Erectile dysfunction Health Article

Definition

Erectile dysfunction (ED) may be defined as the consistent inability to achieve or maintain an erection sufficient to permit satisfactory sexual intercourse. The word "consistent" is included in the definition because most men experience transient episodes of ED that are temporary and usually associated with fatigue, anger, depression or other stressful emotions. The use of the formerly used term "impotence" has been virtually abandoned because of its inherent stigmaof weakness and lack of power.

Erectile dysfunction can occur as part of several mental disorders recognized by the mental health professional's manual, the Diagnostic and Statistical Manual of Mental Disorders,often shortened to the DSM.ED is the main symptom in the disorder the manual calls "male erectile disorder." ED can also be a symptom of other disorders, such as sexual dysfunction due to a general medical condition or substance-induced sexual dysfunction. In this entry, however, ED is examined and discussed as its own medical entity, and not within the strict guidelines of the DSM.

Description

First, it may be useful to understand the mechanisms of normal penile erection. Penile erection occurs essentially when the penis becomes engorged with blood. The anatomical compartments (two corpora cavernosa and one corpus spongiosum) are capable of being distended with seven times their normal amount of blood. When this occurs in association with relaxation of the penile muscles, erection results.

The sequence of events resulting in penile erection is complex. It is usually initiated by sexual arousal stimuli arising in the brainas a result of visual, auditory or olfactory sensations or erotic thoughts. Tactile (touch) sensations of the penis acting through the spinal cord play a similar role. Sexual arousal results in the release of a chemical (nitric oxide) from specialized cells. Nitric oxide causes the formation of a substance (cyclic glutamine monophosphate or cGMP) that is responsible for dilating the blood vessels of the penis and relaxing its muscles, thus allowing for an increase in blood flow and resultant penile erection. Compression of the dilated blood vessels against the firm outer lining of the penis prevents the blood from escaping and perpetuates the erection. A specialized substance (phosphodiesterase 5 or PDE-5), causes the breakdown of cGMP and, with the help of nerves from the sympathetic nervous system, allows the penis to return to its flaccid relaxed state.

Any defect in this complex cascade of events can result in erectile dysfunction.

Different men experience varying patterns of ED. Men with ED may report the inability to experience any erection from the beginning of a sexual experience, while others experience an erection that is not maintained at penetration. Other men may lose the erection during sexual intercourse, and others can only experience erection upon awakening or during self-masturbation.