Frontiers in the Clinical Applications of Botulinum Toxin A as Treatment for Neurogenic Lower Urinary Tract Dysfunction

Lower urinary tract dysfunction in the central nervous system neurogenic bladder and the real-life treatment outcome of botulinum toxin A

Neurogenic lower urinary tract dysfunction (NLUTD) is common in patients with central nervous system (CNS) lesions. Cases of cerebrovascular accidents (CVA), Parkinson's disease, dementia, and other intracranial lesions develop poor bladder control with or without urinary difficulty due to loss of cortical perception of bladder filling sensation and poor coordination of urethral sphincter relaxation during reflex micturition. Patients with CNS lesions usually have overactive bladder (OAB) symptoms, including urgency, frequency, incontinence, voiding symptoms of dysuria, large postvoid residual volume, and retention. In elderly patients with severe CNS disease the OAB symptoms are usually difficult to adequately relieve by medical treatment, and thus, their quality of life is greatly. Botulinum toxin A (BoNT-A) is currently licensed and has been applied in patients with idiopathic and neurogenic OAB due to spinal cord injury or multiple sclerosis. However, the application of BoNT-A in the treatment of urinary incontinence due to NLUTD in chronic CNS lesions has not been well-documented. Although cohort studies and case series support BoNT-A treatment for neurogenic OAB, chronic urine retention after intravesical BoNT-A injection for OAB and exacerbated urinary incontinence after urethral BoNT-A injection for voiding dysfunction have greatly limited its application among patients with NLUTD due to CNS lesions. This article reviews the pathophysiology and clinical characteristics of NLUTD in patients with CNS lesions and the clinical effects and adverse events of BoNT-A injection for patients with NLUTD. A flowchart was created to outline the patient selection and treatment strategy for neurogenic OAB.

[Bladder augmentation in the era of botulinum toxin: Indications and results]

AIM

To determine the surgical indication and results of bladder augmentation (BA) during the last decade in a neurourology center in the era of intradetrusor botulinum toxin injection.

MATERIAL

We conducted a retrospective study that included patients with BA between January 1, 2012 and December 31, 2022 in our centre. We collected pre-operative demographic, clinical, and urodynamic data, BA indication, and associated procedures. We analyzed early and late complications as well as continence and postoperative voiding mode in patients with first BA in a neurological pathology context.

RESULTS

We performed 77 BA over the study period. The main indication was neurogenic overactive bladder, which was secondarily resistant to botulinum toxin. The main associated procedure was continent cutaneous diversion (n=31, 57.4%). Among patients who had a first BA for neurogenic bladder, 34 patients had early complications (50%) including 12 patients with≥Clavien 3 complications (17.6%). After a median follow-up of 33 [14; 55] months, 23 patients had late complications (33.8%) and 59 patients had complete continence (86.8%).

CONCLUSION

In the era of botulinum toxin, the main indication of BA is the secondary failure of botulinum toxin for overactive neurogenic bladder. The BA provided continence in 86.8% of patients. It remains however an intervention with a significant rate of severe complications whose indication must be discussed by a multidisciplinary team.

LEVEL OF EVIDENCE

Weak.

Treating Neurogenic Lower Urinary Tract Dysfunction in Chronic Spinal Cord Injury Patients-When Intravesical Botox Injection or Urethral Botox Injection Are Indicated

Lower urinary tract symptoms (LUTS), such as urgency, urinary incontinence, and/or difficulty voiding, hamper the quality of life (QoL) of patients with spinal cord injury (SCI). If not managed adequately, urological complications, such as urinary tract infection or renal function deterioration, may further deteriorate the patient's QoL. Botulinum toxin A (BoNT-A) injection within the detrusor muscle or urethral sphincter yields satisfactory therapeutic effects for treating urinary incontinence or facilitating efficient voiding; however, adverse effects inevitably follow its therapeutic efficacy. It is important to weigh the merits and demerits of BoNT-A injection for LUTS and provide an optimal management strategy for SCI patients. This paper summarizes different aspects of the application of BoNT-A injection for lower urinary tract dysfunctions in SCI patients and provides an overview of the benefits and drawbacks of this treatment.

The Comparative Effectiveness of Botulinum Toxin-A Injection Therapy Versus Augmentation Uretero-Enterocystoplasty for the Treatment of Lower Urinary Tract Dysfunction

Purpose: We investigated the effectiveness of intravesical botulinum toxin-A (BTX-A) injection therapy in patients with lower urinary tract dysfunction (LUTD) and upper urinary tract (UUT) deterioration and evaluated whether BTX-A injection therapy could substitute for augmentation uretero-enterocystoplasty (AUEC).Methods: Data from a prospective, single-center cohort from 2017–2021 were analyzed. Patients were divided into 2 treatment groups: AUEC and BTX-A (i.e., patients who declined AUEC). Bladder and UUT functions were assessed by comparing clinical information, urodynamic data, laboratory results, and imaging records.Results: In total, 121 patients were enrolled (BTX-A group: 41 patients; AUEC group: 80 patients). The BTX-A group showed a reduced maximum detrusor pressure and increases in the maximum bladder volume and bladder compliance (P<0.05). However, in follow-up evaluations, significantly smaller improvements (all P<0.05) in urodynamic parameters were found in the BTX-A group than in the AUEC group. Notably, there was no significant improvement in vesicoureteral reflux (VUR; P=0.66) or upper urinary tract dilatation (UUTD; P=0.75) in the BTX-A group, and no statistically significant difference in serum creatinine (Scr) levels or the estimated glomerular filtration rate (eGFR) was observed in the follow-up evaluations (all P>0.05). Both VUR and UUTD improved significantly in the AUEC group, and the Scr and eGFR levels significantly improved after AUEC relative to baseline levels (P<0.05). The reduction in the Scr level was significantly lower in the BTX-A group than in the AUEC group during 0–15 months of follow-up (Scr reduction differences, -1.36; P<0.01).Conclusions: Although BTX-A injection therapy was effective for improving bladder function, BTX-A injections did not alleviate UUT deterioration in this study, particularly in patients with advanced-stage LUTD. Conversely, AUEC for LUTD has a well-established role in improving UUT function. Hence, BTX-A injection therapy should not replace AUEC to ameliorate UUT impairment and protect UUT function.

Role of Urological Botulinum Toxin-A Injection for Overactive Bladder and Voiding Dysfunction in Patients with Parkinson's Disease or Post-Stroke

Botulinum toxin A (BoNT-A) paralyzes muscle by blocking acetylcholine release at the synaptic junction. BoNT-A has shown its therapeutic effects in neurological disorders such as Parkinson's disease (PD) and post-stroke spasticity. A high proportion of patients with PD and post-stroke develop neurogenic detrusor overactivity (nDO) and then develop urinary incontinence and overactive bladder (OAB) symptoms. This study aimed to disclose the safety and efficacy of BoNT-A injection in treating bladder and voiding dysfunction in PD and post-stroke patients by reviewing the current evidence. At present, intradetrusor injection of BoNT-A is a Food and Drug Administration (FDA)-approved third-line therapy for nDO and idiopathic OAB. Although intradetrusor injection of onaBoNT-A 200 U is already approved for nDO treatment, most researchers would like to manage PD and post-stroke patients by using onaBoNT-A 100 U intradetrusor injection to achieve long-term efficacy and reduce adverse effects. However, in contrast to its inclusion in the International Continence Society guidelines for PD treatment, the clinical use of BoNT-A for post-stroke patients is limited to experimental use due to the development of urinary retention in about one-fifth of patients. For treating urethral pseudodyssynergia, half of patients may respond to onaBoNT-A 100 U urethral injection. However, refinement is needed to reduce unwanted urinary incontinence.

Molecular Mechanism Operating in Animal Models of Neurogenic Detrusor Overactivity: A Systematic Review Focusing on Bladder Dysfunction of Neurogenic Origin

Neurogenic detrusor overactivity (NDO) is a severe lower urinary tract disorder, characterized by urinary urgency, retention, and incontinence, as a result of a neurologic lesion that results in damage in neuronal pathways controlling micturition. The purpose of this review is to provide a comprehensive framework of the currently used animal models for the investigation of this disorder, focusing on the molecular mechanisms of NDO. An electronic search was performed with PubMed and Scopus for literature describing animal models of NDO used in the last 10 years. The search retrieved 648 articles, of which reviews and non-original articles were excluded. After careful selection, 51 studies were included for analysis. Spinal cord injury (SCI) was the most frequently used model to study NDO, followed by animal models of neurodegenerative disorders, meningomyelocele, and stroke. Rats were the most commonly used animal, particularly females. Most studies evaluated bladder function through urodynamic methods, with awake cystometry being particularly preferred. Several molecular mechanisms have been identified, including changes in inflammatory processes, regulation of cell survival, and neuronal receptors. In the NDO bladder, inflammatory markers, apoptosis-related factors, and ischemia- and fibrosis-related molecules were found to be upregulated. Purinergic, cholinergic, and adrenergic receptors were downregulated, as most neuronal markers. In neuronal tissue, neurotrophic factors, apoptosis-related factors, and ischemia-associated molecules are increased, as well as markers of microglial and astrocytes at lesion sites. Animal models of NDO have been crucial for understanding the pathophysiology of lower urinary tract (LUT) dysfunction. Despite the heterogeneity of animal models for NDO onset, most studies rely on traumatic SCI models rather than other NDO-driven pathologies, which may result in some issues when translating pre-clinical observations to clinical settings other than SCI.

Predictive Factors for a Successful Treatment Outcome in Patients with Different Voiding Dysfunction Subtypes Who Received Urethral Sphincter Botulinum Injection

Voiding dysfunction is a common but bothersome problem in both men and women. Urethral sphincter botulinum toxin A (BoNT-A) injections could serve as an option in refractory cases. This study analyzed the efficacy and outcome predictors of the injections in patients with functional, non-neurogenic voiding dysfunction. Patients who received urethral sphincter BoNT-A injection for refractory voiding dysfunction due to detrusor underactivity (DU) or urethral sphincter dysfunction were retrospectively reviewed. A successful outcome was defined as a marked improvement as reported in the global response assessment. The study evaluated the therapeutic efficacy of urethral sphincter BoNT-A injections and measured the changes in urodynamic parameters after the procedure in the patients. A total of 181 patients including 138 women and 43 men were included. The overall success rate was 64%. A lower success rate was noted in patients with DU compared to those with urethral sphincter dysfunction in both genders. In the multivariable analysis, recurrent urinary tract infection (UTI) and bladder voiding efficiency (BVE) were positive predictors for a successful outcome, while DU was a negative predictor. Urethral sphincter BoNT-A injection is an effective treatment for refractory non-neurogenic voiding dysfunction. Baseline BVE and history of recurrent UTI positively predict a successful outcome. DU is a negative outcome predictor.

Novel botulinum neurotoxin-A tibial nerve perineural injection to alleviate overactive bladder symptoms in male rats

Although tibial nerve modulation has shown to induce positive changes in the overactive bladder (OAB), prolonged therapeutic effects using percutaneous stimulation have not yet been achieved. Intradetrusor onabotulinum toxin A injection can provide prolonged therapeutic effects; however, its delivery requires invasive measures. By applying local relief of tibial nerve neural entrapment with onabotulinum toxin A injection, this study investigated the feasibility and efficacy of combining the abovementioned two therapeutic strategies. An OAB animal model was developed using 12 adult Sprague-Dawley rats with cyclophosphamide intraperitoneal injection. A perineural injection site comparable to the tibial nerve perineural injection site and corresponding to that in humans was identified and developed in rats. The toxin was injected five days after establishing the OAB. The incision was made in the skin on the lateral surface of the thigh. The biceps femoris muscle was cut across, exposing the sciatic nerve and its three terminal branches: the sural, common peroneal, and tibial nerves, and 100 units of onabotulinum toxin A was injected into the surrounding tissue. Five days following injection, cystometry was performed. Inter-contraction time, contraction pressure, and interval of the disease state improved with statistical significance. The OAB animal model showed significant improvement with the tibial nerve perineural injection of botulinum toxin, thereby suggesting the possibility of a comparable treatment adaptation in humans.

Satisfaction with Urinary Incontinence Treatments in Patients with Chronic Spinal Cord Injury

Purpose: To investigate the long-term satisfaction and complications in chronic spinal cord injury (SCI) patients after various bladder management strategies and surgical procedures for the treatment of urinary incontinence. Methods: Patients at a single institution with chronic SCI who received bladder management treatment or surgical procedure to improve urinary continence were retrospectively assessed. Thorough urological examinations and videourodynamic studies were performed. Patients were treated either through conservative approaches including medical treatment, clean intermittent catheterization (CIC), cystostomy, and indwelling urethral catheter, or through surgical procedures including detrusor botulinum toxin (Botox) injections, augmentation, ileal conduit, Kock pouch diversion, continent cystostomy, suburethral sling, and artificial urethral sphincter (AUS) implantation. The patients’ satisfaction with urinary continence improvement, causes of dissatisfaction, long-term complications, and overall satisfaction with bladder and voiding condition were assessed. Results: A total of 700 consecutive patients were enrolled in this study. High satisfaction rates were noted after detrusor Botox injection (81.1%), augmentation enterocystoplasty (91.4%), autoaugmentation (80%), Kock pouch diversion, and continent cystostomy (all 100%). Fair satisfaction rates were noted after ileal conduit diversion (66.7%), suburethral sling (64.3%), and AUS implantation (66.7%). Patients who received conservative treatment with medicines, CIC, cystostomy, or an indwelling urethral catheter all had less-satisfactory outcomes (all < 40%). Conclusion: Overall satisfaction with surgical procedures aimed to improve urinary continence in chronic SCI patients was higher than with conservative bladder management (35.4%). Appropriate surgical procedures for chronic SCI patients with neurogenic lower urinary tract dysfunction (NLUTD) and urological complications yielded satisfaction with both urinary continence improvement and with overall bladder and voiding condition.

Usefulness of videourodynamic study in the decision-making of surgical intervention and bladder management for neurogenic lower urinary tract dysfunction among patients with myelomeningocele

PURPOSE

Neurogenic lower urinary tract dysfunction (NLUTD) is common among children with myelomeningocele (MMC). If NLUTD is not appropriately managed, recurrent urinary tract infection (UTI) can persist and may affect upper urinary tract function. This study investigated the usefulness of videourodynamic study (VUDS) in the urological management of MMC.

METHODS

We retrospectively analyzed 57 patients with MMC who underwent VUDS and received urological treatments at the hospital, including surgeries, minimally invasive therapies, and conservative management. The baseline VUDS parameters of patients who received different treatments were evaluated, and the treatment outcomes of the different treatment subgroups were compared.

RESULTS

There were 29 male and 28 female patients with a mean age of 24.1 ± 15.9 years upon enrollment. Patients had dysuria or urinary retention (n = 42, 73.7%), urinary incontinence (n = 40, 70.2%), recurrent UTI (n = 35, 61.4%), hydronephrosis (n = 27, 47.4%), and vesicoureteral reflux (n = 26, 45.6%). VUDS revealed detrusor sphincter dyssynergia in 32 (56.1%) patients, bladder neck dysfunction in 13 (22.8%), and intrinsic sphincter deficiency in 20 (35.1%). Among them, 21 (36.8%) received surgical intervention, 17 (29.8%) minimally invasive therapy, and 19 (33.3%) conservative management. After a mean follow-up of 8.5 years, the incidence rates of recurrent UTI (61.4% vs 31.6%, p = 0.001), hydronephrosis (47.4% vs 14.0%, p < 0.0001), urinary incontinence (70.2% vs 35.1%, p < 0.0001), and vesicoureteral reflux (45.6% vs 21.1%, p < 0.001) decreased. The overall global response assessment rate was 73.7%, and patients who underwent surgery had the best rate (90.5%). The predictive value of bladder compliance for treatment selection was > 20.5 ml/cm H₂O.

CONCLUSION

VUDS can be used to comprehensively assess lower and upper urinary tract dysfunction among patients with MMC. To improve NLUTD and prevent complications, minimally invasive therapies or surgical procedures should be recommended to patients with MMC who have low bladder compliance.

Development of an Automatic Interpretation Algorithm for Uroflowmetry Results: Application of Artificial Intelligence

Purpose

To develop an automatic interpretation system for uroflowmetry (UFM) results using machine learning (ML), a form of artificial intelligence (AI).

Methods

A prospectively collected 1,574 UFM results (1,031 males, 543 females) with voided volume>150 mL was labelled as normal, borderline, or abnormal by 3 urologists. If the 3 experts disagreed, the majority decision was accepted. Abnormality was defined as a condition in which a urologist judges from the UFM results that further evaluation is required and that the patient should visit a urology clinic. To develop the optimal automatic interpretation system, we applied 4 ML algorithms and 2 deep learning (DL) algorithms. ML models were trained with all UFM parameters. DL models were trained to digitally analyze 2-dimensional images of UFM curves.

Results

The automatic interpretation algorithm achieved a maximum accuracy of 88.9% in males and 90.8% in females when using 6 parameters: voided volume, maximum flow rate, time to maximal flow rate, average flow rate, flow time, and voiding time. In females, the DL models showed a dramatic improvement in accuracy over the other models, reaching 95.4% accuracy in the convolutional neural network model. The performance of the DL models in clinical discrimination was outstanding in both genders, with an area under the curve of up to 0.957 in males and 0.974 in females.

Conclusions

We developed an automatic interpretation algorithm for UFM results by training AI models using 6 key parameters and the shape of the curve; this algorithm agreed closely with the decisions of urology specialists.