Erectile dysfunction (ED) is defined as the persistent inability to achieve and then maintain an erection to permit sexual intercourse.
In the general population ED affects, to a varying severity, up to 52% of men aged 40– 70 years. In 1995, it was estimated that ED affected over 152 million men worldwide. As ED increases in incidence with age (a man aged 70 years is three times more likely to have ED than a man of 40 years) and as we are an ageing population, it is estimated that by the year 2025, over 300 million men worldwide will suffer some degree of ED.
ED is a very distressing condition that not only has a negative impact on the man’s sexual ability but also has damaging repercussions on the couple’s quality of life. ED leads to depression, anxiety and loss of self-esteem and can contribute significantly to 20% of marital breakdowns. Men are reluctant to seek help for fear of not being taken seriously or out of embarrassment and become isolated within their relationship, which may lose all aspects of intimate contact. The tragedy is that treatment is readily available and highly effective, yet for many not utilized. Nearly 90% of men who have successful treatment for their ED report significant improvement of emotional and overall well-being. Encouraging men alone or with their partners to seek help is therefore a major challenge.
Causes of ED
The aetiology of ED was regarded until recently to be predominantly psychogenic, but with our increasing knowledge of the physiology of penile erection and pathophysiology of ED, it is now recognized to be mainly an organic condition, with vascular disease responsible for 70% of cases. For most men, the cause may be multifactoral, especially in the elderly (75% of men aged over 80 years have ED), with endocrine, cellular, neural and iatrogenic causes exacerbating vascular ED or being independently causative. Organic ED will have psychological consequences which must be recognized and addressed as part of the overall management.
Physiology of penile erection
A penile erection occurs in response to stimuli which may be visual, erotic, olfactory, auditory and tactile. It is a neurovascular event that may be modulated by hormonal and psychological factors. On sexual stimulation, there is increased parasympathetic activity and decreased sympathetic activity. The parasympathetic nerves release the neurotransmitters, the most important of which is nitric oxide (NO), which is also released by the endothelium. NO activates a soluble guanylate cyclase, which in turn raises the intracellular concentration of cyclic guanosine monophosphate (cGMP). Cyclic GMP then activates a specific protein kinase, which leads to the inhibition of calcium channels and the opening of potassium channels. The end result is relaxation of the smooth muscle in the penile arteries and the spongy tissue of the corpora cavernosa. A several-fold increase in blood flow to the penis occurs and, as the penis becomes erect with intracavernous pressures up to 100 mgHg, venous out flow is occluded and the erection is sustained. Cyclic GMP is regulated by phosphodiesterase type 5 (PDE5), which enzymatically degrades and inactivates this cyclic nucleotide. Penile rigidity is lost and flaccidity returns. Australia viagra online – cheap and high-quality.
When we consider the cascade of events, there are several areas where disturbances in the neurovascular sequence might lead to ED, but most attention has focused on PDE5 and its inhibition.