Cubital Tunnel Syndrome

Other Names

• Sulcus Ulnaris Syndrome
• Retrocondylar Groove Syndrome
• Ulnar Nerve Entrapment
• Cubital Tunnel Syndrome (CuTS)
• Cubital tunnel compression

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Background

• This page refers to cubital tunnel syndrome (CuTS), an entrapment neuropathy of the Ulnar Nerve within the Cubital Tunnel of the Elbow

History

• First described by Magee and Phalen in 1949
• The term 'cubital tunnel syndrome' first used by Feindel and Stratford in 1958

Epidemiology

• Second most common entrapment neuropathy of upper extremity behind Carpal Tunnel Syndrome
  • This is also the most common location for compression of the ulnar nerve
  • Incidence is 1/13 that of CTS
• Incidence 24.7 per 100,000 (need citation)
  • In the United Kingdom, 25 (male) and 19 (female) cases per 100,000 people per year
• Bilateral 18.6-38.8% of the time
• Prevalence
  • An et al: estimated that 5.9% of the general population have had symptoms of CuTS

Demographics

• Male > Female
• Median age is 46 years, standard deviation 15.7
• More common in white individuals compared to black, hispanic

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Introduction

Ulnar nerve branching patterns at the elbow and wrist

Illustration of the cubital tunnel

Axial view of the elbow and the cubital tunnel with the elbow in extension and flexion (MCL, medical collateral ligament).

Physical examination findings and signs in patients with cubital tunnel syndrome. A Ulnar claw hand with atrophy of the FDI. B Wartenbergs Sign. C Froments Sign. D Jeanne Sign.

General

• The most common symptoms are intermittent numbness and tingling in the ulnar ring and small fingers
• There is no diagnostic gold standard and diagnosis is made based on a combination of suspicion, physical exam and testing
• The vast majority of patients improve with conservative management

Pathophysiology

• For most individuals, repetitive and prolonged elbow flexion can lead to prolonged symptoms
  • Primarily due to unique anatomic relationship of the ulnar nerve to the elbow
  • When elbow is flexed, arcuate ligament compresses the space in the cubital tunnel by 55%
  • The elbow nerve also can be stretched by 4 to 8 mm as it hinges on the medial epicondyle
• Entrapment at the arcade of Struthers
  • Area where ulnar nerve pierces the intermuscular septum about 8 cm proximal to the medial epicondyle, enters posterior compartment
  • Compression can occur here

Etiology

• Can be differentiated into
  • Primary or idiopathic: No morphological abnormalities, especially no bony changes of the elbow joint or space occupying lesions
  • Secondary: deformation or other processes of the elbow joint
• Entrapment occurs at many potential places
• Most common
  • Cubital tunnel (most common)
  • Deep flexor pronator aponeurosis
  • Arcade of Struthers
  • Osborns ligament
• Less common
  • Medial intermuscular septum
  • Medial epicondyle
  • Hypertrophy of the medial head of the Triceps Brachii
  • Fascial bands within FCU
  • Accessory anconeus epitrochlearis muscle (3-23% of population)
  • Aponeurosis of FDS proximal edge

Anatomy of the Cubital Tunnel

• Contains the Ulnar Nerve
  • Nerve roots: C8, T1
  • Enters ulnar sulcus 3.5 cm proximal to medial epicondyle
  • Courses posterior to medial epicondyle, posterior to olecranon before entering cubital tunnel
• Cubital Tunnel
  • Roof: FCU fascia, arcuate ligament of Osbourne (syn. arcuate ligament, epitrochlear anconeus ligament, humero-ulnar arcade)
  • Floor: Ulnar Collateral Ligament, joint capsule, Olecranon
  • Walls: Medial epicondyle, olecranon
• Distal to cubital tunnel, courses deep into the forearm between the ulnar and humeral heads of the FCU
• Note Medial Antebrachial Cutaneous Nerve is very proximal to cubital tunnel

Associated Conditions

• Medial Epicondylitis
• Cubitus varus or valgus deformities
• Burns
• Elbow contracture release
• History of UCL Injury

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Risk Factors

• Obesity
• Male > female
• Tobacco Use
• Diabetes Mellitus

Socioeconomic

• Repetitive work
• Lower education level
  • Thought to be related to increased likelihood of working labor intensive job
• Economic Distress

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Differential Diagnosis

Differential Diagnosis Cubital Tunnel Syndrome

• Carpal Tunnel Syndrome
• Cervical Radiculopathy of C8 and/or T1
• Diabetic Neuropathy
• Hypothyroidism
• Vitamin Deficiency
• Complex Regional Pain Syndrome
• Guyon Canal Syndrome
• Pancoast Tumor
• Thoracic Outlet Syndrome
• Medial Epicondylitis
• Elbow Arthritis
• FCU Tendinitis
• Hypothenar Hammer Syndrome

Differential Diagnosis Elbow Pain

• Fractures
  • Adult
    • Proximal Radius Fracture (Head/Neck)
    • Olecranon Fracture
    • Capitellum Fracture
    • Coronoid Fracture
    • Terrible Triad of Elbow
  • Pediatric
    • Nursemaids Elbow
    • Supracondylar Fracture
    • Lateral Condyle Fracture (Peds)
    • Medial Condyle Fracture (Peds)
    • Olecranon Fracture (Peds)
    • Radial Head Fracture (Peds)
    • Medial Epicondyle Fracture (Peds)
    • Salter Harris Fracture
• Dislocations & Instability
  • Elbow Dislocation
  • Proximal Radioulnar Joint Instability
  • Radial Head Dislocation
• Tendinopathies
  • Lateral Epicondylitis
  • Medial Epicondylitis
  • Distal Biceps Tendon Injury
  • Triceps Tendon Injury
• Bursopathies
  • Olecranon Bursitis
  • Bicipitoradial Bursitis
• Ligament Injuries
  • Lateral Collateral Ligament Injury (Elbow)
  • Ulnar Collateral Ligament Injury
• Neuropathies
  • Cubital Tunnel Syndrome
  • Radial Tunnel Syndrome
• Arthropathies
  • Elbow Arthritis
• Other
  • Valgus Extension Overload
  • Posteromedial Rotatory Instability
  • Posterolateral Rotatory Instability
  • Osteochondral Defect
• Pediatric Considerations
  • Little League Elbow
  • Panners Disease (Avascular Necrosis of the Capitellum)
  • Nursemaids Elbow (Radial Head Subluxation)

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Clinical Features

Physical examination findings and signs in patients with CuTS. A Ulnar claw hand with atrophy of the FDI. B Wartenberg sign. C Froment sign. D Jeanne sign

Claw hand as seen with ulnar neuropathies

Elbow scratch collapse test

History

• Diagnosis can often be made clinically
• Onset is usually acute, or subacute as opposed to chronic and insidious
• Parasthesias in ulnar nerve distribution (4th and 5th digit)
• Pain is not a common or dominant feature but will report vague discomfort of medial elbow, ulnar forearm
• Difficulty with certain activities like opening doors, jars, bottles
• Rapidly fatigues with repetitive activities
• Symptoms worse at night, with flexion
• Sensitivity to medial elbow
• Weakness, muscle atrophy may or may not be reported

Physical: Physical Exam Elbow

• Weakness, atrophy of intrinsic muscles of hand, especially 4th and 5th digit
• Web space atrophy
• Clawing of 4th, 5th digits
• May see subluxing ulnar nerve at elbow with flexion-extension
• Palpation for nerve thickening
  • Sensitivity (28%), specificity (87%), PPD (84%), NPV (33%)
• Palpation for nerve tenderness
  • Sensitivity (32%), specificity (80%), PPD (80%), NPV (32%)

Special Tests

• Tinels Test: Repetitive tapping over the nerve with finger
• Elbow Flexion Compression Test: elbow in maximal flexion, examiner holds pressure at the cubital tunnel
• Scratch Collapse Test: See description
• Froments Sign: Inability to grip piece of paper between the thumb and index finger
• Wartenbergs Sign: Exaggerated abduction of the fifth digit compared to unaffected limb
• Jeanne sign: Weak and unstable pinch with hyperextension of the thumb metacarpophalangeal, thumb adduction
• Masse sign: Palmar arch flattening and loss of ulnar hand elevation
• Pollocks Test: Inability to flex DIPJ of 4th, 5th digits against resistance
• Crossed Finger Test: Inability to cross fingers, compare to unaffected side
• Finger Flexion Sign: Pull piece of paper out of 3rd/4th digits cause MP flexion to compensate for interossei weakness
• Egawas Sign: flex middle finger then abduct to both sides
• Pressure Provocative Test: apply and hold pressure immediately proximal to the cubital tunnel

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Evaluation

High-resolution ultrasound depicting dynamic instability of a hypermobile ulnar nerve (arrow). A The elbow in extension with the ulnar nerve reduced. B The elbow in hyperflexion with the ulnar nerve subluxated and no longer visible.

High-resolution ultrasound for diagnosis in CuTS. A The ulnar nerve (UN) as it courses between the 2 bellies of the FCU. B The UN as it travels around the elbow in the ulnar groove between the medial epicondyle (MEDIAL EPI) of the humerus and the medial head of the triceps (MH-TRI). C The UN (arrows) in a patient which CuTS at the FCU. D The UN (arrows) in a patient with CuTS at the FCU and perched on the medial epicondyle. The nerve’s morphological appearance is abnormally hypoechoic and has lost its normal fascicular echo pattern.

Axial MRI using T2-weighted imaging of the right elbow. A An enlarged and high signal intensity ulnar nerve in a patient with CuTS. B Comparison MRI in a patient without CuTS depicting the internal topography of the ulnar nerve fascicles.

General

• No widely accepted diagnostic gold standard
• Reasons
  • Limitations in accuracy of test
  • Interrater differences seen in tests
  • Positive tests seen in asymptomatic individuals
• Diagnosis is made with a combination of
  • Clinical suspicion
  • Physical exam
  • Interpretation of testing

Radiographs

• Standard Radiographs Elbow
  • Useful screening tool
  • Unlikely to show any pathology in the setting of cubital tunnel syndrome
  • Can see osseus spurring in chronic patients

MRI

• Findings
  • Ulnar nerve thickening
  • Ulnar nerve T2 hyperintensity
  • Edema-like signal changes

Ultrasound

• Findings
  • Nerve appears hypoechoic
  • Ulnar nerve thickening > 9 mm
  • Edematous changes
• Can also evaluate for
  • Subluxation
  • Tumors
  • Ganglia
• Diagnostic Accuracy
  • Ellegaard found a sensitivity of 80.5%
  • Beekman reported a sensitivity of more than 80% in cross sectional area
  • Ultrasound is more sensitive than MRI (93% vs 67%), specificity is the same at 86%
  • Dynamic US (88%) sensitive to predict ulnar nerve instability compared to physical exam (12%)

EMG/NCS

• Useful to confirm diagnosis, especially pre-operatively and to exclude other diagnosis
• Can see decrease in absolute conduction velocity to less than 50 m/s
• Relative drop in conduction velocity of 10 m/s or more across a segment (usually the cubital tunnel)
• Diagnostic accuracy
  • Early disease: can be normal as intermittent compression has not yet decreased nerve conduction velocity
  • Ellegaard found a sensitivity of 70.7%

Interpretation of multiple diagnostic studies

• When US is combined with EMG/NCS, sensitivity increases to 98%

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Classification

McGowan Classification of Ulnar Nerve Dysfunction

• Grade I
  • Minimal Lesion
  • Paresthesia, subjective clumsiness
  • No motor deficit
• Grade II
  • Intermediate lesion
  • Paresthesia and sensory less
  • Motor neuropathy without muscle atrophy
• Grade III
  • Severe lesion
  • Paresthesia and sensory loss
  • Severe muscle deficit, muscle atrophy

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Management

Elbow Flexion Block Splint

Ultrasound-guided injection into the cubital tunnel was conducted via an in-plane technique. (A) The patient was placed in a supine position with the shoulder abducted and the elbow flexed at 90°. (B) The ulnar nerve within the cubital tunnel was identified in transverse plane, and the injection was conducted after aseptic preparation. (C) The needle (arrowhead) passed between the medial epicondyle (ME) and ulnar nerve (dotted circle) at the level of the epicondyle. (D) After the injection, we confirmed that the ulnar nerve was separated from the epicondyle by the effect of hydrodissection. O, olecranon

Nonoperative

• Indications
  • Initial management is conservative almost universally
  • There should be no evidence of axon loss, weakness or atrophy
• Activity modification
  • Avoid certain positions particularly elbow flexion, such as when talking on the telephone
  • Positions in which the medial elbow is resting on a hard surface, such as elbows on arm rests when working on a computer
• Elbow Flexion Block Splint
  • Night bracing in 45° extension with forearm in neutral rotation
  • Hong et al found improvement in symptoms at 1- and 6-month follow up
  • Shah et al found that 88% of patients improved at 1.5-, 3 and 12-months of conservative treatment that included a flexion block splint
  • Svernlov et al found no difference in outcomes between elbow bracing and nerve glide exercises (need citation)
• Physical Therapy
  • Specifically, nerve glide exercises
  • Svernlov et al found no difference in outcomes between elbow bracing and nerve glide exercises (need citation)
• Cubital Tunnel Injection
  • When combined with flexion block splint, no benefit was seem from a corticosteroid injection

Operative

• Indications
  • When conservative therapy fails
  • Severe deficits
• Technique
  • In situ decompression
  • Medical Epicondylectomy
  • Endoscopic Cubital Tunnel Release
  • Anterior Transposition

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Rehab and Return to Play

Rehabilitation

• Typically, so-called nerve flossing or nerve glide exercises

Return to Play

• Variable
• Nonsurgical cases can return to play when symptoms resolve

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Prognosis and Complications

Prognosis

• Conservative management
  • Svernlov et al: 90% improvement in patients treated with early disease (regardless of whether they received education, night time splint or nerve glide exercises)
  • Success is lower in pediatric and adolescent patients but should still be attempted

Complications

• Injury to Medial Antebrachial Cutaneous Nerve
• Recurrence of symptoms
• Neuroma

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See Also

Internal

• Forearm Pain (Main)
• Elbow Pain (Main)
• Arm Pain (Main)
• Elbow Anatomy (Main)
• Physical Exam Elbow

External

• Sports Med Review Elbow Pain: https://www.sportsmedreview.com/by-joint/elbow/

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