Elevation of sensory thresholds in the prostatic urethra after microwave thermotherapy

Lower urinary tract electrical sensory assessment: A systematic review and meta-analysis

Objectives

To summarize the current literature on lower urinary tract electrical sensory assessment (LUTESA), with regard to current perception thresholds (CPTs) and sensory evoked potentials (SEPs), and to discuss the applied methods in terms of technical aspects, confounding factors, and potential for lower urinary tract (LUT) diagnostics.

Methods

The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) statement. Medline (PubMed), Embase and Scopus were searched on 13 October 2020. Meta‐analyses were performed and methodological qualities of the included studies were defined by assessing risk of bias (RoB) as well as confounding.

Results

After screening 9925 articles, 80 studies (five randomized controlled trials [RCTs] and 75 non‐RCTs) were included, comprising a total of 3732 patients and 692 healthy subjects (HS). Of these studies, 61 investigated CPTs exclusively and 19 reported on SEPs, with or without corresponding CPTs. The recording of LUTCPTs and SEPs was shown to represent a safe and reliable assessment of LUT afferent nerve function in HS and patients. LUTESA demonstrated significant differences in LUT sensitivity between HS and neurological patients, as well as after interventions such as pelvic surgery or drug treatments. Pooled analyses showed that several stimulation variables (e.g. stimulation frequency, location) as well as patient characteristics might affect the main outcome measures of LUTESA (CPTs, SEP latencies, peak‐to‐peak amplitudes, responder rate). RoB and confounding was high in most studies.

Conclusions

Preliminary data show that CPT and SEP recordings are valuable tools to more objectively assess LUT afferent nerve function. LUTESA complements already established diagnostics such as urodynamics, allowing a more comprehensive patient evaluation. The high RoB and confounding rate was related to inconsistency and inaccuracy in reporting rather than the technique itself. LUTESA standardization and well‐designed RCTs are crucial to implement LUTESA as a clinical assessment tool.

Possible role of hyposensitivity of C-fiber afferents at the proximal urethra in the development of urge urinary incontinence in patients with detrusor overactivity

OBJECTIVE

The aim of the present study was to investigate associations between urethral sensation and urge urinary incontinence (UUI) in patients with and without detrusor overactivity (DO).

METHODS

The medical records of 80 consecutive patients who underwent filling cystometry and urethral current perception threshold (CPT) tests were examined retrospectively. Following the exclusion of 4 patients not eligible for analysis, patients were classified into neurogenic DO, idiopathic DO, or DO-negative groups based on neurological and cystometric findings (n = 30, 12, and 34, respectively). Eleven DO-negative patients were defined as normal controls on cystometrograms (CMG) using the following exclusion criteria: bladder compliance <12.5 mL/cmH₂ O, volume >275 mL at first filling sensation, and comorbidities possibly affecting lower urinary tract function. Thus, 53 patients were finally included in the study. Proximal urethral CPT was evaluated with intraurethral square-wave stimulation at 3 Hz to activate C-fiber afferents.

RESULTS

Median CPT was higher in neurogenic and idiopathic DO than in the normal CMG group (11.3 and 9.0 vs. 2.8 mA, respectively; P < .05), as well as in patients with UUI (n = 19) compared with non-UUI patients (n = 34; 12.5 vs. 5.4 mA, respectively; P < .05). The proportion of UUI patients was significantly greater in the DO-positive groups than in the normal CMG group (P < .05). CPTs were not associated with bladder capacity at the first filling sensation (r = 0.11).

CONCLUSION

Hyposensitive C-fibers of the proximal urethra may contribute to the development of urodynamic DO as well as UUI in patients complaining of lower urinary tract symptoms.

Management of benign prostatic hyperplasia with silodosin

It has been reported that blockade of α1A-adrenoceptor (AR) relieves bladder outlet obstruction, while blockade of α1D-AR is believed to alleviate storage symptoms due to detrusor overactivity. Silodosin, (-)-1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2trifluoroethoxy) phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7- carboxamide, is a new α1A-AR selective antagonist. Silodosin is highly selective for the α1A-AR subtype, showing an affinity for the α1A-AR that is 583- and 55.5-fold higher than its affinity for the α1B-and α1D-ARs, respectively. In randomized, double-blind, placebo-controlled phase III studies performed in Japan and the United States, silodosin has been shown to be effective for both storage and voiding symptoms associated with benign prostatic hyperplasia. Early effects of silodosin (after 2-6 hours or day 1) on lower urinary tract symptoms have also been reported. In urodynamic studies, detrusor overactivity disappeared in 40% and improved in 35% of patients after administration. In pressure flow studies, the grade of obstruction on the International Continence Society nomogram showed improvement in 56% of patients. The rate of adverse events in the silodosin, tamsulosin and placebo groups was 88.6%, 82.3%, and 71.6%, respectively. The most common adverse event was (mostly mild) abnormal ejaculation (28.1%). However, few patients (2.8%) discontinued silodosin because of abnormal ejaculation. Orthostatic hypotension showed a similar incidence in the silodosin (2.6%) and placebo (1.5%) groups. In conclusion, silodosin improves detrusor overactivity and obstruction and thus may be effective for both storage and voiding symptoms in patients with benign prostatic hyperplasia.

Urethral and Bladder Current Perception Thresholds: Normative Data in Women

PURPOSE

Given increased evidence of sensory dysfunction in lower urinary tract pathology, we determined normative current perception threshold values in the lower urinary tract of asymptomatic women.

MATERIALS AND METHODS

After receiving institutional review board approval women without lower urinary tract symptoms underwent current perception threshold testing of the urethra and bladder using a Neurometer constant current stimulator. Current perception threshold values were determined at 3 frequencies, including 2,000 Hz (corresponding to A-beta fibers), 250 Hz (corresponding to A-delta fibers) and 5 Hz (corresponding to C fibers).

RESULTS

A total of 48 women with a mean age of 38 years (range 23 to 67) underwent current perception threshold testing. Normative values were established for the urethra and bladder at 2,000, 250 and 5 Hz. Median urethral current perception thresholds at 2,000, 250 and 5 Hz were 1.2 (IQR 0.76-1.5), 0.45 (IQR 0.33-0.56) and 0.11 mA (IQR 0.07-0.24), respectively. Median bladder current perception thresholds at 2,000, 250 and 5 Hz were 4.1 (IQR 2.0-6.3), 2.3 (IQR 0.87-5.5) and 1.4 mA (IQR 0.22-2.9), respectively. Urethral and bladder current perception thresholds increased significantly with subject age at all 3 frequencies (p<0.0005). Prior pelvic surgery was associated with an increased bladder current perception threshold at all 3 frequencies (p<0.005) but not with the urethral current perception threshold.

CONCLUSIONS

We report urethral and bladder current perception thresholds for a large sample of asymptomatic women. These reference values may help elucidate changes in afferent nerve function in women with lower urinary tract dysfunction.

Transurethral microwave thermotherapy for the treatment of BPH: still a challenger?

Minimally invasive therapies for treatment of benign prostatic hyperplasia (BPH) compete with the gold standard transurethral resection of the prostate (TURP). Comparisons of efficacy and safety have broadened the knowledge of different treatment modalities. Concerns of quality of life such as unaltered sexual function as well as cost considerations drive the market to develop techniques of lower level invasiveness. Among the competitors the office based transurethral microwave thermotherapy (TUMT) provides the broadest scale of scientific data. Numerous manufacturers sell various modifications of this technology. According to different clinical studies TUMT proved to be an effective, safe, and durable therapy for the treatment of lower urinary tract symptoms (LUTS) secondary to BPH. However, TURP still holds the steadier long-term results and is more effective to reduce obstruction as well as other LUTS.

Urethral Sensitivity in Incontinent Women

OBJECTIVES

The aim of this study was to ascertain whether frequent voiding and urge incontinence are associated with supersensitivity to electrical stimulation in the posterior urethra.

METHODS

Current perception thresholds (CPT) were tested at four stimulus frequencies (1, 3, 20, and 100 Hz; duration 0.5 ms) using a square-wave constant current electrical stimulator connected to ring electrodes on a urethral catheter. The strength of the current at the first tingling sensation was regarded as the CPT. CPT analysis and cystometry were performed on 61 women (ages 28-89 years).

RESULTS

CPTs were significantly higher at lower than at elevated stimulus frequencies, and they were also generally higher in old than in younger patients. Seven women repeated the CPT test after two months, and the thresholds were unchanged. There were no significant differences in sensitivity between patient groups with stress incontinence, urge, or mixed symptoms. Moreover, CPT was not significantly related to bladder volume at first sensation of filling.

CONCLUSION

Measuring CPT is an easy and reproducible method of testing urethral sensibility, but our results do not support the suspicion that urethral hypersensitivity is involved in increased voiding frequency and urge incontinence.

Application of External Microwave Thermotherapy in Urology: Past, Present, and Future

The excellent clinical results of transurethral microwave thermotherapy (TUMT) for the treatment of symptomatic benign prostatic hyperplasia (BPH) gave to TUMT the leading position among the microwave thermotherapy modalities available for the treatment of different urologic conditions. Research in TUMT has focused on operating software, temperature monitoring, intraprostatic heat distribution, cell-kill calculations, and correlations with clinical variables. Randomized comparisons of TUMT with other established therapies for BPH, including transurethral resection, have facilitated the evaluation of the clinical outcome, durability, morbidity, and costs of the treatment. The applications of microwave thermotherapy in other urologic diseases are also presented in this review.

TUMT 2.0: results three months and three years after treatment

OBJECTIVE

To examine the durability of the results following low-power transurethral microwave thermotherapy (TUMT).

MATERIAL AND METHODS

28 patients 55 to 83 years of age with lower urinary tract symptoms (LUTS) and marginal/moderate infravesical obstruction and 4 patients with LUTS, peak urinary flow (Qmax) less than than 15 ml/sec and prostate volume below 40 ml. We used a Prostatron version 2.0.

RESULTS

transurethral resection of the prostate (TURP) was done shortly after treatment in one patient with acute obstruction caused by necrotic tissue. Three months after treatment 15 patients reported that they were cured from LUTS and 10 experienced improvement of symptoms. A significant reduction of the symptom scores was seen among the 31 patients not operated while Qmax was unchanged. Three years after treatment two patients were still cured from LUTS, 9 hadsome reduction of symptoms, and TURP had been done in further three patients. Symptom scores among the 24 patients still in the study were significantly lower than the baseline values but also significantly higher than the symptom scores three months after treatment. Residual urine was reduced while no changes were seen in Qmax.

CONCLUSION

TUMT done by Prostatron version 2.0 causes mainly a reduction of symptoms. Most of the effect disappears after a few years.

High-energy transurethral microwave thermotherapy: symptomatic vs urodynamic success

OBJECTIVE

To evaluate the subjective and objective treatment results of high-energy transurethral microwave thermotherapy (TUMT) for symptomatic benign prostatic hyperplasia (BPH), and investigate the possible variables for predicting symptomatic and/or urodynamic success.

PATIENTS AND METHODS

Between October 1998 and October 2000, 40 men with BPH underwent high-energy TUMT using the Targis device (Urologix, Inc., Minneapolis, MN, USA). Evaluation after treatment included a clinical determination of the symptom score, a urodynamic assessment by peak flow rate and pressure-flow, magnetic resonance imaging (MRI), transrectal ultrasonography and endoscopy. The objective and subjective success was correlated with several variables before, during and after treatment.

RESULTS

All patients completed at least 1 year of follow-up after TUMT as monotherapy. The symptom score improved from a median (range) of 20.5 (11-28) initially to 9 (0-28) (P < 0.001). Twenty-two patients (55%) had a marked and 11 (28%) a moderate response, giving an overall subjective success rate of 83%. Similarly, there was a significant improvement in peak flow rate, from 9.2 (4.4-13.4) to 15 (3.3-22.9) mL/s (P < 0.001). Twenty-one patients (53%) had a maximum flow rate of > 15 mL/s while in eight (20%) it was 10-15 mL/s. Only 20 patients changed from unobstructed on the pressure-flow nomogram, i.e. an overall objective success rate of 50%. Gadolinium-enhanced T1-weighted MRI 1 week after treatment showed a median (range) perfusion defect of 20.7 (5.5-76.6)% of the total gland volume. Despite this persisting in all patients, a well-defined cavity was apparent in only in seven (18%) at the final evaluation. Cystoscopy 1 month after therapy showed evidence of necrotic tissue occupying the prostatic fossa in all patients. Younger patients were more likely to be urodynamically successful, and a higher grade of obstruction predicted symptomatic success.

CONCLUSION

High-energy TUMT can induce considerable necrosis of the prostate, as shown by MRI and cystoscopy. Although there was an adequate improvement in most patients' symptoms, there was a successful urodynamic change to unobstructed in only half the patients. Younger patients and those with a higher grade of obstruction were more likely to have urodynamic and symptomatic success, respectively.