In this blog, PCRI presents an article from guest contributor, Mohit Khera, MD, MBA, MPH.
Before discussing recovery of erectile function in men following radical prostatectomy, it is important to understand the current causes and treatments for ED. There are many causes of ED. ED is a progressive disease in which 40% of men at 40 years old, 60% of men at 60 years old, and 80% of men at 80 years old will develop ED.  The most common causes are associated with diabetes and prostate cancer. Diabetics are four times more likely to have ED because they tend to have poor blood flow and nerve function in their penis. Radical prostatectomy can result in nerve injury to the penis. Unfortunately, some men never recover their erections after surgery. Other causes of ED include smoking, high blood pressure, high cholesterol, and certain medications. Many patients do not realize that beta-blockers, one of the most commonly used blood pressure medications, can be a potential cause of ED. Other causes include psychological issues, such as seen with marital guilt, new relationships, and divorce. In these cases, sex therapy is extremely effective. Peyronie’s disease, which is an abnormal curvature of the penis when it is erect, and penile trauma, can also lead to ED.
ED is a window to a man’s cardiac health and overall health. In fact, the causes of ED and cardiovascular disease are very similar. The common causes include smoking, poor diet and lack of exercise, diabetes, obesity, advanced age, and elevated cholesterol levels. ED is one of the first signs of cardiovascular disease. Studies have shown that from the day a man develops ED, he has a 15% chance of developing a heart attack or stroke within seven years. 
Many men believe that sildenafil (Viagra) is a good treatment for ED. However, you have to ask yourself if sildenafil, or sildenafil-like drugs, such as tadalafil (Cialis), are really addressing the cause of ED. I believe these medications generally do not cure ED, but instead allow the disease to become worse over time. There are two ways to give these medications. One way is to take these medications before sex and the other way is to take a daily dose whether you are having sex or not. These are referred to as “on-demand dosing” and “daily dosing,” respectively. In my opinion, Cialis, when used as on-demand dosing, does not cure the ED problem and actually causes it to worsen. ED is a progressive disease process that can be reversed. Dr. Esposito and colleagues have shown that diet and exercise reverse ED. Other studies have shown that the use of statins improves ED, and makes medications such as Viagra much more effective. Improving diabetic control and stopping smoking are also ways to reverse ED. Finally, daily dosing of Cialis and the use of testosterone have been shown to reverse ED and improve the muscles within the penile tissue. Prior to treating men with ED, I strongly encourage lifestyle modifications in order to reverse the disease process and to prevent further worsening of the disease.
There are many treatment options for men with ED. The most commonly used medications are oral medications, such as sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis), and recently introduced avanafil (Stendra). Stendra is the only FDA approved drug in this class that has an onset as early as 15 minutes. Other treatments include testosterone therapy. Testosterone alone has been shown to improve overall erections in men. Other medications include small suppositories (MUSE) that are placed in the tip of the penis and dissolve, causing blood to enter the penis and permitting an erection. Vacuum erection devices (VEDs) have been available for many years. A VED is simply a cylinder that
is placed on the penis, functioning like a vacuum and causing an erection. The man then places a band at the base of the penis so he can maintain his erection. Another effective treatment for ED is penile injections. These injections administer a small amount of medication that is injected at the base of the penis at the 10 and 2 o’clock position. Usually within 5-10 minutes the man is able to achieve a rigid erection sufficient for sex. This is an effective form of therapy and is also one of the cheapest types of ED medication if obtained from a compounding pharmacy. However, many American men are reluctant to insert a needle into their penis. Finally, there is the penile prosthesis, which was invented in the early 1970s by Dr. Brantley Scott. The penile prosthesis has revolutionized how we treat men for ED. The penile prosthesis involves a surgical procedure where an inflatable device is placed in the penis. There is a pump in the scrotum which allows the man to inflate and deflate the prosthesis. The entire prosthesis is placed inside the body and is not noticeable if a man takes off his clothes. The benefit of the penile prosthesis is that almost every man can be treated for ED if he is willing to have the procedure. Also, a man is able to get an erection whenever he wants for as long as he wants. Many of my patients are also offered a sex therapy referral. Sex therapy is especially helpful in men who suffer from psychogenic ED. Psychogenic ED can occur frequently in men following prostate cancer surgery. One cannot underestimate the large psychological impact radical prostatectomy can have on patients. This can have a devastating psychological impact on the patient and his wife. Many men start to experience ED once they are given the diagnosis of prostate cancer. This is why sex therapy plays such an important role in the recovery of sexual function following prostate cancer treatment.
One of the best ways to improve a man’s erections is to treat his wife. There have been many studies showing that if you increase a woman’s sexual desire, her male partner’s erections also significantly improve. There are also studies showing that if you improve a man’s libido and erections, his wife’s libido and sexual function also improve. The reason for this is that sexual dysfunction is a couple’s disease. You cannot treat one person without at least addressing the other partner. I published a study several years ago demonstrating that one of the best predictors of whether a man would be compliant to a penile rehabilitation program after surgery was based on how good his partners sexual function and desire was. It makes sense that men who have a willing sexual partner are more likely to be motivated to recover their erectile function. The best way to treat sexual dysfunction is to treat both partners together. By treating one partner, you are also treating the other.
As discussed earlier, following a radical prostatectomy, approximately 77% of patients have ED due to blood flow or nerve injury causes. Although the penile nerves may be preserved during a radical prostatectomy, a majority of men suffer from temporary nerve paralysis, which may last from months to years. Nerve injury can also lead to penile scarring. In the past, we gave men Viagra and had them follow-up in 1 year to assess how their erections were progressing. I disagree with this approach, as the penis is mostly composed of muscle, and should be exercised just like any other muscle in the body. For example, if I put your arm in a cast for one year and then took off the cast, you would have muscle wasting (atrophy) and the arm would be weak. The same is true for the penis. The concept of “use it or lose it” is very relevant here. Thus, we now ask patients to start exercising the penis immediately after surgery. This is called penile rehabilitation. The goal of penile rehabilitation is to increase blood flow and oxygen to the penile tissue and thus prevent scarring and permanent damage to the penis. It is important to take this proactive approach because many times the scarring that occurs in the penis after a radical prostatectomy is irreversible.
There are many exciting potential future treatments for ED following radical prostatectomy. Currently, we are working with stem cells to reverse the ED process.  The stem cells are harvested from the patient’s fat and then processed and injected back into the patient’s penile tissue. Our initial human studies were promising, as stem cells allow more blood to flow into the penile tissue as well as increase the muscle within the penile tissue. We are also beginning our study to deliver low intensity shockwave therapy to the penis. In this procedure, a patient undergoes 1500 penile shocks three times per week for six weeks, inducing growth factors and new blood vessels to come into the penile tissue. This technology has been used for several years in Europe, and initial results appear promising in improving overall erectile function.
 Feldman HA, Goldstein I, Hatzichristou DG et al. Impotence and its medical and psychosocial correlates: results of the Massachusetts Male Aging Study. J Urol 1994; 151:54-61.
 Sopko NA, Burnett AL. Erection rehabilitation following prostatectomy--current strategies and future directions. Nat Rev Urol 2016; 13:216-225.
 Thompson IM, Tangen CM, Goodman PJ et al. Erectile dysfunction and subsequent cardiovascular disease. JAMA 2005; 294:2996-3002.
 Esposito K, Giugliano F, Di Palo C et al. Effect of lifestyle changes on erectile dysfunction in obese men: a randomized controlled trial. JAMA 2004; 291:2978-2984.
 Moskovic DJ, Mohamed O, Sathyamoorthy K et al. The female factor: predicting compliance with a post-prostatectomy erectile preservation program. J Sex Med 2010; 7:3659-3665.
 Khera M, Albersen M, Mulhall JP. Mesenchymal stem cell therapy for the treatment of erectile dysfunction. J Sex Med 2015; 12:1105-1106.