RADIAL NERVE INJURY

DR.RAVI KUMAR2ND YEAR P.G

ORTHOPAEDICS

ANATOMY:

• Originates as the terminal branch of the posterior cord of the brachial plexus:– roots from C5, 6, 7, 8, &

T1.– Largest branch of

brachial plexus

Course of Radial Nerve• Descends behind the third part of axillary artery &

upper part of the brachial artery,anterior to subscapularis and tendons of lattismusdorsi and teres major

• With arteria profunda brachii enters posterior aspect of humerus through lower triangular interval– Teres major (superior)– Long head triceps (medial)– Humerus (lateral)

• Gives posterior cutaneous nerve of arm in axilla

Course of Radial Nerve• Comes to lie in distal part of spiral groove with profundi brachii artery– Beneath lateral head of triceps and proximal to origin of medial head

• Gives branches to triceps, anconeus and inferior lateral cutaneous nerve of arm.• Through lateral intermuscular septum 10-12cm above lateral epicondyle

Course of Radial Nerve

• In anterior compartment of arm lies between brachialis and brachioradialis– 1-3 accessory branches to brachialis– Large branch to BR (sometimes this branch given

by superficial radial below elbow)• ECRL generally innervated proximal to elbow

joint

CLASSIFICATION OF NERVE INJURIESSEDDON'S CLASSIFICATION

Neurapraxia -- temporary paralysis of a nerve caused by lack of blood flow or by pressure on the affected nerve with no loss of structural continuity.

Axonotmesis – • neural tube intact, but axons are disrupted. • nerves are likely to recover.

Neurotmesis – • the neural tube is severed. • Injuries are likely permanent without repair.

DEGREE OF INJURY HISTOPATHOLOGICAL CHANGES TINEL SIGNSunderla

ndSeddon Myelin Axon Endoneur

iumPerineuri

umEpineuriu

mPresent Progresse

s Distally

I Neurapraxia

± − −

II Axonotmesis

+ + + +

III + + + + +IV + + + + + −V Neurotm

esis+ + + + + + −

CLASSIFICATION OF NERVE INJURIES

CAUSES

• Radial nerve is most commonly injured peripheral nerve accounting for 70% of all the peripheral nerve injuries of upper extremity.

• CAUSES:• In the axilla: crutch palsy aneursysm of axillary vessels.• In shoulder: fracture and dislocation of upper end of humerus or

by attempts at their reduction.• In the Radial groove: - # 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

CAUSES:

• between spiral groove and lateral epicondyle

-#shaft of humerus

-Supracondylar #humerus

-Lateral epicondyle#

-Cubitus valgus deformity

• AT THE ELBOW:

-Dislocation of elbow

-#neck of radius

-Enlarged bursae

-Rheumatoid synovitis of elbow

-During operation for excision of radius head

RADIAL NERVE INJURY

when injured in the axilla-Total palsy

• When injured in the radial groove-Tricieps muscle escapes and alsoposterior cutaneous nerve -Elbow extenxion is spared -Loss of wrist ,finger extension and thumb extension -Sensory loss on dorsum of first web space

• When injured below elbow-Wrist extension preserved because the branch ECRL arises -- proximal to elbow -Loss of finger and thumb extension -Sensory loss on dorsum of first web space

EXAMINATION:

• inspection• Attitude and deformity : note any typical attitude of the wrist drop• Wasting of the muscles in longstanding paralysis• Skin becomes dry , glossy and smooth with disapperance of

cutaneous folds and subcutaneous fat • Scar or wound• Palpation of the nerve• If there is tenderness on pressure along the course of the nerve-

indicates inflammation of the nerve • In the course of the nerve where complete divison of nerve is

expected feeling of neuroma and glioma almost confirm the diagnosis

TINEL’S SIGN• This sign is determining

- whether a nerve is –interrupted -in process of regeneration

-rate of regeneration -whether a nerve suture has succeded or failed.

• The Tinel sign is elicited by gentle percussion by a finger or percussion hammer along the course of an injured nerve.

• A transient tingling sensation should be felt by the patient in the distribution of the injured nerve rather than at the area percussed, and the sensation should persist for several seconds

after stimulation.• It should be tested for in a distal-to-proximal direction.• Even in incomplete regeneration this sign maybe positive.

EXAMINATION

• Muscles supplied by the radial nerve and how to test each:

• C7,8: triceps - ask patient to extend elbow against resistance.

• C5,6: brachioradialis - ask patient to flex elbow with forearm half way between pronation and supination.

• C6,7: extensor carpi radialis longus - ask patient to extend wrist to radial side with fingers extended.

• C5,6: supinator - with arm by side, ask patient to resist hand pronation.

• C7,8: extensor digitorum - ask patient to keep fingers extended at MCP joint.

• C7,8: extensor carpi ulnaris - ask patient to extend wrist to ulnar side.

• C7,8: abductor pollicis longus - ask patient to abduct thumb at 90° to palm.

• C7,8: extensor pollicis brevis - ask patient to extend thumb at MCP joint.

• C7,8: extensor pollicis longus - ask patient to resist thumb flexion at IP joint.

DIAGNOSITIC TESTS• Electrodiagnostic studies: used for

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 procedures

most commonly used methods are - nerve conduction studies

-EMG -other tests are -sweat test-skin resistance test-electrical stimulation

INDICATIONS FOR 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.

• Time of surgery :-primary repair gives the best result with respect to motor,sensory recovery is indicated in clean sharp nerve injuries 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.

SURGICAL TECHNIQUES• Techniques of neurorrhaphy

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

MANAGEMENT

• Nerve graftingTypes of graft

-Trunk graft -Cable graft-Pedicle nerve graft-Inter fascicular nerve graft-Pre vascularized nerve graft

Source of graft -Sural nerve is probably the best source of graft in majority of cases-Medial and lateral cutaneous nerve at the wrist is an ideal donor graft for fascicular nerve after for digital nerve-Superifical radial nerve is an excellent source of graft generally used in case of radial nerve injuries -Dorsal branch of ulnar nerve can also be used as a graft.

RECONSTRUCTIVE PROCEDURES

• Reconstructive procedures• Tendon transfers• Arthodesis

• Tendon transfers work to correct:– instability– imbalance – lack of co-ordination – restore function by redistributing remaining muscular forces

PRINCIPLES OF TENDON TRANSFER1. Only justified in restoring functional motion of the hand, not just

motion• Not all patients require the same functions/motions2. Patient factors• Age• Functional disabilities with poor non operative prognosis • Ability to understand nature and limitations of surgery, including

aesthetic goals• Motivated to co-operate with post operative physiotherapy3. Recipient site• “Tissue Equilibrium” concept as per Steindler/Boyes• Tissue bed into which transfer is placed should be soft and supple• Good soft tissue coverage• Stable underlying skeleton• Full passive range of motion of joints to be powered• Area to be powered must be sensate

PRINCIPLES OF TENDON TRANSFERDonor muscle factors (APOSLE)

Amplitude of the donor muscle– Should be matched to the unit being replaced

• Finger flexors 60 - 70mm, • finger extensors and EPL 40 - 50mm, • wrist flexors / extensors 30 - 40mm, • brachioradialis 20 - 30mm

Power of the donor muscle– Any transferred muscle loses at least one grade of strength, so only Grade 5

muscles are satisfactory (Grade 4, or 85% normal strength, can be sufficient for some transfers). Donor muscle strength should be maximised pre-operatively.

One tendon, One function– Effectiveness reduced in transfer designed to produce multiple functionsSynergistic muscle groups are generally easier to retrain– Fist group – wrist extensors, finger flexors, digital adductors, thumb flexors,

forearm pronators, intrinsics– Open hand group – wrist flexors, finger extensors, digital abductors,

forearm supinators– Use of synergistic muscles tends to help retain joint balance

PRINCIPLES OF TENDON TRANSFER

Line of transfer– Should approximate pull of original tendon if possible– Acute angles should be avoided

Expendability– Transfer must not cause loss of an essential function

-tendon transfer for radial nerve palsy essential for three functions-wrist extension

-MCP joint extension -Thumb extension

INTERNAL SPLINT

• Burkhalter 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 week

wrist extensor• It continues to act as a substitute in case nerve regeneration is

poor or absent

TENDON TRANSFER

• 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

Current standard tendon transfer protocol BRANDT PT - ECRB FCR - EDC PL - EPL

TENDON TRANSFER

• BOYE’S tendon transfer PT -ECRL and ECRBFCR - EPB and APLFDS middle –EDCFDS ring - EPL and EIPOST OP CARE: immobilization for 6 weeks

usually maintained for 4 weeks followed by a spring loaded extension splint for the wrist and finger.during the cast immobilization the MCP joints held in 40degee of reflection wrist should be fully extended with thumb in abduction and extension

ip joints of fingers in comfortable flexion

NON-OPERATIVE TREATMENT

• SPLINTS• wrist drop can be treated successfully by splints • Bark halter 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 • splints are used for patients who are

debilitated and who reject surgery.

OPPENHEIMER SPLINT

It is a dynamic splint used for radial nerve palsy

it consists of one palmar bar over the prox.phalanx,one distal forearm cuff dorsally and proimal cuff volarly.

Provides global extension of wrist and fingers

Limitation of this splint:restriction of grasp due to palmar bar.

Proximal migration of splint cause friction blisters around the wrist

RECOVERY

• Factors influencing the prognosis for recovery

-age

-level of injury

-delay between the time of injury and repair

-gap between nerve ends

-Condition of the nerve

-type of nerve

-

• Level of injury:

– The more proximal the injury, the more incomplete the overall return of

motor and sensory function, especially in the more distal structures.

• Delay between the time of injury and repair

-Delay of neurorrhaphy affects motor recovery more profoundly than

sensory recovery

-satisfactory reinnervation of muscle can occur after denervation upto 12

months.

-irreversible changes develop in the muscles after 24 months

-with respect to sensory recovery ,nerve can be repaired even after 2 yrs

for satisfactory recovery. However results are best if done earlier.

• Gap between nerve ends

– The methods for closing the gap are

– nerve mobilization

– nerve transposition,

– positioning of the extremity ,

– nerve grafts,

– bone shortening.

Condition of the nerve: A clear cut sharp nerve injury has got better prognosis following

primary repair than crushed or avulsed nerve injuries which needs secondary repair

Type of nerves: pure motor ,pure sensory nerves recover better than mixed nerves

because the consequence of mismatching are not so great in pure motor or sensory

nerves.

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