What to Know About an Axillary Nerve Injury

By Cheryl Whitten, WebMD

Axillary nerve injuries affect the nerve that runs from your neck to your shoulder. They commonly happen when the nerve is overstretched.

Axillary nerve compression and injury often leads to pain and weakness in the shoulder or arm. Most of these types of injuries heal on their own or alongside noninvasive treatments, like pain relievers and physical therapy.

What Is the Axillary Nerve?
Your axillary nerve is a branch of your brachial plexus, which is a bundle of nerves that runs from your neck and upper torso to your shoulders and arms. These nerves are called peripheral nerves because they’re located outside of your brain and spinal cord.

The axillary nerve stems from your C5 and C6 vertebrae in your neck and goes into your shoulder. It helps you rotate your shoulder and lift your arm away from your body.

What Happens When the Axillary Nerve Is Injured?
There are three different types of nerve injuries: neuropraxia, axonotmesis, and neurotmesis.

Neuropraxia. This type of injury happens when the nerve is overstretched, causing the nerve to become physically blocked or compressed.

Axonotmesis. This type of injury happens when the axon is physically disrupted. An axon is a kind of cable at the end of your nerve cells that sends electrical signals. Scar tissue can block axons in nerve tissue.

Neurotmesis. This happens when the axons are completely disrupted, along with all the surrounding tissue. Neurotmesis is typically caused by a nerve rupturing or bursting from a forceful stretch.

What Causes an Axillary Nerve Injury?
Axillary nerve damage can happen for various reasons. Some injuries put direct pressure on the axillary nerve, cause small tears, or compress and block the nerve.

Axillary nerve injuries are typically caused by:

• A fall from heights
• A car accident
• Birth
• Sports contact
• Muscle overuse
• Surgery

These situations lead to shoulder injuries that damage the nerve. Common shoulder injuries include:

• Dislocated shoulder
• Broken arm
• Rotator cuff tear
• Repetitive strain that causes nerve compression or a rare disorder called quadrilateral space syndrome

A rare neurological disease called Parsonage-Turner syndrome also causes axillary nerve injury. This happens when a viral infection, accident, or surgery causes sudden nerve irritation and damage, along with muscle weakness and wasting.

What Are Axillary Nerve Injury Symptoms?
Symptoms from an axillary nerve injury depend on the severity of the damage. They can come on suddenly or happen over time. Symptoms can be mild or severe, temporary or ongoing, and depend on the type of injury.

Axillary nerve injury symptoms include:

• Shoulder or arm muscle weakness
• Shoulder or arm muscle wasting
• Numbness in your arm
• Tingling in your arm
• Loss of feeling in your arm or hand
• Trouble lifting your arm
• Limp hanging arm
• Pain

How Is an Axillary Nerve Injury Diagnosed?
If you have any symptoms, your doctor will do a physical exam and take a history of your symptoms and any injuries. They may also order imaging tests to check for damage.

Physical exam. Your doctor may test the range of motion in your shoulder joint and your muscle strength. They may also test your reflexes and senses, and whether you have movement in your fingers.

X-rays. An X-ray of your shoulder can show broken bones or damage to the tissues around your axillary nerve.

Magnetic resonance imaging. Also called an MRI, this imaging scan can help show damage to the nerve and surrounding soft tissues.

Nerve conduction study. This test looks at how well your nerve is working. A doctor will put small electrodes on your shoulder and nerve area and deliver small electrical charges. The test measures how fast the electrical activity moves through your nerves.

What Is the Treatment for an Axillary Nerve Injury?
In most cases, axillary nerve injuries heal on their own. You’ll need to rest your shoulder, which means avoiding sports and intense activity. Complete rest isn’t necessary, but you’ll need to avoid things like heavy lifting.

Other axillary nerve injury treatments include:

• Steroids to lower inflammation
• Non-steroidal anti-inflammatory drugs (NSAIDs) to lower inflammation and pain
• Pain relievers
• Physical therapy to build muscle strength and flexibility
• Shoulder rotation exercises
• Shoulder and arm stretches

In some cases, you may need surgery to repair the nerve if weakness doesn’t improve, but it’s rare. This surgery involves taking some nerve from your triceps muscle and attaching to your axillary nerve. Over time, it grows into your shoulder muscle and the muscle starts working again.

How Long Does It Take an Axillary Nerve to Heal?
An axillary nerve injury can take anywhere from 3 to 12 months to heal, depending on the severity of the injury. A surgery can lead to a longer recovery time but is usually not necessary. Physical therapy and rest can help speed up your recovery.

If you have sudden or ongoing shoulder pain and trouble lifting your arm, see your doctor.