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Dr. Paduch: Assessment of spinal cord motor generator for ejaculation using transperineal ultrasound in healthy men with normal sexual function.

Herati A, Bolyakov A, Dabaja A, Wosnitzer M, Schlegel PN, Paduch DA.  Assessment of spinal cord motor generator for ejaculation using transperineal ultrasound in healthy men with normal sexual function. J Urol, 2014; 191(4): e331 – e332. Presented at the 2014 Annual Meeting of the American Urologic Association, Orlando, FL.

Introductions and Objectives
Activation of spinal cord motor generator of ejaculation (SCMG-Ej) occurs once a threshold of arousal is reached and results in rhythmic, involuntary contractions of bulbocavernosal muscle (BCM). The objective of this study was to characterize the changes in the BCM during arousal and ejaculation and to establish reproducibility of BCM contractions at two time points as measured by transperineal ultrasound (US).

Methods
Twenty healthy men with normal erectile/ejaculatory function between the ages of 18-29 (n=10) and 45-65 (n=10) were prospectively evaluated with US (Esatote My lab 25 Gold, Indianapolis, IN) by the same practitioner. An 18-MHz linear array transducer was used to determine the change in bulbourethral (δBU) diameter during arousal, the number of BCM contractions, duration of contractions prior to ejaculation, and maximal BU diameter during ejaculation. Video recordings were obtained to determine the force of ejaculation. Orgasm quality was recorded using an 11-point linear scale. Reproducibility was determined by performing repeated US at six weeks. The 2-tailed Wilcoxon signed rank t-test was used to analyze paired data.

Results
The mean age (SD) for the cohort was 39.6 (14.2) years. There was no significant difference (p>0.05) in the median number of BCM contraction, δBU diameter during arousal, maximal BU diameter during ejaculation or force of ejaculation for all men assessed from baseline to the six-week follow-up study. When the cohort was stratified by age (18-29 and 45-65), we found no difference in the median number of contractions (p=0.22 and p=0.24), δBU diameter during arousal (p=0.11 and p=0.54), maximal BU diameter during ejaculation (p=0.26 and p=0.25), or force of ejaculation (p=0.56 and p=0.16) between the two time points. Among men aged 18-29, the median number of contractions (95% Confidence Interval (CI)) were 13 (12 to 14) and 12 (10 to 14) for the first and second assessment with no difference in the duration of contractions (p=0.44) from baseline to follow-up. Similarly, men aged 45-65 did not differ in the median number of contractions 8 (6 to 12) vs. 10 (8 to 14) but did differ in the time of contractions (p=0.03) over the follow-up period.

Conclusions
The number of BCM contractions, δ BU diameter during arousal, maximal BU diameter during ejaculation and force of ejaculation via US showed consistency over the six-week time interval in all men. This study shows for first time that activity of SCMG-Ej is a highly reproducible event not only in same individual but also among men with normal sexual function.

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