The Ulnar Nerve and the Cubital Tunnel
The ulnar nerve travels through the cubital tunnel behind the bone on the inside of the elbow (the "funny bone"), through the origin of the flexor carpi ulnaris muscle, as it enters the forearm, and then along the medial, or inside, aspect of the forearm and across the wrist on the small-finger side of the wrist into the hand.  It supplies the muscles inside the hand, as well as sensation (feeling) to the small finger and half of the ring finger.

Cubital Tunnel Syndrome
With this condition, the ulnar nerve may be entrapped (compressed) as it travels through the cubital tunnel.  It may also be abnormally compressed, either by fibrous bands or by the muscular septum between the muscles of the upper arm, in the region just above the elbow.

Symptoms
There is generally pain around the inside of the elbow, radiating down the inside or medial aspect of the forearm and into the ring and small fingers of the hand.  Numbness and tingling may be evident (just as with ulnar tunnel syndrome, wherein the nerve is compressed at the wrist level).  This numbness and tingling in the ring and small fingers often will cause awakening at night.

Diagnosis
Tapping over the nerve at the elbow, a commonly relied-upon test, may produce a tingling sensation in the distribution of this nerve (into the ring and small fingers).  The presence of this sensation, called a positive Tinel's sign, may thus aid in diagnosing the condition.
Because there is increased pressure on this nerve as it travels behind the elbow when the elbow is bent, a maneuver called an elbow flexion test is also used in diagnosing this condition.  During such testing, subluxation of the ulnar nerve will sometimes occur.  This is where the ulnar nerve actually dislocates, or comes out of its groove behind the elbow, as the elbow is flexed, thus producing severe pain.

Treatment
Conservative treatment for cubital tunnel syndrome is often helpful.  The patient may be given splints to wear so as to avoid the elbow's being in a markedly flexed or bent position, especially at night during sleep.
An elbow sleeve (with a large cushion over the ulnar nerve on the inside of the elbow) may prevent pressure on the nerve and discourage an individual's habit of leaning on the elbow and thus applying pressure to the nerve.
Antiinflammatory medications may also be used and, occasionally, cortisone, although cortisone injections are generally not found to be very helpful with this particular condition.

Surgery
If there is ongoing deterioration of symptomatology and an inability to function or work despite adequate conservative care, then surgical release may be necessary.
Several methods of release of the ulnar nerve at the elbow are available.
The in situ release is a simple release of the nerve as it goes through the various tunnels or areas of compression around the elbow.  The position of the nerve is not changed.
The second method is release of the nerve combined with a transposition, or moving, of the nerve from the region behind the elbow to the region in front of the elbow, thereby avoiding the increase in pressure with elbow flexion (bending).  The nerve may be placed under the skin in the subcutaneous area (in a subcutaneous transposition), or it may be placed beneath the flexor muscles that attach to the elbow.  The latter requires elevating these muscles and replacing them after the nerve has been placed deeply in the forearm.
In recent studies, this placement of the nerve deep in the forearm has been shown to be more reliable in relieving the problem than has subcutaneous transposition, but it requires a larger operation.  Also, rehabilitation and healing may take longer with it than with a subcutaneous transposition.
If the problem is addressed early enough, then a simple in situ release will often suffice.  The particular type of procedure chosen depends on many factors, and each case should be addressed individually.