Erectile Dysfunction

Erectile dysfunction (ED), also called impotence, is the type of sexual dysfunction in which the penis fails to become or stay erect during sexual activity. It is the most common sexual problem in men. Through its connection to self-image and to problems in sexual relationships, erectile dysfunction can cause psychological harm.

In about 80% of cases, physical causes can be identified. These include cardiovascular disease; diabetes mellitus, neurological problems, such as those following prostatectomy, hypogonadism, and drug side effects. About 10% of cases are psychological impotence, caused by thoughts or feelings. The term erectile dysfunction is not used for other disorders of erection, such as priapism.

Symptoms
Erectile dysfunction is characterized by the regular or repeated inability to achieve or maintain an erection of sufficient rigidity to accomplish sexual activity. It is defined as the - persistent or recurrent inability to achieve and maintain a penile erection of sufficient rigidity to permit satisfactory sexual activity for at least 3 months. Erectile dysfunction often has an impact on the emotional well-being of both men and their partners. Many men do not seek treatment due to feelings of embarrassment. About 75% of diagnosed cases of ED go untreated.

Pathophysiology
Penile erection is managed by two mechanisms: the reflex erection, which is achieved by directly touching the penile shaft, and the psychogenic erection, which is achieved by erotic or emotional stimuli. The former involves the peripheral nerves and the lower parts of the spinal cord, whereas the latter involves the limbic system of the brain. In both cases, an intact neural system is required for a successful and complete erection. Stimulation of the penile shaft by the nervous system leads to the secretion of nitric oxide (NO), which causes the relaxation of the smooth muscles of the corpora cavernosa, and subsequently penile erection.

Diagnosis
In many cases, the diagnosis can be made based on the person's history of symptoms. In other cases, a physical examination and laboratory investigations are done to rule out more serious causes such as hypogonadism or prolactinoma. One of the first steps is to distinguish between physiological and psychological ED. Determining whether involuntary erections are present is important in eliminating the possibility of psychogenic causes for ED. Obtaining full erections occasionally, such as nocturnal penile tumescence when asleep, tends to suggest that the physical structures are functionally working.

Treatment
Treatment depends on the underlying cause. In general, exercise, particularly of the aerobic type, is effective for preventing ED during midlife. Counseling can be used if the underlying cause is psychological, including how to lower stress or anxiety related to sex. Medications by mouth and vacuum erection devices are first-line treatments, followed by injections of drugs into the penis, as well as penile implants. Vascular reconstructive surgeries are beneficial in certain groups. Treatments, other than surgery, do not fix the underlying physiological problem, but are used as needed before sex.

Medications
The PDE5 inhibitors sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) are prescription drugs which are taken by mouth. As of 2018, sildenafil is available in the UK without a prescription. Additionally, a cream combining alprostadil with the permeation enhancer DDAIP has been approved in Canada as a first line treatment for ED. Penile injections, on the other hand, can involve one of the following medications: papaverine, phentolamine, and prostaglandin E1, also known as alprostadil. In addition to injections, there is an alprostadil suppository that can be inserted into the urethra. Once inserted, an erection can begin within 10 minutes and last up to an hour. Medications to treat ED may cause a side effect called priapism.