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Tsuyoshi Iwata

Publications and source records attributed to Tsuyoshi Iwata.

4 recordsLinked to original sources
PubMed2004

Neuroselective current perception threshold evaluation of bladder mucosal sensory function.

OBJECTIVE: To evaluate human bladder mucosal sensory function by neuroselective Current Perception Threshold (CPT) measures from healthy and neuropathic bladders. METHODS: Eight healthy volunteers and 38 patients with urinary symptoms underwent conventional urodynamic tests including water-filling cystometry and ice water test. Standardized neuroselective CPT measures were obtained from the left index finger and the mucosa of the posterior bladder wall. Three different CPTs were obtained from each test site using a constant alternating current sinusoid waveform electrical stimulus presented at 2000Hz, 250Hz and 5Hz stimulation frequencies, which could selectively reflect the functions of the large myelinated fibers (A-beta-fiber), the small myelinated fibers (A-delta-fiber), and the unmyelinated fibers (C-fiber), respectively. RESULTS: As the determination of CPT values on the finger skin, the CPT values in the bladder could be determined using the neuroselective measures in all patients but three who had no sensory response (absence of sensation) caused by complete spinal injury. In the 8 patients with detrusor hyperreflexia due to incomplete spinal cord injury (supra-sacral lesion), the bladder CPT value (4.0+/-1.9) at 5Hz was significantly lower (p<0.01) than that in the controls (26.2+/-17.7). In the neurogenic bladders determined to be underactive (n=11, including post pelvic surgery, post infra-sacral level spinal cord injury and diabetes patients), the higher CPT values of bladder mucosal sensory functions were found at 5Hz (p<0.05), 250Hz (p=0.07), and 2000Hz (p<0.05) compared to the controls. CONCLUSIONS: Quantitative neuroselective measurement of CPT values in the human bladder mucosal function was feasible. Hypersensitivity or hyposensitivity of the urinary sensory function could be determined using the CPT values in comparison to control. The quantitative neuroselective estimation of the bladder sensory functions in different types of sensory peripheral nerve fibers may contribute to the appropriate selection of therapeutic strategy in patients with urinary sensory dysfunction.

Adult↗
PubMed2004

Possible contribution of prostatic anterior fibromuscular stroma to age-related urinary disturbance in reference to pressure-flow study.

Recently, we reported that the anterior fibromuscular stroma (AFMS) of the prostate has significant different innervation compared with the other glandular regions of the prostate. In healthy volunteers (n = 12) using transrectal ultrasound (US), or TRUS, monitoring during voiding, we observed dynamic change (p < 0.0001) of the thickness of the AFMS during voiding. The aim of this study was to reveal the possible functional contribution of the AFMS to micturition, as well as the age-related voiding dysfunction. In the patients (n = 56) with voiding dysfunction who underwent both pressure-flow study (PFS) for determining obstruction and TRUS monitoring during voiding, we measured the ultrasonic dynamic change of the lower urinary tract during voiding. In old men with voiding dysfunction, ultrasonic measurements of dynamic change in the AFMS (p < 0.01) as well as the opening urethra (p < 0.05) could contribute to diagnosing of the anatomical localization of obstructive lesions. The poor movement of AFMS could account for the age-related urinary disturbance in the patients without benign prostatic enlargement and without bladder neck obstruction.

Aged↗
PubMed2003

Ultrasonic measurement of bladder weight as a novel urodynamic modality.

Although pressure-flow studies (PFS) are currently recognized as the gold standard for the diagnosis of infravesical obstruction, their clinical use is limited, due to the invasive nature of procedure. Recently, we developed a new urodynamic parameter, ultrasound estimated bladder weight (UEBW), which was calculated from the bladder wall thickness measured ultrasonically and intravesical volume. Our comparative study between UEBW and PFS showed that UEBW diagnosed infravesical obstruction with a diagnosis accuracy of 73% using a cut-off value of 35 gm. UEBW could also be used as a reliable tool in monitoring therapeutic effects on BPH patients in terms of the relief of obstruction. In addition, UEBW is of clinical use in the management of neurogenic bladder dysfunction, in which there was a significant negative correlation noted between UEBW and bladder compliance. Consequently, UEBW could be a reliable predictor for a low-compliant bladder. Since UEBW can be obtained non-invasively, it is readily applicable to pediatric urology. In healthy children, UEBW increased significantly with age. For the evaluation of UEBW in an individual child patient, the deviation from age-matched UEBW, obtained from the formula of the linear correlation between UEBW and age, was employed. In our recent studies, the deviation from age-matched UEBW is likely to be used as a predictor for bladder dysfunction in children, such as secondary vesicoureteral reflux and a low-compliant bladder. In conclusion, UEBW is promising as a non-invasive urodynamic modality capable of evaluating bladder hypertrophy with its functional abnormalities.

Humans↗