Intradetrusor botulinum neurotoxin A (BoNT-A) injections decrease bladder fibrosis secondary to partial urethral obstruction in the male rat model

Onabotulinumtoxin A (Botox): A reasonable alternative for refractory neurogenic bladder dysfunction in children and young adults

AIMS

We aimed to describe the effectiveness of Onabotulinumtoxin A (Botox) in children with neurogenic bladder (NGB) unresponsive to medical therapy to determine urodynamic parameters predictive of success.

METHODS

Children receiving Botox for refractory NGB, between 2008 and 2019, from a single academic center, were included in this study. Botox success was defined as improvement of incontinence and/or urodynamic parameters.

RESULTS

Of 34 patients who received Botox, 13 (38.2%) had a positive response from their first injection, with improvement in capacity by a median of 35% of expected capacity for age compared to only a 9% increase in those who did not respond clinically. When patients were divided into groups by baseline urodynamic parameters, high-pressure (Pdetmax > 20 cm H₂ O) patients had significantly greater improvement in compliance compared with low-pressure patients (p = 0.017). Low compliance patients (<10 ml/cm H₂ O) had a dramatic improvement of 3.08 ml/cm H₂ O in their compliance compared with minimal change in the high compliance group (p = 0.003). Finally, low-capacity (<50% of expected CC) patients had significant improvement in capacity and compliance when compared with high-capacity patients (p = 0.004 and p = 0.036, respectively). Improvement in detrusor overactivity (DO) was noted in both the clinical responders and non-responders.

CONCLUSION

In our series, 38% had clinical success with intradetrusor Botox injections for refractory neurogenic bladder. When successful, improvement in capacity and compliance, DO, and/or incontinence was consistent with prior literature. While we could not determine which parameters predicted success, subdividing patients into categories based on baseline urodynamic parameters identified who would benefit from Botox treatment based on differential improvements in capacity and compliance. At least 1 injection of Botox should be considered for a subset of children with refractory NGB, before undertaking more invasive treatments.

Beyond botulinum neurotoxin A for chemodenervation of the bladder

PURPOSE OF REVIEW

Botulinum neurotoxin A (BoNT/A), or Botox, is a popular option for overactive bladder (OAB) and neurogenic bladder (NGB) with or without incontinence. This review aims to discuss the clinical outcomes of BoNT in adult and pediatric bladder conditions, and introduces the potential benefit of novel, engineered neurotoxins beyond BoNT/A.

RECENT FINDINGS

A large volume of evidence supports the use of Botox for OAB (to reduce urgency, frequency and incontinence episodes), and for NGB (to decrease incontinence and improve bladder capacity and detrusor pressures). Botox is now also Food & Drug Administration (FDA)-approved for pediatric neurogenic detrusor overactivity. However, urinary retention, diminished response over time and treatment failures are prevalent issues with Botox. Modifying natural BoNTs or forming chimeric toxins are alternatives to BoNT/A that may have higher efficacy and lower side-effect profile. One example is BoNT/BMY-WW. This novel engineered toxin binds to a more commonly expressed synaptotagmin receptor, with potentially more potent paralytic effect and less capacity for systemic diffusion.

SUMMARY

Novel engineered neurotoxins may be the next frontier in OAB and NGB therapy.

Botulinum toxin A improves neurogenic bladder fibrosis by suppressing transforming growth factor β1 expression in rats

Background

Intradetrusor botulinum toxin A injection is recommended for the treatment of refractory detrusor overactivity (DO) in patients with neurogenic bladder, however, whether it could inhibit neurogenic bladder fibrosis is uncertain. This study aimed to investigate the effect of botulinum toxin A on neurogenic bladder fibrosis and the underlying mechanism.

Methods

Forty eight Female Wistar rats were evenly randomized into 4 groups: Sham, T10 transection, Early and Late groups. The last three groups were subjected to T10 spinal cord transection, while the Sham group was treated with sham surgery. 0.9% saline was injected into the detrusor in the Sham and T10 transection groups simultaneously with the surgery, while 2 U/rat botulinum toxin A was injected into the detrusor simultaneously with the surgery in the Early group and 4 weeks following the surgery in the Late group. Body/bladder weight, cystometric parameters, bladder Hematoxylin-eosin staining were used to evaluate the bladder fibrosis. Western blot and quantitative Real-time PCR were used to evaluate the expression of bladder transforming growth factor β1.

Results

Compared with the T10 transection group, the bladder/body weight was decreased significantly in the Early and Late groups (P<0.05), along with the significant inhibition of non-voiding contraction (NVC) frequency and amplitude (P<0.05), and the significant increase of bladder volume (P<0.05). The detrusor connective tissue percentage (P<0.05) and the expression of transforming growth factor β1 (P<0.05) also decreased significantly in the Early and Late groups. Those changes were more obviously in the Early group than in the Late group.

Conclusions

Intradetrusor botulinum toxin A injection reduced bladder fibrosis in rats with spinal cord injury (SCI), which was more obviously in the Early group than in the Late group. The mechanisms might be mediated by suppression of transforming growth factor β1 (TGF-β1) expression.

Fibrosis and the bladder, implications for function ICI-RS 2017

AIMS

Most benign bladder pathologies are associated with an increase of extracellular matrix (ECM-fibrosis) and may progress from formation of stiffer matrix to a more compliant structure. The aims were to summarize current knowledge of the origins of bladder fibrosis and consequences in bladder function.

METHODS

A meeting at the International Consultation on Incontinence Research Society 2017 congress discussed the above aims and considered paradigms to reduce the extent of fibrosis. Discussants based their arguments on the basis of their own expertise, supplemented by review of the literature through PubMed. Proposals for future work were derived from the discussion.

RESULTS

Altered urodynamic compliance when ECM deposition is increased is mirrored by changes in the elastic modulus of isolated tissue, whether compliance is decreased or increased. No changes to compliance or fibrosis have been reported after botulinum toxin injections. Several paracrine and autocrine agents increase ECM deposition, the role of TGF-β was particularly emphasized. None of these agents has a net long-term effect on detrusor contractility and the reduction of contractile performance with increased ECM is due solely to a loss of detrusor mass. Several strategies to reduce fibrosis were described, ranging from potential therapeutic roles for vitamin-D or endostatin, manipulation of intracellular pathways that mediate myofibroblast differentiation and the potential role of the anti-fibrotic hormone relaxin. An understanding of epigenetic regulation of ECM deposition was also considered.

CONCLUSIONS

The conclusion that reduced bladder contractile function with increased fibrosis is due largely to the replacement of detrusor with ECM offers a way forward for future research to consider approaches that will restore bladder function by reducing ECM deposition.

Applicability of botulinum toxin type A in paediatric neurogenic bladder management

PURPOSE OF REVIEW

The purpose of this article is to provide an overview about the applicability of botulinum toxin type A (BTX-A) in paediatric neurogenic bladder based on the recently published literature combined with hypothetical notes and future perspectives.

RECENT FINDINGS

The indications, clinical outcomes, urodynamic outcome parameters and cost-effectiveness are presented from recent publications. Also, alternative routes of application of BTX-A in the bladder are discussed as well as the influence of BTX-A on conservative and invasive treatment.

SUMMARY

Intradetrusor BTX-A injections for neurogenic bladder dysfunction are effective in resolving both urinary incontinence and improving urodynamic parameters in most children with a sustained response at repeated injections. In low-compliance bladders, however, if no response is seen after initial BTX-A injection, repeated injections seem to be unnecessary. Because general anaesthesia is mandatory for BTX-A injections in children, alternative routes of application have been investigated such as intravesical installation, electromotive drug application and liposomal drug delivery; however, no definite results have been found in a paediatric clinical setting.

Can bladder fibrosis in congenital urinary tract obstruction be reversed?

A variety of conditions exists in adults and children in which functional or anatomical urinary tract obstructions cause bladder fibrosis, which reduces the bladder's ability to store and empty urine. Current surgical procedures include removal of the obstructions to facilitate bladder emptying or prompt prenatal or postnatal spinal closure to prevent further neurogenic damage. Bladder fibrosis may occur, and it can get worse if a flow hindrance persists or deteriorates. Anti-fibrotic therapeutic strategies that target a variety of factors have been developed in animal models, but currently there are no anti-fibrotic therapies available for clinical use. This review examines the pathogenesis of bladder fibrosis that is caused by congenital obstructions of the lower urinary tract, and it focuses on the principal signalling factors and potential treatment modalities.

Clinical and Urodynamic Results of Repeated Intradetrusor Onabotulinum Toxin A Injections in Refractory Neurogenic Detrusor Overactivity: Up to 5 Injections in a Cohort of Children With Myelodysplasia

OBJECTIVE

To determine the efficacy and safety of repeated intradetrusor onabotulinum toxin A (onaBoNT-A) injections in children with neurogenic detrusor overactivity due to myelodysplasia.

MATERIALS AND METHODS

The study group consisted of 19 children (4 boys and 15 girls) with a mean age of 10.3 ± 3.1 years old, who had received at least 2 injections of 10 U/kg onaBoNT-A for the treatment of urinary incontinence resistant to anticholinergic treatment and clean intermittent catheterization in our clinic, between 2010 and 2015. Controlled urodynamic studies were performed at the baseline and 3 months after each injection.

RESULTS

Eight of the children received 3 injections, 5 children had 4 injections, and 2 children had 5 injections. From the baseline to the fifth injection, the detrusor compliance (1.3, 4.5, 10, 20.7, 18.8, and 16.6 mL/cm H₂O), the maximum bladder capacity (82.0, 157.0, 191.0, 272.0, 299.0, and 210.5 mL), and the maximum detrusor pressure (55.0, 33.0, 22.0, 12.5, 16.0, and 12.5 cm H₂O) were assessed. The findings significantly improved following the first, second, and third injections, when compared with the previous bladder dynamics (P <.05), but the differences with the fourth were not statistically significant (P >.05). The continence periods were similar under clean intermittent catheterization after all of the injections (P <.05), and no severe side effects were observed.

CONCLUSION

Repeated onaBoNT-A injections are a safe treatment modality and can be offered as an effective alternative choice, instead of more invasive surgery, in children with neurogenic detrusor overactivity due to myelodysplasia.