Cubital Tunnel Syndrome

What is the cubital tunnel?
The cubital tunnel is a canal formed between the bones of your elbow and a ligament that lies across the inside of your elbow (where your funny bone is). The ligament is known as the epicondyloolecranon ligament or Osborne band. A large nerve (the ulnar nerve) passes through this tunnel. The nerve provides sensation to the little finger and part of the ring finger, and power to the small muscles within the hand (diagram below).

What is cubital tunnel syndrome?

Cubital tunnel syndrome (CuTS) is a condition where the ulnar nerve is compressed as it oasses through the tunnel at the elbow. CuTS may be associated with swelling in the tunnel, a broken elbow bone, elbow arthritis and other less common conditions. In most cases, however, the cause is unknown.

CuTS commonly affects men who are over 50 but can occur at any age in either sex. CuTS can occur in people who have hobbies or a job involving repetitive elbow movement. Many patients develop symptoms as a result of leaning on the elbow or from direct pressure over the ulnar nerve when using a computer at a desk.

What are the symptoms?
Numbness or tingling of the little and ring fingers are usually the earliest symptom. It is frequently intermittent, but may later become constant. Often the symptoms can be provoked by leaning on the elbow or holding the elbow in a bent position (e.g. on the telephone). Sleeping with the elbow habitually bent can also aggravate the symptoms.

In the later stages, the numbness is constant and the hand becomes weak. There may be visible loss of muscle bulk in severe cases, particularly noticeable on the back of the hand between the thumb and first finger, with loss of strength and dexterity.

How is it Diagnosed? In many cases the diagnosis can usually be made based on patient symptoms and examination. Surgeons will use Tinel’s sign to help make the diagnosis. This involves lightly tapping over the nerve to detect an area of irritation. This will produce a tingling sensation in the hand if the test is positive (see diagram).

A test to measure nerve impulses (nerve conduction study) will usually confirm the diagnosis, and give an idea as to how severe the problem is. This study involves a doctor or specialist technician placing some sticky pads on the arm and measuring the speed taken for signals to be transmitted down the nerve. It can feel uncomfortable but is not usually painful.

What is the Natural History?
The symptoms of cubital tunnel syndrome generally come and go for some time before either settling down or becoming a problem. If there has been a trigger such as a work related or sporting activity then making changes to these activities can help settle symptoms.

If the condition continues to worsen, there is a risk of losing function in the hand, with the ulnar nerve not working. This gives a permanent numbness in the hand, and weakness of hand movements. People worry about deterioration of function, but it usually goes hand in hand with symptoms, so that there is usually plenty warning of deterioration in the function of the ulnar nerve.

What is the treatment?
1) Modification of activity – This is the mainstay of treatment in the early stages. This should include a workstation assessment. Prolonged flexion should be avoided, and any activity which puts direct pressure on the nerve should be modified. Computer keyboards should be placed at the edge of the desk, and a workstation chair should not have an arm rest.

2) Splinting – An elbow splint to prevent the elbow from bending can help if you’re symptoms are brought on by sleeping with your arms bent at night. Activities which provoke the symptoms should be avoided if possible. Buy an elbow splint here.

3) Surgery – Surgery to decompress the nerve is required in severe cases, or in those that do not respond to the non-surgical treatments above. Surgery frequently improves the numbness, but its chief objective is to prevent the progressive muscle weakness and wasting that tends to occur in severe untreated cases. The procedure is performed through a short incision on over the nerve at the elbow, and the thick fibrous tissue overlying the nerve is divided, taking pressure off the nerve.

What is the outcome?
The outcome depends upon the severity of the compression being treated. Numbness frequently improves, though the improvement may be slow. Surgery generally prevents worsening of the muscle weakness, but improvements in muscle strength are often slow and incomplete.

In the mild cases you can expect there to be full resolution of symptoms in most cases, the more severe the case the less predictable the long term outcome in regard to the nerve function fully recovering. The overall satisfaction rate at 1 year following surgery is 85%.

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