Impotence is defined as inability to copulate successfully. It is fairly common defect with the incidence of 10% in the Asian population and up to 15% in the west.
Impotence is an important topic to know about as it is associated with various myths and misconceptions. It was previously thought that 90% of the cases are due to psychogenic causes and only 10% are due to some pathology. But now it is thought that only 10% of cases are psychological in origin and 90% have an important cause which can be treated. To know and understand the basic mechanism for erection in males.
Sexual behaviour, and erection are controlled by important centres in the brain, mese centres are called the medial preoptic and paraventricular nucleus in an area called hypothalamus. Nerve tract start from this areas and run into the spinal cord. These are of 2 types and finally contribute to form the cavernous nerves which supply the penis.
Hence diseases affecting the brain, spinal cord and the cavernous nerves can cause impotence.
Diseases which cause impotence by affecting the centres in the brain are brain trauma, cerebrovascular accidents, Parkinsomom and alzemers disease. The disorders of the spinal cord that cause impotence are spinal trauma, spinal tumours, prolapsed intravetebral disc and multiple sclerosis. However, the degree of impotence depends upon the nature, location and extent of the disease of the spinal cord.
Finally diseases which involve the cavernous nerves are major surgeries on the pelvis, fractures etc. The smaller and final nerve terminals can be affected by alcoholism vitamin deficiency and diabetis.
Now we will briefly discuss the anatomy and physiology of erection.
The penis is made up of 3 cylindrical tissue called corpora. These corpora are extremely vascular and composed of a network of blood vessels called sinusoids. The corpora are supported on the outside by a elastic coat called tunica. The blood supply of the penis is very rich. The penile arteries end by formation of these sinusoids and small veins originate from the sinusoids. In the flaccid (non erect) state small amount of blood enters the sinusoids and then leaves the sinusoids by the way of the veins. Sexual stimulation triggers the rednease of certain subotances from the cavernous nerve. These neurotransmitter substances cause relaxation of small muscle fibres present in the walls of the sinusoids. Once the sinusoids relaxe increased amount of blood comes into the penis and gets trapped inside. This increased inflow of blood and decreased outflow of blood in the sinusoids cause erection. Thus it is clear that diseases which affect the arteries of the penis cause impotence.
This arteriogenic impotence is due to trauma or disease involving the hypogastric, cavernous arteries. The most common cause is atherosclerosis the same age related obliterative disease of blood vessels. The risk factors which promote atherosclerosis are smoking, diabetis mellitus, hyperlipidemia and hypertension. Venous impotence is related to diseases which cause easy drainage of blood from the penis. Another rare cause of impotence is hormonal impotence. Testosterone the main male sex hormone is responsible for the development of the male reproductive organs and secondary sex features. It also affects the libido. Decreased production of testasterone is due to diseases of the brain centres or the testis. Diabetis melitus, the most common endocrinal disorder causes impotence through various mechanism e.g. anterial, neurological rather than producing any hormonal deficiency.
Drug induced impotence
Variety of drugs are associated with impotence commonly used drugs included methyldopa, clonidine, reserpine, gianethidine, phenoxybenzamine, phentolamine, prazocin, thiazide diuretics major tranqouliqess and antipsychotic, antidepressants .
Cigarette smoking reduces the duration and rigidity of erection. Men who smoke more than 40 cigarettes a day have the weakest and shortest erections. Smoking induces vasoconstriction and penile venous leakage because of its contractile effect on the cavernous smooth muscle. Alcohol in small amounts improves erection and sexual drive because of its vasodilatory effect and suppression of anxiety; however large amounts can cause central sedation, decreased libido and transient impotence.
Chronic alcoholism may result in liver dysfunction decreased testosterone and increased estrogen levels and alcoholic polyneuropathy affecting the penile nerves.
Diagnosis of Impotence
It is important to pin point the cause of impotence and then treat the patient. History should be cordial and should include details regarding:
Presence of noctural penile erection
Medical history should include or exclude the presence of various diseases like diabetis, hypertension, peripheral vascular diseases, coronary diseases, renal failure hypertension and drug treatment.
Routine investigations include complete blood count, urine analysis and fasting and postprandial sugars. Routine blood levels of testasterone are not useful unless the clinical picture is suggestive of a hormonal problem. The main test is PIPE (Pharmacologically induced penile erection).
Various drugs can be used for this purpose.
Paverine + largach
Papaverine + alprostadil + phentolamine
If the patient achieves a normal erection as confirmed by the urologist then the patient has a clearcut psychological cause and requires counselling/or psychotherapy.
He may be advised and taught self injection with papavereine for a few weeks to improve his self confidence. Later it can be discontinued. Many patients experience recovery of spontaneous erection with PIPE. However a few things about PIPE need to be mentioned. The first few injections have to be supervized by the urologist. The exact dose needed has be decided by the urologist and the details of the method of injection. The erection produced should not last for more than 45 minutes to 1 hour. If it lasts for a longer time the patient has to report immediately. Persistent erection for more than one hour is called priaprism and has to be treated immediately. Another complication is the occurrence of fibrosis i.e. a small area of hardness at the site of injection.
PIPE cannot be given to patients with bleeding disorders, sickle cell anemia, schizophenia severe psychiatric illness and serious diseases. The second line of investigation is the combination of PIPE and vaccum erection device. The VED is a artificial chamber designed to produce erection. Both PIPE and VED can be combined to produce an erection.
However if the patient fails to get an erection with both the methods then he has a organic problem either arterial or venous impotence. An experienced urologist can differentiate the type of impotence depending upon the response of the patient. There are various other investigative modalities which are not clinically important but are discussed in brief.
Vaccum erection Device VED. It consists of a plastic cylinder connected to a vaccum generating source. The penis is placed inside the device and negative pressure generation is started. After full engorgement of penis the device is removed and at same time a constricting ring of plastic is applied to the base of penis to maintain erection. The erection subsides on removal of the ring, after not more than 30 minutes. The erection produced by a vaccum device is not similar to a physiologic erection. The penis may not be completely rigid and the skin may become cold and dusky. However, it is useful for majority of patients who report satisfaction with it. It is not useful in severe venous leakage, arterial insufficiency, fibrosis and post-infection status.
Complications include penile pain, numbness, difficult ejaculation, ecchymosis. It is more acceptable in older men and is one of the safe and least costly treatment cost varies from Rs. 8,000 to 15,000 and available freely.
Nocturnal penile tumescence or sleep related erection is a recurring cycle of penile erections associated with rapid eye movement sleep in virtually all potent men. It is suggested that the mechanism involved in NPT is similar to spontaneous erections. It is therefore used to distinguish between organic and non-organic causes of erection.
NPT measurement is done in sleep caps with sophisticated monitoring devices that measure
number of erectile episodes
maximum penile rigidity
duration of erection.
This data is measured in conjuction with EEG, EDG and EMA activity.
Although it is a non-invasive test, its usefulness is questioned. No standardized techniques have been established and the parameters in NPT testing do not correlate well with clinical findings.
Non surgical management
Although penile prosthesis remains the good standard and are of the most effective treatments of all types of erectile dysfunction non surgical management should be also be explained to the patient.
Lifestyle change: Change to healthy diet, smoking cessation, alcohol in moderation, low cholesterol diet, for long distance bicycle riders – change in seat or other exercize may be advised.
Change in medication: i.e. in cases of hypertension change from older drugs like methyldopa and reserpine to calcium channel blockers e.g. old antidepressant to trazodone which is known to improve erectile dysfunction.
Pelvic floor muscle exercises: Intensive guided physiotherapy consisting of electrical stimulation of the ischiocavernous muscle graded pelvic floor exercizes and home exercizes is proved beneficial.
There are two types of psychotherapy:
psychoanalysic therapy is based on the theory that sexual dysfunction repressents an underlying subconscious conflict,
symptom oriented counselling i.e. explanation of the cause sexual information reassurance, encouragement.
Hypogonadism: In young males testasterone is given. In older males a digital rectal exam and PSA (prostate specific antigen) level to rule out cancer of prostate has to be done before starting therapy. PSA levels should be monitored during therapy.
Testasterone cyplonate and enanthate 200 mg intramuscularly every 2-3 weeks is advised. Transdermal testasterone preparations eg. testoderm and androderm are available. When applied for 24 hours they provide 5 mg of testaterone per day.
The effectiveness of hormone replacement is disappointing and the response rate is low.
Transmethial alprostadil: This drug is available as a small pellet which when introduced into the urethra can produce an erection. It has to be used 30 minutes prior and the effect last for 30 minutes. The cost is 10 pounds.
Sidanafil citrate/ Viagra: It is available as 50 mg and 100 mg tablets. It is to be given 1 hour prior preferably on empty stomach as food may impair its action. The dose has to be adjusted for each person and can be used once in 24 hours. 100 mg costs 17 pounds. It cannot be given in cases of severe myocardial infarction, severe heart disorders, hepatic dysfunction recent stroke and retinal degeneration. The side effects are headache flushing dizziness, nasal congestion, altered vision and muscle aches.
In patients who fail to get a result on PIPE or VED and other drugs are potential candidates for penile prosthesis.
There are 2 types of penile prosthesis:
The inflatable prosthesis as the name suggests is usually in the flaccid state and can be inflated at will. The rigid or non inflatable penile prosthesis is freely available in India and designed by renowed andrologists, Dr Rupin Shah from Mumbai. It is made up of two salicon cylinders and the these cylinders can be placed in the corpora by a small surgery. The size available are various and the one to be fitted in the patient depends upon the size of the penis.
The cost of the prosthesis is 8-10 thousand only and the operation is simple urination and ejaculation are not affected. The cylinders of silicon placed in the penis keep the penis in a erect state constantly. It has a tinge and can be concealed easily. The remaining erectile tissue in the patient also aids in augmenting the erection produced by the prosthesis.
The complications include infection and erosion of the prosthesis. They are uncommon and can be dealth with.
Thus in conclusion, impotence is a relatively common problem but can be treated adequately.