Techniques for the intradetrusor administration of botulinum toxin

Repeated injections of botulinum toxin-A for idiopathic detrusor overactivity

OBJECTIVES

To report the efficacy and safety of repeated injections of botulinum toxin-A (BTX-A) in treating idiopathic detrusor overactivity refractory to anticholinergics. Furthermore, we describe whether dose alteration in patients with poor responses or voiding dysfunction after initial treatment can improve outcomes.

METHODS

A cohort of 34 patients who participated in a clinical trial was followed up and their progress reported. Twenty from this group had >1 BTX-A injection. Each patient received 200 U BTX-A initially, with subsequent injections between 100 and 300 U, administered by a trigone-sparing flexible cystoscopic technique. Efficacy was measured using voiding diaries and quality of life (QoL) assessed with Incontinence Impact Questionnaire-7 and Urogenital Distress Inventory-6 questionnaires. Urodynamic data were obtained for injections 1-3. All measurements were performed before and 3 months after injections.

RESULTS

Twenty patients received a repeat injection and of these 9 subsequently received a third and fourth injection. Significant improvements in overactive bladder syndrome symptoms and QoL were observed after each injection as compared with baseline. Maximum cystometric capacity and bladder compliance increased with decrease in the maximum detrusor pressure during filling cystometry. When comparing overactive bladder symptoms, QoL, and urodynamic parameters 3 months after the first and last injections, no significant differences were found. Nine patients had their BTX-A dose altered, with better outcomes in 5. The commonest reported problems were difficulty in emptying the bladder and urinary tract infection.

CONCLUSIONS

BTX-A appears to be effective and safe after repeated administration in patients with idiopathic detrusor overactivity. Certain patients will benefit from dose optimization to improve efficacy or prevent voiding dysfunction.

A morphological evaluation of botulinum neurotoxin A injections into the detrusor muscle using magnetic resonance imaging

OBJECTIVES

Although botulinum neurotoxin type A (BoNT/A) intradetrusor injections are a recommended therapy for neurogenic detrusor overactivity (NDO), refractory to antimuscarinic drugs, a standardisation of injection technique is missing. Furthermore, some basic questions are still unanswered, as where the toxin solution exactly spreads after injection. Therefore, we investigated the distribution of the toxin solution after injection into the bladder wall, using magnet resonance imaging (MRI).

METHODS

Six patients with NDO were recruited. Three of six patients received 300 U of BoNT/A + contrast agent distributed over 30 injection sites (group 1). The other three patients received 300 U of BoNT/A + contrast agent distributed over 10 injection sites (group 2). Immediately after injection, MRI of the pelvis was performed. The volume of the detrusor and the total volume of contrast medium inside and outside the bladder wall were calculated.

RESULTS

In all patients, a small volume (mean 17.6%) was found at the lateral aspects of the bladder dome in the extraperitoneal fat tissue, whereas 82.4% of the injected volume reached the target area (detrusor). In both groups there was a similar distribution of the contrast medium in the target area. A mean of 33.3 and 25.3% of the total detrusor volume was covered in group 1 and 2, respectively. Six weeks after injection, five of six patients were continent and showed no detrusor overactivity in the urodynamic follow-up. No systemic side effects were observed.

CONCLUSIONS

Our results provide morphological arguments that the currently used injection techniques are appropriate and safe.

Health economics and intradetrusor injections of botulinum for the treatment of detrusor overactivity

Health economic aspects are crucial in arguing the feasibility of setting up a new service using an unlicensed treatment. Overall, the costs of intradetrusor botulinum neurotoxin-A treatment appear to be modest relative to the improvement in quality of life. However, in managing the overactive bladder, there is a need for a widely accepted definition of 'clinical improvement' or a common outcome measure to direct future clinical and health economic research.

The neural control of micturition

Micturition, or urination, occurs involuntarily in infants and young children until the age of 3 to 5 years, after which it is regulated voluntarily. The neural circuitry that controls this process is complex and highly distributed: it involves pathways at many levels of the brain, the spinal cord and the peripheral nervous system and is mediated by multiple neurotransmitters. Diseases or injuries of the nervous system in adults can cause the re-emergence of involuntary or reflex micturition, leading to urinary incontinence. This is a major health problem, especially in those with neurological impairment. Here we review the neural control of micturition and how disruption of this control leads to abnormal storage and release of urine.

Botulinum toxin for detrusor overactivity and symptoms of overactive bladder: where we are now and where we are going

Botulinum toxin (BTX) treatment for overactive bladder and detrusor overactivity is becoming increasingly recognized as an excellent therapeutic option for treating patients refractory to anticholinergic agents. Results from open-label studies have suggested that this therapy is effective in neurogenic and idiopathic detrusor overactivity, yet validating evidence from randomized, placebo-controlled trials has been unavailable. The exact mechanism of action of BTX in the bladder is controversial, although evidence suggests that apart from preventing the presynaptic release of acetylcholine from the parasympathetic innervation to the bladder, it might have an effect on sensory mechanisms. The latter hypothesis could in part explain its effect on symptoms such as urgency. The purpose of this Review is to present the results of randomized, placebo-controlled trials in which BTX treatment for detrusor overactivity was investigated. Also the evidence supporting its potential dual mechanism of action in the bladder will be considered. In addition, the various techniques of administration of BTX are discussed and avenues for further research suggested.

Efficacy of Botulinum Toxin-A for Treating Idiopathic Detrusor Overactivity: Results From a Single Center, Randomized, Double-Blind, Placebo Controlled Trial

PURPOSE

We evaluated the use of botulinum toxin-A in treating patients with idiopathic detrusor overactivity refractory to anticholinergics.

MATERIALS AND METHODS

This double-blind, placebo controlled trial randomized participants to intradetrusor injections of 200 U botulinum toxin-A (16 patients) or placebo (18 patients). The primary outcome measure was change in maximum cystometric capacity. Secondary outcome measures included changes in overactive bladder symptoms, post-void residual, maximum detrusor pressure during filling cystometry and reflex detrusor volume. Quality of life was assessed using the Incontinence Impact Questionnaire short form 7 and Urogenital Distress Inventory short form 6. Followup occurred at 4 and 12 weeks after injection, at which point the study was unblinded. Further followup in the botulinum toxin-A group occurred at 24 weeks.

RESULTS

Significant increases in maximum cystometric capacity were observed at 4 weeks (difference 144.69 ml, 95% CI 100.95 to 215.75, p <0.0001) and 12 weeks (difference 95.71 ml, 95% CI 47.47 to 172.45, p = 0.001) in patients treated with botulinum toxin-A compared to placebo. Botulinum toxin-A reduced frequency (p <0.001, p = 0.003) and urgency urinary incontinence (p = 0.03, p = 0.008) episodes at 4 and 12 weeks, respectively. Urgency was reduced at 4 weeks (p = 0.005) in the botulinum toxin-A group. In patients receiving botulinum toxin-A, post-void residual increased at 4 weeks (p = 0.024) but became insignificant by 12 weeks (p = 0.406). Of these patients 6 required intermittent self-catheterization. Significant improvements in quality of life were observed following botulinum toxin-A. The extension study suggests that the beneficial effects of botulinum toxin-A are maintained for at least 24 weeks.

CONCLUSIONS

Botulinum toxin-A at 200 U is safe and effective for idiopathic detrusor overactivity and the beneficial effects persist for at least 24 weeks.