1. What is it?

Ulnar neuropathy or cubital tunnel syndrome is a condition of the ulnar or elbow nerve. Irritation of this nerve usually takes place as it runs through the elbow. There the ulnar nerve runs along on the surface on the inside, and along a bone protrusion (known as the "funny bone") and can be liable to compression and damage. This condition is also called cubital tunnel syndrome, after the name of the channel through which the elbow nerve runs ("cubitus" is Latin for elbow).

Sulcus nervi ulnaris syndroom

2. Symptoms

The symptoms are caused by compression or continued irritation of the nerve, and consist of a tingling or painful sensation in the area served by the nerve, i.e. the little finger and part of the ring finger. We have all experienced this when we accidentally hit our "funny bone", which presses on the nerve. There can also be reduced sensation in the little and ring fingers and weakness of the hand, which will also become thinner. A misleading factor in these cases is that the pain and tingling then often subside. In the most advanced stages, positional changes develop in the fingers due to the loss of strength in the small muscles of the hand (claw hand); the tingling and pain have then often already disappeared.

The tingling symptoms are ongoing and can be worsened by moving the elbow. The tingling can be cumbersome, but if the patient experiences sensitivity disorders and weakness, which can sometimes appear quite early in the course of the disease, a visit to the doctor is essential. Cubital tunnel syndrome can sometimes appear in both arms.

3. Cause

Mostly there is no particular reason for the ongoing irritation of the nerve at its compression point in the elbow, but regular strong elbow bending and extending movements (for example when operating machinery) can cause the symptoms to appear. In a minority of patients the nerve is overly mobile and when bending the elbow repeatedly slides over the protruding bone (the medial epicondyle). The nerve can also be compressed if the connective tissue sheath running over it from the medial epicondyle to the tip of the elbow (the olecranon, or elbow bone) is too narrow. This can cause irritation of the nerve. Finally, the nerve can also become damaged due to an external injury, continued pressure or an earlier injury such as a fracture.

4. Examination

The type of symptoms will already give some indication of the appropriate diagnosis. Upon physical examination the doctor will often find sensitivity disorders in the little finger and in the adjacent half of the ring finger, and sometimes also a weakening in the small hand muscles so that the patient is no longer able to close and spread out his or her fingers. The hand muscles can become thinner (atrophy), so that the hand becomes "knuckly" and hollows develop between the small (metacarpal) bones of the centre of the hand. Often the nerve is sensitive to pressure in the area in which it transits through the elbow, so that the painful tingling symptoms can be produced by tapping on the nerve. A similar syndrome involving tingling in the hand, which because of its resemblance can cause confusion as concerns the diagnosis, occurs with compression of the nerve by a cervical hernia, due to arthritis (wear and tear) of the cervical vertebrae, or with narrow spatial relationships in the shoulder area (also called scalenus syndrome or cervical rib syndrome). The neurological examination must rule out these causes if appropriate, as they would require a different type of treatment. A muscle examination called electromyography or EMG (a test that measures muscle response and which will show a delayed response of the electrical nerve activity in the area of the ulnar nerve that is located around the elbow) can be used to confirm the diagnosis. Besides ensuring the correct diagnosis, this test also helps rule out whether the nerve may be pinched elsewhere. If a bone anomaly is suspected, an X-ray of the elbow may also be taken.

5. Treatment

Once the diagnosis is certain to be cubital tunnel syndrome, the neurosurgeon will discuss the treatment options with the patient. Sometimes no treatment is necessary, or it is possible to wait and see if the symptoms resolve by avoiding arm movements that are too intensive. If the troublesome tingling and pain in the little and the ring finger persist, an operation may be necessary. In the procedure, the nerve is exposed within the elbow and displaced a little towards the inside, where it is less constrained among the soft tissue; this is called ulnar transposition, or moving the nerve to the top side of the elbow. Sometimes the nerve will merely be released from compression but not relocated (ulnar neurolysis, surgical freeing of the ulnar nerve), in which the sheath running from the ulnar epicondyle to the point of the elbow is cut. This procedure can take place under local anaesthesia, where only the arm is numbed, or alternatively under general anaesthesia. If there is no more tingling but sensitivity problems and weakness are the main symptoms, and if these symptoms have been present for a longer period of time, surgery will have little or no effect. Anticoagulants (blood thinning medicine) must be discontinued before the operation in consultation with the doctor.

6. After the operation

The procedure can be carried out in a day clinic, on an outpatient basis or with a (short) hospital admission, and the patient is usually issued with a sling. After a few hours the anaesthesia will wear off and any post-operative pain can be relieved with paracetamol, potentially combined with codeine.

The patient can move his or her fingers and hand as usual. Resting the elbow for approximately two weeks is recommended to help the wound to heal. The wound must be kept dry. Patients should contact their GP or the treating neurosurgeon in case of excessive pain or discharge from the wound. The stitches will be removed after approximately two weeks.

7. Consequences of the operation

The tingling in the fingers will gradually diminish. Little or no improvement can be expected in patients with sensitivity deficiency, and certainly in cases of loss of strength in the hand. The unpleasant sensations often do resolve. Regardless of the suturing method, the scar around the elbow can be somewhat unsightly, but becomes acceptable over time.

8. Complications

Complications can occur with any surgery, and thus also with ulnar transposition and/or neurolysis. However, they are rare and consist mostly of infections and post-operative bleeding. The most frequent complication is that the operation does not lead to the expected result and that the tingling and pain continue. Sometimes repeat surgery is indicated, but it is also possible that there is injury to the nerve which cannot be surgically repaired.