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ENTRAPMENT NEUROPATHIES

AROUND ELBOW

Dr. Mahima AgrawalMBBS, MD, DNB, MNAMS PMR

Assistant Professor, Dept. of PMR,JLNMC, Ajmer

Contents Definition Etiology Pathophysiology Diagnostic evaluation Differential diagnosis Management Specific Entrapment neuropathies

DEFINITION It is a neuropathy due to a structural abnormality, such as

compression, displacement, or traction of the nerve, or by an intrinsic abnormality of the nerve, such as nerve cell tumor

With these lesions, stretching and angulation of the nerve may be as important a source of injury as compression

ETIOLOGY

ETIOLOGY

ETIOLOGY

ETIOLOGY Trauma, direct pressure and space-occupying lesions

at any level in the upper extremity

There are other situations that are not a direct cause of nerve compression, but may increase the risk and may predispose the nerve to be compressed specially when the soft tissues are swollen like synovitis, pregnancy, hypothyroidism, diabetes or alcoholism

RELEVANT ANATOMYPeripheral nerve

Epineurium

Fascicle

Endoneurium

Perineurium

Artery and Vein within the

perineurium

Layers of nerve

PATHOPHYISOLOGYAcute nerve compression

Pressures exceeding 20 mm Hg Reduced epineurial blood flow

Pressures exceeding 30 mm Hg Inhibits anterior and retrograde axonal transport

Pressures exceeding 80 mm Hg Cessation of intraneurial blood flow

These changes are transitory Reversible in short term

Example is Tourniquet palsy

RELEVANT ANATOMY

Blood Nerve Barrier

PATHOPHYISOLOGYRepetitive stress, prolonged compression

Wallerian degeneration

Localized demyelination

Demyelination of nerve fibres

Double Crush Syndrome

DOUBLE CRUSH AND MULTIPLE CRUSH SYNDROMES

A proximal level of nerve compression could cause more distal sites to be susceptible to compression

The summation of compression along the nerve would result in alterations of axoplasmic flow and subsequent pathology and symptomatology

The possibility of a distal site of compression making the more proximal nerve susceptible to secondary compression: A reverse double crush

Systemic diseases such as obesity, diabetes, thyroid disease, alcoholism, rheumatoid arthritis and neuropatthies lower the threshold for the occurrence of a nerve compression and alter axoplasmic transport rendering that nerve more susceptible to develop compression neuropathy and act as a ‘crush’

Entrapment Neuropathy in Diabetes

DM is a significant predisposing factor for entrapment neuropathiesTN-C(Tenascin-C) expression in the endoneurium is closely correlated with nerve function Metabolic and phenotypic abnormalities of endoneurial and perineurial

fibroblasts lies behind the vulnerability of DM patients to entrapment neuropathy

In contrast to angiopathies, retinopathy, and nephropathy, three representative complications of DM, mast cells do not play significant roles in the onset or progression of the entrapment neuropathy associated with DM

Ref: Histol Histopathol (2008) 23: 157-166 http://www.hh.um.es

CLINICAL SCENARIOTemporal sequence

Irritative orinflammatory pain

Paraesthesia (Tingling , Burning)

Ablative Numbness

Weakness and atrophy

Dry, thin, hairless skin

Ridged, thickened, cracked nails

Recurrent skin ulcerations

Clinical evaluation History Electro diagnosis: mainstay

• Nerve Conduction studies(NCS)• Electromyography(EMG)

Electromyography (EMG) EMG tests detect abnormal electrical activity in motor

neuropathy and can help differentiate between muscle and nerve disorders

ELECTRODIAGNOSISSensory nerve conduction studies are the earliest to show abnormality of slowing (focal demyelination) in the nerve across the site of the entrapment

Slow transmission rates and impulse blockage tend to indicate damage to the myelin sheath, while a reduction in the strength of impulses at normal speeds is a sign of axonal degeneration

Motor conduction abnormalities generally present later with slowing across the site followed by loss of axons (both sensory and motor) if the entrapment is unrelieved

Needle electromyography is used to detect axon loss which is chronic unless there is a super added acute external pressure on an existing entrapped nerve

Nerve biopsy Although this test can provide valuable information about the degree of nerve damage, it is an invasive procedure that is difficult to perform and may itself cause neuropathic side effects

Skin biopsy (examine nerve fibre endings) This test offers some unique advantages over NCV tests and nerve biopsy. Unlike NCV, it can reveal damage present in smaller fibres; in contrast to conventional nerve biopsy, skin biopsy is less invasive, has fewer side effects, and is easier to perform

Magnetic resonance imaging (MRI) can show muscle quality and size, detect fatty replacement of muscle tissue, and can help rule out tumors, herniated discs, or other abnormalities that may be causing the neuropathy

Ultrasound: The impact of sonography on clinical management has yet to be determined, even though upper extremity nerves are well-depicted Sonographically

DIFFERENTIAL DIAGNOSIS Myelopathy

Brachial plexopathy

Radiculopathy

Other central nervous system disorders, that can mimic peripheral nerve entrapment

Painful rheumatologic and orthopaedic disorders; and other psychological entities, such as somatoform and factitious disorders

TREATMENTTreat the underlying cause

Infection

Toxin exposure

Medication related toxicity

Vitamin deficiencies

Hormonal deficiencies

Autoimmune disease Management of

systemic diseases

Early management of injuries

TREATMENT

Healthy lifestyle

Optimal weight

Balanced diet

Exercising

Limiting alcohol consumption

Correcting vitamin deficiencies

TREATMENT Symptom Management 1. Nonsteroidal anti-inflammatory drugs (NSAIDs) for mild

pain 2. Antidepressants (tricyclic antidepressants such as

amitriptyline or newer serotonin-norepinephrine reuptake inhibitors such as duloxetine hydrochloride or venlafaxine)

3. Anticonvulsants (tricyclic antidepressants such as amitriptyline or newer serotonin-norepinephrine reuptake inhibitors such as duloxetine hydrochloride or venlafaxine)

4. Antiarrythmics (Mexiletine) 5. Narcotic agents ( Tapentadol)

TREATMENT 6. Topically administered medications

• Lidocaine• Capsaicin• Topical agents are generally most appropriate for

localized chronic pain such as herpes zoster neuralgia (shingles) pain

7. TENS 8. Allied medicine (Acupuncture, massage etc.) 9. Orthosis 10. Surgery 11. Trans cranial magnetic stimulation

Corticosteroids Steroid injections (such as cortisone or prednisolone) shrink the

swollen tissues and relieve pressure on the nerve

Corticosteroid injections are helpful for pregnant patients, as their symptoms often go away within 6 - 12 months after pregnancy

Most doctors limit steroid injections to about three per year, because they can cause complications, such as weakened or ruptured tendons, nerve irritation, or more widespread side effects

Low-Dose Oral Corticosteroids: A short course (1 - 2 weeks) of oral corticosteroid medicines may provide relief for some people, but the relief does not usually last.

Recent Advances USG guided percutaneous injection, hydrodissection,

and fenestration• An extension of blind steroid injection with advantage

of safety, accuracy of medication placement, effectiveness, non invasiveness, ease of performance and lower cost than open surgical release

REF: Vol.10,No.3,2010,Journal of Applied research

Research areas in nerve injury”Molecular factors”CLASS AGENT(S) ACTIONNeutrophic Factors andChemoattractants

Ciliary Neutrophic factor (CNTF)Nerve growth factor (NGF)Insulin-like growth factors (IGFs)Brain-derived Neutrophic factor(BDNF)NT-3NT-4

Promote neuronal survival andregrowthAttract and guide axon

Chemorepellent Factors

SemaphorinsNetrinsOthers

Selectively repel some types ofaxons

Inhibitors of Connective TissueFormation

Inhibitors of fibroblastsCollagenasesOthers

Decrease fibrosis at the site ofnerve injury to promote axonalregeneration

TYPES OF ENTRAPMENT NEUROPATHIES

Nerve involved Site of entrapmentMedian N.(wrist) (Elbow)Ulnar N. (wrist) (Elbow)Lower trunk or medial cord of branchial plexusSuprascapular NRadial Nerve (Elbow)

Carpal tunnelBetween heads of Pronator teresAnterior Interosseous Nerve syndromeGuyon’s canal (Ulnar tunnel)Bicipital groove, Cubital tunnelCervical rib or band at thoracic outletSpinoglenoid notchRadial tunnel—at point ofentrance into supinator muscle (arcade of Frohse)Posterior Interosseous Nerve syndrome

MEDIAN NERVE

Median nerve in anterior elbow. Passing between two heads of Pronator teres muscle and into the forearm beneath the edge of the fibrous arch of flexor digitorum sublimis

MEDIAN NERVE Possible areas for median nerve compression proximal

to the carpal tunnel: The ligament of Struthers The bicipital bursa Anomalous arteries, and anomalous muscles (such as

Gantzer's muscle, an accessory FPL muscle)

Pronator syndrome Anterior interosseous nerve syndrome The last two remain the two most frequently referenced

compression neuropathies of the median nerve in the forearm

PRONATOR SYNDROME Compression of the median nerve as it passes between the

two heads of the pronator teres muscle, Bicipital aponeurosis

Compression is due to hypertrophy and imbalance of regional tissues

Development of fibrous tissue due to inflammatory processes from repetitive stress, decreasing range of motion and increasing stresses

Symptoms Insidious onset No history of trauma Aching pain in the proximal, volar forearm Paraesthesias radiating into the median innervated fingers Worsened by repetitive pronosupination movements and

wrist flexion Carpenters, frequent computer users with

a mouse, weight lifters, athletes especially yoga, golf and tennis

PRONATOR SYNDROME

PRONATOR SYNDROME Discriminating clinically between PS and CTS: Loss of sensation over palmar cutaneous branch territory No Tinel's on the wrist No nocturnal disturbance Pain on resisted pronation from a neutral position, especially as the elbow is

extended If resisted contraction of the FDS to the middle finger reproduces symptoms,

median nerve compression at the level of the fibrous arch between the heads of the FDS might be suspected

If symptoms are elicited by resisted flexion of the forearm in full supination, compression at the more proximal level of the lacertus fibrosus might be considered

ANTERIOR INTEROSSEOUS NERVE SYNDROME

Site of compression essentially same for both Pronator syndrome(PS) and AIN

PS:Vague volar forearm pain,Median nerve parasthesias,minimum motor findings

AIN:Pure motor palsy of any or all three 1.FPL,2.FDP of index and middle fingers,3.PQ.

Surgical indications for nerve decompression include persistent symptoms for >6 months in patients with PS or for a minimum of 12 months with no signs of motor improvement in those with AIN syndrome


Pain may be present in the forearm along the course of the nerve

Inability to make an “OK” sign when asked by the examiner to flex his thumb interphalangeal joint and index finger distal interphalangeal joint

In patients with mild AIN compression, subtle weakness of these muscles may be the only clinical finding

Such weakness of the FPL and index finger FDP may be uncovered by asking the patient to pinch a sheet of paper between his thumb and index finger using only the fingertips and then trying to pull the paper away


A patient with AIN syndrome may be unable to hold on to the sheet of paper with just his fingertips and may compensate by using a more adaptive grip in which the interphalangeal joint of the thumb and distal interphalangeal joint of the index finger remain extended

Differential diagnosis Brachial neuritis Viral neuritis (Parsonage–Turner syndrome) Rupture of the FPL tendon

RADIAL NERVE

Anterior view of radial nerve course. PIN entrapment occurs because of prominent radial recurrent artery(RRA), medial edge of ECRB, proximal edge of S (Arcade of frohse, RN (Radial nerve), SRN (Superficial Radial Nerve)

RADIAL NERVE ENTRAPMENT

Anatomy- Formed from posterior cord to emerge between long and lateral heads of triceps, spiral groove of humerus proceeding medially to laterally to emerge between brachialis and brachioradialis on lateral elbow to enter the radial tunnel

On exit from radial tunnel, the deep branch pierces the supinator and exits the posterior aspect to emerge as Posterior interosseous nerve


RADIAL NERVE ENTRAPMENT Anatomically, there are five potential sites of compression of

the Radial nerve in the area of the radial tunnel• Fibrous bands of tissue anterior to the radiocapitellar joint between the

brachialis and brachioradialis• The recurrent radial vessels that fan out across the PIN at the level of

the radial neck as the so-called leash of Henry• The leading (medial proximal) edge of the extensor carpi radialis brevis

(ECRB)• The proximal edge of the superficial portion of the supinator,

commonly referred to as the arcade of Fröhse• The distal edge of the supinator muscle


Radial nerve compression can lead to either radial tunnel syndrome or posterior interosseous nerve syndrome (also called Supinator syndrome)

POSTERIOR INTEROSSEOUS NERVE SYNDROME

PIN is a branch of the radial nerve, originating in the lateral intermuscular septum

Purely motor function Innervates the supinator, extensor carpi ulnaris, extensor

digitorum communis, extensor digiti minimi, abductor pollicis longus, extensor pollicis longus and brevis, and extensor indicis proprius muscles

Most common in racquet sports, bowlers, rowers, discus throwers, golfers, swimmers

All involve repetitive supination and pronation May occur in synovitis, neoplasm etc

POSTERIOR INTEROSSEOUS NERVE SYNDROME

Symptoms and signs: Inability to extend fingers and thumb ECRL function intact—the wrist extends and radially

deviates

Whereas patients with PIN syndrome have a loss of motor function, patients with RTS typically, present with mobile wad and lateral forearm pain without motor involvement

RADIAL TUNNEL SYNDROME Symptoms and signs: Pain distal to lateral epicondyle, tenderness over the radial tunnel along the

path of PIN Pain worsened by extending the elbow, pronating the forearm and flexing

the wrist Pain with resisted active supination or wrist extension Pain with active supination against resistance Pain with wrist extension against resistance Pain with resisted middle finger extension at the metacarpophalangeal joint No neurological deficit Pain disappears after instilling local anaesthetic at the site of entry of PIN

RADIAL TUNNEL SYNDROME There is no motor weakness Unlike a case of lateral epicondylitis the pain is not on the

lateral epicondyle of the humerus but slightly distal to it It is described as being in the area of the mobile wad and

radial tunnel Differential diagnosis: Lateral epiconylitis Osteoarthritis of the radial capitellar joint Impingement of the articular branch of the radial nerve Synovitis of the radiocapitellar joint Muscle tear of the extensor carpi radialis brevis

ULNAR NERVE

Course of ulnar nerve from posterior view. It travels deep to the flexor carpi ulnaris muscle beneath the arcuate ligament

CUBITAL TUNNEL SYNDROME Entrapment of the ulnar nerve is the second most common

compression neuropathy in the upper extremity after CTS The arcade of Struthers is a band of fascia that connects the

medial head of the triceps with the intermuscular septum of the arm

The cubital tunnel is a fibroosseous channel formed by the olecranon process laterally, the posterior cortex of the medial epicondyle medially, the elbow joint capsule and posterior bundle of the medial collateral ligament anteriorly, and the ligament of Osborne (the cubital retinaculum) posteriorly

Cubital Tunnel Syndrome

•Truck drivers who lean the flexed elbow against the open window of their truck•Constant cell-telephone users •Baseball pitchers are also at risk because of the valgus stress that is induced in the late cocking and early acceleration phases of throwing

•Recurrent anteriordislocation of the ulnar nerve•Risk factors for ulnar nerve dislocationinclude cubitus varus deformity, an absent or lax ligament of Osborne, a hypertrophic medial head of the triceps, or an accessory head of the triceps and the dislocation may be associated with activities that involve resisted elbow extension, such as the early acceleration phase of throwing and bench press

CUBITAL TUNNEL SYNDROME

TAKE HOME MESSAGE Entrapment neuropathies are

far more common than thought These syndromes are

underdiagnosed Early diagnosis can lead to

faster and near complete recovery

Conservative management followed by surgery in non responsive cases gives good results

References

Theodore T. Miller, William R. Reinus. Nerve Entrapment Syndromes of the Elbow, Forearm, and Wrist

Adam’s and Victor’s Principles of neurology

Entrapment Neuropathies John D. England, MD

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