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 move the body's muscles for walking and sense that the feet are cold. 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, symptoms may range from mild to serious, 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 can cause muscle weakness, painful cramps and 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 walking, keeping your balance with your eyes closed, fastening buttons, or sensing pain or changes in temperature. Injury of sensory nerves also may cause pain.
• 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 digestion. Symptoms may include excessive sweating, changes in blood pressure, the inability to tolerate heat and gastrointestinal symptoms.

Many peripheral nerve injuries affect more than one type of nerve fiber, so you may experience a range of symptoms.

When to see a doctor

If you experience weakness, tingling, numbness or a total loss of feeling, see your healthcare professional to find out 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 can stretch, compress, crush or cut nerves.
• Medical conditions, such as diabetes, Guillain-Barre syndrome and carpal tunnel syndrome, can damage nerves.
• Autoimmune diseases including lupus, rheumatoid arthritis and Sjogren syndrome also can damage nerves.

Other causes include narrowing of the arteries, changes in hormone balance and tumors.

Risk factors

People who experience physical trauma or play sports may be at higher risk of an injury that can stretch or crush peripheral nerves. People with certain medical conditions also may be at higher risk of peripheral nerve injuries. These conditions, especially diabetes, may put nerves at greater risk of compression.

Diagnosis

To diagnose peripheral nerve injuries, your healthcare professional reviews your medical history. You're asked about any accidents or previous surgeries you've had and about your symptoms. Your healthcare professional also conducts a physical and neurological exam. If there are symptoms of a nerve injury, you may need 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 suggest 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

If a nerve is injured but not cut, the injury is more likely to heal. Injuries in which a nerve has been completely cut are harder to treat, and recovery may not be possible.

Your treatment is based on the extent and cause of your injury and how well the nerve is healing.

• If your nerve is healing properly, you may not need surgery. You may need to rest the affected area until it's healed. Nerves recover slowly, and maximal recovery may take many months or several years.
• Regular checkups allow your healthcare professional to make sure your recovery is on track.
• If your injury is caused by a medical condition, your healthcare professional treats the condition.
• Depending on the type and severity of your nerve injury, you may need medicines such as aspirin or ibuprofen (Advil, Motrin IB, others) to relieve your pain. Medicines used to treat depression, seizure or insomnia may be used to relieve nerve pain. Some people with peripheral nerve injuries may need corticosteroid injections for pain relief.
• Your healthcare professional may recommend physical therapy to prevent stiffness and restore function.

Surgery

If your injury does not seem to be healing properly, you may need surgery. A surgeon can use EMG testing in the operating room to assess whether scarred nerves are recovering. Doing an EMG test directly on the nerve is more accurate and reliable than doing the test over the skin.

Sometimes a nerve sits inside a tight space similar to a tunnel or is squeezed by scarring. When this happens, a surgeon may enlarge the tight space or free the nerve from the scar.

If a section of an injured nerve is cut completely or damaged beyond repair. A surgeon can remove the damaged section and directly reconnect healthy nerve ends. This is known as nerve repair. Or the surgeon may implant a piece of nerve from another part of the body to close a gap between the nerves. This is known as a nerve graft. These procedures can help nerves regrow.

If you have a serious nerve injury, surgery can restore function to critical muscles by transferring tendons from one muscle to another.

Preparing for an appointment

Many 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 medicines 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 medicines, vitamins and supplements that you take.
• Ask questions. Children and adults with peripheral nerve injuries have several options for restoring lost function. Be sure to ask about all the treatments available to you or your child. If you run out of time, ask to speak with a nurse or have your healthcare professional call you later.