Causes
Mononeuropathies are usually caused by pressure on a nerve just under the
skin near the knee, elbow, shoulder, or wrist. Some nerves close to the
surface of the body, such as the median nerve in the wrist, the ulnar nerve
in the elbow, the radial nerve in the upper arm, and the peroneal nerve
in the calf, are more easily injured than other nerves. The injuries result
in the following mononeuropathies: carpal tunnel syndrome, ulnar
nerve palsy, radial nerve palsy, and peroneal nerve palsy.
For example, making the same wrist movement over and over can cause pressure
on the median nerve in the wrist, causing carpal tunnel syndrome.
Polyneuropathy has many causes, including alcoholism, diseases such as diabetes,
cancer, and end-stage kidney failure, and exposure to poisonous chemicals such
as lead. Hypothyroidism, a hormonal condition in which the thyroid
gland doesn't work normally, can also cause neuropathy. Some neuropathies are
due to inherited medical conditions that get worse with time, and others can
be caused by certain medications. Vitamin deficiencies can also cause polyneuropathy.
Guillain-Barré syndrome is a very serious form of polyneuropathy.
Sometimes people with the disease become paralyzed. It is probably caused
by an autoimmune reaction. The body's immune system attacks the nerve's myelin
sheath, a coating that helps carry a signal along the nerve. Guillain-Barré
syndrome can develop suddenly between five days and three weeks after a person
has had an infection, a vaccine, or surgery.