What is Cubital Tunnel Syndrome?
Cubital tunnel syndrome (also called ulnar nerve entrapment at the elbow) is when the nerve that goes down the arm gets irritated or compressed (pressed down) at the elbow. This can cause tingling, numbness, or weakness in the fingers, and pain from the elbow to the hand. This nerve is called the ulnar nerve, but many people know it as the “funny bone” nerve. It’s the nerve that causes pain and tingling when you bump your elbow in just the right spot.
The ulnar nerve travels from your spinal cord in your neck down the arm to the side of your hand where the pinky finger is. Along the way, the nerve passes through a very narrow space in the elbow called the cubital tunnel. It doesn’t have much room or protection as it passes through this space, which is why it’s easy for the nerve to get irritated or compressed. The compression can cause problems with the nerve from the elbow to the hand.
The most common symptoms of cubital tunnel syndrome are:
- Tingling and numbness in the pinky and ring fingers
- Pain in the lower arm, between the elbow and wrist
If the nerve continues to be compressed, it won’t send signals to the muscles and the hand will get weaker. When this happens, a person may have these symptoms:
- Weakness in the hand
- Trouble with gripping or grasping things
- Trouble with writing or other movements with the hand
Cubital tunnel syndrome is caused by irritation or pressure on the arm’s ulnar nerve. The ulnar nerve is easily compressed because it has to go through a very narrow space in the elbow without much padding from soft tissue like muscles or fat. These are the most common causes of ulnar nerve irritation and pressure:
- The elbow is bent for long periods of time. This can happen during sleep or while awake.
- The nerve is getting constant pressure. This can happen when someone rests the elbow on an armrest or leans on the elbow for long periods of time.
- The nerve is not sliding properly. When you bend your elbow, the ulnar nerve slides over the bone in the elbow. For some people, the nerve snaps back and forth over that bone. This can irritate the nerve.
- Less commonly, fluid in the elbow presses on the nerve. A medical condition that causes fluid to build up in the elbow could put pressure on the ulnar nerve.
Diagnosis and Tests
To diagnose cubital tunnel syndrome, you can expect the doctor to:
- Ask about the symptoms in your arm and hand, and when you notice them the most.
- Look at your arm and possibly tap on your funny bone to see how the nerve responds.
- Ask you to move your neck, shoulder, elbow, and wrist in certain ways to see if any positions make it worse.
- Check to see how much feeling and strength you have in your hand and fingers.
- Consider an X-ray to see if a problems with the arm bone is causing the problem.
- Consider referring you to a specialist for a nerve conduction test to see how well the ulnar nerve is working.
- Eliminating or reducing pressure on the nerve. For example, you can change the way you sit at your desk to avoid having your elbows rest on the desk or armrests of your chair.
- Changing position of the elbow. To keep your arm straight at night, you can wear an elbow pad backwards or loosely wrap a towel around the arm at the elbow and tape it in place. Or, your doctor might prescribe a brace to use.
- Taking nonsteroidal anti-inflammatory medicine (NSAIDs) like aspirin, ibuprofen, or naproxen to reduce swelling and inflammation in or around the nerve.
- Doing exercises. You may be prescribed physical therapy or exercises that will help the nerve slide appropriately.
Having surgery. In severe cases or if other treatments don’t work, you may need surgery. The doctor may recommend any of these surgeries:
- Cubital tunnel release. This makes more room for the nerve without moving it.
- Ulnar nerve anterior transposition. The ulnar nerve is moved from where it usually is (sliding behind the bony knob on your elbow) to the front of that bony knob.
- Medial epicondylectomy. The bony knob on the inside of the elbow is removed. This keeps the nerve from getting caught on it.
Cubital tunnel syndrome can be prevented by not:
- Bending the elbow for long periods of time.
- Putting pressure on your elbow for long periods of time.
Some people may not be able to prevent cubital tunnel syndrome because of the anatomy of their elbow — the way the bones, nerves, and soft tissues come together in the elbow.