RADIAL NERVE PALSY

Dr Manoj DasOrtho ResidentInstitute Of medicine, TUTH, Nepal

Radial Nerve

• Largest branch of the brachial plexus• Arises from the posterior cord of the brachial plexus (C5–T1)• Mixed nerve

Anatomy

Course of Radial Nerve (RN) in the arm

In the axilla, RN lies anterior to subscapularis,

teres major and LD

• Sensory supply: Posterior cutaneous nerve of arm

RN leaves the axilla via the triangular space

• Motor supply: long head of Triceps

It then comes to lie along spiral groove on posterior aspect of

humeral shaft along with arteria profunda brachii

RN then leaves the spiral groove by piercing the lateral intermuscular

septum to enter the anterior compartment of the arm, 10-12 cm

above the lateral epicondyle

• Motor supply: Brachialis (lateral part), BR, ECRL

Anterior to lateral epicondyle, RN divides

into its terminal branchesHere it lies b/w brachialis and BR

Deep terminal branch → Posterior interosseous nerve (PIN)Supinator

EIP

EDC and EDMECUECRB

Superficial terminal branch

Radial Nerve Proper

EPLEPB

APL

PIN reaches the back of forearm by passing around the lateral aspect of the radius b/w the superficial and deep heads of the Supinator to supply all extensor compartment muscles

Finally, PIN ends by supplying carpal joint sensation

BRECRL

Dorsal Radial Sensory Nerve

Dorsal digital nerves

Radial styloid

8 cm

Dorsal radial nerve courses through the

forearm immediately deep

to the BR

It emerges b/w tendons of BR and

ECRL ≈ 8 cm proximal to radial styloid, to become

subcutaneous

It crosses the anatomical

snuffbox b/w EPB and EPL, dividing

into multiple branches to

supply sensation to hand

Course of Radial Nerve (RN) in the forearm

Lower lateral cutaneous nerve of armPosterior cutaneous nerve of arm

Posterior cutaneous nerve of forearm

Dorsal radial sensory nerve

Gives sensibility to the dorsum of the hand over the radial two-thirds, the dorsum of the thumb, and the index, middle finger proximal to the distal interphalangeal joint.

Cutaneous innervation from radial nerve

- crutch palsy - aneursysm of

axillary vesselsTotal palsy

Aetiology and clinical features

Very high radial nerve palsy

Clinical features

- # shaft of humerus -prolonged application of

tourniquet -pressure on arm as in

Saturday night paralysis -injections -from excessive callus

formation of old fracture impinging on the nerve

- Elbow extension spared

- Lost: Wrist, thumb and finger extension; sensation over 1st web space

High radial nerve palsy Clinical features

-Dislocation of elbow

-#neck of radius

-Enlarged bursae

-Rheumatoid synovitis of elbow

-During operation for excision of radius head

- Elbow extension spared with weak wrist extension and radial deviation

- Lost – thumb , finger extension: sensory over dorsum of 1st web space

Low radial nerve palsy Clinical features

Diagnosis

Mechanism of injury (e.g. sharp penetrating vs. blunt trauma)

Timing of injury

Loss of motor and sensory function

Presence of pain

Interval recovery of function in patients presenting late

History

Assessment of motor function

Assessment of sensory function

Assessment of involved joints

Physical Examinatio

n

Individual muscles innervated by the nerve are tested to determine what is functioning and what is not:▪Helps to determine the level of injury▪Guides future surgical planning

▪Elicitation of Tinel’s sign▪Specific sensory testing

Each joint is taken through its passive range of motion to assess for suppleness → presence of fixed joint contractures in delayed presentations is associated with poor treatment outcomes

Specific sensory testsTest Perception Main receptor CommentsStatic 2 point discrimination (2PD)

Tactile Merkel cell ▪Evaluates sensory receptor innervation density▪Normal distance: 6mm

Moving 2PD Tactile Meissner corpuscle ▪Normal distance: 3mm

Tuning fork (250 Hz)

Vibration Pacinian corpuscle

Tuning fork (30 Hz) Vibration MeissnerSemmes-Weinstein monofilament test

Pressure Merkel

Ten test (moving light touch)

Pressure Merkel ▪Reliability comparable to monofilament test

Cold-heat test Temperature Free nerve endings•Changes in Vibration and Pressure thresholds are seen in early nerve compression but are unreliable for evaluating nerve lacerations•Changes in sensory receptor innervation density (2PD) are seen in chronic nerve compression but are reliable for evaluating nerve lacerations

Commonly used EDT -Electromyography (EMG) -Nerve conduction studies (NCS)

1.   Documentation of injury   2.    Location of insult   3.    Severity of injury   4.    Recovery pattern   5.    Prognosis   6.    Objective data for impairment documentation   7.    Pathology   8.    Selection of optimal muscles for tendon transfer procedure

Electrodiagnostic testing

Limitations of EDT:▪Evaluates only large myelinated fibres → smaller axons

conveying pain and temperature are not assessed▪Changes in unmyelinated nerve fibres, which are the first

to be affected in nerve compressions, are not evaluated▪Performing the test before 3-6 weeks post injury can give

inaccurate results▪Very proximal or distal nerve injuries are difficult to assess▪Unreliable assessment of multi-level injuries▪Examiner dependant

Nerve conduction studies (NCS)2 electrodes are placed along the course of the nerve. The first electrode stimulates the nerve to fire, and the second electrode records the generated action potential

Amplitude• represents the size of the

response• proportional to the number of

depolarizing axons in the nerve

Latency• the delay in response

following stimulation

Conduction velocity

Sensory nerve action potential (SNAP)

• Response obtained when the recording electrodes is placed proximally along the sensory nerve, toward the spinal cord

Electromyography (EMG)

Insertional activity• Activity observed when a

needle electrode is inserted into the muscle

▪Fibrillation potentials ▪Fasciculations

• Seen when the muscle is at rest

• Absent in normal muscles

Motor unit potentials (MUPs)

• Generated by the muscle during a voluntary contraction

• Evaluates the integrity of neuro-muscular junction

Sequence of events in nerve compression

Focal demyelination

Axonal damage at the compression site

Further axonal loss

Axonal sprouting producing collateral re-innervation

Remyelination following decompression

▪↑Latency▪↓Nerve conduction velocity

Associated Electrodiagnostic findings

▪↓SNAP▪↓CMAP

▪↑Insertional activity▪Fibrillation potentials and fasciculations

▪’Giant’ MUPs

▪Normalization of NCV▪Loss of ‘giant’ MUPs

Non-operative -full passive range of motion in all

joints of the wrist and hand and prevention of contractures, including that of the thumb-index web

- splints wrist drop can be treated successfully

by splints Barkhalter has observed that grip

strength may be increased by 3 to 5 times by simply stabilizing the wrist with splints

Many types of splints have been described

Each patient individual need should be dictate the type of splinting used

TREATMENT

INTERNAL SPLINTBurkhalter proposed early transfer of PT-ECRB to restore wrist

extension as an adjunct to nerve repair.

It restores the power grip quickly and effectively since wrist extension is restored

Advantages are: It works as a substitute during nerve regrowth and largely eliminates

an external splint

Subsequently the transfer aids the newly innervated and weak wrist extensor

It continues to act as a substitute in case nerve regeneration is poor or absent

Green’s operative hand surgery

In a sharp injury exploration is indicated for diagnostic, therapeutic and prognostic purposes

In avulsion , blasting injures –to identification of the nerve injury and making the ends of the nerve with sutures for later repair.

When a nerve deficit follows blunt or closed trauma, and no clinical or electrical evidence of regeneration has occurred after an appropriate time, exploration of the nerve is indicated.

INDICATIONS FOR SURGERY

-primary repair gives the best result with respect to motor,sensory recovery, is indicated in clean sharp nerve injuries and carried out in first 6-8 hours.

-delayed,primary repair carried out between 7-18days -primary repair fascicular alignment because of minimal excision of the nerve ends.

-Secondary repair-preferable only in crushed,avulsed injuries where patients life is seriously endangered.it is done at delay of 3-6 wks.

Time of surgery

Seddon has suggested the maximum length of time that may be required for motor recovery to first manifest itself can easily be calculated by measuring the distance on the x-ray from the fracture site to the point of innervation of the brachioradialis muscle (approximately 2 cm above the lateral epicondyle)

Green's Operative Hand Surgery

Nerve Exploration If No Return After a Longer Waiting Period

SURGICAL TECHNIQUES

Techniques of neurorrhaphy -partial neurorrhaphy -epineural neurorrhaphy -perineural neurorrhaphy -epiperineural neurorrhaphy -interfasicular nerve grafting

Tendon transfersArthodesisTendon transfers work to correct:

instabilityimbalance lack of co-ordination restore function by redistributing remaining

muscular forces

RECONSTRUCTIVE PROCEDURES

A patient with irreparable radial nerve palsy needs to be provided with

(1) wrist extension.(2) finger (metacarpophalangeal [MP] joint)

extension.(3) a combination of thumb extension and

abduction.

Requirements in a Patient with Radial Nerve Palsy

Robert jones described 2 sets of tendon transfers1916: PT - ECRL and ECRB

FCU - EDC III,IV,V FCR - EDCII,EIP and EPL

1921: PT - ECRL and ECRB FCU - EDC III,IV,V FCR - EDCII,EIP , EPL,APL ,EPB

TENDON TRANSFER

Green’s operative hand surgery

Campbell’s operative orthopaedics

a long arm splint is applied that immobilizes the forearm in 15 to 30degrees of

pronation. the wrist in approximately 45 degrees of extension. the MP joints in slight (10 to 15 degrees) flexion. the thumb in maximum extension and abduction. The proximal interphalangeal joints of the fingers are

left free.

The cast is removed 4 weeks postoperatively; removable short arm splints to hold the wrist, fingers, and thumb in extension are made, which the patient wears for an additional 2 weeks, removing them only for exercise.

Postoperative Management

Radial Nerve Compression Syndromes

Wartenberg’s syndrome

• Aka: Cheiralgia paresthetica• D/t compression of Superficial radial nerve

as it emerges b/w ECRL and BR, 8 cm proximal to radial styloid

isolated pain or paresthesias over the dorsoradial aspect of the hand

preceding history of trauma to the area (i.e., handcuffs, forearm fracture)

Differentiating Wartenberg’s syndrome from de Quervain’s tenosynovitis

A Tinel’s sign over the superficial sensory radial nerve is the most common exam finding

Clinical features

presence of motor weakness suggests a more proximal site of compression

Also seen in patients who use forearms in pronated position for extended periods → in pronation, the tendons of BR and ECRL approximate and may compress the nerve

▪In WS, pain is exacerbated by pronation, while in DQT pain is elicited with changes in thumb and wrist position▪DQT - normal sensation in the dorso-radial hand▪DQT - pain on percussion over the 1st extensor compartment

Electrodiagnostic testing is of limited value in Wartenberg’s syndrome

Posterior interosseous nerve (PIN) syndrome

• D/t compression of PIN in the radial tunnel• Most common causes include:

▪Tumors such as lipomas, ganglia ▪Rheumatoid synovitis ▪Septic arthritis ▪Vasculitis

The radial tunnel is a 5 cm space bounded by:▪Dorsally: capsule of the radiocapitellar joint ▪Volarly: the BR▪Laterally: the ECRL and ECRB muscles ▪Medially: the biceps tendon and brachialis muscles

Within radial tunnel, there are 5 potential sites of compression: ▪fibrous bands to the radiocapitellar joint between the brachialis and BR ▪the recurrent radial vessels (leash of Henry)▪the proximal edge of the ECRB ▪the proximal edge of the Supinator (arcade of Fröhse)▪the distal edge of the Supinator

BR

Supinator

arcade of Fröhse

ECRL

PIN

Diagnosis

loss of finger and thumb extension

Weak wrist extension with radial deviation (since ECRL innervation is intact)

Intact passive tenodesis effect (rules out extensor tendon rupture)

EMG testing is helpful to confirm the diagnosis and monitor motor recovery

Radial Tunnel syndrome

• Similar to PIN syndrome, it is also d/t compression of PIN in the radial tunnel

• Not considered a true compression neuropathy by some

Radial Tunnel Syndrome is a clinical diagnosis

Radial Tunnel

Syndrome

Tenderness over radial tunnel (lateral proximal

forearm, 3-4 cm distal to lateral epicondyle over the mobile wad)

Pain at ECRB origin with

resistance of middle finger

extension

Pain with resisted forearm

supination↑ Pain on

combined elbow extension, forearm

pronation, and wrist flexion

Transmuscular Brachioradialis-Splitting Approach

Posterior (Henry or Thompson Approach)

Anterior (Modified Henry) Approach

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