Cubital Tunnel Syndrome
(Ulnar Nerve Entrapment)

The cubital tunnel syndrome is a condition caused by pressure at the elbow on the ulnar nerve. The nerves are the structures carrying the messages between the brain, the spinal cord and the body parts. A nerve is unable to function properly once it is compressed. The ulnar nerve entrapment at the elbow is the second most common entrapment syndrome after the carpal Tunnel Syndrome.

The ulnar nerve carries the signals for sensation in our little finger and in one half of our ring finger. It allows the muscles of the hand to perform fine motions of the fingers. With such syndrome, individuals will demonstrate difficulty in handling objects and performing gripping motions. They may feel numbness, pain, and a tingly sensation that many may describe like when a funny bone is hit. The ulnar nerve is also responsible for the activities of some muscles of the forearm.

The ulnar nerve runs from the side of our neck down to our fingers. At the elbow, this nerve is most exposed for compression while passing through a groove formed by muscle, bone and ligament on the posteromedial aspect of the elbow. This passage is called the Cubital tunnel. Once the nerve become compressed, it will send faulty signals down to the forearm, hand and fingers. This nerve is responsible for providing the sensation over half of the ring finger and the little finger, muscles of the forearm (flexors) as well as muscles of the hand (interossei +Adductor Pollicis) receive an innervation from the ulnar nerve. These fine motions find their importance when one has to manipulate objects.

 

The cause of a Cubital Tunnel Syndrome is not always well known but several factors may appear to contribute especially, the repeated range of motions of the elbow. Il looks like the Flexor Carpi Ulnaris (FCU) muscle can become irritated by such motion and apply pressure over the nerve. Other causes like acute or neglected fractures, bone spurs, swelling, soft tissue cysts, any other disease affecting the elbow can play a role in this pathology. Like rheumatoid arthritis etc.

Cubital Tunnel Syndrome, frequently causes numbness and tingling to the ring finger and little finger in a permanent way or presenting in transient or recurrent symptoms, more often with the elbow in a bending position especially when slipping. Additional symptoms of poor finger coordination and weak grip or pinch can be seen while the individual is holding on an instrument or playing the piano by example (adductor pollicis muscle). If left untreated, the situation may deteriorate and lead to permanent changes in loss of sensation and motion or even contracture flexion of the ring and little fingers. The condition can become chronic and permanent deformation as the “Christ Hand” position can be seen, as described in the French literature, mimicking the position of Christ’s fingers when absolving his disciples.

Why do we have an Ulnar Nerve entrapment at the elbow? It can happen when the elbow is exposed to prolonged stretching especially when the elbow is kept bent for long periods or simply when the nerve is subject to direct pressure while in contact with a solid surface like a metallic surface. The same can happen at the wrist level if one lean on the handlebars during a long bike ride. There is also a Guyon tunnel where a branch of the ulnar nerve passes at the wrist level. One will feel then the extremity “Going to sleep” or while bumping the elbow one may describe a sensation of “hitting a funny bone” because of an electrical shock or can describe simply a tingling sensation. In some people, the nerve does not lie properly in the cubital tunnel and can shift across the medial epicondyle and can sub-luxate while the elbow passes from a flexed to an extended position. Such repeated motions can cause irritation of the nerve. Fluid build-up or long-standing effusion at the elbow can exceptionally compress on the ulnar nerve.

To diagnose such pathology, one should perform an proper examination of the extremity and review the medical history of the patient. It is important to look for, clinically, where the compression may be, in evaluating the forearm, the elbow, the hand and the fingers for strength and range of motion.as well as sensation. Percussion over the nerve along its trajectory may reveal a tingling sensation which is the principle of a “Tinel’s sign” causing a discomfort at percussion.

Imaging studies like simple X-rays has been used in search of bony pathology.as well as MRI and CT scan to locate bone spurs which may compress the nerve. This allows us to evaluate the bone condition at the elbow because of the close contact of the nerve to the bone. MRI will provide details in the anatomy of the soft tissues at the elbow. MR Neurography is also an MRI with special techniques and sequences enhancing images of the nerve, used the same way a standard MRI is performed. These modalities present some of the non-invasive ways to evaluate the elbow. Ultrasound has been a useful tool used by others……

Most clinicians will rely on an Electromyography (EMG) and a Nerve Conduction Study (NCS) to evaluate the function of the nerve and this will help in specifying the site of the compression. The Electromyography (EMG) will evaluate the ongoing muscle activity and the response of the muscle when the nerve is stimulated, The Nerve Conduction Study (NCS) will measure the amount and the speed of conduction of an electrical impulse through the nerve while innervating a muscle. Often, a surgeon may be so sure of the diagnosis that it become unnecessary to perform such test. The same can be seen with carpal tunnel syndrome or other peripheral nerve compression. The pressure we are facing with defensive Medicine, obligate us to perform these tests prior to initiate any treatment especially when surgery is contemplated as the definitive method of treatment.

 A view of the medial aspect of the elbow

Most cases of Cubital Tunnel Syndrome respond to non-surgical treatments once taken in proper consideration. Treatment varies with restriction of activity, rest, and pain relief as well as anti-inflammatory medication. The importance in avoiding external pressure over the medial aspect of the elbow is paramount. Padded splints or braces can be beneficial especially while sleeping or driving. Avoid any prolonged pressure over the medial aspect of the elbow. Rarely, we will encourage warm compresses or even prescribe physical therapy sessions with heat and ultrasound therapy. Repetitive motions should be avoided in order to ease the inflammatory process.

Sub-cutaneous view of the anatomy of the elbow (medial)

I use in a routine basis, on any of my patient with peripheral nerve entrapment or neuropathy, B6 (Pyridoxine) medication as I was taught in medical school on patient suffering from Tuberculosis taking “INH”. mediation and developing peripheral neuropathy. I have learned from my rotation at the Sanatorium of our country.