Simply defined, impotence is the failure to achieve erection, ejaculation, or both.(1) Men may present with one or a combination of complaints: loss of libido, inability to initiate or maintain an erection, premature ejaculation, ejaculatory failure, or inability to achieve orgasm. The selection and success of therapy is dependent upon understanding the cause, and thus it is necessary to evaluate all aspects of sexual function.

Impotence may be caused by a variety of endocrine, vascular, neurologic, or psychiatric diseases. It may actually be the presenting symptom in some systemic diseases, or can be a side effect caused by certain medications. It was previously thought that most erectile dysfunction was psychologically based. It is now thought that the majority of men with sexual dysfunction actually have a component of underlying organic disease.

A decrease or loss of desire (libido) may be due to hormone deficiency arising from either pituitary or testicular disease, psychological disturbance, or to some types of prescribed or habitually abused drugs.(1) If a hormonal deficiency is suspected, a blood test may be recommended to determine hormonal levels. A condition known as hypogonadism may also result in abnormal erectile function. The minimal level of testosterone necessary for normal erectile function is unknown.

Failure of erection may be caused by a number of conditions, grouped in general into endocrine, drug, local, neurologic, and vascular disorders.

Premature ejaculation is a disorder that seldom has an organic cause. It is usually related to anxiety in a sexual situation, undue pressure placed on oneself concerning sexual performance, or an emotional disorder. Behavioral therapy has been the most successful treatment of this disorder.

Absence of emission may be produced by four major causes. These are retrograde ejaculation, sympathetic denervation, androgen deficiency, or some drugs. Androgen deficiency generally causes a decrease in secretions and volume of ejaculate. These drugs include guanethidine, phynoxybenzamine, phentolamine, and sertraline, which frequently impair ejaculation. Sympathetic denervation may occur as a result of surgery where there is a resultant lack of smooth muscle contraction at the time of ejaculation. Retrograde ejaculation may occur after bladder or neck surgery, or may spontaneously develop in diabetic men.

Absence of orgasm is most frequently due to psychiatric disorder, particularly if libido and erectile function are normal.