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Erectile Dysfunction

Pathology || Signs and Symptoms || Diagnosis || Treatment || Overview
Related Articles || References and Resources || Comment


Erectile dysfunction affects a significant number of men around the world. It is a source of embarrassment for many, which contributes to reluctance in seeking medical attention. There are different causes of erectile dysfunction, which include: psychological, neurological, vascular, and endocrine.

Categories of erectile
(1) Psychological
(2) Neurological
(3) Vascular
(4) Endocrine
Each etiology has its own pathology. Psychological erectile dysfunction may be due to partner discord, stress, anxiety, and guilt. Psychological erectile dysfunction can further exacerbate itself since the man continues to worry about it, which results in continued dysfunction.

Neurological injury to the spinal cord or nerves going to the penis can also cause erectile dysfunction. Damage to the pudendal nerve, which provides sensation to the genitalia, can result in difficulty obtaining an erection after appropriate stimulation. In addition, damage to the parasympathetic nerves, which allow the penis to fill with blood, or the sympathetic nerves, which allow ejaculation can also contribute to erectile dysfunction.

Since an erection is based on adequate blood flow to the penis, any problems that cause dysfunction of the blood vessels can cause erectile dysfunction. For example atherosclerotic disease can decrease blood flow making it difficult to achieve an erection. Years of high cholesterol, hypertension, and/or diabetes can further exacerbate vascular problems.

Last, but not least, endocrinological problems can cause erectile dysfunction. For example, low testosterone levels can cause decreased libido leading to erectile difficulties. Excessive prolactin levels, which can be seen in some pituitary tumors, can also lead to impotence. In general, endocrine problems are a rare cause of erectile dysfunction in men.

Signs and Symptoms

The name speaks for itself. The main symptom of erectile dysfunction is failure to achieve and/or maintain an erection. However, other important signs and symptoms that may seem unrelated may give clues to what is causing the dysfunction.

For example, numbness and tingling in the fingertips and toes may signify a peripheral neuropathy, which is often seen in long standing diabetes. Diabetes is a common cause of erectile problems. In addition, excessive prolactin can cause lactation and growth of breast tissue (even in men!). Smaller than normal testes may indicate other endocrine and hormonal problems. Spinal cord or nerve damage may manifest as bowel or bladder incontinence, and decreased anal sphincter tone on physical exam.

It is also important to ask about nocturnal and early morning erections, especially in cases of psychological impotence. Men who are able to achieve morning erections rarely have organic causes for their erectile dysfunction.


The diagnosis of erectile dysfunction is based on finding the underlying cause.

The first step is to determine if the erectile dysfunction is psychological versus non-psychological. Patients with psychological erectile problems will often continue to have erections at night while sleeping. Men with other causes of erectile dysfunction fail to have nocturnal erections.

Once psychological causes have been ruled out, numerous blood tests are often done based on other symptoms or signs. If diabetes is suspected blood sugar levels and hemoglobin A1C levels are checked. Prolactin, testosterone, and gonadotropin levels (ie: FSH and LH) can be checked to rule out hormonal problems. Vascular problems can usually be diagnosed if evidence of vascular disease exists elsewhere. For example, patients who've had heart attacks, peripheral vascular disease, or strokes likely have an increased risk of vascular erectile dysfunction.


Non-psychological disease is treated with a class of medications known as "phosphodiesterase inhibitors". They include sildenafil (Viagra®), tadalafil (Cialis®), and vardenafil (Levitra®). They work by inhibiting the breakdown of a molecule known as cyclic-GMP. This molecule causes the relaxation of smooth muscle, which allows more blood to flow into the penile tissues.

Patients who cannot take these medications may be candidates for penile prosthetic devices such as inflatable balloon pumps.

Testosterone can be given in men who are found to be deficient in this hormone. It is not recommended for non-deficient men.


Erectile dysfunction may affect up to 25% of middle aged and elderly men. It has numerous causes. The etiologies include psychological, vascular, endocrinologic, and neurologic problems. Diagnosis is based on history of erectile problems, as well as other symptoms that may help determine the cause. Treatment is with phosphodiesterase inhibitors and prosthetic devices.

References and Resources

(1) Berookhim BM, Bar-Chama N. Medical implications of erectile dysfunction. Med Clin North Am. 2011 Jan;95(1):213-21.

(2) Albersen M, Mwamukonda KB, Shindel AW, et al. Evaluation and treatment of erectile dysfunction. Med Clin North Am. 2011 Jan;95(1):201-12.

(3) Kumar V, Abbas AK, Fausto N. Robbins and Cotran Pathologic Basis of Disease. Seventh Edition. Philadelphia: Elsevier Saunders, 2004.

(4) Bickley LS, Szilagyi PG. Bates' Guide to Physical Examination and History Taking. Ninth Edition. New York: Lippincott Williams and Wilkins, 2007.

(5) Le T, Bhushan V, Grimm L. First Aid for the USMLE Step 1. New York: McGraw Hill, 2009.

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