Erectile Dysfunction (ED)

What Is ED?

ED is defined as the inability to get and maintain an erection that is sufficient for satisfactory sexual intercourse. In simple terms it means soft penis during sex. 
How Does Erection Occur?
The process of erection begins with stimulation either by sight, smell or taste which then causes the release of chemicals called nitric oxide (NO) from the walls of blood vessels and nerve endings. This chemical then activates another chemical called guanylate cyclase, which in turn increases another chemical known as cyclic guanosine monophosphate (cGMP). This chemical (cGMP) causes relaxation of the smooth muscles in the penis. This causes the blood vessels bringing blood to the penis to dilate (vasodilatation) which in turn will lead to increased blood flow into the penis. What happens next is engorgement of the penis which gives it the erection and rigidity. 
The erection and rigidity is maintained because the engorgement of the penis compresses the blood vessels draining blood out from the penis. Therefore drainage of blood is impeded and the engorgement of the penis with blood stays. 
To reverse this, another chemical called the 5-phosphodiesterase, is produced. This chemical causes the breakdown of cGMP, which will then lead to softening or flacidity of the penis.
Causes Of ED
Since the process of erection requires stimulation, intact nerves and blood vessels, any diseases or conditions that affect any of these may lead to ED. Psychological conditions such as depression and stress are not uncommonly associated with ED. Certain medications/drugs like those used to treat hypertension and psychiatric disorders may cause ED. Recreational drugs like marijuana are also notorious for it. Other than that, diseases that affect the blood vessels like cholesterol clogging the vessels (atherosclerosis) as well as those affecting the nerves like diabetes (neuropathy) will lead to ED. Surgeries around the pelvis like the removal of the prostate (prostatectomy) and trauma are also other common causes of ED. Hormones like testosterone also play a role in erection and when there are low levels of testosterone(hypogonadism), erection will be affected.
Most of the time, no special test is required to make a diagnosis. Doctors commonly use a questionnaire known as the International Index of Erectile Function (IIEF) to grade the severity of the ED. The other grading is the Erection Hardness Score (EHS).
A physical examination as well as some simple blood tests for sugar (glucose), cholesterol and testosterone will usually be done.
In certain cases, further tests like nocturnal penile tumescence test (NPT), cavernosogram, areteriogram or colour Dopper ultrasound may be needed. These tests are usually done for more complicated cases and in those not responding to treatment. In the NPT test, it measures tumescence and rigidity at both the base and the tip of the penis (via bands placed around the tip and base of the penis) and recordings are made throughout the night before computer-based analysis of the results. Cavernosogram is mainly used to look for venous leak i.e. blood escaping too quickly from the penis to maintain erection. Penile arteriogram on the other hand is to assess the flow of blood into the penis. Colour Doppler ultrasound assesses the flow of blood in and out of the penis.
There are a few treatment options for ED. 
1) Healthy lifestyle
Maintaining a healthy lifestyle by itself has been proven to be effective and may be the only treatment needed. It is still important to maintain a healthy lifestyle even when other treatments are given as well. Healthy lifestyle means no smoking, reduction of weight, well balanced diet as well as exercise.
2) Phosphodiesterase-5 Inhibitors (PDE5 Inhibitor)
These are pills/medications taken orally. Examples are sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra). These medications  blocks the action of the chemical known as phosphodiesterase-5 (which breaks down cGMP). Therefore, it increases the concentration of cGMP in the penis and thus increases blood flow and engorgement in the penis. Side effects of PDE5 inhibitors include redness of the face (flushing), headache and backache. It should be used with caution in those with heart diseases. Those on medications known as nitrates for heart problems should avoid PDE5 inhibitors. It needs to be noted that stimulation is still needed before the medication works.
3) Intracavernosal Prostaglandin Injection.
These are medications (prostaglandin) which are injected directly into the penis. It causes an increase in the concentration of chemicals known as cyclic adenosine monophosphate (cAMP). cAMP similarly to cGMP, causes increased blood flow to the penis causing erection. This action is direct and no stimulation is needed. Possible complications include bleeding and plaques formation in the penis.
4) Vacuum Erection Device
This is an appliance which is used to cup the penis. Suction is then applied to create a vacuum around the penis. This will draw out blood to the penis causing it to get engorged and achieve erection. A band is then applied at the base of the penis to keep the blood trapped in the penis therefore maintaining the erection. The drawback of this device is that the penis feels cold and there may be numbness and bruises around the penis.
5) Penile Implants.
These are devices which are inserted via surgery into the penis. There are the inflatable and semi-rigid ones. The semi-rigid (malleable) types are basically rods which are inserted into the penis to give the erection and rigidity. The inflatable penile implant consists of two cylinders inserted into the penis. There is a pump which sends water into the cylinders, causing them to get inflated and this results in an erect penis. This pump is inserted into the scrotum. When erection is not needed, a valve is pressed which sends the water back to a reservoir causing the cylinders to be deflated. The success rate is above 95% though cost is a major factor as the device costs above RM20,000.
6) Psychological Treatment
Finally, there is also cognitive behavioural therapy (CBT) and sex therapy which may be able to help those who have no problem with the nerves or blood supply to the penis but are affected by their emotional and mental well being. It can also be used together with the other medical therapies.
Written by Christopher Ho Chee Kong. Last review: August 2013.
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