Therapeutic effect of urethral sphincter onabotulinumtoxinA injection for urethral sphincter hyperactivity

Efficacy of transurethral botulinum toxin A injections for bladder outlet obstruction: A systematic review and meta-analysis

INTRODUCTION

Botulinum toxin A (BoNT-A) injections in the prostate gland have been used as a minimally invasive option for treating bladder outlet obstruction (BOO). However, the efficacy of transurethral BoNT-A injections for BOO is not well established in the literature. The aim of this study is to collect evidence on the efficacy of transurethral BoNT-A injections for the treatment of BOO.

MATERIALS AND METHODS

This systematic review and meta-analyses was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. A systematic literature search was performed till December 2022. The study population consisted of adult patients diagnosed with BOO, who underwent transurethral injections of BoNT-A for the treatment of BOO.

EVIDENCE SYNTHESIS

Out of 883 records, we identified seven studies enrolling 232 participants, of which only one nonrandomized controlled trial was found. Four prospective studies and two retrospective studies. Three studies included patients with lower urinary tract symptoms (LUTS) and benign prostatic hyperplasia (BPH) and were included in the meta-analysis. Three studies included patients with urethral sphincter hyperactivity. One study included patients with primary bladder neck disease (PBND). All studies showed significant improvements from baseline in maximum urinary flow rate (Qmax), International Prostate Symptom Score (IPSS), and postvoid residual (PVR) at 3 and 6 months. The adverse events were mild in all studies. Hematuria, UTI, and urinary retention were reported across all studies.

CONCLUSION

In conclusion, transurethral BoNT-A injections have been shown to improve LUTS, QoL, and urodynamic parameters of individuals with BOO at 3 and 6 months after injections, and no serious adverse effects have been reported. However, data on the long-term benefits of this treatment are scarce, and more prospective, randomized studies with larger samples examining various injection techniques, dosages, and extended follow-up of recurrent injections are needed.

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.

Transurethral Incision of the Bladder Neck with or without Additional Procedure Resumes Spontaneous Voiding in Female Voiding Dysfunction-A Long-Term Retrospective Follow-Up

AIM

This study evaluated the long-term effectiveness of transurethral incision of the bladder neck (TUI-BN) with or without an additional procedure for female voiding dysfunction.

METHODS

Women with voiding difficulty who underwent TUI-BN in the last 12 years were included. All patients underwent a videourodynamics study (VUDS) at baseline and after TUI-BN. A successful outcome was defined as having a voiding efficiency (VE) increase by ≥50% after treatment. Patients with insufficient improvement were chosen for repeated TUI-BN, urethral onabotulinumtoxinA injection, or transurethral external sphincter incision (TUI-ES). The current voiding status, surgical complications, and additional surgeries were evaluated.

RESULTS

A total of 102 women with VUDS evidence of a narrow bladder neck during voiding were enrolled. The long-term success rate of the first TUI-BN was 29.4% (30/102) and increased to 66.7% (34/51) after combining TUI-BN and an additional procedure. The overall long-term success rates were 74.6% in women with detrusor underactivity (DU), 52.0% in detrusor overactivity and low contractility, 50.0% in bladder neck obstruction, 20.0% in hypersensitive bladder, and 75% in stable bladder (p = 0.022). Patients with a lower maximum flow rate (Qmax), (p = 0.002), lower voided volume (p < 0.001), lower corrected Qmax (p < 0.001), lower ladder contractility index (p = 0.003), lower voiding efficiency (p < 0.001), but larger post-void residual volume (p < 0.001) had a satisfactory surgical outcome. Spontaneous voiding was achieved in 66 (64.7%) patients, de novo urinary incontinence in 21 (20.6%), and vesicovaginal fistula in 4 (3.9%), all were repaired.

CONCLUSIONS

TUI-BN alone or in combination with an additional procedure was safe, effective, and durable in patients with DU to resume spontaneous voiding.

Botulinum toxin A injection to the external urethral sphincter for voiding dysfunction in females: A tertiary center experience

AIM

The aim of this study is to examine the functional outcomes of ona-botulinum toxin A (BTX-A) injection into the external urethral sphincter (EUS) for female patients with nonneurogenic nonrelaxing sphincter as the underlying cause of voiding dysfunction (VD).

METHOD

A retrospective analysis was performed for all the patients with the urodynamic findings of higher than expected maximum urethral closure pressure (MUCP) who received their first injection during the study period. All patients were evaluated with preoperative videourodynamic study and urethral pressure profilometry and received 100 U of EUS BTX-A. Patients aged less than 18 years and those with neurogenic bladder were excluded. All patients were followed up with the free flow, postvoid residuals (PVR), and patient global impression of improvement (PGI-I) scale at 6 weeks and then at 3 monthly intervals.

RESULT

We identified 35 female patients with a mean age of 37.5 ± 15 years (range 18-72 years) with a mean follow-up of 20 months. More than 50% of patients had a history of prior surgical intervention and 28 (80%) patients were catheter dependent, a suprapubic catheterization, or clean intermittent self-catheterization. Mean MUCP was 97.1 ± 22 cm of water. After treatment with BTX-A, 21 (60%) patients were able to void per urethral (p = 0.02). The mean maximum flow rate (Qmax) improved from 8.8 to 11 mls/s and the mean PVR decreased from 200 to 149 mls (p < 0.05). On multivariate analysis, we identified high preoperative PVR, high preoperative actual MUCP, and previous surgical intervention (urethral dilatation, sacral neuromodulation, and pelvic surgery) as predictors of successful voiding restoration. The mean duration of response was 4.7 months, 46% of patients requested repeat injection, and 29% were established on maintenance injections. On the 5-point PGI-I score, 13 (37%), 12 (34%), and 10 (29%) patients reported good, some, and no improvement, respectively. Quality of life was also improved in 60% of patients. Two patients had transient stress urinary incontinence (for <6 weeks) and there were no significant long-lasting adverse events.

CONCLUSION

EUS BTX-A is a valid treatment option for VD considering therapeutic options are limited. The patient must be made aware of the need for repeat treatments.

Clinical Application of Botulinum Neurotoxin in Lower-Urinary-Tract Diseases and Dysfunctions: Where Are We Now and What More Can We Do?

Botulinum toxin A (Botox) had been considered a promising drug that has an effect on functional disorders of the lower urinary tract. Because Botox exhibits anti-inflammatory and antispasmodic effects, Botox injection into the bladder can decrease detrusor contractility, reduce bladder hypersensitivity, and eliminate painful sensations. Injecting Botox into the bladder outlet can relax the hyperactivity of the bladder neck, and of the urethral smooth and striated muscles. Based on these therapeutic effects, Botox has been widely applied to treat lower-urinary-tract dysfunctions (LUTDs) such as overactive bladder and neurogenic detrusor overactivity. However, this treatment has not been licensed for use in other LUTDs such as interstitial cystitis, voiding dysfunction due to benign prostatic hyperplasia in men, and dysfunctional voiding in women. Botox has also not been approved for the treatment of children with overactive bladder and dysfunctional voiding; in patients with spinal cord injuries with detrusor sphincter dyssynergia and autonomic dysreflexia; or for poorly relaxed external sphincter in non-neurogenic patients. This article reviews the current knowledge regarding Botox treatment for LUTDs and discusses the potential clinical applications of Botox, as well as work that can be conducted in the future.

Treatment outcomes of detrusor underactivity in women based on clinical and videourodynamic characteristics

PURPOSE

Treatment of voiding dysfunction due to detrusor underactivity (DU) remains challenging. This study sought to determine the characteristics of video urodynamic study (VUDS) in female DU and outcomes after active treatment.

METHODS

A total of 409 female patients with VUDS-proven DU were recruited. All patients received conservative bladder management, with others receiving active treatment, such as oral medication, transurethral incision of bladder neck (TUI-BN), surgery for prolapse, and urethral botulinum toxin A (BoNT-A) injection, according to their VUDS characteristics. Treatment outcomes were then analyzed by different VUDS characteristics.

RESULTS

Satisfactory treatment outcomes were noted in 123 patients (30.0%), among whom 35 and 88 had a VE of > 90% and > 66.7%, respectively. A total of 165 patients (40.3%) had voiding efficiency (VE) of 33.3-66.7%, whereas 121 (29.6%) remained unable to void (12.5%) or had a VE of < 33.3% (17.1%). Conservative treatment had the worst outcome. Patients with normal or slightly reduced bladder sensation (49.3%) and those with a post-void residual (PVR) of < 250 mL (59.4%) displayed better satisfactory outcome after treatment; while TUI-BN and urethral BoNT-A injection promoted better treatment results. Patients with detrusor acontractility and a PVR of ≥ 500 mL still achieved high VE rates (> 66.7%) after TUI-BN. A 56.3% satisfactory outcome was achieved after TUI-BN, whereas 58.1% satisfactory outcome was noted in those with a tight external sphincter after medical treatment.

CONCLUSION

Female patients with DU exhibited VE improvement after active treatment. Patients with very low detrusor contractility and absent bladder sensation generally exhibited poor treatment outcomes.

Effect of videourodynamic subtypes on treatment outcomes of female dysfunctional voiding

INTRODUCTION AND HYPOTHESIS

Dysfunctional voiding (DV) is not uncommon in women and is typically challenging to treat. This study retrospectively investigated the long-term treatment outcomes of DV women with different videourodynamics (VUDS) characteristics.

METHODS

Data of women with VUDS-proven DV (n = 302) were retrospectively analyzed. All patients at first received biofeedback pelvic floor muscle training and medications; urethral sphincter botulinum toxin A injection was administered after treatment failure. Long-term follow-up outcomes were graded by global response assessment (GRA) and objective responses of decrease of detrusor pressure (Pdet), increase in maximum flow rate (Qmax) and voiding efficiency (VE). The treatment outcomes were investigated among different VUDS subgroups.

RESULTS

Of 302 women, 165 (54.6%) had mid-urethral DV, 117 (38.7%) had distal urethral DV, and 20 (6.6%) had both bladder neck dysfunction (BND) and mid-urethral DV. A total of 170 (56.3%) patients were available for follow-up VUDS after treatment. Pdet was decreased in all three subgroups, but increase in Qmax and VE was only noted in the BND plus DV subgroup. Overall, 120 (70.6%) patients showed improvement (GRA ≥ 1), including 14 with BND plus DV (93.3%), 50 with mid-urethral DV (60.8%) and 56 with distal urethral DV (77.8%) (p = 0.044). All three subgroups showed significant reduction in bladder outlet obstruction index after treatment, with BND plus DV subgroup showing the greatest reduction.

CONCLUSIONS

Women with DV have different VUDS characteristics resulting from different pathophysiological mechanisms and treatment results. The VUDS characteristics may help predict treatment outcomes of female DV.

Therapeutic outcome of active management in male patients with detrusor underactivity based on clinical diagnosis and videourodynamic classification

Detrusor underactivity (DU) could be resulted from many different etiologies. Patients with DU might have reduced bladder sensation, low detrusor contractility, and large post-void residual volume. This study analyzed therapeutic outcome of active management for male DU patients, based on clinical and urodynamic characteristics. Male DU patients aged > 18 years old were retrospectively reviewed from the videourodynamic study (VUDS) records in recent 10 years. The patients’ demographics, VUDS results, treatment modalities, and treatment outcome were analyzed. The treatment outcomes were compared among patients with different DU subgroups, clinical diagnosis and treatment modalities. Patients with voiding efficiency of > 66.7% were considered having a successful treatment outcome. For comparison, 30 men with normal VUDS finding served as the control arm. Most of the DU patients had reduced bladder sensation. The reduced bladder sensation is closely associated with low detrusor contractility. After active treatment, a successful outcome was achieved in 68.4% of patients after bladder outlet surgery, 59.1% after urethral botulinum toxin A injection, and 57.6% after medical treatment, but only 18.2% after conservative treatment. A successful treatment outcome was achieved in patients with an intact detrusor contractility, either low (69.2%) or normal voiding pressure (81.8%), and in patients with a normal or increased bladder sensation (78.1%). However, patients with detrusor acontractile (41.3%) or absent bladder sensation (17.9%) had less favorable treatment outcome after any kind of urological management. This study revealed that active management can effectively improve voiding efficiency in patients with DU. The normal bladder sensation, presence of adequate detrusor contractility, and bladder outlet narrowing during VUDS provide effective treatment strategy for DU patients. Among all management, BOO surgery provides the best treatment outcome.

Therapeutic Efficacy of Urethral Sphincteric Botulinum Toxin Injections for Female Sphincter Dysfunctions and a Search for Predictive Factors

External urethral sphincter (EUS) dysfunction is a common, bothersome female voiding dysfunction. This study aims to analyze the characteristics of different types of female EUS dysfunction, as well as to determine the outcome predictors of sphincteric botulinum toxin A (BoNT-A) injection. Women receiving sphincteric BoNT-A injections for refractory EUS dysfunction were retrospectively reviewed. A comparison of the baseline clinical, urodynamic parameters and the treatment responses were made for patients with different EUS dysfunctions. A total of 106 females were included. Significantly increased detrusor overactivity, detrusor contracting pressure and the bladder outlet obstruction index with decreased urge sensation were noted in patients diagnosed with dysfunctional voiding or detrusor sphincter dyssynergia comparing to those diagnosed with poor relaxation of the external urethral sphincter. The average subjective improvement rate was 67% for the injection. The therapeutic effect was not affected by the type of EUS dysfunction. The multivariate analysis revealed that bladder neck narrowing and catheterization history were predictive of negative outcomes. There is a distinct urodynamic presentation for each type of female EUS dysfunction. Sphincteric BoNT-A injection provides a good therapeutic outcome for refractory EUS dysfunction. A narrowing bladder neck and a history of catheterization suggest poor therapeutic outcomes.

Therapeutic Effects of Urethral Sphincter Botulinum Toxin A Injection on Dysfunctional Voiding with Different Videourodynamic Characteristics in Non-Neurogenic Women

Although female dysfunctional voiding (DV) is common in urological practice, it is difficult to treat. This study evaluated the therapeutic efficacy of urethral botulinum toxin A (BoNT-A) on non-neurogenic female DV. Based on the videourodynamic study (VUDS), the DV was classified into three subgroups according to the obstructive site. A successful treatment outcome was defined as an improvement of voiding efficiency by 10% and reported global response assessment by ≥1. The study compared therapeutic efficacy, baseline urodynamic parameters, and changes in urodynamic parameters between the treatment success and failure groups and among three DV subgroups. Predictive factors for successful treatment were also investigated. A total of 81 women with DV were categorized into three groups: 55 (67.9%) had mid-urethral DV, 19 (23.5%) had distal urethral DV, and 7 (8.6%) had combined BN dysfunction and mid-urethral DV after BN transurethral incision. The treatment outcome was successful for 55 (67.9%) patients and failed for 26 (32.1%). Successfully treated patients had a significant decrease of detrusor pressure, post-void residual volume, and bladder outlet obstruction index, as well as an increase in voiding efficiency at follow-up versus the treatment failure group. The logistic regression of urodynamic parameters and clinical variables revealed that a greater volume of first sensation of filling predicts a successful BoNT-A treatment outcome (p = 0.047). The urethral BoNT-A injection is effective in treating non-neurogenic women with DV, with a success rate of 67.9%. The videourodynamic characteristics of DV may differ among patients but does not affect the treatment outcome.

Role of videourodynamic study in precision diagnosis and treatment for lower urinary tract dysfunction

Lower urinary tract symptoms (LUTS) are complicated and cannot be used alone to diagnose lower urinary tract dysfunctions (LUTDs) and guide treatment. Patients with bladder outlet obstruction (BOO), impaired detrusor contractility, and hypersensitive bladder might present with voiding predominant symptoms, whereas patients with detrusor overactivity (DO), dysfunctional voiding, or BOO might also present with storage symptoms. To clearly identify the pathophysiology of LUTD, a comprehensive urodynamic study (UDS) including pressure flow and image during the storage and emptying phases, naming videourodynamic study (VUDS), is necessary. This study is especially mandatory in the diagnosis of (1) male LUTS refractory to medical treatment for benign prostatic hyperplasia, (2) female voiding dysfunction and urinary retention, (3) diagnosis of overactive bladder syndrome refractory to first-line medication, (4) management of female stress urinary incontinence and postoperative LUTS, (5) diagnosis and management of neurogenic LUTD, (6) pediatric urinary incontinence and enuresis, (7) geriatric urinary incontinence, and (8) recurrent bacterial cystitis. Although VUDS should not be used as a screening test for any LUTS, it should be considered when the initial management cannot relieve LUTS, or when invasive surgical procedure is planning to undertake for patients with refractory LUTS. VUDS should be recommended as the second-line investigation when the initial diagnosis and treatment based on the symptoms alone or noninvasive tests fail to improve LUTS.

Mechanism of Action of Botulinum Toxin A in Treatment of Functional Urological Disorders

Intravesical botulinum toxin (BoNT) injection is effective in reducing urgency and urinary incontinence. It temporarily inhibits the detrusor muscle contraction by blocking the release of acetylcholine (Ach) from the preganglionic and postganglionic nerves in the efferent nerves. BoNT-A also blocks ATP release from purinergic efferent nerves in the detrusor muscle. In afferent nerves, BoNT-A injection markedly reduces the urothelial ATP release and increases nitric oxide (NO) release from the urothelium. BoNT-A injection in the urethra or bladder has been developed in the past few decades as the treatment method for detrusor sphincter dyssyndergia, incontinence due to neurogenic or idiopathic detrusor overactivity, sensory disorders, including bladder hypersensitivity, overactive bladder, and interstitial cystitis/chronic pelvic pain syndrome. Although the FDA only approved BoNT-A injection treatment for neurogenic detrusor overactivity and for refractory overactive bladder, emerging clinical trials have demonstrated the benefits of BoNT-A treatment in functional urological disorders. Cautious selection of patients and urodynamic evaluation for confirmation of diagnosis are crucial to maximize the successful outcomes of BoNT-A treatment.