Detrusor overactivity: an overview

Intravesical Injection of Botulinum Toxin Type A in Men without Bladder Outlet Obstruction and Post-Deobstructive Prostate Surgery

Purpose: A significant proportion of men without bladder outlet obstruction (BOO) have been reported to have overactive bladders (OAB). This article aimed to review the specific group of reports on the use of botulinum toxin type A (BTX-A) injections into the bladder wall. Materials and methods: Original articles reporting men with small prostates without BOO were identified through a literature search using the PubMed and EMBASE databases. Finally, we included 18 articles that reviewed the efficacy and adverse effects of BTX-A injections in men. Results: Of the 18 articles screened, 13 demonstrated the therapeutic efficacy and adverse effects of BTX-A injections in men. Three studies compared BTX-A injection response between patients without prior prostate surgery and those undergoing prior prostate surgery, including transurethral resection of the prostate and radical prostatectomy (RP). Patients with prior RP experienced better efficacy and had a low risk of side effects. Two studies focused on patients who had undergone prior surgery for stress urinary incontinence, including male sling and artificial urethral sphincter surgery. The BTX-A injection was a safe and effective procedure for this specific group. OAB in men was found to have a different pathophysiology mechanism from that in female patients, which may decrease the efficacy of BTX-A injection in men. However, patients with small prostates and low prostate-specific antigen levels demonstrated better efficacy and tolerability after BTX-A injection. Conclusions: Although intravesical injection of BTX-A was a good option for controlling refractory OAB in men, the evidence-based guidelines are still limited. Further research is necessary to better understand the role of BTX-A injections on various aspects and histories. Therefore, treating patients using strategies tailored to their individual conditions is important.

Efficacy and safety of mirabegron in the treatment of overactive bladder syndrome after radical prostatectomy: a prospective randomized controlled study

Objectives

To evaluate the effects of mirabegron in the treatment of overactive bladder syndrome (OAB) after radical prostatectomy (RP).

Patients and methods

A total of 108 post-operative RP patients were randomly assigned to either the mirabegron (study) or the placebo (control) group. The Overactive Bladder Syndrome Self-Assessment Scale (OABSS) was selected as the primary endpoint, and the International Prostate Symptom Score (IPSS) and Quality of Life (QOL) score were selected as secondary endpoints. Statistical analysis was performed using IBM SPSS Statistics 26, and the treatment effects were compared between the two groups using independent samples t-test.

Results

In total, 55 patients were included in the study group and 53 patients in the control group. The mean age was(70.08 ± 7.54)years. There was no statistical difference in the baseline data between the two groups. OABSS scores decreased significantly in the study group compared to the control group during drug treatment (6.67 ± 1.06 vs. 9.14 ± 1.83, p < 0.01) and were better than the control group during the follow-up at week 8 and week 12. In addition, the decrease in IPSS scores (11.29 ± 3.89 and 15.34 ± 3.54, p<0.01) and the increase in QOL scores (2.40 ± 0.81 vs. 3.20 ± 1.00) were statistically significant in the study group. And the patients in the study group had better improvement in voiding symptoms and quality of life than the control group during the follow-up period.

Conclusion

Daily administration of 50 mg mirabegron after RP surgery significantly improved the symptoms of OAB after surgery with fewer side effects. Additional randomized controlled trials should be conducted in the future to further evaluate the efficacy and safety of mirabegron.

Association of genetic polymorphisms in the pore domains of mechano-gated TREK-1 channel with overactive lower urinary tract symptoms in humans

AIMS

Mechanosensitivity of the urinary bladder is regulated by many factors including mechano-gated two-pore domain (K₂ P, KCNK) potassium channels. TWIK-related K⁺ channel, TREK-1, is a predominantly expressed member of K₂ P channel family in the human detrusor, and its expression and function are diminished in patients with overactive lower urinary tract symptoms (LUTS). The changes in channel activity may result from spontaneously occurring gene mutations. The aim of this study was to compare single nucleotide polymorphisms (SNPs) in TREK-1 channel between patients with LUTS and healthy donors.

METHODS

Six SNPs (rs370266806, rs373919966, rs758937019, rs769301539, rs772497750, and rs775158737) in two pore domains of human TREK-1 gene were analyzed using TaqMan SNP genotyping assay with manufacturer-designed primers and allele-specific probes. The screening was done in control bladders and detrusor specimens from patients with overactive LUTS. Statistical analyses were performed using R, Fisher's exact test and Hardy-Weinberg Equilibrium.

RESULTS

Six SNPs in two pore domains of the human TREK-1 gene were analyzed in human bladder specimens. The frequencies of rs758937019-CT genotype (P = 0.0016) and rs758937019-T allele (P = 0.0022) were significantly higher in the group with overactive LUTS. There was no significant association of rs775158737-GA genotype and rs775158737-A allele with the overactive LUTS, though they were present only in the overactive LUTS group.

CONCLUSIONS

Our results provide evidence that altered expression and function of TREK-1 channel in patients with overactive LUTS could be due to genetic polymorphisms in the pore domains of TREK-1 channel (rs758937019).

Altered expression and modulation of the two-pore-domain (K2P) mechanogated potassium channel TREK-1 in overactive human detrusor

Detrusor overactivity (DO) is the abnormal response of the urinary bladder to physiological stretch during the filling phase of the micturition cycle. The mechanisms of bladder smooth muscle compliance upon the wall stretch are poorly understood. We previously reported that the function of normal detrusor is regulated by TREK-1, a member of the mechanogated subfamily of two-pore-domain potassium (K_2P) channels. In the present study, we aimed to identify the changes in expression and function of TREK-1 channels under pathological conditions associated with DO, evaluate the potential relationship between TREK-1 channels and cytoskeletal proteins in the human bladder, and test the possibility of modulation of TREK-1 channel expression by small RNAs. Expression of TREK-1 channels in DO specimens was 2.7-fold decreased compared with control bladders and was associated with a significant reduction of the recorded TREK-1 currents. Isolated DO muscle strips failed to relax when exposed to a TREK-1 channel opener. Immunocytochemical labeling revealed close association of TREK-1 channels with cell cytoskeletal proteins and caveolins, with caveolae microdomains being severely disrupted in DO specimens. Small activating RNA (saRNA) tested in vitro provided evidence that expression of TREK-1 protein could be partially upregulated. Our data confirmed a significant downregulation of TREK-1 expression in human DO specimens and provided evidence of close association between the channel, cell cytoskeleton, and caveolins. Upregulation of TREK-1 expression by saRNA could be a future step for the development of in vivo pharmacological and genetic approaches to treat DO in humans.

Idiopathic and neurogenic detrusor overactivity: do the different patterns have urodynamic characteristics related to gender or neurological condition?

OBJECTIVES

To evaluate the urodynamic characteristics of the two patterns (phasic, P and terminal, T) of detrusor overactivity (DO) according to gender and neurological condition.

MATERIALS AND METHODS

Urodynamic characteristics of DO were analysed in a population with proven urodynamic DO (127 women and 76 men, respectively with 48 and 43 neurological diseases (encephalic, incomplete medullar lesion or peripheral)). Phasic DO is characterized by phasic waves with or without leakage while terminal DO is defined by a single non-inhibited contraction resulting in incontinence. Parameters analysed for both patterns of DO (among other parameters) included: volume and amplitude of the first non-inhibited detrusor contraction (NIDC#1), and for phasic DO: duration of pressure rise during NIDC#1 and number of NIDC.

RESULTS

Phasic DO was observed in younger patients in the whole population whatever the gender (women: 55.9 years vs. 64.7 years, p = 0.0052; men: 57.4 years vs. 67.8 years, p = 0.0038). Volume at NIDC#1 was greater for neurological PDO (significant in women: 185 vs. 125 mL, p = 0.0223). Other parameters were not significantly different whatever the gender. Amplitude of NIDC#1 during PDO was significantly lower than that of NIDC during terminal DO (TDO) in both genders whatever the neurological condition (p < 0.0001). Volume at NIDC#1 in both patterns was dependent on the level of neurological lesion.

CONCLUSION

The main difference between the patterns of DO is that PDO occurs in younger individuals. There is no significant difference between urodynamic characteristics of each pattern whatever gender or neurological status. Further studies will provide additional information on the impact of the level of neurological lesion on the pattern of DO.

Review on ultrasound measurement of bladder or detrusor wall thickness in women: techniques, diagnostic utility, and use in clinical trials

PURPOSE

To provide a narrative review of literature evaluating ultrasound techniques for the measurement of bladder wall hypertrophy in women as an alternative to invasive urodynamic assessment for the diagnosis of lower urinary tract symptoms (LUTS).

METHODS

A literature review was performed using PubMed and all paper journals of congress abstracts searching for articles on ultrasound measurement of bladder wall thickness (BWT) or detrusor wall thickness (DWT) published between January 1990 and May 2012. Each study was classified with a level of evidence using the Oxford Centre for Evidence-based Medicine classification (2009).

RESULTS

Ultrasound measurement of bladder wall hypertrophy is not standardised, and techniques vary widely according to anatomical approach, ultrasound frequency and other factors. This review compared transvaginal, translabial/transperineal and suprapubic approaches for ultrasound BWT/DWT measurement. BWT/DWT measurements correlated well with urodynamic diagnoses of detrusor overactivity (DO) using all three ultrasound techniques. BWT values were consistently higher in women with DO than in women with stress incontinence, although threshold values for the differential diagnosis of DO varied between clinical studies (5.0-6.5 mm using transvaginal ultrasound). Few data were available on the use of translabial or suprapubic ultrasound in women. Inter- and intraobserver variability was higher with transperineal and suprapubic ultrasound, and these techniques appear less reliable than transvaginal ultrasound. Studies suggest that BWT is reduced in response to antimuscarinic therapy in women with overactive bladder or DO.

CONCLUSIONS

Data from clinical trials suggest that transvaginal ultrasound measurement of BWT is a reliable method of diagnosing DO in women with LUTS, and BWT decreases during antimuscarinic therapy.

Trafficking of intermediate (KCa3.1) and small (KCa2.x) conductance, Ca(2+)-activated K(+) channels: a novel target for medicinal chemistry efforts?

Ca(2+)-activated K(+) (KCa) channels play a pivotal role in the physiology of a wide variety of tissues and disease states, including vascular endothelia, secretory epithelia, certain cancers, red blood cells (RBC), neurons, and immune cells. Such widespread involvement has generated an intense interest in elucidating the function and regulation of these channels, with the goal of developing pharmacological strategies aimed at selective modulation of KCa channels in various disease states. Herein we give an overview of the molecular and functional properties of these channels and their therapeutic importance. We discuss the achievements made in designing pharmacological tools that control the function of KCa channels by modulating their gating properties. Moreover, this review discusses the recent advances in our understanding of KCa channel assembly and anterograde trafficking toward the plasma membrane, the micro-domains in which these channels are expressed within the cell, and finally the retrograde trafficking routes these channels take following endocytosis. As the regulation of intracellular trafficking by agonists as well as the protein-protein interactions that modify these events continue to be explored, we anticipate this will open new therapeutic avenues for the targeting of these channels based on the pharmacological modulation of KCa channel density at the plasma membrane.

Modulation of bladder afferent signals in normal and spinal cord-injured rats by purinergic P2X3 and P2X2/3 receptors

OBJECTIVE

To evaluate the role of bladder sensory purinergic P2X3 and P2X2/3 receptors on modulating the activity of lumbosacral neurones and urinary bladder contractions in vivo in normal or spinal cord-injured (SCI) rats with neurogenic bladder overactivity.

MATERIALS AND METHODS

SCI was induced in female rats by complete transection at T8-T9 and experiments were performed 4 weeks later, when bladder overactivity developed. Non-transected rats were used as controls (normal rats). Neural activity was recorded in the dorsal horn of the spinal cord and field potentials were acquired in response to intravesical pressure steps via a suprapubic catheter. Field potentials were recorded under control conditions, after stimulation of bladder mucosal purinergic receptors with intravesical ATP (1 mm), and after intravenous injection of the P2X3/P2X2/3 antagonist AF-353 (10 mg/kg and 20 mg/kg). Cystometry was performed in urethane-anaesthetised rats intravesically infused with saline. AF-353 (10 mg/kg) was systemically applied after baseline recordings; the rats also received a second dose of AF-353 (20 mg/kg). Changes in the frequency of voiding (VC) and non-voiding (NVC) contractions were evaluated.

RESULTS

SCI rats had significantly higher frequencies for field potentials and NVC than NL rats. Intravesical ATP increased field potential frequency in control but not SCI rats, while systemic AF-353 significantly reduced this parameter in both groups. AF-353 also reduced the inter-contractile interval in control but not in SCI rats; however, the frequency of NVC in SCI rats was significantly reduced.

CONCLUSION

The P2X3/P2X2/3 receptors on bladder afferent nerves positively regulate sensory activity and NVCs in overactive bladders.

Role of botulinum toxin-A in refractory idiopathic overactive bladder patients without detrusor overactivity

BACKGROUND

To evaluate the efficacy of intradetrusor botulinum toxin-A (BTX-A) in idiopathic overactive bladder patients (OAB) refractory to anti-muscarinic therapy, without detrusor overactivity (DOA) on urodynamics.

METHODS

Patients with refractory idiopathic OAB without DOA on urodynamics were prospectively enrolled. Subjects completed a 3-day voiding diary (3-VD), urogenital distress inventory-6 questionnaire (UDI-6) and graded their quality of life on a 10-cm visual analog scale (VAS) prior to study enrollment and at week 12 postinjection. All patients underwent multichannel urodynamics at study enrollment and 12 weeks postinjection. Improvement was analyzed based on 3-VD, UDI-6 questionnaire, VAS scores, and urodynamic parameters at week 12 postinjection compared to study enrollment.

RESULTS

The study included 32 patients. Mean ± SD age was 56 ± 16. There were 27 women and 5 men. Nineteen patients had OAB without incontinence (OAB-dry) and 13 patients had OAB with incontinence (OAB-wet). In OAB-dry patients, mean ± SD urinary frequency dropped from 24 ± 11 to 10 ± 4 by week 12. In OAB-wet patients, mean ± SD urge incontinence episodes dropped from 7.9 ± 5 to 0 ± 2.6 by week 12. Mean UDI-6 and VAS scores improved significantly in both groups by week 12 (P = 0.0001). On comparing urodynamic parameters, OAB-wet patients showed significant decrease in maximum detrusor pressure during the voiding phase at week 12 compared to baseline values (P = 0.02).

CONCLUSIONS

Refractory idiopathic OAB patients without DOA on urodynamics may benefit from intradetrusor BTX-A.