Compression Ulnar Neuropathy at the Elbow
ART Literature Review:
by Everett Johnson, DC, ART
Compression Ulnar Neuropathy at the Elbow.
Entrapment lesions of peripheral nerves are very common clinical disorders. Nerves may be compressed at any site along their course of travel through the periphery. Compression of the ulnar nerve at the elbow, called cubital tunnel syndrome, is the second most common nerve entrapment site after carpal tunnel syndrome (1) (2). This condition causes considerable discomfort for the patient and if it progresses may cause loss of function of the hand.
ANATOMY OF THE ULNAR NERVE AND CUBITAL TUNNEL
The ulnar nerve descends as a terminal branch from the medial cord of the brachial plexus consisting of fibers from the C8 and T1 nerve roots. It descends the area of the medial brachium anterior to the medial intermuscular septum and pierces the septum, just inferior to the Arcade of Struthers approximately two-thirds of the way down the arm. The ulnar nerve then travels posterior to the septum and just anterior to the triceps muscle. It then enters a groove on the dorsal aspect of the medial epicondyle of the humerus. From the groove on the humerus it continues to descend to the forearm by traveling deep and between the two heads of the flexor carpi ulnaris muscle and just superficial to the ulnar collateral ligament (3). The floor of the cubital tunnel is a groove on the posterior aspect of the medial epicondyle of the humerus and is covered by the ulnar collateral ligament. The roof of the tunnel is formed by a retinaculum that spans over the groove on the posterior humerus. Other sites above or below the elbow may also compress the ulnar nerve as it descends the arm and should be ruled out with proper history and examination.
There are five locations where the ulnar nerve may become trapped around the elbow (4).
1. Arcade of Struthers
2. medial intermuscular septum
3. medial epicondyle
4. cubital tunnel
5. deep flexor aponeurosis
The cubital tunnel is noted as being the most likely area where the ulnar nerve can become trapped around the elbow. When we examine the anatomic arrangement of the tunnel and the nerve passing through it we see the path the ulnar nerve takes through the cubital tunnel is narrow and restricted by the bony aspects of the tunnel, the fibrous retinaculum and connective tissue connecting the two heads of the flexor carpi ulnaris covering it. Movements of the elbow require that the ulnar nerve slide and stretch through the tunnel, which increases pressure on the ulnar nerve. Flexion of the elbow also changes the shape of the cubital tunnel from oval to ellipse (4) (6). The fibrous retinaculum covering the roof of the tunnel is also tightened with various flexion positions of the elbow, mostly greater than ninety degrees.
The Arcade of Struthers is reported as only being present in about thirteen
percent of the population, and when it is present it is not reported as a structure that normally compresses the ulnar nerve. The Arcade of Struthers is reported to be a problem after translocation of the ulnar nerve is performed (3) (5).
Some muscular anomalies have been found in the region of the medial elbow that may contribute to the compression of the ulnar nerve as well. Osborne’s ligament is a band of connective tissue that spans the area between the two heads of the flexor carpi ulnaris muscle (4) and, if present, causes compression of the ulnar nerve.
Several factors are thought to be associated with the development of cubital tunnel syndrome which include gender, smoking and alcohol consumption, body mass index and occupation requiring repetitive arm motion or the use of vibrating tools (6) (7) (8).
In a study (7) looking at these risk factors the authors found that the incidence of ulnar nerve compression was higher in male gender and increased BMI, statistically in the study they performed these were not considered risks. They go on to define a person’s total working experience or education related to their particular job or field of employment. The less education required for a job, typically the more physical the job becomes, and an increased risk of ulnar entrapment at the elbow occurs. Occupations requiring a higher education level are typically less physically demanding leading to a decreased risk of developing an ulnar nerve entrapment.
A study performed in 2004 (8) suggested that ulnar nerve entrapment at the elbow is associated with strongly with “holding a tool in position”, repetitively. These workers typically used tools such as pliers, shoe rivets, spatulas and screwdrivers. They also suggest that “holding a tool in position” had a more detrimental effect than working with vibrating tools.
Prolonged compression of the nerve is also suggested as a risk factor for entrapment of the ulnar nerve in the cubital tunnel. Compression of the nerve in the tunnel may be from two separate sources that occur together. First, the nerve is compressed by flexion of the elbow to ninety degrees or more. Flexion of the elbow has been shown to decrease the space in the tunnel and cause compression of the ulnar nerve. Second, after flexing the elbow it is placed on a solid surface and used to support the weight of the upper torso. What was just described has been termed “cellphone elbow” (9). Cell phone use is up to an estimate five billion people globally (10). The exact incidence of cell phone elbow is not known, but considering the popularity of cell phone usage there will hopefully be some data to report soon.
Typical patient presentation for this condition ranges from complaints of numbness or tingling in the small finger and the medial aspect of the ring finger in early cases to severe cases where motor nerves are involved and muscle wasting and clawing of the hand become present (6) (11). Weakness progresses from clumsiness and loss of dexterity of the intrinsic muscles of the hand and leads to loss of grip and pinch strength. Atrophy of the intrinsic muscles of the hand occurs in advanced states along with clawing of the ring and little finger, referred to as “claw hand”.
Clinically it is important to properly diagnose this condition as an entrapment of the ulnar nerve versus carpal tunnel syndrome. Many patients present with the statement of “I have carpal tunnel” since they read about the symptoms online. Taking a thorough history and doing a proper examination of the area of complaint should make the diagnosis simple. Referral for electrodiagnostic studies may be helpful, but typically back up what is found on the history and physical exam.
Determining the correct site of compression of the ulnar nerve must be done. How would one differentiate compression of the ulnar nerve in the cubital tunnel from compression at Guyon’s canal? Ask the patient about numbness in their hand. Typically, patients will not have numbness over the dorsal aspect of the ulnar side of the hand if ulnar nerve is compressed at Guyon’s canal. Check muscle strength of flexor carpi ulnaris and flexor digitorum profundus muscles for the ring and little finger as these muscles are innervated before Guyon’s canal. Ruling out a cervical nerve root lesion would include testing the muscle to the hand that are innervated by the C8 portions of the median nerve including the flexor digitorum profundus tendons for the index and middle finger, flexor pollicis longus and the thenar muscles. Imaging and electrodiagnostic studies are helpful in determining the correct site of lesion as well.
Conservative treatment of mild cases of ulnar nerve compression at the cubital tunnel is recommended for the first three months of the condition (12). A range of 50 to 90% efficacy has been reported in the literature (1) (11) (12). Conservative management in these cases refers to lifestyle modification, splinting and physical therapy. The use of manual soft-tissue techniques to release the tissues non-invasively was cited in one study (11) that mentioned using Active Release Techniques as a way to free adhesions from scar tissue.
Surgical release of the structures involved in compression of the ulnar nerve in the cubital tunnel is recommended in the literature if the mild cases do not resolve or if a patient presents with severe symptoms. Surgical release involves may involve transposition of the ulnar nerve out of the cubital tunnel to decrease the compression on the nerve or it may concern resecting the tissues causing the insult to the nerve (Osborn’s ligament) or excising the medial epicondyle of the humerus.
There are no reports to support the efficacy of manual soft-tissue techniques as a means for successfully treating this condition, though anecdotally many people have been helped using manual therapy techniques.
1. Outcomes for Peripheral Nerve Entrapment Syndromes. Robert Spinner, MD. 2006, Clinical Neurosurgery, pp. 287-288.
2. Associations between work-related factors and specific disorders at the elbow: a systemic literature review. Rogier van Rijn, Bionka Huisstede, Bart Koes, Alex Burdorf. s.l. : Rheumatology, 2009, Vol. 48.
3. Standring, Susan. Gray’s Anatomy, The Anatomic Basis for Clinical Practice. Spain : Elsevier, 2008. 978-0-443-06684-9.
4. Cubital Tunnel Syndrome. Cutts, Steven. s.l. : Postgrad Med J, 2007, Vol. 83.
5. Operative Illustrations of the Osborne’s Ligament. Serkan Simsek, ER Uygur, Adnan Demirchi, Mehmet Sorar. 2, s.l. : Turkish Neurosurgery, 2011, Vol. 21, pp. 269-270.
6. Wheeless, Clifford. Duke Orthopaedics. Wheeless Textbook of Orthopaedics. [Online] [Cited: July 28, 2011.] http://www. wheelessonline.com/ortho/arcade_of_struthers.
7. Risk factors for ulnar nerve compression at the elbow: a case control study. RHMA Bartels, ALM Verbeek. s.l. : Acta Neurochir, 2007, Vol. 149, pp. 669-674.
8. Incidence of ulnar nerve entrapment at the elbow in repetitive work. Alexis Descatha, Annette Leclerc, Jean-Francois Chastang, Yves Roquelaure. 3, 2004, Vol. 30.
9. Michael Darowish, Jeffery Lawton, Peter Evans. What is cell phone elbow, and what should we tell our patients? Cleveland Clinic Journal of Medicine. 2009, Vol. 76, 5.
10. Whitney, Lance. Cell phone subscriptions to hit 5 billion globally. Cnet Reviews. [Online] Cnet, 2009. [Cited: 07 28, 2011.] http:// reviews.cnet.com/8301-13970_7-10454065-78.html.
11. A review of compressive ulnar neuropathy at the elbow. Chad Robertson, John Saratsiotis. 5, s.l. : Journal of Manipulative and Physiological Therapeutics, 2005, Vol. 28.
12. Techniques for successful management of ulnar nerve entrapment at the elbow. Dellon, A. 1, s.l. : Neurosurgery Clinics of North America, 1991, Vol. 2.