Corpus cavernosum electromyography during morning naps in healthy volunteers : further evidence that corpus cavernosum potentials reflect sympathetically mediated activity

PURPOSE: We assessed the practicability of corpus cavernosum (CC) electromyography (EMG) in volunteers during morning naps in the laboratory and further validated this method. MATERIALS AND METHODS: A total of 11 healthy volunteers with a mean age of 23.8 years (range 19 to 31) were included. CC-EMG was started between 6:30 a.m. and 7 a.m. Two surface electrodes were placed at the base of the penis bilaterally and a reference electrode was placed on 1 kneecap. A strain gauge or Barlow gauge (Behavioral Technology, Salt Lake City, Utah) was used to monitor changes in penile circumference. Subjects were asked to sleep. Recording duration was 2 to 3 hours. Two recordings were performed per subject. RESULTS: Full erection was observed on 17 of the 22 recordings (77%), partial erection was noted on 3 (14%) and no tumescence was observed on the other 2 (9%). CC potentials consistently disappeared during tumescence and erection, while continuous CC potential oscillations reappeared during detumescence. During flaccidity bursts of CC potentials and electrical silence were recorded. Penile shrinkage was observed to accompany CC potentials but not to accompany electrical silence. CONCLUSIONS: CC-EMG during morning naps is a practical and valid method for investigating CC electrophysiology. CC-EMG signal patterns during tumescence, detumescence and flaccidity fit the existing theory that CC potentials reflect cavernou