Erectile dysfunction (ED) is a common problem in men, with the incidence increasing with age.  There are 4 main causes of ED: psychological, hormonal, vascular and neurological.  Many men will have more than one cause, although one usually predominates.  An erection is a hydraulic process.  Arteries to the penis relax, allowing blood to flow in.  At the same time, the veins become compressed, preventing the blood from flowing out.  This causes the pressure to rise in the penis and the penis enlarges and becomes more rigid, similar to a balloon being filled with air.  After a man ejaculates or stops being stimulated, the arteries constrict, decreasing blood flow into the penis.  At the same time the veins relax, allowing blood to flow out more easily.  This is akin to the balloon being deflated.

In men less than 40 years old, psychological factors are is by far the most common problem, usually due to “performance anxiety”.  Both younger and older men may also have a problem with low testosterone.  Testosterone is needed to maintain a healthy sex drive and the proper responsiveness of the penis to stimulation.  Low testosterone can lead to a decreased sex drive, ED, depression, weight gain and a feeling of lethargy.

As men grow older, vascular and neurologic problems become much more common.  There are two types of vascular problems.  The first is insufficient blood flow into the penis and the second is venous incompetence.  Insufficient blood flow in is usually caused by atherosclerosis (hardening of the arteries) or by anti-hypertensive medication.  The cause of venous incompetence is not clear and is very difficult to treat.  Neurological problems are caused by diabetes which leads to neuropathy or by spinal cord injury.

There are a variety of diagnostic tests which are used to determine the underlying cause of ED and to suggest the best treatment option.  A variety of treatments are available, including tablets, suppositories, injections, constriction devices and surgery.

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