Download - Peripheral Nerve Injuries
PERIPHERAL NERVE INJURIES
PATHOLOGY
Nerves can be injured by ischaemia ,compression, traction, laceration or burning.
Aetiology:-Direct trauma
- Systemic causes-DM,leprosy,lead poisoning
- Entrapment neuropathies
e.g.,carpal tunnel,cubital tunnel,supinator syndromes
Nerve injuries types-Seddon’s
Neurapraxia
Axonotmesis Neurotmesis
NeurapraxiaA reversible physiological nerve conduction block followed by spontaneous recovery after
a few weeks .It is due to mechanical pressure causing segmental demyelination and is seen typically in crutch palsy, Saturday night
palsy,tourniquet palsy .
Axonotmesis There is loss of conduction but the nerve is in
continuity and the neural tubes are intact. The denervated target organs (motor end-plates
and sensory receptors) gradually atrophy, and if they are not re- in nervated within 2 years they
will never recover .
NeurotmesisIn Seddon's original classification, neurotmesis meant division of the nerve trunk
BRACHIAL PLEXUS
MEDIAN NERVE INJURY
FindingMuscle NervePlexusRoot
Thumb Abd APBMedian Lower trunkC8T1
Medial cord
Thumb oppOPMedianLower trunkC8T1
Medial cord
Sensory lossMedian------Median claw hand-loss of lat 2 lumbricals
Oschners clasp test(pointing index) Ape thumb deformity Pen test
Median Nerve
FindingMusclePNPlexus*RootWr dropECR, ECURadialPOST C C5,6,7,8
Fing dropEDC,EIRadial POST C C7, C8
Elb flxBRRadialPOST C C5,C6
Th ExtEPL, EPBRadialPost CC7,8
Sens ----Radial------
RADIAL NERVE INJURY
Triceps, long head
Triceps, lateral headTriceps, med hd
Brachioradialis
ECRL
ECRBSuperficial
SupinatorRadial sens
Ext Digit
Abd Pol LongusPost Interosseous
Ext Pol Longus
Ext Pol Br
Ext Indicies
ULNAR NERVE INJURY
FindingMusclePNPlexusRoot
Fing AddPalm IntUlnarMCc8,T1
Fing AbdDors IntUlnarMCC8T1
Ulnar claw hand-due to loss of intrinsic function
Card test-Finger adduction
Froments book test-Adductor pollicis
Ulnar nerveElbow
Flexor carpi ulnaris
Flex Dig Prof III/IV
Dorsal uln cut
Wrist
Adductor PollicusAbductor
Flex Pollicus BrOpponens Digiti MinimiFlexor
Dorsal/palmar
Interosseous
3rd/4th lumbricals
THE DEGREE OF INJURY
Tinel's sign -peripheral tingling or dysaesthesia' provoked by percussing
the nerve . In a neurapraxia, Tinel's sign is
negative. In axonotmesis, it is positive at the site
of injury because of sensitivity of the regenerating axon sprouts.After a delay of a few days or weeks, the Tinel sign will then advance at a
rate of about 1mm each day .
THE DEGREE OF INJURYElectromyogram (EMG)&Nerve conduction study(NCS)
Studies can be helpful (Campion, 1996). If a muscle loses its nerve supply, the EMG will show denervation potentials at the third
week .This excludes neurapraxia but it does not distinguish between axonotmesis and
neurotmesis;
PRINCIPLES OF TREATMENT
Treating underlying cause Oral corticosteroids-to reduce
inflammation & edema
Active and passive physiotherapy to muscles
Galvanic stimulation Dynamic splints –To prevent
contracture of the affected muscle
PRINCIPLES OF TREATMENT
Nerve exploration
. Exploration is indicated:
(1) if the nerve was seen divided and needs to be repaired;
(2) type of injury (e.g. a knife wound or a high energy injury) suggests that the nerve has been divided or severely damaged;
(3) if recovery is inappropriately delayed and the diagnosis is in doubt.
Epineurial neurorrhaphy
Perineurial (fascicular) neurorrhaphy
Nerve grafting Free autogenous nerve grafts can be used
to bridge gaps too large for direct suture. The sural nerve is most commonly used
Neurotization
Care of paralysed parts
While recovery is awaited the skin must be protected from friction damage and bums.
The joints should be moved through their full range twice daily to prevent stiffness and minimize the work required of muscles when they recover.
'Dynamic' splints may be helpful.
Tendon transfers
Motor recovery may not occur if the axons, regenerating at about 1mm per day, do not reach the muscle within 18-24 months of injury. The principles can be summarized as follows:
Tendon transfers
The donor muscle should be expendable Have adequate power Be an agonist or synergist The recipient site should be stable Have mobile joints and supple tissues The transferred tendon shouldbe routed
subcutaneously Have a straight line of pull Be capable of firm fixation
Radial nerve –tendon transfer
Robert jones transferBoyds transfer
CLAW HAND-ULNAR&MEDIAN
Boyds transferRiordan transferFowlers technique
Common peroneal nerve palsy
Trauma at fibular neck DM,leprosy,injectionpalsy,compression neuropathy(lithotomy)
- causes foot drop & toe drop & sensaory impairment over dorsum of foot
- Foot drop preventive splint
- transtibial & transosseous transfer