Objective: Determine long-term effect of English botulinum neurotoxin type A (BoNTA; Dysport) for refractory neurogenic detrusor overactivity (NDO) for possible reduction of BoNTA efficacy after repeated injections.
Methods: Between 1999 and 2005, 199 patients with spinal cord lesions with refractory NDO were treated with Dysport. All patients underwent a clinical examination, urinalysis, and videourodynamic study at baseline and at 3, 6, and 12 mo after each treatment, as well as a visual analogue scale (VAS) assessment and a bladder diary checked for 1 wk before each visit. We used 1000, 750, 500 IU BoNTA at the beginning of our experience, and thereafter we mainly used 750 IU. Outcome measures included frequency of urge urinary incontinence (Incontinence Episode Frequency [IEF] test); urodynamic parameters including maximum cystometric bladder capacity (MCBC), reflex volume (RV), bladder compliance (BC); number of pads/condoms; antimuscarinic drug consumption; short- and long-term side-effects; and quality of life measured with VAS.
Results: No statistically significant differences were found in efficacy duration with the three Dysport doses (p=0.5274). The difference between the intervals of injections was not statistically significant (p=0.2659). MCBC, RV, and BC improved significantly after treatment compared with baseline values (p<0.001) and there were no statistically significant differences after each retreatment or regarding Dysport dose (p>0.05). There was a significant improvement in patient satisfaction after each retreatment as expressed on the VAS (p<0.001). There was a significant reduction in IEF score and pads/condoms use in the first 4 wk after each treatment (p<0.0001).
Conclusion: After repeated injections the effect of BoNTA remained constant.