Is efficacy of repeated intradetrusor botulinum toxin typeA (Dysport super(+)) injections dose dependent? Clinical and urodynamic results after four injections in patients with drug-resistant neurogenic detrusor overactivity

Objective: To assess the effects of two different doses of botulinum toxinA (Dysport super(+): 500 and 1,000IU) injected repeatedly into the bladder for the treatment of neurogenic detrusor overactivity (NDO) in terms of safety, durability, and improvement of continence status and urodynamic parameters. Patients and methods: In this study we analyzed the effects of successive doses of 500 or 1,000IU of Dysport super(+), endoscopically injected into the detrusor muscle. Clinical, urodynamic, and satisfaction assessments were performed at baseline and 6weeks after each injection. The results of injections and corresponding follow-ups were analyzed and compared with baseline. Results: Twenty-two patients (13 men and 9 women) with repeated four injections were included, of whom 12 (55%) with mean age 35.7years (range 16-52years) received 500IU of BTX-A and 10 (45%) with mean age 33.8years (range 18-50years) received 1,000IU in each treatment. No statistically significant differences were found in efficacy duration with the two Dysport doses (500IU: 7.7months, 1,000IU: 8.5months; P>0.05). Maximum cystometric capacity (MCC), reflex volume (RV), and bladder compliance (BC), and patient satisfaction improved significantly after each treatment compared with baseline values and there were no statistically significant differences after each retreatment for the two treatment groups (P>0.05). Conclusions: After repeated injections the effect of BTX-A remained constant. The cause of repeat treatment is relapse of overactive bladder symptoms. Results with the 500 and 1,000IU doses were interesting and approximately equivalent in terms of duration and efficacy, with better but not significant results when 1,000IU was used. The optimum dose of Dysport for incontinence secondary to NDO is not yet defined; 1,000IU probably has a nonsignificant longer effect than 500IU but may expose the patient to major complications. Further studies evaluating the clinical efficacy of 750IU of Dysport are necessary.