What is the Radial Nerve?
The radial nerve is a nerve that runs down the underside of the arm and controls movement in the triceps (muscle located at the back of the upper arm). The radial nerve is also responsible for extending the wrist and fingers, and controls sensation in a portion of the hand.
Injury to the radial nerve is called radial neuropathy or radial nerve palsy, and it may be caused by physical trauma, infections, or even exposure to toxins. It often causes numbness and tingling, burning pain or can be painless.
In many cases, this condition will improve with time if the underlying cause of the injury is treated.
Causes of Radial Nerve Injury
Injury to the radial nerve can occur in a number of different ways. These include:
- fracturing the humerus (upper arm bone)
- sleeping with the upper arm in an awkward position
- pressure from leaning the arm over the back of a chair (called “Saturday night palsy” when caused by consuming too much alcohol and falling asleep in this position)
- using crutches
- falling on or receiving a blow to the arm
- motor vehicle accident
- long-term constricting of the wrist (for example, by wearing a tight bracelet or watch strap)
Symptoms of an Injury to the Radial Nerve
Injury to the radial nerve usually causes symptoms in the back of the hand, near the thumb, and in the pointer and middle fingers. Symptoms may include:
- sharp or burning pain
- numbness or tingling
- trouble straightening the arm
- trouble moving the wrist and fingers
- “drooping” of the wrist and fingers (not being able to extend or straighten the wrist or fingers), also called “wrist drop”
- weakness in a hand grip
Testing for and Diagnosing a Radial Nerve Injury
If you think you have injured your radial nerve, your doctor will start by asking you about your symptoms and when they began. This may help pinpoint what caused the injury.
Your doctor will also complete a physical examination. He or she will look at your affected arm, hand, and wrist, and compare it to your healthy arm, hand, and wrist. He or she may ask you to extend and rotate your arm to see if your range of motion has been affected. Your doctor will also ask you to extend your wrist and fingers, checking for any weakness, loss of muscle tone, and finger or wrist drop.
Your doctor may order tests to rule out other causes of your symptoms. A blood test may be ordered to check for any abnormalities with your blood sugar, vitamin levels, kidneys, and thyroid. Abnormalities in these areas may indicate other conditions, such as diabetes, vitamin deficiencies, or diseases of the kidney and liver, which are associated with nerve damage. A computerized tomography (CT) scan or magnetic resonance imaging (MRI) may be done to look for problems in your head, neck, or shoulders that may be putting pressure on your radial nerve.
Electromyography (EMG) or nerve conduction may be performed. An EMG measures the electrical activity in your muscle, while a nerve conduction test measures the speed at which impulses travel along your nerves. These tests can help determine if the problem is in your nerve or muscle, and also identify if there has been any damage to the radial nerve.
In very rare cases, your doctor may request a nerve biopsy. This involves taking a small sample of the nerve and examining it to determine what is causing the damage.
The goal of treatment for radial nerve injury is to relieve symptoms while allowing movement of the wrist and hand. Treatment will depend on the underlying cause of the condition. In some cases, symptoms will slowly go away without intervention. Your doctor may prescribe medication or other therapies to help manage your symptoms.
Treatment options include:
- pain medication
- anti-seizure medications or tricyclic anti-depressants (prescribed to treat pain)
- steroid injections
- anesthetic creams or patches
- braces or splints
- physical therapy to help build and maintain muscle strength
- acupuncture—inserting thin needles into various pressure points throughout the body. According to the Mayo Clinic, this alternative method may reduce symptoms in the majority of people with radial neuropathy. However, long-term treatment is required (Mayo Clinic, 2010).
Some people choose transcutaneous electrical nerve stimulation (TENS) to treat nerve damage. This ongoing therapy involves placing several adhesive electrodes on the skin near the affected area. A gentle electric current is delivered through the electrodes at varying speeds.
Most people with a radial nerve injury will recover within three months of treatment. However, there are some cases where surgery is required. Surgery to relieve pressure on the nerve may be necessary if the nerve is entrapped or there are masses on the nerve. If there is a loss of sensation or movement, or symptoms do not improve, surgery may also be necessary (NYU).
This type of surgery will repair any damage to the nerve. After surgery, a brace or splint will be necessary to allow the injury heal. Your doctor will then refer you to a physical therapist for rehabilitation to restore range of motion and strength.
How Can I Prevent Radial Nerve Injury?
Avoiding prolonged pressure on the upper arm can prevent most cases of radial nerve injury. Avoid other behaviors that can lead to nerve damage, such as repetitive motions or cramped positions when sitting or sleeping.
If nerve damage is the result of an underlying medical condition, such as diabetes or alcoholism, talk to your doctor about how to manage your symptoms.