Ulnar Nerve Decompression

Ulnar nerve entrapment occurs when the ulnar nerve in the arm becomes compressed or irritated. The ulnar nerve is one of the three main nerves in your arm. It travels from your neck down into your hand, and can be constricted in several places along the way. Depending upon where it occurs, this pressure on the nerve can cause numbness or pain in your elbow, hand, wrist, or fingers.

Sometimes the ulnar nerve gets compressed at the wrist, beneath the collarbone, or as it comes out of the spinal cord in the neck. The most common place where the nerve gets compressed is behind the elbow.

When the nerve compression occurs at the elbow, it is called “cubital tunnel syndrome.”

If symptoms do not disappear despite conservative medical treatment and changes in your daily activities, your doctor may determine that surgery is the best treatment to stop further damage to the ulnar nerve.

The aim of surgical treatment is to simply release the pressure and stress on the ulnar nerve as it passes through the cubital tunnel. This procedure is called nerve decompression or transposition. With this technique, the surgeon creates a brand new tunnel where the nerve is in a more comfortable position.

Medical History and Physical Examination

After discussing your symptoms and medical history, your Wisconsin Bone & Joint orthopaedic doctor will examine your arm and hand to determine which nerve is compressed and where it is compressed.

Some of the physical examination tests your doctor may do include:

  • Tap over the nerve at the funny bone. If the nerve is irritated, this can cause a shock into the little finger and ring finger — although this can happen when the nerve is normal as well.
  • Check whether the ulnar nerve slides out of normal position when you bend your elbow.
  • Move your neck, shoulder, elbow, and wrist to see if different positions cause symptoms.
  • Check for feeling and strength in your hand and fingers.

Tests

X-rays. These imaging tests provide detailed pictures of dense structures, like bone. Most causes of compression of the ulnar nerve cannot be seen on an x-ray. However, your doctor may take x-rays of your elbow or wrist to look for bone spurs, arthritis, or other places that the bone may be compressing the nerve.

Nerve conduction studies. These tests can determine how well the nerve is working and help identify where it is being compressed.

Nerves are like “electrical cables” that travel through your body carrying messages between your brain and muscles. When a nerve is not working well, it takes too long for it to conduct.

During a nerve conduction test, the nerve is stimulated in one place and the time it takes for there to be a response is measured. Several places along the nerve will be tested and the area where the response takes too long is likely to be the place where the nerve is compressed.

Nerve conduction studies can also determine whether the compression is also causing muscle damage. During the test, small needles are put into some of the muscles that the ulnar nerve controls. Muscle involvement is a sign of more severe nerve compression.

Procedure

Cubital tunnel release. In this operation, the ligament “roof” of the cubital tunnel is cut and divided. This increases the size of the tunnel and decreases pressure on the nerve.

After the procedure, the ligament begins to heal and new tissue grows across the division. The new growth heals the ligament, and allows more space for the ulnar nerve to slide through.

Cubital tunnel release tends to work best when the nerve compression is mild and the nerve does not slide out from behind the bony ridge of the medial epicondyle when the elbow is bent.

Ulnar nerve anterior transposition. More commonly, the nerve is moved from its place behind the medial epicondyle to a new place in front of it. This is called an anterior transposition of the ulnar nerve. The nerve can be moved to lie under the skin and fat but on top of the muscle (subcutaneous transposition), within the muscle (intermuscular transposition) or under the muscle (submuscular transposition).

Recovery

Cubital tunnel surgery is an outpatient procedure. A soft dressing and occasionally a splint is applied after surgery, and sutures are removed about 7 – 10 days after the procedure. Occasionally, physical therapy may be useful for functional return.

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