The ulnar nerve is one of the three main nerves in the arm. It travels from under the collarbone, along the inside of the upper arm, through a tunnel (called the cubital tunnel) behind the inside, or body side, of the arm in the area commonly called the "funny bone." From there it travels under muscles on the inside of the forearm and into the hand on the pinky side of the palm. When the nerve goes into the hand, it travels through another tunnel called Guyon's canal. To view all the information on ulnar nerve entrapment please view the following: non-surgical treatment, surgical treatment and rehabilitation.
This nerve provides sensation to the little finger and the half of the ring finger that is near the little finger. It also controls most of the little muscles in the hand that help with fine movement and some of the larger muscles in the forearm that help to make a strong grip.
If the ulnar nerve becomes compressed, you may experience a tingling or "falling asleep" feeling in the ring and little finger, especially when the arm is bent. You may also have aching pain on the inside of the elbow, or even have trouble moving fingers or manipulating objects.
The most common site for compression is behind the elbow, but it can also be compressed at the wrist, beneath the collarbone, or as it comes out of the spinal cord at the neck.
Exact causes of ulnar nerve compression are not known. Some factors include prior fractures of the elbow, bone spurs, swelling of the elbow joint or cysts. A direct blow to the inside of the elbow, leaning on the elbow for prolonged periods or repetitive activity that requires a bent elbow can irritate the nerve if it is already compressed. If the ulnar nerve is compressed at the wrist, the cause is more likely to be a cyst in Guyon's canal.
Symptoms
Common symptoms of ulnar nerve entrapment include numbness and tingling in the ring finger and little finger. These may come and go, but happen more often when the elbow is bent, such as when driving or talking on the phone. Also, you may be awakened at night because your fingers are numb. In addition, you may also have weakness of grip and difficulty with finger coordination, as when typing or playing an instrument.
If the nerve is very compressed or has been compressed for some time, muscle wasting may occur. This cannot be reversed. It is important to see a doctor, therefore, as soon as you experience any of the symptoms of entrapment. If these symptoms interfere with normal activities or last more than a few weeks, the doctor will probably refer you to an orthopedic specialist.
Diagnosis
The doctor will try to determine the site of the compression by tapping the nerve at the "funny bone." If the nerve is irritated, you may feel a shock into the ring and little fingers at this time. The doctor will probably also move the shoulder, elbow and wrist to see if this causes symptoms. Both fingers will also be tested for sensation.
Although compression itself cannot be seen on X-ray, the doctor may X-ray the elbow or wrist to look for bone spurs, arthritis or other places where bone may be compressing the nerve. If compression in the wrist is suspected, the doctor may recommend a CT scan (computed tomography) or MRI (magnetic resonance image) to see if a cyst or other abnormality is causing the compression.
Nerve conduction studies may also be employed to determine how well the nerve is working and to help localize the problem site. During this test, the nerve is stimulated in one place to measure the amount of time it takes for the response to be received at another. If the conduction takes longer than it should, this is apt to be the compression site. The doctor may also insert a small needle in some of the muscles the ulnar nerve controls to test for muscle wasting.
Unless a lot of muscle wasting has occurred, the doctor will probably suggest non-surgical treatment to begin. Examples:
• Avoid frequent use of the arm with the elbow bent . If you use a computer frequently, make sure your chair is not too low. Do not rest the elbow on the armrest.
• Avoid leaning on the elbow or putting pressure on the inside of the arm . Do not drive with your arm resting on the open window.
• Keep the elbow straight at night while you are sleeping . Wrap a towel around the straight elbow, wear an elbow pad backwards or use a special brace.
With your doctor's approval, you might want to take anti-inflammatory medications such as ibuprofen to help reduce swelling around the nerve. Also, your doctor may prescribe special exercises to keep the arm and wrist from getting stiff.
If the palliative strategies fail to relieve pain and numbness, the doctor may recommend surgery to take pressure off the nerve. This can be done at the site of the compression, elbow or wrist, or at both places if necessary.
There are several ways to relieve compression around the elbow. If the compression is mild, only the "roof" or top is taken off the cubital tunnel. More often, though, the nerve is repositioned from the back of the elbow to the front. The nerve can also be moved to lie in other positions: under the skin and fat but on top of the muscle, within the muscle or under the muscle. Your doctor will explain his recommendations for you.
If the nerve is compressed at the wrist, the surgeon will make a zigzag incision at the base of the palm on the pinky side. He or she will then open the roof of Guyon's canal to take the pressure off the nerve. If there is a cyst or other reason for compression, it will be removed at the same time.
Surgery is usually done on an outpatient basis, but an overnight stay in the hospital may be recommended. You may need to wear a splint for a couple of weeks or longer, depending on the type of surgery. Physical therapy may also be recommended to help you regain strength and motion in the arm.
The results of the surgery are generally good, although it may take a while to be sure, as nerves recover slowly.
The source for this information is the American Academy of Orthopaedic Surgeons.