Impotence is the inability to attain or maintain an erection of the penis that is firm enough for sexual intercourse.

To initiate and maintain an erection, the penis must fill with blood. Nerve signals cause the blood to flow there. The blood vessels expand so blood can fill it. Meanwhile, other blood vessels constrict, trapping blood inside.

The following factors can cause erectile dysfunction:

Venous Leak

A leak in the blood vessels in the penis can allow blood to escape. This means that an erection cannot be made or may not last long. Injury or disease can cause a venous leak.

Neurovascular Function
  • Problems with nerve signals and blood flow
  • Nerve dysfunction—can reduce feeling in the penis, resulting in impotence
  • Diabetes —interferes with nerve signals
  • Complete loss of nighttime erections
  • Hardening of the arteries —can cause reduced blood flow
  • Peripheral neuropathy, spinal cord injury, and surgery—can damage nerves
  • Side-effects from medications

Blood Vessels and Nerves of Male Pelvis
Nerves, blood vessels, penis
© 2011 Nucleus Medical Media, Inc.

Psychological Factors

The brain causes many of the nerve signals needed for an erection. Emotional problems may play a role in men who suddenly develop impotence.