EVALUATION OF NOCTURNAL PENILE TUMESCENCE (NPT) IN THE DIFFERENTIAL DIAGNOSIS OF IMPOTENCE Masaharu Aoki, Yoshiaki Kumamoto, Kazutomi Mohri and Kazunori Ohno Department of Urology, Sapporo Medical College (Director: Prof. Y. Kumamoto) Recently, NPT (nocturnal penile tumescence) recording has been regarded as a useful method in differentiating between organic and functional impotence. In this study we present our results of the method. 1. NPT recording was carried out on 13 normal subjects. In all normal subjects NPT was observed 3 to 7 times. The maximum increase in penile circumference ranged from 16 to 35 mm (mean+s. D.: 24.0 + 5.8 mm) and the mean duration time of NPT ranged from 14. 0 to 34. 2 minutes (23.9+6.0 min.). 26. 4% of total sleeping time was spent in penile tumescence. 2. NPT recording was performed on 31 impotent patients (17 patients with and 14 patients without organic factors). NPT in all patients without organic factors were almost normal. 4 patients with organic factors showed normal NPT, while the maximum increase in circumfernce was diminished obviously in the other patients. 3. From these results, it is presumed that the diagnosis of organic impotence could be made if the maximum increase in circumference is within 9 mm or the mean duration time is within 10 minutes. However, if the maximum increase in circumference is over 10 mm and the mean duration time is more than 10 minutes, no diagnostic conclusion could be derived from NPT alone. A multidisciplinary approach will be necessary to the differential diagnosis of impotence, becanse the diagnostic capacity of NPT is still limited.
Table 1 Results of NPT recording in 1 normal subjects Fig. 1 Increase in penile circumference on each NPT episode
Fig. 2 Tumescence time on each NPT episode in normal subjects Table 2 Data of impotent patients Patients without any organic factors Patients with organic factors
Table 3 Results of N PT recording in impotent patients without any organic factors Table 4 Results of NPT recording in impotent patients with organic factors
Table 5 Change of penile circumference in artificial full erection Fig. 3 Relationship between maximum increase in circumference and mean NPT time Normal cases Impotent cases organic factor(-) organic factor(s)
Fig. 4 Relationship between maximum increase in circumference and number of N PT episodes Normal cases Impotent cases organic factor(-) rganic factor()