Peripheral nerve injuries
These types of injuries affect the nerves that link the brain and spinal cord to nerves in other parts of the body.
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
If a nerve is injured but not cut, the injury is more likely to heal. Injuries in which the nerve has been completely severed are very difficult to treat, and recovery may not be possible.
Your doctor will determine your treatment 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.
- You'll need regular checkups to make sure your recovery stays on track.
- If your injury is caused by a medical condition, your doctor will treat the underlying condition.
- Depending on the type and severity of your nerve injury, you may need medications such as aspirin or ibuprofen (Advil, Motrin IB, others) to relieve your pain. Medications used to treat depression, seizures or insomnia may be used to relieve nerve pain. In some cases, you may need corticosteroid injections for pain relief.
- Your doctor may recommend physical therapy to prevent stiffness and restore function.
Surgery
If your injury does not seem to be healing properly, your 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. In these cases, your surgeon may enlarge the tight space or free the nerve from the scar.
Sometimes a section of a nerve is cut completely or damaged beyond repair. Your surgeon can remove the damaged section and reconnect healthy nerve ends (nerve repair) or implant a piece of nerve from another part of your body (nerve graft). These procedures can help your nerves regrow.
If you have a particularly severe nerve injury, your doctor may suggest surgery to restore function to critical muscles by transferring tendons from one muscle to another.
To repair a damaged nerve, a surgeon removes a small part of the sural nerve in the leg and implants this nerve at the site of the repair.
Sometimes the surgeon can borrow another working nerve to make an injured nerve work (nerve transfer).
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.