Introduction
- Robert C. Manske, PT, DPT, MEd, ATC, SCS, CSCS
- Mark Stovak, MD, FACSM, FAAFP, CAQSM
Epidemiology
The epidemiology of forearm nerve entrapments is dependent upon type.
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Median
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Carpal tunnel syndrome
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Most common nerve entrapment in upper extremity
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Twice as common in females
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Most commonly between ages of 45 and 54 years of age
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Can occur frequently during pregnancy
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Common in fast-pitch softball pitchers
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May be related to occupational, gripping, or other athletic pursuits
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Pronator syndrome
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Common in athletes such as fast-pitch softball pitchers
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Anterior interosseous nerve (AIN) entrapment
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Entrapped in forearm
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Radial (least common form of nerve entrapment)
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Radial tunnel syndrome
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Only 1% to 2% of upper extremity entrapments
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Most commonly in fourth to sixth decades of life
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Posterior interosseous nerve (PIN) entrapment
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Often misdiagnosed as tennis elbow
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Seen in throwing sports
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Superficial branch (Wartenberg’s syndrome)
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Common with handcuffs or wrist straps
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Ulnar
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Cubital tunnel
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Second most common entrapment location in upper extremity
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More commonly seen in males than females
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Common in throwing athletes but can also be seen in skiing, weight lifting, and racquet sports
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Guyon’s canal
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Often seen in bicyclists from gripping handlebars (especially off-road)
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Pathophysiology
Intrinsic Factors
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Median
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Repetitive or overuse
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Underlying disease such as diabetes mellitus, thyroid myxedema, rheumatological disease, acromegaly, amyloidosis, renal dialysis, and alcoholism increase risk
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Size of median nerve and contents inside carpal tunnel exceed that of space available or are too large
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Large forearm musculature increases risk of pronator syndrome or AIN entrapment
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Radial
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Vulnerable to injury at several points along anatomical course:
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Proximally at axilla
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Shaft of humerus in spiral groove (Saturday night palsy)
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Compression by lateral head of triceps
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At radial tunnel by fibrous bands or edge of extensor carpi radialis brevis—PIN
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Arcade of Frohse, sometimes called the supinator arch, is a fibrous arch over the PIN
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Supinator muscle—PIN
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Between brachioradialis and extensor carpi radialis longus—PIN
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Superficial branch at distal radial forearm
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Ulnar
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Vulnerable to injury at several points along anatomical course:
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Proximally at axilla
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Arcade of Struthers, a canal formed by a short band of fibrous tissue proximal to medial epicondyle
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Medial head of triceps muscle
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Medial epicondyle
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Ulnar groove
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Cubital tunnel
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Flexor aponeurosis
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Guyon’s tunnel, a bony tunnel in the proximal wrist formed by the pisiform and the hamate bones
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Extrinsic Factors
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Median
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Direct trauma—AIN
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Overuse injury causing swelling to finger/wrist/forearm musculature
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Vibration at the hand and wrist
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Radial
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Direct trauma to distal radial forearm—superficial branch
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Fracture of humeral shaft—proximal radial nerve
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Compression from hypertrophy of muscles/tennis elbow straps—PIN
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Ulnar
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Direct trauma—Guyon’s canal
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Traction following ulnar collateral ligament insufficiency
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Fracture callus
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Traumatic Factors
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Median
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Carpal tunnel syndrome
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Direct trauma
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Compression by other tendons of extrinsic finger flexors
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Fractures
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Radial
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Direct trauma to distal radial forearm—superficial branch
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Direct trauma to proximal arm—Saturday night palsy
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Fracture of humeral shaft
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Ulnar
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Direct trauma in axilla—crutches
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Direct trauma in hand/wrist—Guyon’s canal
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Compression from muscles/tendons (medial head of triceps)
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Fracture callus
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Bone spurs
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Pressure from combined movements of wrist extension and elbow flexion
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Classic Pathological Findings
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Median
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Carpal tunnel syndrome
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Aching, burning and paraesthesia in thumb, forefinger, middle finger, and wrist
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Symptoms worse at night
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Grip weakness
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Weakness in hand and wrist
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Thenar muscle atrophy if chronic
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Loss of two-point discrimination
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Pain with fast-pitch softball
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Pronator syndrome
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Forearm pain with similar symptoms
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AIN
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Weakness of flexion of first and second DIP joints so cannot make the O-sign
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Radial
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Proximal injury
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Weakness of elbow flexion or extension
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Mild weakness of wrist/finger extension
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Loss of sensation of posterior arm, forearm, and hand
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Wrist drop
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PIN
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Forearm pain despite its being a purely motor nerve
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Superficial branch
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Radial wrist and index finger/thumb numbness/tingling
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Ulnar
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Sensory changes fourth and fifth digits
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Hypothenar muscular atrophy if chronic
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Pincer grip weak—Froment sign
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Problems opening jars
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Fatigue with repetitive hand finger motions
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Clinical Presentation
History
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Median
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Trauma or repetitive activities
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Sports or vocation that involves repetitive gripping/vibration
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Sports or vocation that involves repetitive supination or pronation
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Radial
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Compression at axilla such as falling asleep with arm over back of chair
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Repetitive wrist and forearm movements
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Repetitive gripping, pinching, or grasping activities
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Ulnar
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Trauma or repetitive activities
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Throwing or overhead sports that require elbow flexion/extension
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Occupation involving repetitive elbow flexion/extension
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Repetitive gripping/vibration
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Physical Examination
Abnormal Findings
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Median
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Carpal tunnel syndrome
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Paraesthesia and numbness in hand (fingers 1 to 3) and wrist
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Atrophy of abductor pollicis brevis if chronic
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Positive Phalen’s test ( Figure 13-1A )
FIGURE 13-1
A, Diagram of Phalen’s test. B, Diagram of Tinel’s test.
(Redrawn from Brotzman SB: Hand and wrist injuries: Nerve compression syndromes. In Brotzman SB, Manske RC, editors: Clinical orthopaedic rehabilitation , ed 3. Philadelphia, 2011, Elsevier, Fig 1-24AB .)
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Positive Tinel’s test ( Figure 13-1B )
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Hypertrophy of pronator teres muscle (pronator teres syndrome)
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Weakness of flexion first and second finger DIP joints (AIN)
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Radial
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Posterior interosseus nerve
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Dull ache in lateral elbow
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Pain over extensor mass
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Pain with resisted supination
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Pain with extension of middle finger
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Paraesthesia over dorsal hand and radial forearm (superficial branch)
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Ulnar
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Cubital tunnel syndrome
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Pain to palpation/Tinel’s sign of medial elbow in cubital fossa
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Paraesthesia in ulnar side of fourth and fifth digits
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Loss of fine motor control of hand and fingers
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Pain to palpation/Tinel’s sign at Guyon’s canal
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Pertinent Normal Findings
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Median, radial, and ulnar
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Normal sensation in remaining fingers
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Usually no signs of autonomic nervous system dysfunction
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Imaging
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Median, radial, and ulnar
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Electrodiagnostic studies—both electromyography/nerve conduction study (EMG/NCS)
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Routine radiographic series to evaluate for bone spurs
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Ultrasonography for tenosynovitis or nerve swelling
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Magnetic resonance imaging
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Differential Diagnosis
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Median
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Anterior interosseous syndrome—jersey finger
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Pronator syndrome—medial epicondylitis
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Carpal tunnel syndrome—flexor tendon tenosynovitis
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Brachial neuritis
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Humeral supracondylar process syndrome
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Medial epicondylitis
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Myopathies
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Thoracic outlet syndrome
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Tumor or space-occupying lesion
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Radial
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PIN—lateral epicondylitis
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Brachial neuritis
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De Quervain’s/intersection tenosynovitis
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Humeral supracondylar process syndrome
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Myopathies
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Thoracic outlet syndrome
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Tumor or space-occupying lesion
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Ulnar
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Cubital tunnel syndrome—subluxing ulnar nerve
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Brachial neuritis
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Cervical radiculopathy
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Medial epicondylitis
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Myopathies
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Thoracic outlet syndrome
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Tumor or space-occupying lesion—Guyon’s canal
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Ulnar artery aneurysms or thrombosis—Guyon’s canal
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Treatment
Nonoperative Management
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Median, radial, and ulnar
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Counterforce bracing
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Splinting/casting to reduce swelling and active inflammation
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Electrical modalities to treat pain and swelling
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Ice for pain control and prevention of swelling
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Soft-tissue stretching and mobilization to reduce tension/fibrosis in muscles surrounding nerves
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Neural mobilization or nerve gliding techniques
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Total arm strengthening and localized strengthening for dynamic control
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Avoid or eliminate aggravating factors
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Ergonomic assessment for work
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Sports biomechanical assessment (tennis racquet assessment, throwing assessment)
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Antiinflammatory medications—nonsteroidal antiinflammatory drugs (NSAIDs)/steroids
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Perineural steroid injections
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Iontophoresis or phonophoresis
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Neurolysis
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Guidelines for Choosing Among Nonoperative Treatments
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Choose the best option for each patient in an individualized fashion by involving the patient in the decision-making process
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Need to discern if the etiology of the entrapment is inflammatory or mechanical or both and the underlying etiology before deciding on a management plan
Surgical Indications
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Median, radial, and ulnar
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No absolute surgical indications—it is always the patient’s decision
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Relative surgical indications
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Severe or worsening neurological symptoms
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Failure to respond to appropriate conservative treatment
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Unexplained symptoms inconsistent with pathology
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EMG/NCS showing moderate to severe nerve injury that is consistent with the symptoms
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Aspects of History, Demographics, or Exam Findings That Affect Choice of Treatment
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Treatment options are based on the best options for pain management, correction of the underlying etiology of the problem, and rehabilitation to help prevent future reoccurrences from the preceding list
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Avoid NSAIDs/steroids if history of abdominal pain/ulcers/gastritis/gastrointestinal (GI) bleed
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If pain with neural tension testing—add nerve glides
Aspects of Clinical Decision Making When Surgery Is Indicated
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Muscle atrophy/weakness
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Inability to work secondary to the loss of function or pain
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Worsening symptoms despite appropriate conservative care
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Moderate or severe nerve damage by EMG/NCT
Evidence
Related posts:
Adhesive Capsulitis and Glenohumeral Arthritis
Patellar Instability
Midfoot Strains and Sprains and Lisfranc Injuries
Triangular Fibrocartilage Complex Injuries
Leg Pain in the Athlete: Stress Fractures, Medial Tibial Stress Syndrome, and External Compartment Syndromes
Ulnar Collateral Ligament Injuries
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