ENTRAPMENT NEUROPATHIES OF THE UPPER LIMB

Jerry Antony

• Entrapment neuropathy is caused by the direct pressure

on a single nerve.

• Symptoms & signs depend on which nerve is affected.

• Earliest symptoms to occur: tingling & neuropathic pain.

• Followed by reduced sensation or complete numbness

• Muscle weakness is noticed later, followed by muscle

atrophy.

Pathophysiology

COMPRESSIONVENOUS

OBSTRUCTION + ISCHEMIA

ANOXIC SEGMENT

NEURAL EDEMA &

DILATATION OF SMALL VESSELS

EXACERBATION OF ORIGINAL

COMPRESSION

CONT OF VICIOUS CYCLE

PERSISTENT EDEMA + ANOXIA/HYPOXIA

FIBROSIS

IMPAIRMENT OF SUPPLY

DEFICIENCY OF VITAL

NUTRIENTS

FUNCTIONAL IMPAIRMENT

PERMANENT IMPAIRMENT

OF FUNCTION IF LEFT

UNTREATED

MEDIAN NERVE

• 3 important compression neuropathies from distal to

proximal

CARPAL TUNNEL SYNDROME

ANTERIOR INTEROSSEOUS SYNDROME

PRONATOR SYNDROME

CARPAL TUNNEL SYNDROME• Results from compression of the median nerve within the

carpal tunnel.• Most common compression neuropathy in the upper limb.

ANATOMYCylindrical cavity connecting the volar forearm with the palm.• Floor: transverse arch of carpal bones• Medially: hook of hamate, triquetrum & pisiform• Laterally: scaphoid, trapezium & fibro osseous flexor carpi

radialis sheath.• Roof: proximally flexor retinaculum, transverse carpal ligament

over the wrist and aponeurosis between thenar & hypothenar muscles distally.

CONTENTS:• Tendons of flexor digitorum superficialis & profundus in a

common sheath• Tendon of flexor pollicus longus in an independent sheath• Median nerve

ETIOLOGY:

• DECREASE IN SIZE OF CARPAL TUNNELBony abnormalities of the carpal bonesAcromegaly

• INCREASE IN CONTENTS OF CANALForearm & wrist fractures (colle’s, scaphoid)Dislocations & subluxations (scaphoid rotary subluxation, lunate

volar dislocation)Post traumatic arthritis (osteophytes)Aberrant muscles (lumbricals, palmaris longus, palmaris

profundus)Local tumours (neuroma, lipoma, ganglion, cysts, multiple

myeloma)Persistent medial arteryHyrertrophic synoviumHematoma (hemophilia, anti coagulation therapy, trauma)

• NEUROPATHIC CONDITIONSDMAlcoholismDouble crush syndromeExposure to industrial solvents

• INFLAMMATORY CONDITIONSRheumatoid arthritisGoutNon specific tenosynovitisInfections

• EXTERNAL FORCESVibrationDirect pressure

• ALTERATIONS OF FLUID BALANCEPregnancyMenopauseEclampsiaThyroid disorders (esp. hypothyroidism)Renal failureLong term hemodialysisRaynaud’s diseaseObesity

CLINICAL FEATURES: • SIGNS : Tinel's sign, thenar atrophy, sensory changes in the

distribution of median nerve • Tinel’s sign: percussing the

median nerve at the wrist.

• Phalen’s test:Patient places elbow on table,

forearm vertical with wrist flexed.Numbness & Tingling in median nerve

distribution occurs in 60 seconds in + ve cases.

• Reverse Phalen’s test:Sustained extension of the wrist may also

aggravate the symptoms. Not a reliable test.

• TOURNIQUET TEST: Inflating a BP cuff on the arm to a pressure above systolic

pressure will initiate symptoms (paraesthesia & numbness).

• DURKAN’S TEST: Application of direct pressure on the carpal tunnel with either

pressure manometer or by thumb of the examiner for 30 seconds will produce the symptoms.

SENSORY TESTS• Weber’s 2 point discrimination test:

Test is positive in about one-third cases.• Semmes - Weinstein monofilaments:

Monofilaments of increasing diameters are touched to palmar side of the digit until the patient can tell which digit is touched.

INVESTIGATIONS:• Electro diagnostic studies:

Most reliable confirmatory test.

Conduction time & latency for both sensory & motor conduction is

determined.

• CT & MRI:

If mass is suspected within the carpal tunnel

• LABORATORY TESTS: specific cause is suspected

Renal & thyroid function, RA factor, ESR, Anti nuclear antibody, uric acid,

blood sugars.

Radiographs: Wrist AP, Lateral, Carpal tunnel views. Useful in detecting

congenital anomalies, fractures, Calcific deposits or tumours of carpal

bones.

TREATMENT:

• NON OPERATIVE

• OPERATIVE

NON OPERATIVE:Activity modificationNSAID’SSplintingTreating the underlying diseaseLocal steroid injections

OPERATIVE: OPEN CARPAL TUNNEL RELEASE ENDOSCOPIC CARPAL TUNNEL RELEASE

INDICATIONS:Failure of non operative treatmentWeakness/atrophy of abductor pollicis brevisObjective sensory changesElectrophysiological evidence of thenar muscle denervation

OPEN CARPAL TUNNEL RELEASE:• Incision & deeper dissection are performed ulnar to the

longitudinal plane between the ulnar border of the ring finger & a point along the wrist crease noted by flexing the ring finger against the palm.

• Transverse carpal ligament is divided proximally to distally.• Complete demonstration of the recurrent branch of median

nerve should be performed.

COMPLICATIONS:• Incomplete division of transverse carpal ligament.• Division of palmar cutaneous branch or motor branch of median nerve.• Injury to superficial palmar vascular arch.• Reflex sympathetic dystrophy.• Palmar hematoma.• Loss of grip strength.

ENDOSCOPIC CARPAL TUNNEL RELEASE

Emerging technology for open decompression of the carpal tunnel.

CONTRAINDICATIONS:Co existent ulnar tunnel release.Limited wrist & finger extension.TenosynovitisPrevious surgery

ANTERIOR INTEROSSEOUS SYNDROME

• Anterior interosseous branch of the median nerve supplies the flexor digitorum profundus to the index finger, flexor pollicis longus & pronator quadratus.

• Provides sensation to the volar aspect of carpus.

• POTENTIAL SITES OF COMPRESSION:Fibrous bands of the flexor digitorum superficialisFibrous bands of the deep or superficial heads of the pronator

teres.

• LESS COMMMON CAUSESAnomalous musclesEnlarged / thrombosed vesselsTumoursEnlarged bursae

CLINICAL FEATURES:• Weakness of flexion in the IP joint of the thumb.• Weakness of flexion in the DIP joint of index finger.• No sensory loss• Pain is exacerbated by exercise & relieved by rest.• Number of cases occur due to a viral neuropathy.

TREATMENT• INITIALLY: CONSERVATIVE• SURGICAL: INDICATIONS

No resolution of symptomsSevere symptoms

• SURGICAL EXPLORATION: Identification & division of the offending structure.

PRONATOR SYNDROME

Anatomical sites of compression:Below lacertus fibrosusBetween the 2 heads of pronator teres

CLINICAL FEATURES

• Ache or discomfort in the fore arm associated with

weakness or clumsiness of the hand.

• Numbness in the distribution of the median nerve.

• Night pain is not common.

• Phalen’s test & Tinel's sign: negative

• Difficult to demonstrate electrophysiological abnormality.

TREATMENT

• CONSERVATIVE:NSAID’SSplinting with the elbow at 90 degrees, slight forearm

pronation & wrist flexion.

• SURGICAL:Exploration of distal 5 to 8 cm of the course of the

median nerve in the arm combined with its course in the upper forearm.

Possible sites checkedAppropriate release is done.

ULNAR NERVE

• Ulnar nerve gets entrapped at 2 common sites:

At the elbow (cubital tunnel syndrome)

Guyon’s canal (ulnar tunnel syndrome)

CUBITAL TUNNEL SYNDROME• Second commonest nerve entrapment of the upper limb• ANATOMY: CUBITAL TUNNEL

Starts at the groove between the olecranon & the medial epicondyle.

Tunnel is formed by a fibrous arch connecting the 2 heads of the flexor carpi ulnaris & lies just distal to the medial epicondyle.

CAUSES OF ENTRAPMENT• ARCADE OF STRUTHER’S: Formed by superficial muscle

fibres of the medial head of triceps attaching to the medial epicondyle ridge by a thickened condensation of fascia.

• Tight fascial band over the cubital tunnel.• Medial head of triceps• Aponeurosis of flexor carpi ulnaris• Recurrent subluxation of ulnar nerve, results in neuritis.• Osteophytic spurs• Cubitus valgus following supra condylar fracture.

CLINICAL FEATURES• Numbness involving the little finger & the ulnar half of the

ring finger.• Hand weakness & clumsiness• Tenderness over the ulnar nerve at the elbow.• Tinel’s sign is positive: exacerbation of paraesthesia’s with

light percussion over the ulnar nerve.• Advanced cases : clawing of the ring & little fingers

TREATMENT

• NON OPERATIVE: Early stages

Activity modification

Immobilization of the elbow in 30 degrees of extension, followed by

periods of mobilization with elbow padding.

• SURGICAL:

Decompression of the nerve by dividing of the basic offending

structure.

Anterior transposition of the ulnar nerve

Medial epicondylectomy

ULNAR TUNNEL SYNDROME• Ulnar nerve is compressed as it passes through

GUYON’S canal in the wrist.• Less common than entrapment of the ulnar nerve at the

elbow.

ANATOMY:GUYON’S CANAL

• ROOF: composed of palmar carpal ligament blending into the FCU tendon attaching to the pisiform & the pisiohamate ligaments.

• Medial wall : pisiform & pisiohamate ligament.• Lateral wall: hook of hamate & some fibres of the transverse

carpal ligament.• Ulnar nerve enters guyon’s canal accompanied by ulnar A &

Ulnar V.• Guyon’s canal lies in the space between flexor retinaculum &

volar carpal ligaments.

• The anatomy of distal ulnar tunnel is divided into 3 zones.

• Zone 1:proximal to the bifurcation of the ulnar nerve &

consists of both sensory & motor fibres of the nerve.

• Zone 2: represents the motor branch of the ulnar N distal

to the bifurcation.

• Zone 3: represents the sensory branches of the ulnar

nerve beyond its bifurcation.

Clinical presentations:

• ZONE 1 LESIONS : Mixed sensory & motor loss.

• ZONE 2 LESIONS : Isolated motor deficit.

• ZONE 3 LESIONS : Isolated ulnar N sensory loss.

• Common Causes in zone 1 & 2: ganglions, fractures of

the hook of hamate.

• Zone 3: ulnar artery thrombosis

OTHER CAUSES:• Malunited fracture of fourth/fifth metacarpal.• Anomalous muscles• Occupational trauma

INVESTIGATIONS• X RAY : Oblique/carpal tunnel views

Delineate bony anatomy to diagnose hook of hamate fractures.

• MRI: Ganglia, space occupying lesions

TREATMENT• Operative release of the canal by reflecting the FCU,

pisiform & pisiohamate ligament ulnarly.• Distal deep fascia of the forearm below the wrist crease

should be released.• Resection of any space occupying lesion• Treatment of hook of hamate fractures.

RADIAL NERVE

• POSTERIOR INTEROSSEOUS NERVE SYNDROME

• RADIAL TUNNEL SYNDROME

• WARTENBERG’S SYNDROME

PIN SYNDROMEANATOMY

Proximal to the elbow joint, the radial nerve branches into the superficial radial nerve & the PIN.

The PIN travels around the radial neck and through the interval between the 2 heads of the supinator muscle.

This opening which has an overlying compressive fibrous arch is known as arcade of frosche.

Clinical features:• Initially, presents with a dull ache in the proximal

forearm.• Later, there is difficulty in extending the fingers & the

thumb.

Etiology: Ganglion cyst Proliferative synovitis (rheumatoid arthritis)

• Electro diagnostic testing may localize the site of compression.

• Initially : observation & non operative treatment.• Operative methods: exploration & appropriate division of

compressing structures.

RADIAL TUNNEL SYNDROME

• The PIN passes between the 2 heads of the supinator

muscle in the radial tunnel.

• Boundaries of radial tunnelMedial: biceps tendonLateral : brachioradialis & extensor carpi

radialis longus & brevis tendonsRoof: brachioradialisfloor :deep head of the supinator muscle

• Pain is often acute & can mimic tennis elbow.

• Electrophysiological studies shows no abnormality.

• Treatment: non-operative: Activity modification, splinting,

NSAID’S & rest.

• Surgical decompression is often combined with lateral

epicondyle release.

WARTENBERG’S SYNDROME• Compression of the superficial branch of the radial nerve

can occur most commonly as it exits from beneath the brachioradialis in the forearm.

• Nerve can get trapped b/w the ECRL & the brachioradialis, especially with pronation in the forearm.

ETIOLOGY• Mass effect• Direct trauma

Clinical Features: • Numbness and / pain in the dorsal & radial aspects of the

hand.• Positive Tinel's sign• Symptoms can be further elicited by forceful pronation of

the forearm.

• TREATMENT• Conservative: activity modification, NSAID’S, Steroid

injections, splinting & occupational therapy.• Failure of conservative therapy: surgical exploration &

decompression.

Thank You