Peripheral nerve injuries

Overview

Peripheral nerves send messages from the brain and spinal cord to the rest of the body. They help do things such as sense that the feet are cold and move the body's muscles for walking. Peripheral nerves are made of fibers called axons that are insulated by surrounding tissues.

Peripheral nerves are fragile and easily damaged. A nerve injury can affect the brain's ability to communicate with muscles and organs. Damage to the peripheral nerves is called peripheral neuropathy.

It's important to get medical care for a peripheral nerve injury as soon as possible. Early diagnosis and treatment may prevent complications and permanent damage.

Symptoms

With a peripheral nerve injury, you may experience symptoms that range from mild to seriously limiting your daily activities. Your symptoms often depend on which nerve fibers are damaged:

• Motor nerves. These nerves regulate all the muscles under your conscious control, such as those used for walking, talking and holding objects. Damage to these nerves is typically associated with muscle weakness, painful cramps and uncontrollable muscle twitching.
• Sensory nerves. Because these nerves relay information about touch, temperature and pain, you may experience a variety of symptoms. These include numbness or tingling in the hands or feet. You may have trouble sensing pain or changes in temperature, walking, keeping your balance with your eyes closed, or fastening buttons.
• Autonomic (aw-tuh-NOM-ik) nerves. This group of nerves regulates activities that are not controlled consciously, such as breathing, heart and thyroid function, and digesting food. Symptoms may include excessive sweating, changes in blood pressure, the inability to tolerate heat and gastrointestinal symptoms.

You may experience a range of symptoms because many peripheral nerve injuries affect more than one type of nerve fiber.

When to see a doctor

If you experience weakness, tingling, numbness or a total loss of feeling in a limb, see your health care provider to determine the cause. It's important to treat peripheral nerve injuries early.

Causes

Peripheral nerves can be damaged in several ways:

• Injury from an accident, a fall or sports, which can stretch, compress, crush or cut nerves
• Medical conditions, such as diabetes, Guillain-Barre syndrome and carpal tunnel syndrome
• Autoimmune diseases including lupus, rheumatoid arthritis and Sjogren's syndrome

Other causes include narrowing of the arteries, hormonal imbalances and tumors.

Diagnosis

Your doctor will review your medical history, ask about any accidents or previous surgeries, and discuss your symptoms with you. Your doctor will also conduct a physical and neurological examination. If your neurological examination shows signs of a nerve injury, your doctor may recommend diagnostic tests, which may include:

• Electromyography (EMG). In an EMG, a thin-needle electrode inserted into the muscle records the muscle's electrical activity at rest and in motion. Reduced muscle activity can indicate nerve injury.
• Nerve conduction study. Electrodes placed at two different points in the body measure how well electrical signals pass through the nerves.
• Magnetic resonance imaging (MRI). MRI uses a magnetic field and radio waves to produce detailed images of areas affected by nerve damage.
• Ultrasound. Like MRI, these high-frequency sound waves produce detailed images of the area affected by nerve damage.

Treatment

Preparing for an appointment

A number of tests may be used to help diagnose the type and severity of peripheral nerve injury. When you make your appointment, be sure to ask whether you need to prepare for these tests. For instance, you may need to stop taking certain medications for a few days or avoid using lotions the day of the test.

If possible, take along a family member or friend. Sometimes it can be difficult to absorb all the information you're given during an appointment. Someone who accompanies you may remember something that you forgot or missed.

Other suggestions for getting the most from your appointment include:

• Write down all your symptoms, including how you were injured, how long you've had your symptoms and whether they've gotten worse over time.
• Make a list of all medications, vitamins and supplements that you're taking.
• Don't hesitate to ask questions. Children and adults with peripheral nerve injuries have several options for restoring lost function. Be sure to ask your doctor about all the possibilities available to you or your child. If you run out of time, ask to speak with a nurse or have your doctor call you later.