Ulnar Nerve Entrapment at the Elbow

March 3, 2020

Ulnar nerve entrapment at the elbow, also known as cubital tunnel syndrome, is a common sports injury in throwing and racket sports that require repetitive elbow flexion and extension combined with ulnar and radial deviation of the wrist. String musicians, such as guitar, bass and violin players, also get this injury, usually on the fret hand, as the fingers and wrist flexor muscles are used to hold the strings. In a position of full forearm supination and elbow and wrist flexion, the contracted wrist flexors subject the medial epicondyle to excessive and prolonged strain. These repetitive activities create valgus tension on the medial elbow, which contributes to a soft tissue adhesion and eventual entrapment of the ulnar nerve. The ulnar nerve passes posterior to the medial epicondyle and is secured by ligamentous tissue that is located deep to SI 8 (xiaohai).

Continuing along the Small Intestine channel approximately 1 cun distal from SI 8 and the medial epicondyle, the ulnar nerve passes through a tunnel of aponeurotic tissue that connects the humeral and ulnar heads of the flexor carpi ulnaris (FCU). This soft tissue passageway
for the ulnar nerve is called the cubital tunnel and it is a common site for ulnar nerve entrapment.

Numbness and tingling in the ring finger and little finger are common symptoms of ulnar nerve entrapment. Often, these symptoms are intermittent and can happen more often when the elbow is bent, such as when driving or holding a phone to the ear. This condition can be exacerbated by particular sleeping positions. Many people sleep on their sides with their arm tucked under themselves in a position of elbow flexion, forearm supination and wrist flexion, which can aggravate the symptoms of ulnar nerve compression. The patient will often wake with the last two fingers numb and tingling. The symptoms of ulnar nerve entrapment presents similarly to that of thoracic outlet syndrome, so these two conditions must be differentiated. The common orthopedic examinations are Tinel’s sign at the elbow and also Elbow Flexion Test. Tinel’s sign is not as reliable of examination and a false positive is a common result of this test.

Elbow Flexion Test

This test is used to assess for the presence of ulnar nerve entrapment in the cubital tunnel at the elbow. The position of the elbow flexion test emphasizes stretching of the flexor carpi ulnaris. The tendon of this muscle is often involved in soft tissue entrapments of the ulnar nerve at the elbow.

  1. Elbow Flexion Test.

    The patient flexes their elbows and externally rotates the shoulder joints with abduction. The wrists are extended and deviated to the radial side. This position is common among food and beverage servers when holding a service tray slightly above shoulder level.

  2. Have the patient hold this position for 3-5 minutes, noting any tingling or paresthesia within the ulnar nerve distribution along the Small Intestine or Heart channels of the forearm or hand.

  3. A positive test indicates ulnar nerve entrapment in the cubital tunnel

 

 

An Additional Binding Region of the Heart and Small Intestine Channel Sinews (Jingjin)

The diagnosis of ulnar nerve entrapment at the elbow (i.e., cubital tunnel syndrome) can be made from the patient’s signs and symptoms that match the history and applicable orthopedic examinations. Digital imaging and possible EMG studies are useful to assess the extent of the nerve entrapment and nerve signaling potential.

 

Because the stress on the medial elbow is frequent, even in the activities of everyday living, this region of the elbow anatomy should be assessed and treated in cases involving the Fire element channels before the signs and symptoms of cubital tunnel syndrome are experienced. Because there are varying levels of nerve entrapment, vertebral spondylosis is a good example, mild ulnar nerve compression can disrupt nerve conduction velocity proximal and distal to the actual impingement site. Nerve compression can alter cellular metabolism and action potentials necessary for efficient muscle contraction. Eventually, soft tissue adaptations can occur with pain and dysfunction often found away from the entrapment site. Mild ulnar nerve compression in the cubital tunnel is an early stage of neuropathy, a silent contributor to injury, before the actual signs and symptoms of cubital tunnel syndrome occurs.  The flexor carpi ulnaris belongs to both the Heart and Small Intestine channel sinews (jingjin) and this anatomical location should be considered as a binding region that occurs in the different areas of the channel sinews. Binding regions are particular to the jingjin terminology and are discussed as areas where the qi and blood has a tendency to “bind” or “stagnate”. For example, in the literature, the binding region of the HT jingjin is at the medial elbow and the Small Intestine jingjin the binding region is found slightly proximal to the medial elbow (Fig. 5). The cubital tunnel, where the ulnar nerve can become entrapped is found slightly distal to the elbow and should be included as a region of binding. The acupuncture treatment as described above can soften the tension in these myofascial channels and should be considered as an adjacent or distal treatment for any pain or injury involving the Fire element channels.

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