Botulinum-A toxin injections into the detrusor muscle decrease nerve growth factor bladder tissue levels in patients with neurogenic detrusor overactivity.
PURPOSE: We investigated the effects of BTX-A on visceral afferent nerve transmission by measuring bladder tissue NGF levels in patients with neurogenic detrusor overactivity before and after intravesical treatment with BTX-A. We also compared the bladder tissue NGF content with clinical and urodynamic data. MATERIALS AND METHODS: A total of 23 patients underwent clinical evaluation and urodynamics with detection of the UDC threshold, maximum pressure and maximum cystometric capacity before, and at the 1 and 3-month followups. Endoscopic bladder wall biopsies were also obtained at the same time points. NGF levels were measured in tissue homogenate by enzyme-linked immunosorbent assay (Promega, Madison, Wisconsin). RESULTS: At 1 and 3 months mean catheterization and incontinent episodes were significantly decreased (p <0.05 and <0.001, respectively). On urodynamics we detected a significant increase in the UDC threshold and maximum cystometric capacity, and a significant decrease in UDC maximum pressure at the 1 and 3-month follow-ups compared to baseline (each p <0.001). At the same time points we detected a significant decrease in NGF bladder tissue content (each p <0.02). CONCLUSIONS: BTX-A intravesical treatment induces a state of NGF deprivation in bladder tissue that persists at least up to 3 months. As caused by BTX-A, the decrease in acetylcholine release at the presynaptic level may induce a decrease in detrusor contractility and in NGF production by the detrusor muscle. Alternatively BTX-A can decrease the bladder level of neurotransmitters that normally modulate NGF production and release.