Ulnar neuropathy at the elbow (UNE) is injury to the ulnar nerve in the elbow region causing localized pain, numbness, and/or weakness in an ulnar distribution. Cubital tunnel syndrome is a subtype of UNE in which the entrapment of the ulnar nerve occurs at the humeroulnar arcade, an aponeurosis connecting the two heads of the flexor carpi ulnaris. Tardy ulnar palsy is a specific type of UNE that occurs after an old elbow injury.
UNE may be caused by extrinsic or intrinsic compression or stretch. Common etiologic factors include repetitively leaning elbows on hard surfaces, compression by normal or anomalous anatomic structures, repetitive/prolonged elbow flexion, perioperative positioning, chronic subluxation, or acute or chronic complications of elbow trauma.
Epidemiology including risk factors and primary prevention
- The incidence of ulnar neuropathy is estimated to be approximately 24.7 per 100,000 person/years.1 The incidence is higher in manual laborers1 and wheelchair users.2
- Work related factors such as “holding a tool in a position” increase risk of UNE by 3.5 times.20
- Bilateral involvement is common in patients diagnosed with UNE on one side.3
- Systemic diseases, such as diabetes and rheumatoid arthritis, are often associated with UNE.4
- Smoking, related work experience and education level were identified as risk factors for developing UNE that required surgical treatment.21
There are several potential sites of entrapment of the ulnar nerve in the region of the elbow:
- The most common site of entrapment4 is in the retro-epicondylar groove just behind the medial epicondyle of the humerus, where there is very little soft tissue protecting the ulnar nerve from external compression.
- At the humeroulnar arcade (also known as the cubital tunnel), an aponeurotic band about 1-2 cm distal to the medial epicondyle.
- At the exit of the ulnar nerve from the flexor carpi ulnaris muscle, about 4 cm distal to the medial epicondyle, the least common site of compression.4
Compression or entrapment at any of these sites may result in focal demyelination, axon loss, or both.
UNE frequently spares the ulnar innervated forearm muscles (flexor carpi ulnaris and flexor digitorum profundus to digits 4/5), while commonly affecting the ulnar innervated hand muscles, particularly the first dorsal interosseous muscle.18,32 The terminal sensory branch of the ulnar nerve is affected more frequently in UNE than the dorsal cutaneous or palmar cutaneous branches. These predilections are considered to be due to the fascicular arrangement of the ulnar nerve in the elbow region, predisposing some fascicles to be more susceptible to injury.5
Specific secondary or associated conditions and complications
Complex regional pain syndrome is a rare complication of chronic UNE.
2. ESSENTIALS OF ASSESSMENT
The following presenting symptoms are the most common: sensory changes in the dorsal and palmar surfaces of the small finger and ulnar half of the ring finger.22, 19
Weakness or loss of coordination in the involved hand suggests motor involvement.
There is often local pain at the medial elbow that may radiate to the hand.
Thorough sensory and motor testing should be performed of the entire involved limb.
Attention should be paid to excluding disorders that may mimic ulnar neuropathy, particularly C8 radiculopathy, lower trunk/medial cord brachial plexopathy, or carpal tunnel syndrome.
Special tests and signs:
- Tinel’s sign at the elbow may reproduce sensory symptoms of numbness and paresthesias in the medial 2 digits, and potentially some discomfort in the elbow region.
- Wartenberg’s sign: when placing the affected hand in a pocket, the small finger is abducted and does not enter the pocket. This is caused by weakness of ulnar-innervated palmar interossei, which are responsible for finger adduction.
- Froment’s sign: when attempting to firmly grasp a sheet of paper between the thumb and index finger, thumb interphalangeal flexion suggests substitution of the median-innervated flexor pollicis longus for a weak ulnar-innervated adductor pollicis.
- An ulnar claw hand may develop with severe denervation of hand intrinsic muscles. This is recognized by flexion of the distal interphalangeal and proximal interphalangeal joints and extension of the metacarpophalangeal joints of the ring and small fingers with attempted extension of the hand. These findings occur as a result of weakness of the third and fourth lumbricals. The ulnar claw hand should not be confused with the median nerve benediction sign, which has a similar static appearance, but occurs with attempted hand closing.
- Elbow flexion test: holding the elbow in maximal flexion for up to 3 minutes and monitoring for onset or increase in sensory symptoms.
- Palpable, ulnar nerve subluxation with elbow flexion and extension, which may reproduce symptoms.
- Provocative tests (Tinel’s sign, elbow flexion compression test, and palpation at the elbow) have been shown to have poor sensitivities and modest specificities, and do not provide added value to routine clinical examination.29
- A thorough history of occupational and other repetitive tasks should be performed.
- Difficulty with fine motor tasks is common.
- Diminished grip strength may impair functional or occupational tasks, including activities of daily living, such as buttoning a shirt.
- A patient-reported outcome measure, The Patient-Rated Ulnar Nerve Evaluation (PRUNE) has been developed and validated for use in patients with UNE. It may be used on initial evaluation and to track progress over time.28
Laboratory studies, such as fasting blood sugar for diabetes or rheumatoid factor for rheumatoid arthritis, can provide ancillary data for overall patient management, but are not specific to UNE.
- Magnetic Resonance Imaging (MRI) and ultrasound have shown promise in the diagnostic evaluation of UNE, although their routine use is not recommended.
- MRI can be used to look for enlargements of the ulnar nerve and abnormal T2 signal, both of which have shown to have high sensitivity and specificity in diagnosing UNE23, as well as localize the lesion to the elbow in patients with non-localizing neurophysiologic evaluations.35
- Multiple studies16,17,34 have shown that comparing cross sectional area on ultrasound of the affected ulnar nerve to normative values can be used to diagnose UNE with similar sensitivities and specificities when compared to electrodiagnosis; however, ultrasound has not been shown to be of additional benefit to the patient in terms of clinical outcomes, when combined with electrodiagnostic tools.31
Supplemental assessment tools
Electrodiagnostic testing is useful to confirm the diagnosis of UNE, as well as differentiate UNE from cervical radiculopathy, polyneuropathy or median mononeuropathy.18
- Slowing in the across-elbow segment of the ulnar nerve suggests focal demyelination caused by compression/entrapment and can be used to localize the lesion of the ulnar nerve to the region of the elbow.22 Ulnar motor conduction is typically recorded at the abductor digiti minimi (ADM) muscle; however, conduction to the first dorsal interosseous muscle is recommended as an alternate recording site when UNE is strongly suspected, but no lesion is identified when recorded at the ADM.4
- Short segment incremental studies (inching studies) may be used to confirm the diagnosis and to identify the precise location of entrapment.8
- Abnormal spontaneous activity in ulnar-innervated hand intrinsic muscles suggests axon loss.
- Testing of contralateral side may be considered to compare amplitudes especially if there are symptoms, because UNE has been found to occur bilaterally in about 39%3 of cases.
Early predictions of outcomes
- The presence of atrophy, weakness, claw deformity, and/or axon loss detected by electrodiagnostic testing suggests severe nerve injury, and predicts worse outcomes.9,27
- A large review of outcomes10 suggests that mild neuropathy is more likely to improve with conservative treatment, while moderate/severe neuropathy may require surgery.24
- Duration of symptoms, whether greater or less than 3 months, is an early predictor of outcome after surgery, but is not predictive of longer term outcomes after 1 year.18
Repetitive/prolonged elbow flexion (e.g., sleeping with the elbows flexed, using the phone) and resting the elbow on hard surfaces for prolonged periods (e.g., driving or working at a desk) are risk factors for the development of UNE.
Social role and social support system
For conservative treatment options (splinting, patient education, occupational therapy), compliance with treatment requires active participation on the part of the patient and may require modifications to activities in the workplace or home.
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
Dellon’s review10 uses a staging system to predict outcomes with treatment:
- Mild neuropathy has about a 50% success rate with conservative treatment.
- Moderate or severe neuropathy has poorer outcomes with conservative treatment and likely requires surgery.
- A large meta-analysis of 6 RCTs in 2012 could not conclude based on imaging, clinical, or electrophysiologic characteristics, the best treatment option for UNE.15
Treatment guidelines for work-related UNE recommend surgical exploration and release if: conservative management has failed, the condition interferes with work or activities of daily living, and the diagnosis has been established.
At different disease stages
- Conservative treatment options include patient education, activity modifications, night splinting to prevent elbow flexion, elbow padding or protective splinting, and occupational therapy for ergonomic evaluation.
- Conservative treatment is appropriate for mild to moderate UNE.24, 32
- Patient education and activity modification alone may be sufficient to improve symptoms in many patients with mild UNE.11
- Night splinting should limit elbow flexion to less than 60-70 degrees of flexion from full extension.
- Elbow padding may prevent external pressure on the ulnar nerve near the medial epicondyle.
- Surgical referral should be considered in confirmed cases when conservative treatment fails, or if significant weakness, atrophy, or clawing is present.
- Multiple studies including a comprehensive meta-analysis12found no significant difference in outcomes between patients treated with simple ulnar nerve decompression versus decompression with nerve transposition.25
- Surgical failure may be the result of an incorrect preoperative diagnosis, the presence of concomitant conditions, inadequate decompression, intraoperative injury to nearby nerves, postoperative nerve subluxation, or postoperative scarring or contracture.13
Coordination of care
A team approach to treatment requires excellent communication between the patient, electromyographer, therapists, and surgeons. Occupational therapy may be beneficial throughout the disease in order to address any deficits in functional activities, including activities of daily living that result from UNE, and to prevent further injury to the nerve by addressing risk factors and ergonomic issues.
Patient & family education
- Family education is vital to the success of conservative treatments, and postoperative compliance can influence the success of a surgical procedure.
- One study showed that patient education alone may be adequate for the treatment of some patients with mild UNE.11
Local corticosteroid injection has been shown to be beneficial in the treatment of entrapment neuropathies such as carpal tunnel syndrome 33, however, a recent RCT in patients with UNE, failed to show significant benefit of a local steroid injection compared to injection with placebo.26
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
Excluding diagnoses that may mimic UNE, symptoms are vital to arriving at the correct diagnosis. Mimicking conditions include C8 radiculopathy and lower trunk or medial cord brachial plexopathy. Because a pancoast tumor and true neurogenic thoracic outlet syndrome are potential causes of lower trunk plexopathy, it is important to exclude these diagnoses. Clues to alternative diagnosis include sensory symptoms extending proximally past the wrist into the medial forearm, an area supplied by the medial antebrachial cutaneous nerve, which originates from the medial cord of the brachial plexus, as well as neck pain radiating into the arm.
Although weakness in the ulnar-innervated forearm muscles may occur in UNE, it is rare in mild or moderate cases because of elective fascicular involvement.
Nerve conduction studies of the dorsal ulnar cutaneous (DUC) nerve can help distinguish a UNE from an ulnar neuropathy at the wrist. However, many cases of UNE spare the fibers to the DUC because of selective fascicular involvement. Therefore, one can exclude ulnar neuropathy at the wrist with an abnormal DUC nerve studies; however, one cannot assume that a normal DUC nerve excludes UNE.
4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
See the Imaging section for details on the use of MRI and ultrasound in the evaluation UNE.
5. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
- Retrospective studies attempting to see if electrodiagnostic criteria can be used to predict outcomes have shown that severe preoperative electrophysiologic findings of motor nerve involvement may be associated with poorer outcomes.27Further prospective studies evaluating this question need to be done.
- Prospective studies to evaluate different surgical techniques in specific sites of entrapment are needed
- Mondelli M, Giannini F, Ballerini M, Ginanneschi F, Martorelli E. Incidence of ulnar neuropathy at the elbow in the province of Siena (Italy). J Neurol Sci. 2005;23:5-10.
- Boninger ML, Robertson RN, Wolff M, Cooper RA. Upper limb nerve entrapments in elite wheelchair racers. Am J Phys Med Rehabil. 1996;75:170-176.
- Harmon RL. Bilaterality of ulnar neuropathy at the elbow. Electromyogr Clin Neurophysiol. 1991;31:195-198.
- American Association of Electrodiagnostic Medicine, Campbell WW. Guidelines in electrodiagnostic medicine. Practice parameter for electrodiagnostic studies in ulnar neuropathy at the elbow. Muscle Nerve Suppl. 1999;8:S171-S205.
- Stewart JD. Peripheral nerve fascicles: anatomy and clinical relevance. Muscle Nerve. 2003;28:525-541.
- Beekman R, Visser LH, Verhagen WI. Ultrasonography in ulnar neuropathy at the elbow: a critical review. Muscle Nerve. 2011;43:627-635.
- American Association of Electrodiagnostic Medicine, Olney RK. Guidelines in electrodiagnostic medicine. Consensus criteria for the diagnosis of partial conduction block. Muscle Nerve Suppl. 1999;8:S225-S229.
- Campbell WW, Pridgeon RM, Sahni KS. Short segment incremental studies in the evaluation of ulnar neuropathy at the elbow. Muscle Nerve. 1992;15:1050-1054.
- Robinson, LR. Traumatic injury to peripheral nerves. Muscle Nerve. 2000;23:863-873.
- Dellon LA. Review of treatment results for ulnar nerve entrapment at the elbow. J Hand Surg Am. 1989;14:688-700.
- Nakamichi K, Tachibana S, Ida M, Yamamoto S. Patient education for the treatment of ulnar neuropathy at the elbow. Arch Phys Med Rehabil. 2009;90:1839-1845.
- Caliandro P, La Torre G, Padau R, Giannini F, Padual L. Treatment for ulnar neuropathy at the elbow. Cochrane Database Syst Rev. 2011 Feb 16;(2):CD006839.
- Ruchelsman DE, Lee SK, Posner MA. Failed surgery for ulnar nerve compression at the elbow. Hand Clin. 2007;23:359-371.
- Macadam SA, Bezuhly M, Lefaivre KA. Outcomes measures used to assess results after surgery for cubital tunnel syndrome: a systematic review of the literature. J Hand Surg Am. 2009;34:1482-1491.
- P, La Torre G, Padua R, Giannini F, Padua L. Treatment for ulnar neuropathy at the elbow. Cochrane Database Syst Rev. 2012 July 11: 7: CD006839.
- Radhika S, Lee YL, Low SF, Fazalina MF, Sharifah Majedah IA, Suraya A, Rajesh S, Jamari S, Tan HJ, Norlinah MI. Role of high resolution ultrasound in ulnar nerve neuropathy. Med J. Malaysia. 2015 Jun; 70(3):158-61.
- Kim JH, Won SJ, Rhee WI, Park HJ, Hong HM. Diagnostic cutoff value for ultrasonography in the ulnar neuropathy at the elbow. Ann Rehabil. Med. 2015 Apr; 39(2):170-5.
- Burns P, Kim M, Gaston G, Haase S, Hammert W, Lawton J, Merrell G, Nassab P, Yang L, Chung K. Predictors of functional outcomes after simple decompression for ulnar neuropathy at the elbow: A multicenter Study by the SUN Study Group. Arch Phys Med Rehabil. 2014 Apr;95(4):680-5.
- Stewart. JD. The variable clinical manifestations of ulnar neuropathies at the elbow. Journal of Neurology, Neurosurgery, and Psychiatry 1987;50:252-258.
- Van Rijn RM, Huisstede BM, Koes BW, Burdorf A. Associations between work-related factors and specific disorders at the elbow: a systematic literature review. Rheumatology. 2009 May; 48(5):528-36.
- Bartels RH, Verbeek AL. Risk factors for ulnar nerve compression at the elbow. A case control study. Acta Neurochir (Netherlands). 2007;149(7):669-74.
- Campbell WW. Diagnosis and management of common compression and entrapment neuropathies. Neurol Clin. 1997;15(3):549.
- Baumer P, Dombert T, Staub F, Kaestel T, Bartsch AJ, Heiland S, Bendszus M, Pham M. Ulnar neuropathy at the elbow: MR neurography-nerve T2 signal increase and caliber. Radiology. 2011;260(1):199.
- Svernlov B, Larsson M, Rehn K, Adolfsson L. Conservative treatment of the cubital tunnel syndrome. J Hand Surg Eur Vol. 2009;34(2):201.
- Bartels RH, Verhagen WI, van der Wilt GJ, Meulstee J, van Rossum LG, Grotenhuis JA. Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: Part 1. Neurosurgery. 2005;56(3):522.
- vanVeen KE, Albias KC, Alons IM, Kerklaan JP, Siegersma MC, Wesstein M, Visser LH, Vankasteel V, Jellema K. Corticosteroid injection in patients with ulnar neuropathy at the elbow: A randomized, double-blind, placebo-controlled trial. Muscle Nerve. 2015 Sep;52(3):380-5
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- MacDermid JC, Grewal R. Development and validation of the patient-rated ulnar nerve evaluation. BMC Musculoskeletal Discord. 2013 Apr 26; 14:146.
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Original Version of the Topic:
Kevin F. Fitzpatrick, MD. Ulnar nerve mononeuropathy at the elbow. Publication Date: 2012/07/25
Thiru M. Annaswamy, MD
Nothing to Disclose
Dominic Jacobelli MD, UT
Nothing to Disclose