In an attempt to understand better the role of vascular and neurogenic alterations in the pathophysiology of diabetic impotence, 29 impotent male patients with diabetes mellitus (DM) were investigated by means of doppler ultrasound examination (DUE) of penile arteries, sacral evoked responses (SERs), peripheral nerve conduction studies, and, in most cases, nocturnal penile tumescence monitoring (NPTM). Fourteen patients showed isolated alterations of penile vascular supply, four isolated alterations of penile segmental innervation, and seven combined vasculogenic and neurogenic abnormalities; finally, in four patients, DUE, SERs, and NPTM were normal. One patient, in spite of the presence of marked vasculogenic and neurogenic alterations, showed nocturnal penile erections. Results confirm that vascular obstruction, more than nerve damage, plays a primary role in the pathophysiology of diabetic erectile failure, and stress the importance of psychogenic factors. The observation that some patients presented marked involvements of both arterial supply and neurological pathways only a few years, or even 1 year, after the diagnosis of the disease, indicates the need of an early screening of the vascular and neurological status, even in asymptomatic patients. Furthermore, all patients with altered SERs had peripheral neuropathy; on the other hand, six patients with peripheral neuropathy had normal SERs. This result stresses the diagnostic importance of the electrophysiologic studies of sacral segmental innervation and indicates further that in a comprehensive diagnostic protocol of diabetic impotence the study of SERs should be performed only in patients with peripheral neuropathy.
