brain, spinal cord, and nerve disorders
Mononeuropathy
Causes of Mononeuropathy
Physical injury is the most common cause of a mononeuropathy. Injury is commonly caused by pressure on a nerve, such as the following: Prolonged pressure on a nerve that runs close to the surface of the body near a prominent bone, such as a nerve in an elbow, a shoulder, a wrist, or a knee (as may occur during a long, deep sleep, especially in alcoholics) Pressure from a misfitting cast or from crutches that fit poorly or that are used incorrectly Pressure from staying in a cramped position for a long time, as when gardening or when playing cards with the elbows resting on a table Pressure may also injure nerves when people cannot move for long periods, as when they are under anesthesia for surgery, are confined to bed (particularly older people), are paralyzed, or have lost consciousness. Less commonly, nerve injury results from the following: Accidents Prolonged exposure to cold or heat Radiation therapy for cancer Repeated injuries, such as those due to tight gripping of small tools or to excessive vibration from an air hammer Infections, such as Leprosy or A pocket of blood (hematoma) Cancer, which may directly invade a nerve If the pressure on the nerve is mild, people may feel only pins-and-needles sensations without any weakness. For example, people may hit their elbow (funny bone), or a foot may fall asleep. These episodes can be considered temporary mononeuropathies. Nerves that run close to the body’s surface near a bone are more vulnerable to injury. For example, the following nerves may be damaged: Median nerve in the wrist (as occurs in Carpal Tunnel Syndrome ) Peroneal nerve near the knee (resulting in Peroneal nerve palsy ) Radial nerve in the upper arm (resulting in Radial Tunnel Syndrome ) Ulnar nerve in the elbow (resulting in ulnar nerve palsy, as occurs in Cubital Tunnel Syndrome ) Using crutches that are the wrong height can damage a nerve in the armpit and make the hand and wrist weak. 