Erectile Dysfunction: Epidemiology, Physiology, and Etiologies
- ED affects approximately 20 million men in the United States and has been predicted to reach 322 million cases worldwide by 2025.
- ED has been used as a predictor for cardiovascular disease or stroke. It is estimated that men with moderate to severe ED are at a 65% increased risk of developing coronary artery disease and 43% increased risk of a having a stroke within 10 years compared with men without ED.
- Nitric oxide (NO) is the primary neurotransmitter involved in penile erections. NO promotes generation of cyclic guanosine monophosphate (cGMP), which results in decrease in intracellular calcium and leads to intracavernosal trabecular relaxation, which in turn maximizes blood flow and engorgement. Detumescence occurs when NO-mediated vasodilation terminates due to metabolism of cGMP.
- The etiology of ED is most commonly vasculogenic; however, a variety of other etiologies exist. Psychogenic ED is increasingly recognized as a common cause.