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Chapter: Medicine and surgery: Genitourinary system

Impotence - Disorders of the male genital system

Inability to achieve or sustain a sufficiently rigid erection in order to have sexual intercourse. - Definition, Incidence, Aetiology, Pathophysiology, Clinical features, Complications, Investigations, Management, Prognosis.





Inability to achieve or sustain a sufficiently rigid erection in order to have sexual intercourse. Occasional episodes of impotence are considered normal, but if erectile dysfunction precludes more than 75% of attempted intercourse, a man is considered ‘impotent’. Also called male sexual dysfunction.




This has been underestimated in the past, due to the reluctance of men to discuss this and the assumption that impotence is inevitable with advancing age. With greater understanding, increased availability of treatment and more widespread discussion of the problem, 40% of men aged 40 are recognised to have some degree of sexual dysfunction, increasing by approximately 10% with each decade.




The cause is pyschogenic in 25% of cases, drugs (25%) and endocrine abnormalities (25%). The other 25% are caused by diabetes, neurological and urological/pelvic disease.


Psychogenic causes can be divided into following:


·        Depression, causing loss of libido and erectile dysfunction. Many impotent men also become depressed.

·        Performance anxiety occurs in men who, after one or more episodes of erectile dysfunction, become so anxious that subsequent attempts at intercourse fail, leading to escalation of the problem.


·        Distraction or loss of focus, e.g. by work issues or other tasks that need to be done, can cause loss of erection during sexual intercourse.




·        Commonly used drugs can cause impotence such as antihypertensives, in particular thiazide diuretics, anti-depressants and drugs used to treat peptic ulcer disease. Barbiturates, corticosteroids, phenothiazines and spironolactone may reduce libido.


·        Nicotine and alcohol. Recreational drugs such as cocaine and hallucinogenic drugs can cause impotence with long-term use.




·        Testosterone not only acts to increase libido, but is needed for a rigid erection, by maintaining nitric oxide synthase levels in the penis. Oestrogen therapy (e.g. for prostate cancer) can also result in impotence.


·        Hyperprolactinaemia, hyperthyroidism and hypothy-roidism.


·        Diabetes lowers intracavernosal levels of nitric oxide synthase, and these patients also have increased atherosclerosis which can impair blood supply. Auto-nomic neuropathy is also an important factor.


Central sexual impulses (e.g. caused by images or sounds) pass to T11-L2, which then sends signals to the pelvic vessels, to increase blood supply to the penis. There is also a reflex arc at S2–S4 which means that genital stimulation increases vascular flow. Neurological disease at any level can therefore interfere with sexual function.



Clinical features


Some features in the sexual history, medical history or examination may point towards a cause. Complete loss of erections, including nocturnal erections, suggests a neurological or vascular cause. Sudden loss of sexual function without any previous history of problems, or major genital surgery, suggests performance anxiety, stress or loss of interest in the sexual partner. Ability to generate an erection, but then inability to sustain it may be due to anxiety or to a problem with vascular supply, or nitric oxide synthase levels, e.g. in diabetes. It is important to take a drug history and enquire about possible features of depression, smoking, alcohol or drug abuse.



Simple hormonal tests for prolactin levels, thyroid function tests, testosterone levels are sometimes useful. Di-abetes mellitus should be looked for by urine dipstick/ blood sugar levels.




Oral treatments include Sildenafil (Viagra) is a type 5 phosphodiesterase inhibitor, which allows cyclic GMP to accumulate (nitric oxide induced vasodilatation is mediated by cyclic GMP which is catabolised by type 5 phosphodiesterase), so increasing the ability to generate and maintain an erection. It needs to be taken 1 hour before sex, and its effects last for 4 hours. Its vasodilation effects can cause headache, dizziness, a blue tinge to vision (reversible) and even syncope. It is contraindicated with concomitant nitrate use (including sublingual and GTN patch) within 24 hours, as profound hypotension can result. There are now two newer similar drugs – vardenafil and tadalfil, which have a more rapid onset, but longer duration of action, allowing more spontaneity.


Anti-depressants such as selective serotonin reuptake inhibitors may be useful, particularly for premature ejaculation.


Penile self-injection with vasoactive drugs such as papaverine, or alprostadil suit some individuals. An important side-effect is priapism – a prolonged erection which may need surgical intervention to remove clot.


Vacuum devices can be used to ‘suck’ blood into the penis and then a ring is applied at its base to maintain the erection. Ejaculation is not possible with these devices.


Surgical intervention involves the implantation of a prosthesis into the corpus cavernosa.


Psychological counselling is useful for those with a psychological cause.

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