Carpal tunnel syndrome is, far and away, the most common nerve compression disorder of the upper extremity. The second most common is cubital tunnel syndrome....
The cubital tunnel is...
- a passageway between...
- the bony prominence of the inside elbow (medial epicondyle)
- the tip of the elbow (olecranon process).
- The roof of this tunnel is formed by a firm tissue called fascia.
Through this passageway travels the ulnar nerve as it crosses behind the elbow. After exiting the tunnel, the ulnar nerve passes between the two origins of the flexor carpi ulnaris muscle.
The ulnar nerve...
- provides sensation to the little finger and half of the ring finger
- innervates several muscles in the forearm
- controls many of the small muscles in the hand responsible for coordinating finger motion and pinch
Pathology - The Cubital Tunnel Syndrome
Cubital tunnel syndrome is caused by increased pressure in the cubital tunnel resulting in compression of the ulnar nerve. When the ulnar nerve is pushed up against the fascia or bones, blood flow to the nerve is restricted, causing a sensation often described as "pins and needles" to the small and ring fingers. In severe or chronic cases, numbness can be constant.
There are many ways in which the ulnar nerve may be injured or compressed in the cubital tunnel:
- Either a severe, direct impact to the inner aspect of the elbow or chronic pressure to this area (such as supporting the arm by resting on the elbow) may produce swelling and inflammation within the cubital tunnel irritating the ulnar nerve. Over time, this may lead to the formation of scar tissue in and about the ulnar nerve.
- The fascial covering of the cubital tunnel may lose its ability to stabilize the ulnar nerve with elbow motion. The nerve then becomes exposed to repetitive trauma as it slides in and out of its normal position.
- Injury to the bones of the elbow joint may produce changes in the alignment or carrying angle of the joint. This may place tension on the ulnar nerve or narrow the size of the cubital tunnel.
- As the floor of the cubital tunnel is formed by the elbow joint, arthritis may produce swelling or enlargement of the joint which in turn narrows the cubital tunnel compressing the ulnar nerve.
- Tumors such as ganglion cysts or anomalous structures such as an extra muscle may compromise the space available for the ulnar nerve within the cubital tunnel.
Signs and Symptoms
Most cubital tunnel syndrome victims report intermittent numbness or tingling in the ring and little fingers. These symptoms may occur with prolonged flexion of the elbow or resting against the elbow. There may be an associated aching discomfort along the inner forearm or elbow. If nerve damage persists, there is loss of sensation in the ring and little fingers.
Eventually there is loss of strength in the muscles supplied by the ulnar nerve. Patients usually note a loss of pinch and grip strength. There may be difficulty crossing the index finger and middle fingers. Severe cases will reveal loss of muscle bulk or wasting over the little finger aspect of the palm and along the back of the first web space or base of the index finger.
Other conditions resembling cubital tunnel syndrome include compression of the nerves in the neck and shoulder area, or compression of the ulnar nerve in the wrist. These conditions can often be excluded by physical examination; however, it may be necessary to obtain special x-rays, vascular tests, or nerve testing to help with the diagnosis.
- Conservative treatment:
- avoidance of activities that may provoke further symptoms, such as minimizing elbow flexion
- wearing a splint at night to restrict elbow flexion
- during the day, wearing an elbow pad
- oral anti-inflammatory medications
- When conservative treatment fails, or when symptoms are severe and/or longstanding, I usually recommend surgery....
- incision on the inner elbow
- cut (release) the fascia forming the roof of the tunnel
- possibly move the nerve out of the cubital tunnel to the front of the elbow
- The pressure on the ulnar nerve is relieved.
Following surgery, the arm is immobilized in a long-arm bulky dressing with a plaster splint.
Elevation and finger motion is important to prevent swelling during the post-operative period. The splint is usually removed at 10 to 14 days after surgery to permit suture or staple removal. Additional elbow immobilization may be required up to 3 weeks following surgery. Once therapy is started at the elbow, splinting between exercises is sometimes helpful for comfort and protection until normal motion has been restored. Strengthening of the extremity begins 4 to 8 weeks after surgery depending upon the procedure performed.
Recovery from cubital tunnel surgery requires 2 to 3 months before resuming unrestricted use of the extremity. Several months may be required before the maximum benefits of surgery are achieved. In severe cases with loss of sensation and muscle wasting, complete recovery may not be possible. With proper diagnosis and appropriate treatment, progression of this condition may be prevented.