Causes and Treatment of Radial Nerve Injuries

The radial nerve runs down the arm and to the fingertips. If it's injured, radial nerve pain usually occurs when your palm is pressed against something and your wrist is bent back.

It's typically a sharp, radiating, or burning pain. This usually occurs in the back of the hand, around the thumb, and in the middle and index fingers. Often, the pain is accompanied by the inability to fully straighten your arm or fingers.

Along its path to your fingertips, the radial nerve sends messages to muscles in your arm and hand to trigger movement. It receives sensory messages to send back to the spinal cord and brain allowing you to feel sensations. Depending on where the nerve damage occurs, sensory and motor (movement) symptoms can vary.

This article discusses the different locations of radial nerve injuries and the symptoms you may have with each. It also covers how these injuries usually happen, what the prognosis is, and how they are treated.

Injury at the Axilla

The radial nerve branches from the brachial plexus, a network of nerves at the root of the neck. It then travels under the arm close to the armpit (axilla). Improper use of crutches is a common cause of radial nerve compression at this point.

Symptoms can include the following:

• You may have arm weakness, particularly if you're pushing something away. That's because the radial nerve is responsible for controlling the triceps muscles situated at the back of the arm.
• It may also be impossible to bend your wrist back, resulting in "wrist drop."
• Finger extensor muscles may also be weakened, making it difficult to fully open your hand.
• You may experience tingling and numbness from the back of the arm to the hand. This can also be felt along the side and back of the thumb.

Injury at the Spiral Groove

From the axilla, the radial nerve travels down the arm and wraps around the humerus (the large bone between the shoulder and elbow). It's situated in a channel known as the spiral groove. The nerve can become compressed within this groove.

Symptoms of a spinal groove injury include the following:

• You have trouble bending your wrist back and straightening your fingers.
• You may notice weakening of the brachioradialis muscle in the forearm. This muscle helps you bend your elbow and turn your hand so your palm is facing up.

Posterior Interosseous Nerve Injury

Just before the elbow, a section of the radial nerve branches off to the posterior interosseous nerve. This is responsible for straightening muscles below the elbow.

Unlike other branches of the radial nerve, the posterior interosseous nerve has no sensory receptors and is purely responsible for muscle movement. As a result, injuries are characterized by muscle weakness but no abnormal sensation.

Symptoms include the following:

• The inability to extend your fingers is often a tell-tale sign.
• An injury to this nerve can be very painful, especially when the fingers are extended.

Superficial Radial Neuropathy

The radial nerve passes the elbow and continues down to the back of the hand, where it serves a purely sensory function.

At that point, the nerve is most susceptible to injury at the wrist. This could happen when the wrists are bound or handcuffs are worn too tightly.

Symptoms include the following:

• The pattern of numbness is usually worst from the wrist to the back of the thumb.
• It may also be accompanied by a "pins and needles" sensation or shooting pains up or down the back of the hand.

Prognosis and Treatment

When a radial nerve injury is diagnosed, treatment is usually conservative and includes:

• Wrist splints, or braces, which provide support to stabilize your wrists and maintain function
• Pain management with nonsteroidal anti-inflammatory drugs (NSAIDs), like aspirin or Advil (ibuprofen)
• Physical therapy to help restore movement through exercises
• A nerve block when pain is severe. This uses an injection of local anesthetic near the nerve to lessen pain.

Recovery time can range from a couple of weeks to six months. If your pain and disability don't improve, your healthcare provider may order tests. These can include nerve conduction studies, which test for nerve damage, or electromyography (EMG), which looks at your muscles' electrical activity.

You may need surgery if the nerve is:

• Entrapped, such as in radial tunnel syndrome, and requires surgical release
• Compressed by a growth, such as a tumor, that needs to be removed
• Torn and needs repair or reconstruction. This repair may involve a nerve graft, where a new nerve is added to the damaged nerve. It could also involve a nerve transfer, where another nerve is rerouted to the injured nerve.

Summary

Radial nerve injuries can occur in different parts of the arm, causing different symptoms based on the location. They can occur in areas from near the armpit (axilla) to around the wrist (superficial radial neuropathy).

An injury near the armpit can cause arm weakness, particularly in the back of your arm. Injuries in the spinal groove can make it difficult to bend your wrist back or open your hand.

Injuries to the posterior interosseous nerve can make it impossible to extend your fingers. And an injury at the wrist can cause numbness through the thumb or pins-and-needles sensations in the hand.

Treatment for radial nerve injuries may include wrist splints, over-the-counter pain medication, physical therapy, or surgery. Injuries can take a couple of weeks or up to six months to heal.