PURPOSE: Quantitative somatosensory testing, including vibration, pressure, spatial perception and thermal thresholds of the penis, has demonstrated neuropathy in patients with a history of erectile dysfunction of all etiologies. We evaluated which measurement of neurological function of the penis was best at predicting erectile dysfunction and examined the impact of location on the penis for quantitative somatosensory testing measurements.
MATERIALS AND METHODS: A total of 107 patients were evaluated. All patients were required to complete the erectile function domain of the International Index of Erectile Function (IIEF) questionnaire, of whom 24 had no complaints of erectile dysfunction and scored within the "normal" range on the IIEF. Patients were subsequently tested on ventral middle penile shaft, proximal dorsal midline penile shaft and glans penis (with foreskin retracted) for vibration, pressure, spatial perception, and warm and cold thermal thresholds.
RESULTS: Mixed models repeated measures analysis of variance controlling for age, diabetes and hypertension revealed that method of measurement (quantitative somatosensory testing) was predictive of IIEF score (F = 209, df = 4,1315, p <0.001), while site of measurement on the penis was not. To determine the best method of measurement, we used hierarchical regression, which revealed that warm temperature was the best predictor of erectile dysfunction with pseudo R(2) = 0.19, p <0.0007. There was no significant improvement in predicting erectile dysfunction when another test was added. Using 37C and greater as the warm thermal threshold yielded a sensitivity of 88.5%, specificity 70.0% and positive predictive value 85.5%.
CONCLUSIONS: Quantitative somatosensory testing using warm thermal threshold measurements taken at the glans penis can be used alone to assess the neurological status of the penis. Warm thermal thresholds alone offer a quick, noninvasive accurate method of evaluating penile neuropathy in an office setting.
PMID: 12771767 [PubMed - indexed for MEDLINE]
Note:
Blustein et al. carefully retracted the foreskin for the purposes of this experiment. The contribution of the nerves of the foreskin and the ridged band to sensitivity, pleasure, and satisfaction, therefore, were excluded from the testing. Moreover, this experiment was carried out under static conditions. The foreskin, however, moves dynamically during coitus through its gliding action, thereby stimulating the nerve endings in the foreskin and providing pleasure and satisfaction to the individual. The evidence provided by this study, therefore, points to the foreskin, not the glans penis, as the major source of penile sensitivity, pleasure, and satisfaction.
Citation:
Bleustein CB, Eckholdt H, Arezzo JC, Melman A. Quantitative somatosensory testing of the penis: optimizing the clinical neurological examination. J Urol 2003;169(6):2266-9.
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