(141) Can a Nocturnal Penile Tumescence and Rigidity Test Detect Organic Aetiology of Erectile Dysfunction? A Peripheral and Penile Vascular Study Free

In the diagnostic workup of erectile dysfunction (ED) the Nocturnal Penile Tumescence and Rigidity test (NPTR) is being used less and less because of its inconvenience but also in part because of the intrinsic limits of this test. In particular, the NPTR has been considered very useful to diagnose psychogenic ED when it is positive (normal) but less informative when it is negative (pathological) because of the high incidence of false negatives. Other tests have been suggested to better diagnose an organic ED, especially the dynamic Penile Colour-Doppler Ultrasound (PCDU) to study the penile vascular response and detect a vasculogenic ED.

The purpose of the study was to explore the value of a pathological NPTR by investigating relationship between the NPTR result and the peripheral vascular health at the carotid, brachial and cavernous arteries.

We conducted an observational study involving patients with ED who had undergone a NPTR as part of their ED diagnostic workup. We assessed their peripheral vascular health through (1) the measurement of the intima-media thickness at the carotid arteries (cIMT), (2) the measurement of the flow-mediated dilation at the brachial artery (FMD), and (3) performing a PCDU.

Globally, our patients presented with a normal cIMT, FMD and Peak Systolic Value (PSV) in the PCDU. The group with pathological NPTR were significantly older than patients with normal NPTR (55.6 vs 44.1 years, p=0.002), had a higher prevalence of hypertension (50.0 vs 6.8%, p=0.001), longer hypertension duration (8.0 vs 1.3 years, p=0.035), a higher prevalence of diabetes mellitus (42.9 vs 6.8%, p= 0.004), higher blood glucose (111 vs 92 mg/dl, p=0.004) and higher blood triglycerides levels (188 vs 96 mg/dl, p=0.002). Furthermore, they showed lower PSV (46.2 vs 71.0 cm/s, p=0.002) while we did not find significant differences as regards cIMT and FMD between the two groups. Interestingly, the prevalence of patients with pathological PSV (<35 cm/s) was higher among patients with a pathological NPTR but without reaching the statistical significance. However, when adopted an age-dependant cut-off described in the literature (PSV < age x 0.7 + 6.73) the difference between the two groups became significant (50.0 vs 11.4%, p=0.005). Finally, the correlation analysis showed a significant correlation between PSV and the cIMT (-0.352, ρ=0.009), the maximum number of events in the RPTR record (+0.344, ρ=0.012), and the mean tip tumescence (+0.303, ρ=0.036). When corrected for age, these associations lost their statistical significance.

This study demonstrates the diagnostic value of a pathological NPTR which suggests an organic aetiology of the ED and associates with pathological findings in the PCDU. Age appears to be one of the most important risk factors for ED, even when other risk factors are present. Finally, when using a PCDU to diagnose vasculogenic ED, a cut-off of 35 cm/s might be less sensitive than an age-dependent cut-off to detect early impairments of penile endothelial function.

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