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HealthInfo Canterbury

What is ulnar nerve compression?

Ulnar nerve compression is a common condition affecting a nerve that travels down the inside of your arm, around the inside of your elbow and finishes on the little-finger side of your hand. This is called the ulnar nerve.

When your ulnar nerve is damaged, or compressed, it affects the strength and feeling you have in your hand, and sometimes your arm.

Exactly what symptoms you get will depend on where the nerve is affected, but it is likely you will have tingling or numbness in your little and ring fingers, and pain or aching on the inside of your elbow or forearm. At night this may be bad enough to wake you.

In serious cases of ulnar nerve compression your ring and little fingers may become weak, so your fingers bend, creating a "clawed hand".

The symptoms of ulnar nerve compression often get worse when you bend your elbow for a long time (for example, when you're talking on the phone), lean on your elbow, or use a tool that you have to grip strongly.

Ulnar nerve compression affects men more often than women, and is more common in older people. It is also called ulnar neuropathy and, sometimes, cubital tunnel syndrome.

What causes it?

Ulnar nerve compression is often caused by the nerve on the inside of your elbow being squashed (compressed) or stretched. Behind your elbow crease the nerve is close to your skin, and is also relatively easy to damage.

Sometimes it happens because of a broken bone (fractured humerus) or another injury to your arm. Other times it's caused by something simple, such as leaning on your elbow, pulling your arm, or sleeping with a bent elbow.

It can also happen if your nerve is compressed at your wrist, although this is less common. This can happen because of a broken bone in your wrist or an injury on your wrist below your little finger. It can also happen from repeatedly using your hand in a certain way, such as using heavy hand tools for a long time, pushing someone in a wheelchair, or grasping handlebars for a long time while riding a bike.

Occasionally the ulnar nerve can be compressed in your armpit area, for example if you hang your arm over a chair or use crutches. Other less common causes include infection, inflamed blood vessels, or a lump in your armpit.

How do I know if I have ulnar nerve compression?

Your GP is likely to diagnose ulnar nerve compression after talking to you and examining your arm.

Usually investigations such as blood tests and X-rays aren't helpful, although your doctor may ask for these if they are trying to rule out something else that may be causing your symptoms.

You may be referred to a specialist for what are called nerve conduction studies. These measure how well and how quickly your ulnar nerve conducts electrical signals. A specialist may also arrange for you to have an MRI.

On the next page: Living with ulnar nerve compression

Written by HealthInfo clinical advisers.Endorsed by clinical directors, Orthopaedics Department and Plastics Department, Canterbury DHB. May 2017.

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