Erectile dysfunction

Abstract

Erectile dysfunction is a common problem that is frequently unrecognised. The aetiology is frequently multifactorial. Erection of the penis is mediated by parasympathetic stimulation (S2-S4) and detumescence via the sympathetic pathway (T11-L2). Parasympathetic stimulation results in arteriolar dilatation and cavernosal smooth muscle relaxation. Smooth muscle relaxation is mediated principally by nitric oxide. Sildenafil (Viagra) acts by inhibiting phosphodiesterase 5, which augments the effects of nitric oxide, by inhibiting the catabolism of cGMP. Sildenafil has markedly altered the management of patients presenting with erectile dysfunction. Other treatment approaches, however, are still important. These include intracavernosal injections of alprostadil (Caverject, Viridal), transurethral alprostadil (MUSE), vacuum devices, prostheses and psychosexual counselling.