Cubital tunnel syndrome

What is cubital tunnel syndrome?

Cubital tunnel syndrome is a condition that affects the ulnar nerve where it crosses the inside edge of the elbow. It is also called ulnar nerve entrapment or neuritis. The symptoms are very similar to the pain that comes from hitting your funny bone. When you hit your funny bone, you are actually hitting the ulnar nerve on the inside of the elbow. There, the nerve runs through a passage called the cubital tunnel. When this area becomes irritated from injury or pressure, it can lead to cubital tunnel syndrome.

What is the cubital tunnel?

The ulnar nerve actually starts at the side of the neck, where the individual nerve roots leave the spine and travels down the arm to the hand. As it crosses the elbow the ulnar nerve passes through a tunnel formed by muscle, ligament, and bone just behind the inside edge of the elbow. This is the cubital tunnel and it helps to keep the ulnar nerve in the correct place and let it slide freely when you bend and straighten the elbow. You may be able to feel it if you straighten your arm out and rub the groove on the inside edge of your elbow.

The ulnar nerve supplies feeling to the little finger and half the ring finger. It works the muscle that pulls the thumb into the palm of the hand, and it controls the small muscles (intrinsics) of the hand.

What causes cubital tunnel syndrome?

Cubital tunnel syndrome has several possible causes. Part of the problem may lie in the way the elbow works. The ulnar nerve actually stretches several millimeters when the elbow is bent. Sometimes the nerve will shift or even snap over the bony medial epicondyle. (The medial epicondyle is the bony point on the inside edge of the elbow.) Over time, this can cause irritation. One common cause of problems is frequent bending of the elbow, such as pulling levers, reaching, or lifting. Constant direct pressure on the elbow over time may also lead to cubital tunnel syndrome. The nerve can be irritated from leaning on the elbow while you sit at a desk or from using the elbow rest during a long drive or while running machinery. The ulnar nerve can also be damaged from a blow to the cubital tunnel.

What are the symptoms?

Numbness on the inside of the hand and in the ring and little fingers is an early sign of cubital tunnel syndrome. The numbness may develop into pain. The numbness is often felt when the elbows are bent for long periods, such as when talking on the phone or while sleeping. The hand and thumb may also become clumsy as the muscles become affected. Tapping or bumping the nerve in the cubital tunnel will cause an electric shock sensation down to the little finger. This is called Tinel's sign.

How is it diagnosed?

Your doctor will take a detailed medical history. You will be asked questions about which fingers are affected and whether or not your hand is weak. You will also be asked about your work and home activities and any past injuries to your elbow. Your doctor will then do a physical exam. The cubital tunnel is only one of several spots where the ulnar nerve can get pinched. Your doctor will try to find the exact spot that is causing your symptoms. You may need to do special tests to get more information about the nerve. One common test is the nerve conduction velocity (NCV) test. The NCV test measures the speed of the impulses traveling along the nerve. Impulses are slowed when the nerve is compressed or constricted. The NCV test is sometimes combined with an electromyogram (EMG). The EMG tests the muscles of the forearm that are controlled by the ulnar nerve to see whether the muscles are working properly. If they aren't, it may be because the nerve is not working well.

What is the treatment?

Nonsurgical treatment:
The early symptoms of cubital tunnel syndrome usually lessen if you just stop whatever is causing the symptoms. Limit the amount of time you do tasks that require a lot of bending in the elbow. Take frequent breaks. If necessary, work with your supervisor to modify your job activities. Anti-inflammatory medications may help control the symptoms. If your symptoms are worse at night, a lightweight plastic arm splint or athletic elbow pad may be worn while you sleep to limit movement and ease irritation. Wear it with the pad in the bend of the elbow to keep the elbow straight while you sleep. You can also wear the elbow pad during the day to protect the nerve from the direct pressure of leaning. Doctors commonly have their patients with cubital tunnel syndrome work with a physical or occupational therapist. At first, your therapist will give you tips how to rest your elbow and how to do your activities without putting extra strain on your elbow. Your therapist may apply heat or other treatments to ease pain. Exercises are used to gradually stretch and strengthen the forearm muscles.

Surgical treatment:
Your symptoms may not go away, even with changes in your activities and nonsurgical treatments. In that case, your doctor may recommend surgery to stop damage to the ulnar nerve. The goal of surgery is to release the pressure on the ulnar nerve where it passes through the cubital tunnel. Usually it is only necessary to release the pressure on the nerve by incising the tissue that forms the roof of the cubital tunnel. This is called an ulnar nerve decompression. Sometimes the ulnar nerve is unstable and moves more than it should. If this is the case then your surgeon may combine decompression with a transposition procedure. In this procedure, the surgeon forms a completely new tunnel from the flexor muscles of the forearm. The ulnar nerve is then moved (transposed) out of the cubital tunnel and placed in the new tunnel.