Objective        To study the clinical outcome of ketamine-related bladder dysfunction after intravesical injection of botulinum toxin A.       Methods        Six male patients with ketamine-related bladder dysfunction at the age of 18-36 years

who failed to routine treatment with ketamine

antibiotics

and M-blockers

were enrolled in this study. Their symptoms included severe frequency and urgency of micturition

nocturia

urodynia or hematuria. Botulinum toxin A (200 U) was uniformly injected into 30 sites of the musculus detrusor vesicae under a cystoscope. Micturition

overactive bladder symptoms score (OABSS) and improved symptoms were recorded before and after 4 weeks of treatment. The therapeutic effect of intravesical botulinum toxin A injection were assessed.       Results        The biopsy of bladder tissue from 6 patients showed inflammatory changes in bladder mucosa. The frequency of daytime micturition and nocturia decreased from 24.2±5.9 to 12.8±2.5 and from 16.8±5.3 to 6.7±3.0 respectively(P0.01)

the urine volume increased from 31.3±10.8 ml to 67.8±23.7 ml (P0.01)

the OABSS decreased from 9.7±1.5 to 7.0±1.7 (P0.01)

and the symptoms such as urodynia

bladder pain and hematuria were significantly improved 4 weeks after treatment. No adverse drug reactions such as acute urinary retention was observed in the 6 patients.       Conclusion        Intravesical injection of botulinum toxin A is a safe and effective treatment modality for ketamine-related bladder dysfunction. However

its long-term effect needs to be further observed in the follow-up of such patients.