Histologic features in the urinary bladder wall affected from neurogenic overactivity--a comparison of inflammation, oedema and fibrosis with and without injection of botulinum toxin type A.

OBJECTIVES: To study histological features and morphological differences in bladder wall specimen from patients with and without botulinum toxin A injections and to compare those issues in responders and non-responders to the toxin therapy.
MATERIAL AND METHODS: Bladder wall specimen obtained from cystectomy in 45 patients with neurogenic overactive bladders with and without injection of botulinum toxin A into the detrusor muscle for treatment of neurogenic incontinence were evaluated concerning the histological criteria inflammation, oedema and fibrosis of the bladder wall.
RESULTS: Bladder wall specimen obtained from patients suffering from neurogenic detrusor overactivity showed important histological alterations. Generally, inflammatory infiltration, oedema and fibrosis of the bladder wall were frequently observed. When comparing specimen from patients who had received botulinum toxin injection to those from patients who had not, there was no difference concerning inflammation and oedema. However, patients who had received botulinum toxin injection showed significantly less fibrosis of the bladder wall than those who had not received the toxin injection (p<0.00073). When comparing specimen from responders and non-responders to the botulinum toxin therapy, there was no difference in inflammation. Although not significant, a trend was observed that responder to the toxin therapy had less fibrosis and oedema of the bladder wall than non-responder.
CONCLUSION: In our study injection of botulinum toxin into the detrusor muscle did not lead to increased fibrotic activity within the bladder wall, on the contrary patients with previous botulinum toxin injection revealed significant less fibrosis than patients without toxin injection.