Cubital Tunnel Syndrome
Cubital Tunnel Syndrome (Entrapment of the ulnar nerve at the elbow)
Ulnar nerve entrapment at the elbow (that is also known as Cubital Tunnel Syndrome in analogy with Carpal Tunnel Syndrome) is a medical condition given by compression of the ulnar nerve inside the cubital tunnel.
The cubital tunnel is a passageway located at the medial edge of the elbow. It has bony borders (given by the medial epicondyle of the humerus and the olecranon process of the ulna) with an overlying thick fibrous sheath (known as Osborne’s aponeurosis) spanning the two prominences. The ulnar nerve courses inside the cubital tunnel and then in between the two heads of the flexor carpi ulnaris muscle.
Elbow flexion can result in a change of the cross sectional geometry of the cubital tunnel from round to flattened and triangular, with increasing pressure inside it. Moreover elbow flexion causes elongation of the nerve during its course inside the cubital tunnel. Therefore the ulnar nerve is normally subjected to stretch and compression forces that are moderated by its ability to glide in its anatomic path around the elbow.
Dynamic ultrasounds have also demonstrated that in more than 15% of the population, elbow flexion is associated with tendency of the ulnar nerve to subluxate.
The majority of these neuropathies are idiopathic (no exact cause is identified to be related with the onset of the symptoms) and the entrapment of the ulnar nerve along its course in the cubital tunnel generally seems to be related with a remarkable thickening of Osborne’s aponeurosis or the presence of fibrous bands bridging the two heads of flexor carpi ulnaris. Entrapment of the ulnar nerve at the elbow can also occur as consequence of:
- conditions that modify the bony architecture (e.g. rheumatic diseases such as rheumatoid arthritis or elbow traumas) of the cubital tunnel
- presence of tumors (e.g. lipomas) inside the cubital tunnel
- repeated steroid injections in the elbow
Symptoms of Cubital Tunnel Syndrome
Cubital Tunnel syndrome presents higher incidence in men in comparison with women. This might be explained as related with anatomical differences in the two genders: in men the tubercle of the coronoid process (eminence of the olecranon) is larger and the nerve and the vessels passing by it are less protected by subcutaneous fat when compared with women.
Symptoms of Cubital Tunnel Syndrome are:
- Numbness along the ring and the little finger, mostly occurring at night or after prolonged elbow flexion.
- Numbness is often associated with pain in the same territory and radiating along the upper arm, often even up to the shoulder.
- Pain and numbness can become so intense that patients are often sleepless through the night, uselessly trying to find relief.
Long standing Cubital Tunnel Syndrome may lead to nerve damage that results in:
- Constant numbness and sensory loss along the ring and little finger.
- Weakness and progressive loss of interossei muscles
Cubital Tunnel Syndrome can be cured.
- In mild cases, conservative treatment (e.g. wearing splints at night to avoid prolonged elbow flexion while sleeping) may be tried although recurrence of symptoms is likely.
Surgery is the definitive solution and consists in relieving the compression on the ulnar nerve cutting Osborne’s aponeurosis; in many cases, such as when the syndrome was the consequence of a trauma on the elbow or there is a tendency of the nerve to subluxation, only decompression is not enough and the nerve must be transposed ( that means surgically displaced out of its original location and brought on anteriorly and medially so that elbow flexion cannot not result in stretching it anymore). The procedure is preferably carried under general anesthesia. Decompression and transposition of the ulnar nerve do not require postoperative immobilization, post-procedural recovery is generally quick with no limitation in the range of elbow movements.
- Surgery generally allows relief of pain and numbness
- Long standing muscle atrophy often persists even after surgery
Well known predisposing factors to the onset of Cubital Tunnel Syndrome are:
- metabolic derangements such as diabetes
- rheumatic diseases
- minor elbow traumas or elbow fractures
- lying with flexed elbows on hard surfaces (e.g. clerks sitting at a desk) or sleeping with flexed elbows
- working in prolonged elbow flexion (e.g. musicians such as flautists or fiddlers are often prone to develop the syndrome)
At the Neuro Spinal Hospital expert medical assessment and treatment are provided.
Once it is diagnosed and correctly treated Cubital Tunnel Syndrome offers a good prognosis, with relief of symptoms. As a general rule, the earlier the condition is diagnosed and treated, the better the outcome for the patient.