 3 weeks afterwards for 21 weeks, with one exception (31 weeks).

Results
Average maximal detrusor pressure decreased by 50.8% and average bladder capacity at maximal detrusor pressure increased by 68% in five subjects after single instillation of capsaicin. Clinical benefit from single instillation lasted over 21 weeks and same as the subject with two instillations. Maximal effect on detrusor pressure appears during 6∼9 weeks period and bladder capacity during 9∼15 weeks period. Although autonomic dysreflexia in 5 of 6 subjects during instillation and macroscopic hematuria in 2 subjects during the 1st two days were noted, they were resolved spontaneously.

Conclusion
Single and repeated intravesical instillation of capsaicin were safe and effective in the management of neurogenic bladder with DH in traumatic spinal cord injured patients.