Mononeuropathy, or focal neuropathy, is damage to a specific nerve in the face, middle of the body (torso) or leg. It’s most common in older adults. Mononeuropathy often strikes suddenly and can cause severe pain. However, it usually doesn’t cause any long-term problems.
Symptoms usually go away without treatment over a few weeks or months. Your specific signs and symptoms depend on which nerve is involved. You may have pain in the:
- Shin or foot
- Lower back or pelvis
- Front of thigh
- Chest or abdomen
Mononeuropathy may also cause nerve problems in the eyes and face, leading to:
- Difficulty focusing
- Double vision
- Aching behind one eye
- Paralysis on one side of your face (Bell’s palsy)
Sometimes mononeuropathy occurs when something is pressing on a nerve (nerve compression). Carpal tunnel syndrome is a common type of compression neuropathy in people with diabetes. It can cause numbness or tingling in your hand or fingers, except your pinkie (little finger). Your hand may feel weak, and you may drop things.
Causes | Damage to nerves and blood vessels
The exact cause likely differs for each type of neuropathy. Researchers think that over time, uncontrolled high blood sugar damages nerves and interferes with their ability to send signals, leading to diabetic neuropathy. High blood sugar also weakens the walls of the small blood vessels (capillaries) that supply the nerves with oxygen and nutrients.
However, a combination of factors may lead to nerve damage, including:
- Inflammation in the nerves caused by an autoimmune response. The immune system mistakes nerves as foreign and attacks them.
- Genetic factors unrelated to diabetes may make some people more likely to develop nerve damage.
- Smoking and alcohol abuse damage both nerves and blood vessels and significantly increase the risk of infection.
Anyone who has diabetes can develop neuropathy, but these risk factors make you more likely to get nerve damage:
- Poor blood sugar control. Uncontrolled blood sugar puts you at risk of every diabetes complication, including nerve damage.
- Diabetes history. Your risk of diabetic neuropathy increases the longer you have diabetes, especially if your blood sugar isn’t well-controlled.
- Kidney disease. Diabetes can damage the kidneys. Kidney damage sends toxins into the blood, which can lead to nerve damage.