ICS
1999, Denver
Video presentations
The contribution of the prostatic anterior fibromuscular stroma to the opening
the urethra
O. Ukimura, E. Inui, A.
Ochiai, Y. Naya, M. Kojima, T. Miki
Kyoto Prefectural
University of Medicine, Kyoto, Japan
Aims of study
The zonal anatomy of the prostate by McNeal (l) showed clearly that the prostate has an anterior fibromuscular stroma (AFMS), which is composed mainly of smooth muscle at the anterior portion to the arethra. It blends proximately with the detrusor muscle fibers at the bladder neck, laterally with the prostatic capsule, and distally its thickness increases to about the level of the verumontanum. In the young male, up to one third of the prostate may be attributed to these fibromuscular tissues. Despite detailed anatomical description of the AFMS, its physiological function and pathogenesis remain unknown. We hypothesized that the AFMS could contribute actively to micturition. Since in BPE patients the AFMS could be stretched outward by the en1arged transition zone (TZ) as a so-called thin surgical capsule, we hypothesized that the stretched AFMS might lose its contribution to micturition. Fortunately, the AFMS is clearly visible in the young male with the use of transrectal sonography (TRS) as the mainly anterior portion of the urethra, and its sovement during voiding is monitored easily, as previously reported (2). In this video presentation, real time monitoring with TRS was ab1e to demonstrate the dynamic movement of the fibromuscular elements in the AFMS during voiding. In addition, in aged patients with LUTS, monitoring of the prostate during voiding demonstrated the possible pathophysiological contribution of the AFMS.
Methods
In this video presentation, voiding processes were demonstrated in healthy young males as well as elderly patients with LUTS. Subjects underwent TRS using ultrasonic diagnostic equipment (Aloka SSD-2000), providing bi-plane transrectal sonograms of the urethra as well as the prostate during voiding.
In healthy young males, in the longitudinal view, the portion anterior to the urethra corresponds to the AFMS and almost all the portion posterior to the urethra corresponds to the glandular zones (GZ) including the peripheral and central zones. In the transverse view, the area of AFMS was observed as hypoehoic. With the aim of quantitative evaluation of the fibromuscular elements in the AFMS, we measured the velocity (mm/sec) of the movement of the pixels.
Results
In healthy young males, using a longitudinal view of the prostate during the hesitation time before the passing of urine, the likely active movement of the pixels corresponded to the fibromuscular elements in the AFHS. This was observed toward the different directions from the vertical to the axis of the urethra, although the pixels in the GZ did not move at all. The maxisum velocity of the movement of the pixels in the AFNS was 3.2 m/sec. In contrast, when the urine started to pass, the likely passive movement of the AFMS caused by the passing urine was also observed toward the vertical direction to the axis of the urethra.
Using a transverse view, during voiding, the opening directions of the urethral wall were observed only anterior-radially within the area of the AFMS, syncronized with the movement of the pixels only in the AFMS but not in the GZ.
In an elderly patient suspected of having a bladder neck contracture, the striking difference from a healthy male was the lack of bladder neck opening, which was syncronized with the observed moverent of the pizels in the AFMS in the healthy young male. In a patient with an enlarged TZ, neither the movement of the TZ nor that of the stretched AEMS were observed at all during voiding.
Conclusions
The movesent of the AFHS may be not only passive caused by the passing urine but also active in itself. Age-related disorder of the movement of the AFMS could relate to the pathophysiology of the openinq of the urethra.
References
Source: 29 th International Continence Society Annual Meeting, August 22-26, 1999, Video Demonstration