Atrophy of the Corpus Cavernosum

What the corpus cavernosum does

The penis contains three cylinders of erectile tissue. The two corpora cavernosa run along the top and do most of the work of erection. The corpus spongiosum underneath surrounds the urethra and forms the head of the penis.

The corpora cavernosa are made of a sponge-like network of smooth muscle and blood spaces, wrapped in a tough sheath called the tunica albuginea. During arousal, nerves release nitric oxide, the smooth muscle relaxes, blood floods in, and the expanding tissue compresses the veins against the sheath, trapping blood. This veno-occlusive mechanism keeps the erection firm.

How atrophy and fibrosis develop

Erectile tissue needs regular oxygen-rich blood flow, which happens during erections, including the several erections that occur naturally during sleep each night. When erections stop for months, or blood supply or nerve signals are damaged, the tissue is starved of oxygen. Smooth muscle cells die and are replaced by collagen scar tissue.

Scarred tissue cannot expand or compress the veins, so blood leaks out. This is called venous leak or veno-occlusive dysfunction, and it is a major reason erectile dysfunction becomes resistant to tablets.

Causes and risk factors

• Prostate cancer treatment: radical prostatectomy can bruise or cut the nerves for erection, and radiation damages small blood vessels. Without erections for many months, the tissue atrophies. Shortening of around 1 to 2 cm is common after surgery. See prostate cancer.
• Ischemic priapism: an erection lasting more than 4 hours deprives the tissue of oxygen. After about 24 to 48 hours, extensive fibrosis is likely. See priapism.
• Peyronie's disease: scar plaques form in the tunica albuginea, causing curvature, indentation and shortening, and can affect the underlying tissue.
• Diabetes: damages nerves and small blood vessels.
• Vascular disease: atherosclerosis, high blood pressure, high cholesterol and smoking reduce blood flow.
• Low testosterone: testosterone helps maintain erectile tissue health.
• Trauma: penile fracture or pelvic fractures.
• Infection or removal of a penile implant, which leaves dense scarring.
• Repeated injections of erectile medicines, occasionally.
• Aging.

Symptoms

• erectile dysfunction: erections that are not firm enough or fade quickly
• tablets such as sildenafil or tadalafil that worked before but no longer do
• shortening of the penis, both flaccid and erect
• reduced girth
• curvature, an hourglass shape or indentation
• a firm or woody feel to the shaft
• loss of morning erections

Diagnosis

• History: onset of erection problems, response to medicines, prostate treatment, priapism, diabetes, smoking and medicines.
• Physical examination: penile length, texture, plaques and testicles.
• Blood tests: testosterone, glucose and HbA1c, and cholesterol.
• Penile Doppler ultrasound: after injecting a medicine that triggers an erection, ultrasound measures blood flow in and out. High outflow points to venous leak. Ultrasound also shows fibrosis and plaques.
• MRI in selected cases, such as after priapism, to map scarring.

Treatment

Penile rehabilitation (prevention)

After prostate cancer treatment, urologists often recommend starting early efforts to keep oxygenated blood flowing into the tissue:

• regular low-dose PDE5 inhibitors (tadalafil or sildenafil)
• a vacuum erection device used daily for several minutes
• penile injections when tablets do not work

Evidence that rehabilitation restores natural erections is mixed, but vacuum devices can help preserve length.

Treating the cause and risk factors

• prompt treatment of priapism within hours
• stopping smoking, managing diabetes, blood pressure and cholesterol, and exercising
• testosterone replacement if levels are clearly low and there is no contraindication
• Peyronie's disease treatments such as traction therapy, injections or surgery

Treating erectile dysfunction

• PDE5 inhibitors: often less effective when fibrosis is extensive
• Intracavernosal injections (alprostadil or combination drugs)
• Intraurethral alprostadil
• Vacuum erection devices with a constriction ring
• Penile prosthesis (implant): inflatable or malleable cylinders placed in the corpora cavernosa. It is the most reliable treatment for severe fibrosis, with high satisfaction rates. Implant surgery in heavily scarred tissue is technically harder and best done by an experienced surgeon.

Penile traction devices may help regain some length, particularly after prostatectomy or in Peyronie's disease.

Outlook

Early-stage changes can be slowed, and some function may return as nerves recover after prostate surgery, which can take up to 2 years. Established fibrosis is usually permanent, but nearly everyone can regain sexual function with injections or an implant. Counseling and involving a partner improve satisfaction.

Frequently asked questions

What is atrophy of the corpus cavernosum?

It is loss of the smooth muscle in the penis's main erectile chambers, with replacement by scar tissue (fibrosis). The tissue can no longer fill with blood and trap it, leading to erectile dysfunction, shortening and reduced girth.

What causes corporal fibrosis?

Common causes include prolonged lack of erections after prostate cancer surgery or radiation, ischemic priapism, Peyronie's disease, diabetes, smoking and vascular disease, low testosterone, penile trauma, and removal of an infected penile implant.

Can corpus cavernosum atrophy be reversed?

Established scarring is generally permanent. Early changes may be slowed with penile rehabilitation using tablets, vacuum devices or injections, and by treating risk factors. Erections can almost always be restored with injections or a penile implant even when fibrosis is advanced.

Why does the penis shrink after prostate surgery?

After prostatectomy, nerve injury stops erections for months, and the lack of oxygen-rich blood flow causes erectile tissue to scar and contract. Shortening of 1 to 2 cm is common. Early rehabilitation, such as using a vacuum device, may reduce length loss.

Is a penile implant an option for cavernosal fibrosis?

Yes. A penile implant is often the most effective treatment when fibrosis prevents other methods from working. Surgery is more complex in scarred tissue, so choose a urologist experienced in implant surgery. Satisfaction rates for patients and partners are high.