Cubital tunnel syndrome

What is it?

Cubital tunnel syndrome is the second most common "nerve compression syndrome" in the upper limb, after carpal tunnel syndrome. In this case, the ulnar nerve is compressed as it passes behind the medial epicondyle of the elbow (also known as the funny bone) en route from the arm to the forearm.

What are the symptoms?

Typical symptoms include intermittent pins and needles and numbness in the little and ring fingers of the hand, which are often worse at night. Sometimes this is accompanied by a feeling of discomfort in the medial side of the elbow and forearm. As the condition progresses the numbness can become constant. In rare cases the compression is severe and longstanding enough to cause weakness and wasting of the majority of the small muscles of the hand.

How is it diagnosed?

The diagnosis can be confirmed by the use of nerve conduction studies and electromyography (EMG). These tests are carried out by a consultant neurophysiologist. It is my practice to request these tests prior to any surgery. In the early stages of the condition however, the results of these tests may be normal.

How is it treated?

In its early stages, and particularly when the symptoms are chiefly nocturnal, cubital tunnel syndrome can be treated by the application of a splint to the elbow at night, which prevents excessive flexion of the elbow during sleep. If this simple measure does not work, or if troublesome symptoms return, surgical decompression of the nerve is usually required.

Decompression of the ulnar nerve is accomplished with a 5cm incision on the medial side of the elbow. The ligament overlying the nerve is divided, as well as any other structures that might be compressing it. Once this is done, the nerve is assessed for "instability" - in other words, it is examined when the elbow is flexed and extended, to see whether it has a tendency to jump backwards and forwards over the funny bone (medial epicondyle). If it does, then it is permanently transposed to a position in front of the medial epicondyle, to avoid irritation of the nerve in the future. This is a somewhat longer operation, which requires a longer incision and is known as an "anterior subcutaneous transposition" of the ulnar nerve.

Some surgeons advocate the use of a "medial epicondylectomy" (removal of the bony prominence on the medial side of the elbow) rather than an anterior transposition, but Mr. Gidwani has not found this to be necessary in his practice. He will be able to discuss the pros and cons of the operative options with you prior to any decision to proceed to surgery.

Some important things to be aware of are:

  1. In patients with symptoms of intermittent pins and needles or numbness only, the surgery should lead to complete resolution of those symptoms in the majority of cases.
  2. Where there is already a degree of weakness or wasting, or indeed permanent numbness, the resolution of symptoms is less predictable. The main reason for carrying out surgery in such cases is in fact to prevent further deterioration of the strength and function of the intrinsic muscles of the hand.

Post-operatively the patient is kept in a bulky bandage for around two weeks, given a sling for comfort and encouraged to use the elbow normally for light daily activities, as pain allows. Sutures are removed/trimmed after two weeks, and it takes between 6 and 12 weeks for the elbow to return to normal.

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