Erectile response to visual erotic stimuli before and after intracavernosal papaverine, and its relationship to nocturnal penile tumescence and psychometric assessment.

Three methods of assessing erectile capacity--nocturnal penile tumescence (NPT), response to visual erotic stimuli (VES) and to intracavernosal papaverine (ICI)--have been assessed in 42 men presenting with erectile dysfunction. There was some overlap but also important differences between the 3 measures. Subjects were divided into "high" and "low" NPT groups. The "high" group produced greater erectile responses to both VES and ICI. The combination of VES and ICI was the best discriminator of the two NPT groups, and may be of diagnostic value, particularly in younger men, reducing the need for repeated injections and higher doses of papaverine. In the "low" NPT group, presumed predominantly organic, the ICI response correlated better than the VES response with NPT. In the "high" NPT group, the opposite applied, suggesting that in "psychogenic" cases, response to ICI may be modified by psychological mechanisms which could be of aetiological importance and which deserve further study. These three methods should be regarded as measuring different aspects of erectile function and not as alternative diagnostic procedures. More research is required before their respective diagnostic values are established.