Reproducibility of electrical sensory testing in lower urinary tract at weekly intervals in healthy volunteers and women with non-neurogenic detrusor overactivity.

OBJECTIVE: To evaluate the reproducibility of a standardized technique of current perception threshold measurements with square wave and sine wave current, with monopolar and bipolar electrodes in a cohort of patients with overactive bladder (OAB) and healthy volunteers. METHODS: We enrolled 6 female nulliparous healthy volunteers and 11 female patients with OAB. Current perception threshold measurements of the bladder were performed using several techniques. The same sequence was used for all 3 measurements performed at weekly intervals to assess the reproducibility. An intraclass correlation coefficient >0.75 was considered as very good reproducibility. RESULTS: All the different stimulation forms were well tolerated by all participants and all experienced stimulation at 2.5-Hz and 95-Hz square wave current. The results with sine wave current showed less uniform results. The intraclass correlation showed the greatest reproducibility with bipolar stimulation at a current of 95 Hz. Sine wave current at 5 Hz and 250 Hz showed low reproducibility. Bipolar stimulation had significantly lower thresholds than monopolar stimulation (P < .0001). No significant differences were found between the healthy subjects and the patients with OAB for the 4 settings. CONCLUSION: In the healthy volunteers and patients with OAB, the determination of the current perception threshold in the bladder using a standardized method is feasible and well tolerated, with both bipolar and monopolar stimulation. In our study, square wave current showed strong reproducibility at weekly intervals at 2.5 Hz and 95 Hz. However, sinusoid current gave weak reproducibility.

Reproducibility of urodynamic filling sensation at weekly interval in healthy volunteers and in women with detrusor overactivity.

AIMS: To evaluate the reproducibility of bladder sensation during standardized filling cystometry in female volunteers and overactive bladder (OAB) patients, repeated with weekly interval. METHODS: We recruited 13 female nulliparous volunteers (age 21-47) and 17 female patients with OAB between (age 18-72). They participated in three investigation periods, each separated by 7 days to assess reproducibility of sensation related to standardized cystometry. Subjects were asked to report all sensations they felt during bladder filling. RESULTS: The previously described pattern of sensation was reported during bladder filling in all. Consecutive sensations corresponded to statistically higher bladder volumes. Volumes, at which different sensations of bladder filling were reported, were significantly higher in controls than in OAB patients [first sensation of filling (FSF) P = 0.003, first desire to void (FDV) P < 0.0001, and strong desire to void (SDV) P < 0.0001]. The sensation/volume ratios were significantly higher in patients with OAB than in the healthy volunteers: FSF occurred at mean 46% and FDV at mean 73% of SDV in OAB patients, compared to 36% and 64% in healthy volunteers. Sensations proved highly reproducible when determined with weekly interval. CONCLUSIONS: Our data demonstrate that cystometric filling sensation determined in a standardized way with weekly interval is highly reproducible in healthy and in OAB patients. This finding has, in our opinion, clinical importance as it shows that the technique is reliable both for a sensory evaluation of the LUT as to study influence of treatment aimed at changing this sensation.

The effect of intravesical oxybutynin on the ice water test and on electrical perception thresholds in patients with neurogenic detrusor overactivity.

AIMS: The C-fiber-mediated bladder-cooling reflex and the determination of the current perception thresholds (CPTs) permit to investigate afferent LUT pathways. They have both been proposed to detect and differentiate neurologic bladder dysfunction. This study evaluates, prospectively, the effect of oxybutynin, an antimuscarinic with direct antispasmodic effect on smooth muscle, on repeated ice water test (IWT) and CPTs in patients with a known incomplete neurogenic bladder. METHODS: Patients with a known incomplete lesion of the bladder innervation, detrusor overactivity during cystometric bladder filling and a continuous positive response to repeated IWT were included. After the initial tests, 30 mg intravesical oxybutynin (1 mg/ml) was instilled and left in the bladder for 15 min. Afterwards CPTs and IWT were re-assessed. RESULTS: After the drug application, the bladder-cooling reflex could not be initiated, even after three instillations, in 16/17 patients. The bladder CPT increased from 29.7 +/- 11.3 to 39.1 +/- 15.7 mA after oxybutynin (P = 0.001). No difference was found in CPT of the left forearm (P = 0.208). CONCLUSIONS: Intravesical oxybutynin blocks the bladder-cooling reflex and increases but does not block CPT sensation in the bladder in most patients with incomplete neurogenic lesion and detrusor overactivity. These results help explain the clinical effect of intravesical oxybutynin in neurogenic patients. They also indicate that a pharmacological local influence on C-fiber-related activity can give different clinical effects.

Can a faked cystometry deceive patients in their perception of filling sensations? A study on the reliability of spontaneously reported cystometric filling sensations in patients with non-neurogenic lower urinary tract dysfunction.

AIMS: To evaluate the reliability of spontaneously reported bladder sensations during real and faked cystometry in patients with non-neurogenic lower urinary tract dysfunction. METHODS: Fifty-nine patients with non-neurogenic lower urinary tract dysfunction were submitted to a real and faked filling cystometry and were asked to describe all bladder-related sensations they experienced during the investigations. All patients were told that the bladder had to be filled twice, but during the faked cystometry, no water was infused in the bladder. RESULTS: During the real cystometry, the normal pattern of filling sensation was reported by 88%. During the faked cystometry, none of the patients reported the normal pattern of filling sensations. Five patients reported first sensation of filling, one first desire to void (FDV). None of the patients reported a strong desire to void (SDV) during the faked cystometry. CONCLUSIONS: Asking patients with a non-neurogenic lower urinary tract dysfunction to report on the bladder filling sensations during cystometry is a valid method for sensory evaluation. A minority of patients may report some sensation of bladder filling even without actual bladder filling. Memory and habituation may play a role in the perception of bladder sensation and one should be aware of this. However, reporting some sensation during faked cystometry not necessarily means the evaluation of the perception of bladder filling is unreliable.

Repeated ice water tests and electrical perception threshold determination to detect a neurologic cause of detrusor overactivity.

OBJECTIVES: To explore the added value of a repeated ice water test (IWT) and electrical perception threshold (EPT) measurement in the search for a neurologic cause of idiopathic detrusor overactivity (DOA). METHODS: The IWT, if originally negative, was repeated up to three times, and EPT measurements were done in 63 patients with neurologic DOA, 117 patients with idiopathic DOA without outflow obstruction, and 30 women with stress urinary incontinence without DOA. RESULTS: Although the IWT was positive in 46% of the neurologic patients if used once, this percentage became 86% when the IWT was repeated. In nonneurologic patients, one IWT was positive in only 7% and when repeated, the positive test rate increased to 24%. IWT, even repeated, remained negative in the women with stress urinary incontinence. The EPTs were not significantly different between the neurologic and nonneurologic patients with a positive IWT, except after the third instillation. In those with negative IWTs, the EPTs were significantly different between the neurologic and nonneurologic patients, independent of the number of IWTs done. If the EPTs were compared within each group between those with positive and negative IWTs, the difference was not significant at the first IWT. However, the difference became statistically significant after two IWTs for the nonneurologic group and after three IWTs for both groups. CONCLUSIONS: Our results have shown that repeating the IWT will increase its positivity. Combining the IWT and EPT will reinforce the results of both tests and can indicate more clearly the possibility of an unsuspected neurologic pathologic finding in patients with idiopathic DOA.

Detrusor overactivity. Does it represent a difference if patients feel the involuntary contractions?

PURPOSE: We evaluated the differences between patients with overactive bladder (OAB) who felt involuntary detrusor contractions during cystometry (detrusor overactivity [DO]) and those who did not feel them. MATERIALS AND METHODS: We prospectively studied 45 patients with symptoms of nonneurogenic, nonobstructed overactive bladder and with DO on cystometry. All patients underwent videourodynamics, the ice water test and electrical perception threshold determination. Continence, urodynamic parameters, data from specific sensory evaluation and outcome of drug treatment were examined. RESULTS: Almost half of our patients did feel the contractions of DO and half did not. The groups differed significantly. Those without DO sensation were more frequently incontinent, had more involuntary detrusor contractions and these occurred earlier during bladder filling. They had involuntary start of voiding more frequently, more pathological sensation of bladder filling and lower electrical sensory thresholds. The results of drug treatment were better in the group who felt DO. CONCLUSIONS: Contractions of DO are felt by some of the patients and they differ from those patients who do not feel such contractions. It is likely that this finding reflects the existence of different OAB conditions with a different neuropathological cause and a different treatment outcome. Therefore, we suggest that specific tests for the evaluation of sensation in the lower urinary tract should be part of the diagnosis of patients with DO and symptoms of OAB.