Department of Men's Health University Medical Center Hamburg-Eppendorf Hamburg 20214 Germany;
Department of Urology University Medical Center Hamburg-Eppendorf Hamburg 20214 Germany;
Department of Urology Klinikum Weiden Weiden 92637 Germany;
Department of Urology University of Cologne Cologne 50924 Germany;
phosphodiesterase; sexual dysfunctions; psychological; sildenafil citrate; erectile funcion;