Cubital Tunnel Syndrome: Diagnosis and Management Samir K. Trehan, MD, John R. Parziale, MD, and Edward Akelman, MD  Cu b i t a l t u nn e l s y n d r o m e is, a f t e r c a r p a l During elbow flexion, the ulnar nerve Populations at risk for cubital tunnel tunnel syndrome, the second most com- is stretched 4.5 to 8 mm (since it lies pos- syndrome include patients with diabetes, mon compression neuropathy of the up- terior to the axis of motion of the elbow) obesity, as well as occupations involving per extremity. Patients often present with and the cubital tunnel cross-sectional area repetitive elbow flexion and extension, pain, paresthesias and/or weakness that if narrows by up to 55% as intraneural pres- holding tools in constant positions and left untreated may lead to significant dis- sures increase up to 20-fold.2, 3 As a result, using vibrating tools. The prevalence ability. This article reviews the etiology, repeated and sustained elbow flexion can within these populations ranges from diagnosis and management of cubital irritate the ulnar nerve and eventually lead 2.8% among workers whose occupations tunnel syndrome. to cubital tunnel syndrome. This relation- require repetitive work (e.g., assembly ship between prolonged elbow flexion line workers, packagers and cashiers) to An a t o m y a n d Et i o l o g y and cubital tunnel syndrome has been 6.8% in floor cleaners to 42.5% among The ulnar nerve originates from reported in patients who habitually sleep vibrating tool operators.4 branches of the C8 and T1 spinal nerve in the fetal position or sleep in the prone roots and is the terminal branch of the me- position with their hands tucked under Clinical Ev a l u a t i o n a n d dial cord of the brachial plexus. In the arm, the pillow. More recently, this relationship Diagnosis the ulnar nerve courses between the medial has been reported in patients with fre- Diagnosis of cubital tunnel syndrome head of the triceps and the brachialis mus- quent prolonged cell phone use (i.e. “cell requires a thorough history and physical cles. It then travels posterior to the medial phone elbow”). Cubital tunnel syndrome examination. Patients frequently initially epicondyle of the humerus and enters the can also develop in patients years after present with intermittent paresthesias, cubital tunnel. The roof of the cubital tun- elbow trauma leading to cubitus varus numbness and tingling in the small fin- nel consists of Osborne’s ligament, which deformity, such as supracondylar humerus ger and ulnar half of the ring finger (i.e., spans from the medial epicondyle of the fractures (i.e., “tardy ulnar nerve palsy”). ulnar nerve distribution). As the disease humerus to the olecranon of the ulna, and Other causes of cubital tunnel syndrome progresses, these symptoms may become the floor consists of the medial collateral include chronic external compression more constant and patients may complain ligament and joint capsule of the elbow. (e.g., wheelchair-bound patients and of elbow pain in the region of the cubital After exiting the cubital tunnel, the ulnar truck drivers), ulnar collateral ligament tunnel (i.e., the “funny bone” area). nerve passes between the humeral and ul- laxity (e.g., baseball pitchers), local edema Patients may also initially present with nar heads of the flexor carpi ulnaris muscle or inflammation, space-occupying lesions non-specific complaints of hand clumsi- and enters the anterior compartment of (e.g., tumor) and repeated subluxation or ness or weakness, however atrophy of the the forearm. In the forearm, it courses dislocation of the ulnar nerve. intrinsic hand muscles innervated by the between, and innervates, the flexor carpi The incidence of cubital tunnel ulnar nerve is a sign of advanced disease. ulnaris and ulnar half (i.e., fourth and fifth syndrome in the general population Motor impairment may manifest as grip fingers) of the flexor digitorum profundus has been reported at 24.7 per 100,000.4 weakness (e.g., difficulty opening bottles muscles. The ulnar nerve then divides into superficial and deep branches. The deep branch innervates the hypothenar, third and fourth lumbrical, interosseous, ad- ductor pollicis and deep head of the flexor pollicis brevis muscle, and the superficial branch provides sensory function for the medial hand. Ulnar nerve compression most com- monly occurs at the elbow. At the elbow, the ulnar nerve can be compressed at five sites: the arcade of Struthers, medial intermuscular septum, medial epicondyle, cubital tunnel and deep flexor pronator aponeurosis.1 (Figure 1) Ulnar nerve compression within the cubital tunnel, known as cubital tunnel syndrome, is the Figure 1. Ulnar nerve anatomy and sites of compression around the elbow. By permission of most common site of compression. Mayo Foundation for Medical Education and Research. All rights reserved. 349 Volume 95 No. 11 No v e m b e r 2012 or jars), hand clumsiness (e.g., difficulty be evaluated for medial epicondylitis and typing) or difficulty with precision pinch elbow instability. activities (e.g., buttoning buttons).1 During the work-up of patients with Since patients with mild disease may suspected cubital tunnel syndrome, it is have no symptoms at the time of examina- important to consider other potential sites tion, various provocative exam techniques of ulnar nerve compression, C8 radicul- may aid in diagnosis of these patients. opathy, thoracic outlet syndrome, vascular The elbow flexion test is performed by disease, amyotrophic lateral sclerosis and placing the elbow in maximal flexion peripheral neuropathy (which can be and full supination. The test is positive if secondary to chronic alcoholism, diabetes,

paresthesias, numbness or tingling are re- vitamin B12 deficiency and hypothyroid- produced in the ulnar nerve distribution. ism among other causes). Patients with This test has been reported to be 75% C8 radiculopathy can have co-existent sensitive after one minute. Tinel’s test, cubital tunnel syndrome—a phenom- in which the cubital tunnel is tapped by enon referred to as “double crush”—and the examiner’s finger, may also reproduce therefore one diagnosis does not preclude symptoms and has been reported to be the other. 70% sensitive. Finally, compression of Although no disease-specific out- the nerve for one minute just proximal come measures have been validated for Figure 2. First dorsal interosseous muscle to the cubital tunnel with the elbow in cubital tunnel syndrome, numerous atrophy secondary to ulnar nerve neuropathy. 20° flexion and full supination is 89% severity scales have been reported based sensitive when performed alone and 98% on findings from history and physical degrees from the horizontal) maximizes sensitive when performed in combination examination.7 McGowan first classified test sensitivity by providing the great- with the elbow flexion test.1, 5 cubital tunnel syndrome severity into est correlation between the skin surface With advanced disease, objective three categories: mild, moderate and se- measurement and true nerve length.1, 9 findings of weakness in the muscles in- vere. Mild disease is defined as occasional Needle EMG examination should al- nervated by the ulnar nerve may be noted paresthesias, positive Tinel’s sign and ways include the first dorsal interosseous on examination. Patients may have weak subjective weakness. Moderate disease is muscle, which is the most frequent muscle finger abduction secondary to interos- defined as occasional paresthesias, positive to first demonstrate abnormalities follow- seus muscle atrophy. In particular, the Tinel’s sign and objective weakness. Severe ing ulnar nerve compression.9 In addition, first dorsal interosseous muscle can be disease is defined as constant paresthesias electrodiagnostic testing has been shown examined by asking the patient to abduct and muscle wasting.8 to have prognostic value in predicting the index finger against resistance. Small subjective recovery.10 finger abduction following extension of La b o r a t o r y , Ra d i o g r a p h ic a n d MRI may be helpful if a space-occu- the digits may also be noted (Wartenberg El e c t r o d i a g n o s t ic As s e s s m e n t pying lesion is suspected, but otherwise is sign), which patients may notice by the Diagnostic testing may be helpful not routinely used. In addition to also be- small finger being caught when trying to in patients with suspected cubital tunnel ing useful for visualizing space-occupying place the hand inside of a pant pocket. syndrome. Radiographs of the elbow may lesions, ultrasound has recently been Patients may also be unable to grasp with identify osteophytes, bone fragments or proposed as a diagnostic tool for cubital a key-pinch grip and instead compensate malalignment in patients with arthritis or tunnel syndrome via measurement of with a fingertip grip (Froment sign) sec- a history of trauma. Electromyographic nerve diameter. A literature review of ondary to adductor pollicis, first dorsal (EMG) and nerve conduction studies may clinical trials of ultrasonagraphy used to interosseous and flexor pollicis brevis be helpful in confirming the diagnosis of test ulnar neuropathy at the elbow noted atrophy. (Figure 2) Finally, severe clawing ulnar neuropathy at the elbow, assisting that numerous studies had significant of the ring and small fingers (i.e. flexion in precise localization of the compressive methodological flaws, some studies were of the interphalyngeal joints with exten- lesion (e.g., proximal versus distal to the uncontrolled, and that the study designs sion of the metacarpophalyngeal joints) innervation of the flexor carpi ulnaris), differed significantly. The authors con- may be noted secondary to lumbrical and quantifying the degree of the neurologic cluded that the role of ultrasound in interosseous muscle atrophy.6 deficit and/or identifying alternate sites ulnar neuropathy at the elbow could not Physical examination must also of nerve dysfunction simulating cubital be firmly established. include investigation of potential under- tunnel syndrome such as cervical radicu- lying causes for cubital tunnel syndrome. lopathy, brachial plexopathy and/or ulnar Ma n a g e m e n t Thus, the elbow should be examined for nerve compression at the wrist at Guyon’s Conservative Management range of motion, crepitus, ligament stabil- canal. Ulnar nerve compression can be In the absence of intrinsic muscle ity and deformity. In particular, patients diagnosed if motor nerve conduction ve- atrophy, conservative treatment should whose chief complaint is medial elbow locity (NCV) across the elbow is less than be attempted. Non-operative treatment pain (as opposed to paresthesias, numb- 50 m/s. Performing NCV studies with the includes patient education and activity ness, tingling or hand clumsiness) should elbow in moderate flexion (i.e., 70 to 90 modification to avoid elbow flexion and/ 350 Medicine & Health/Rhode Island or cubital tunnel compression. Depend- dylitis may benefit from partial medial activities through open-kinetic chain ing on the provocative activity, this can epicondylectomy, although this procedure exercises. A rehabilitation program may be accomplished by wearing an elbow has been associated with increased me- be necessary for six weeks or more post- extension splint at night (or, more simply, dial elbow pain post-operatively. Finally, operatively.15 limiting elbow flexion by wrapping a pil- endoscopic ulnar nerve release has been low around the anterior elbow), adjusting reported to have a similar success rate Co nc l u s i o n s posture at work to reduce elbow flexion, to open procedures with potentially less Cubital tunnel syndrome is a com- using a hands-free headset with cell phone post-operative pain. A common surgical mon cause of upper extremity pain and use, or padding the posterior surface of complication of all of these techniques is disability. The treating clinician should the elbow. In addition, non-steroidal potential injury to the posterior branch of possess a high degree of familiarity with anti-inflammatory drugs or ice can be the medial antebrachial cutaneous nerve. the relevant aspects of anatomy, epide- used to reduce acute pain and inflam- Taken together, given the similarity in miology and clinical presentation. The mation. Following resolution of acute outcomes reported between the surgical diagnosis of cubital tunnel syndrome fre- symptoms, physical therapy is initiated to treatments for cubital tunnel syndrome, quently requires a combination of clinical first establish pain-free range of motion of the choice of procedure is based largely suspicion and may require electrodiagnos- the affected extremity and then increase on surgeon experience and sometimes tic confirmation. Once diagnosed, cubital strength. Dellon, et al. reported symptom underlying etiology.1 tunnel syndrome is initially treated by improvement in 90% of patients with conservative measures focused on patient mild disease and 38% of patients with education and avoidance of provocative moderate disease. A history of elbow When patients activities. In the presence of intrinsic trauma is a poor prognosticator and risk fail to respond hand muscle atrophy or persistent severe factor for eventual surgery.11 symptoms, operative treatment should to conservative be considered. Operative Management measures, have When patients fail to respond to con- Re f e r e nc e s servative measures, have persistent severe persistent severe 1. Palmer BA, Hughes TB. Cubital tunnel syndrome. J Hand Surg Am. Jan 2010;35(1):153–63. symptoms or present with intrinsic muscle symptoms or 2. Werner CO, Ohlin P, Elmqvist D. Pressures atrophy, operative management should be recorded in ulnar neuropathy. Acta Orthop considered. Surgical options include ulnar present with Scand. Oct 1985;56(5):404–6. nerve in situ decompression, anterior 3. Apfelberg DB, Larson SJ. Dynamic anatomy of intrinsic muscle the ulnar nerve at the elbow. Plast Reconstr Surg. transposition of the ulnar nerve (subcu- Jan 1973;51(1):79–81. taneous, intramuscular or submuscular), atrophy, operative 4. van Rijn RM, Huisstede BM, Koes BW, Burdorf partial medial epicondylectomy and endo- management should A. Associations between work-related factors scopic ulnar nerve decompression. Studies and specific disorders at the elbow: a systematic be considered. literature review. Rheumatology (Oxford). May of in situ decompression report 75% to 2009;48(5):528–36. 90% of patients achieve good or excellent 5. Novak CB, Lee GW, Mackinnon SE, Lay L. pain relief, while 7% to 15% do not ben- Po s t -Op e r a t i v e Rehabilitation Provocative testing for cubital tunnel syndrome. efit.12 Despite discussion in the literature Once the incision and soft tissues J Hand Surg Am. Sep 1994;19(5):817–20. 6. Folberg CR, Weiss AP, Akelman E. Cubital regarding in situ decompression’s poten- have healed, rehabilitation therapies tunnel syndrome. Part I: Presentation and di- tial advantages (e.g., minimal disruption are often used to help the patient re- agnosis. Orthop Rev. Feb 1994;23(2):136–44. of the ulnar nerve’s vascular supply) and gain pain-free range of motion, normal 7. Macadam SA, Bezuhly M, Lefaivre KA. Out- disadvantages (e.g., limited exposure to strength and function. The extent and comes measures used to assess results after sur- gery for cubital tunnel syndrome: a systematic explore other potential sites of ulnar nerve duration of a post-operative rehabilita- review of the literature. J Hand Surg Am. Oct compression and risk of post-operative tion program varies with the extent of 2009;34(8):1482–91 e1485. ulnar nerve subluxation) versus anterior injury and the physical demands of a 8. McGowan AJ. The results of transposition of the ulnar nerve for traumatic ulnar neuritis. J Bone transposition, two meta-analyses have return to normal activities such as ADLs, Joint Surg Br. Aug 1950;32-B(3):293–301. demonstrated similar outcomes between occupational activities or sports. Goals 9. Practice parameter: electrodiagnostic studies in these techniques.13, 14 In the 7% to 15% of a postoperative rehabilitation program ulnar neuropathy at the elbow. American Asso- of patients who have recurrent disease include (a) full active range of motion ciation of Electrodiagnostic Medicine, American Academy of Neurology, and American Academy following in situ decompression, many for elbow flexion, extension, prona- of Physical Medicine and Rehabilitation. Neu- can be successfully treated with anterior tion and supination, (b) normal elbow rology. Mar 10 1999;52(4):688–90. transposition of the ulnar nerve.14 strain, with balance maintained between 10. Friedrich JM, Robinson LR. Prognostic indica- Patients with post-traumatic elbow agonists and antagonists muscles, and (c) tors from electrodiagnostic studies for ulnar neuropathy at the elbow. Muscle Nerve. Apr stiffness or deformity, ulnar nerve sub- resumption of sports-specific and work 2011;43(4):596–600. luxation, ulnar collateral ligament laxity specific functional activities. Exercises to 11. Dellon AL, Hament W, Gittelshon A. Non- and “tardy ulnar nerve palsy” may benefit establish neuromuscular control include operative management of cubital tunnel syn- from initial anterior transposition of the proprioceptive neuromuscular facilitation drome: an 8-year prospective study. Neurology. Sep 1993;43(9):1673–7. ulnar nerve. Patients with medial epicon- and progression from closed-kinetic chain 351 Volume 95 No. 11 No v e m b e r 2012 12. Abuelem T, Ehni BL. Minimalist cubital tun- Samir K. Trehan, MD, is a second year Co r r e s p o n d e nc e nel treatment. Neurosurgery. Oct 2009;65(4 orthopaedic surgery resident at Hospital for Suppl):A145–9. John R. Parziale, MD 13. Goldfarb CA, Sutter MM, Martens EJ, Manske Special Surgery in New York, NY University Rehabilitation, Inc. PR. Incidence of re-operation and subjective John R. Parziale, MD, is a Clinical 450 Veterans’ Memorial Parkway, outcome following in situ decompression of Associate Professor, Department of Ortho- Building #12 the ulnar nerve at the cubital tunnel. J Hand paedics, Warren Alpert Medical School of Surg Eur Vol. Jun 2009;34(3):379–83. East Providence, RI 02914 14. Macadam SA, Gandhi R, Bezuhly M, Lefaivre Brown University phone: (401) 435-2288 KA. Simple decompression versus anterior sub- Edward Akelman, MD, is a Professor, fax: (401) 435-2282 cutaneous and submuscular transposition of the Department of Orthopaedics, Warren Alpert e-mail: [email protected] ulnar nerve for cubital tunnel syndrome: a meta- Medical School of Brown University analysis. J Hand Surg Am. Oct 2008;33(8):1314 e1311–2. 15. Hertling D KR, ed Management of Common Disclosure of Financial Interests Musculoskeletal Disorders. Physical Therapy The authors and/or their spouses/ Priciples and Methods. 4 ed. Philadelphia: Lip- pincott Williams & Wilkins; 2006. significant others have no financial inter- ests to disclose.

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