What Is the Radial Nerve?
The radial nerve runs down the underside of the arm and controls movement of the triceps (the muscle located at the back of the upper arm). The radial nerve is also responsible for extending the wrist and fingers, and it controls sensation in part of the hand.
Injury to the radial nerve may result in radial neuropathy, or radial nerve palsy. Radial nerve injury may be due to physical trauma, infection, or even exposure to toxins. It often causes numbness and tingling or burning pain. It can also be painless.
In many cases, this condition will improve if the underlying cause of the injury is treated.
Causes of Radial Nerve Injury
Injury to the radial nerve has a variety of possible causes. These include:
- fracturing the humerus (a bone in the upper arm)
- 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
- long-term constriction of the wrist (for example, by wearing a tight bracelet or watch)
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 index 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 and fingers), also called “wrist drop” and “finger drop”
- weak hand grip
- analgesic or anti-inflammatory medications
- anti-seizure medications or tricyclic antidepressants (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)
Testing for and Diagnosing a Radial Nerve Injury
If you think you’ve 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 do a physical exam. They will look at your affected arm, hand, and wrist, and compare it to your healthy arm, hand, and wrist. They 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. They may order blood tests to check your blood sugar and vitamin levels, as well as your kidney and thyroid function. Abnormalities in these areas may point to other conditions associated with nerve damage, such as diabetes, vitamin deficiencies, or diseases of the kidney and liver. A computerized tomography (CT) scan or magnetic resonance imaging (MRI) test can also look for diseases within your head, neck, or shoulders that may result in pressure on your radial nerve.
Electromyography (EMG) and nerve conduction are other tests your doctor may choose. An EMG measures the electrical activity in your muscle, and 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 they can also help determine if the radial nerve is damaged.
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. In some cases, symptoms will go away slowly without intervention. Your doctor may prescribe medication or other therapies to help manage your symptoms.
Treatment options include:
Some people choose transcutaneous electrical nerve stimulation (TENS) to treat nerve damage. This therapy involves placing several adhesive electrodes on the skin near the affected area. The electrodes deliver a gentle electric current at varying speeds.
Most people with a radial nerve injury will recover within three months of treatment. However, there are some cases that ultimately require surgery. 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 don’t improve, surgery may also be necessary.
This type of surgery will repair any damage to the nerve. After surgery, a brace or splint is necessary to allow the injury to 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? | Prevention
Avoid prolonged pressure on the upper arm to prevent most cases of radial nerve injury. Avoid other behaviors that can lead to nerve damage, such as repetitive motions or remaining in cramped positions while 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.