BASICS
DESCRIPTION
- Compression of the ulnar nerve on the medial aspect of the elbow where it enters the cubital tunnel results in cubital tunnel syndrome (CuTS). Elbow pain, loss of grip strength, and paresthesias of the forearm, wrist, and 4th and 5th fingers are the most common symptoms.
- Synonym(s): ulnar neuropathy
- Compression of the ulnar nerve at the wrist results in ulnar tunnel syndrome (UTS).
EPIDEMIOLOGY
- Predominant sex: male > female (3 to 8 times more common)
- Elbow is the most common site of compression of ulnar nerve resulting in CuTS.
- Less common sites of entrapment include the following:
- Arcade of Struthers
- Medial intermuscular septum
- Medial epicondyle
- Deep flexor pronator aponeurosis (1)
- CuTS is second to carpal tunnel syndrome as the most common nerve compression of upper extremity (2).
ETIOLOGY AND PATHOPHYSIOLOGY
- The ulnar nerve is the terminal branch of the medial cord of the brachial plexus; it is composed of portions of the C8 and T1 nerve roots.
- The ulnar nerve becomes more superficial as it enters the ulnar sulcus near the medial epicondyle. The nerve runs posteriorly to the medial epicondyle and medial to the olecranon to enter the cubital tunnel (2).
- The cubital tunnel is a fibro-osseous canal bordered by the arcuate ligament of Osborne as the roof and the medial collateral ligament of the elbow, the joint capsule, and the olecranon as the floor.
- The distance from medial epicondyle to olecranon increases 5 mm for every 45 degrees of elbow flexion.
- Elbow flexion places stress on medial (ulnar) collateral ligament, overlying retinaculum, and ulnar nerve.
- The cubital tunnel shape changes from circular to ovoid and loses 2.5 mm of height with elbow flexion.
- Loss of height of cubital tunnel with elbow flexion decreases tunnel volume by 55%, doubling intraneural pressure on the ulnar nerve.
- Maximal pressure on the ulnar nerve in cubital tunnel is created by shoulder abduction, elbow flexion, and wrist extension.
- Elbow flexion decreases volume of cubital tunnel, causing compression of the ulnar nerve.
- Compression of the ulnar nerve causes pain at the medial elbow and symptoms in the forearm and hand.
- Compression prior to or within the Guyon canal produces intrinsic muscle weakness and dorsolateral sensation loss (3).
- Etiologies include constricting fascial bands, subluxation of ulnar nerve over medial epicondyle, cubitus valgus, bony spurs, hypertrophied synovium, tumors, ganglia, or direct compression of ulnar nerve as it crosses the cubital tunnel.
- Compression by ganglia, anomalous musculature, carpal bone fracture, or direct hypothenar pressure results in ulnar tunnel syndrome (4).
RISK FACTORS
- Patients who sleep with their elbows bent and arms overhead
- Patients with occupations demanding prolonged flexion of the elbows (5)[A]
- Athletes in throwing sports, racquet sports, weightlifting, skiing, and cycling
- Preexisting polyneuropathy
- Patients on hemodialysis
- Patients in a prolonged dependent position (e.g., post surgery, ICU) where the elbow rests against firm bedding
GENERAL PREVENTION
- Avoid long periods of elbow flexion, pressure on elbows or anterior ulnar aspect of the wrist.
- Sleep with elbows straight; avoid sleeping with arms overhead.
- Proper ergonomic posture
COMMONLY ASSOCIATED CONDITIONS
- Ulnar nerve subluxation
- Ulnar collateral ligament laxity
- Osteoarthritis of elbow joint
- Carpal tunnel syndrome
DIAGNOSIS
HISTORY
- Nocturnal elbow pain; medial elbow pain
- Paresthesias along medial forearm, wrist, and 4th and 5th digits
- Paresthesias: intermittent at first then more constant
- History of elbow trauma
- Repetitive elbow flexion and extension (e.g., hammering)
- Overhead-throwing athlete or repetitive elbow motion
- Chronic symptoms: loss of grip strength and loss of fine motor skills in hand
PHYSICAL EXAM
- Inspect carrying angle of both elbows.
- Palpate medial epicondyle and cubital tunnel for tenderness or ulnar nerve subluxation.
- Assess elbow range of motion.
- Positive Hoffman-Tinel test (CuTS) (percussion at ulnar nerve reproduces symptoms) (4)
- Pain on palpation over ulnar nerve
- Atrophy of intrinsic hand muscles
- Loss of sensation of 5th digit and medial 4th digit
- Wasting of hypothenar muscles and flexion contracture of 4th and 5th digits (ulnar claw)
- Wartenberg sign: clawing or abduction of the 5th digit with extension.
- Assess ability to cross 2nd and 3rd digits.
- Evaluate grip and pinch strength.
- Froment sign: Hyperflexion of the interphalangeal joint of the thumb while trying to secure a sheet of paper between the thumb and 1st finger as the examiner pulls the paper away (4)
- Assess vibration and light touch sensation.
- Scratch-collapse test: Patient faces the examiner with arms adducted, elbows flexed, hands outstretched, and wrist in neutral position. The examiner gently pushes against both forearms, asking the patient to maintain steady resistance. The examiner scratches the skin overlying the potentially compressed ulnar nerve. The test is positive if the patient decreases resistance. Sensitivity for the scratch collapse was 69% compared with 54% and 46% for Tinel test and elbow flexion-compression test, respectively. Tinel test, however, had the highest negative predictive value (98%) of all tests for cubital tunnel (6).
- Intact sensation of dorsolateral hand implies nerve compromise distal to the takeoff of the dorsal sensory branch.
- Sensory loss to dorsolateral hand without hypothenar and interosseous weakness implies compression of superficial branch of ulnar nerve.
DIFFERENTIAL DIAGNOSIS
- C8-T1 radiculopathy
- Brachial plexopathy
- Thoracic outlet syndrome
- Carpal tunnel syndrome
- Medial epicondylitis
- Ulnar collateral ligament injury
- Pancoast syndrome
- Metabolic disorders creating peripheral neuropathies
- Multiple sclerosis and other myelopathies
DIAGNOSTIC TESTS & INTERPRETATION
McGowan grades quantify the degree of physical exam findings for cubital tunnel syndrome:
- McGowan grade I: no wasting or weakness of intrinsic muscles, feeling of clumsiness in affected hand, mild paresthesias in ulnar nerve distribution
- McGowan grade II: intermediate lesions with weak interossei and muscle wasting
- McGowan grade III: severe lesions with paralysis of interossei and a marked weakness of the hand
Initial Tests (lab, imaging)
- X-ray may reveal osteophyte impingement of cubital tunnel or hamulus fracture in the wrist. Radiographs may also show signs of instability, deformity from old trauma, or presence of a supracondylar process (which can cause median nerve compression). Include anteroposterior (AP), lateral, and cubital tunnel views (1).
- Cubital tunnel view: Elbow is maximally flexed, and x-ray beam is shot as an AP view of the distal humerus.
Follow-Up Tests & Special Considerations
- Chest x-ray if patient has history of smoking and ulnar nerve symptoms (to exclude Pancoast tumor)
- MRI may show inflammation and irritation of the ulnar nerve (not routinely necessary).
- High-resolution musculoskeletal ultrasound
Diagnostic Procedures/Other
- 1 mL lidocaine and 20 to 40 mg methylprednisolone injected into ulnar groove, parallel to ulnar nerve for CuTS (7)
- Electromyogram with nerve conduction studies (EMG/NCS) is not essential when diagnosis is obvious on clinical exam. Use to determine the efficacy of conservative treatment or when the diagnosis is unclear.
Test Interpretation
Delayed conduction of solely the ulnar nerve on an EMG/NCS implies a likely compressive neuropathy. Subjective improvement after diagnostic injection indicates anatomic site of compression at injection site.
TREATMENT
- Mild cubital tunnel syndrome can often be treated without surgery. Consider surgery if no change after 3 months.
- If provocative causes can be identified and avoided, some recovery is likely.
- Patients with progressive or constant symptoms and/or muscle atrophy typically require surgical intervention (1)[C].
- If UTS is caused by direct compression, activity modification is effective (8)[C].
- Conservative treatment is initial approach if no motor weakness (4,9)[C].
GENERAL MEASURES
- Activity modification
- Avoid aggravating activities.
- Avoid prolonged elbow flexion.
- Avoid prolonged pressure/compression of ulnar nerve at elbow or wrist.
- Ice for symptom relief
- Splint or brace while sleeping to keep affected elbow in extension and take pressure off cubital tunnel (e.g., wrap towel around elbow and hold in place with tape; use a small size soft knee splint placed backward on the elbow, tie a scarf around waist then around wrist).
- For cyclists with UTS, frequent hand repositioning on handlebars is recommended.
- Physical therapy (nerve mobilization techniques and forearm and wrist stretching)
- Workplace/ergonomic modifications (e.g., correct posture, avoid long periods with elbows bent)
- Otherwise, activity is as tolerated.
MEDICATION
First Line
NSAIDs and activity modification to limit elbow flexion or hypothenar pressure; corticosteroid injection into the cubital tunnel (7)[B]
ISSUES FOR REFERRAL
CuTS: Failure of 3 to 6 months of conservative treatment, loss of grip strength, flexion contracture of 4th and 5th digits, and positive EMG for motor conduction delay merit surgical consultation (9)[C].
UTS: organic compressive lesion, motor deficit, failure of conservative treatment or dysesthesia >36 hours after wrist fracture (4)[C]
ADDITIONAL THERAPIES
Hand therapy and custom-splint prescription
COMPLEMENTARY & ALTERNATIVE MEDICINE
Vitamin B6 (100 mg/day) is not effective in randomized trials.
SURGERY/OTHER PROCEDURES
- Goal of surgery in CuTS is to create more space for the ulnar nerve (9).
- Multiple surgical options exist for the treatment of CuTS. Overall results have essentially been equivalent. The choice of surgical procedure is based on multiple factors, and a single surgical approach cannot be applied to all clinical situations (10)[A].
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
- In severe cases, the nerve damage may be permanent.
- Patients with symptoms lasting >6 months have a worse prognosis.
DIET
No restrictions
PATIENT EDUCATION
- Use correct posture; avoid putting pressure on elbows, and place padding under elbows.
- Inability to fully extend affected fingers is a sign of severe ulnar nerve damage. Patients with this level of irritation usually do not recover, even with surgery.
PROGNOSIS
- Both conservative and surgical methods result in good to excellent results in 85-90% of cases.
- For McGowan grade III: Anterior IM transposition has best outcome (9)[C].
COMPLICATIONS
Anterior transposition and simple decompression may be complicated by recurrent subluxation of the ulnar nerve.
REFERENCES
11 Hariri S, McAdams TR. Nerve injuries about the elbow. Clin Sports Med. 2010;29(4):655-675.22 Palmer BA, Hughes TB. Cubital tunnel syndrome. J Hand Surg Am. 2010;35(1):153-163.33 Cheng CJ, Mackinnon-Patterson B, Beck JL, et al. Scratch collapse test for evaluation of carpal and cubital tunnel syndrome. J Hand Surg Am. 2008;33(9):1518-1524.44 Chen SH, Tsai TM. Ulnar tunnel syndrome. J Hand Surg Am. 2014;39(3):571-579.55 van Rijn RM, Huisstede BM, Koes BW, et al. Associations between work-related factors and specific disorders at the elbow: a systematic literature review. Rheumatology (Oxford). 2009;48(5):528-536.66 Anderton M, Webb M. Cubital tunnel syndrome. Br J Hosp Med (Lond). 2010;71(11):M167-M169.77 Rampen AJ, Wirtz PW, Tavy DL. Ultrasound-guided steroid injection to treat mild ulnar neuropathy at the elbow. Muscle Nerve. 2011;44(1):128-130.88 Murata K, Shih JT, Tsai TM. Causes of ulnar tunnel syndrome: a retrospective study of 31 subjects. J Hand Surg Am. 2003;28(4):647-651.99 Mowlavi A, Andrews K, Lille S, et al. The management of cubital tunnel syndrome: a meta-analysis of clinical studies. Plast Reconstr Surg. 2000;106(2):327-334.1010 Mitsionis GI, Manoudis GN, Paschos NK, et al. Comparative study of surgical treatment of ulnar nerve compression at the elbow. J Shoulder Elbow Surg. 2010;19(4):513-519.
ADDITIONAL READING
- Assmus H, Antoniadis G, Bischoff C, et al. Cubital tunnel syndrome-a review and management guidelines. Cent Eur Neurosurg. 2011;72(2):90-98.
- Shi Q, MacDermid JC, Santaguida PL, et al. Predictors of surgical outcomes following anterior transposition of ulnar nerve for cubital tunnel syndrome: a systematic review. J Hand Surg Am. 2011;36(12):1996.e6-2001.e6.
SEE ALSO
Epicondylitis
CODES
ICD10
- G56.20 Lesion of ulnar nerve, unspecified upper limb
- G56.22 Lesion of ulnar nerve, left upper limb
- G56.21 Lesion of ulnar nerve, right upper limb
- S54.00XA Injury of ulnar nerve at forearm level, unspecified arm, initial encounter
- S54.01XA Injury of ulnar nerve at forearm level, right arm, initial encounter
- S54.02XA Injury of ulnar nerve at forearm level, left arm, initial encounter
ICD9
- 354.2 Lesion of ulnar nerve
- 955.2 Injury to ulnar nerve
SNOMED
- Cubital tunnel syndrome
- Ulnar neuropathy
- lesion of ulnar nerve (disorder)
- Injury of ulnar nerve (disorder)
- Ulnar nerve entrapment at elbow (disorder)
CLINICAL PEARLS
- Elbow flexion decreases depth of cubital tunnel, compressing the ulnar nerve, and contributing to CuTS.
- Sleeping with the elbow bent and arm overhead can exacerbate symptoms.
- Improper posture when working at a desk can also exacerbate symptoms.
- Conservative treatment consists of ice, rest, hand therapy, splint fabrication, and activity modifications for 3 months.
- Both conservative and surgical treatments have good long-term results. Choice of therapy depends of duration of symptoms and patient preference.