Traumatic Peripheral Nerve Injury

TJOK MAHADEWA, M.D.Presented in Block Neuroscience 27th May 2009

IntroductionDegradation and regeneration of peripheral nerves is distinct from that of nerves in the central nervous systemPrognosis of peripheral nerve injury is dependant upon age, the nerve injured, the level of the injury, the degree of injury and the timing of repairA sophisticated degradation process occurs following injury, before regeneration of a nerve can take placeManagement of peripheral nerve injuries has remained largely unchanged over the last centuryManagement of peripheral nerve injuries requires a multi-disciplinary team

Signs and SymptomsPainAbnormal SensationsWeaknessLoss of motor functionLoss of active ROM

RadiculopathyProcess affecting the nerve root, most commonly by a herniated discWeakness in muscles supplied by the nerve root (myotome)Sensory loss in the area of the skin supplied by the nerve root (dermatome)

MononeuropathyDysfunction of a single peripheral nerveWeakness in muscles supplied by the nerveSensory loss in the area of the skin supplied by the cutaneous branches of the nerve

Brachial PlexopathyCan refer to involvement of the entire plexus, or parts of the plexusTrunk lesionCord lesionDistribution of weakness and numbness depends upon the part of the plexus affected

Sensory Supply to the ArmBecause fibers from different nerve roots come together and then split apart in the plexusA dermatome may include areas of the skin supplied by different peripheral nervesA single nerve may supply sensation to skin covered by more than one dermatome

Sensory Supply to the ArmBecause of the pattern of root contribution to the plexus:An upper trunk lesion has sensory loss in the combined C5,6 dermatomesA middle trunk lesion has sensory loss in the C7 dermatomeA lower trunk lesion has sensory loss in the combined C8T1 dermatomes

Dermatomes of the Posterior Arm

Dermatomes of the Anterior Arm

Principles of LocalizationCertain sites are prone to nerve entrapments/injuriesNerve opposing boneUlnar nerve at the elbowClosed spacesCarpal tunnelAdjacent structuresMedian nerve at the elbow, adjacent to the brachial artery

Order in which branches ariseMovements at specific jointsSingle nerveElbow extensionRadialMultiple nervesElbow flexionMusculocutaneousRadial

DiagnosisEMGNCSMRITreatmentOBSERVATIONMedicationSURGERY FOR NERVE REPAIR

Case A 38 yo woman was the restrained passenger in a car struck head onShe braced her hands on the dashboard immediately prior to impactShe suffered bilateral fractures of the humerus at the spiral (radial) grooveShe complains of diffuse aches in her arms and neck and weakness in her arms

Case On exam she has:Bilateral wrist and finger drop (ie profound weakness of wrist and finger extension at the MCPs)Weakness of supinationWeakness of elbow flexion with forearm held so that thumb is toward shoulder, but not with hand held in supinationRemainder of strength exam is normalShe has numbness in the posterior forearm extending into dorsum of hand into thumb and proximal index finger

Triceps, long headTriceps, lateral headTriceps, med hd

BrachioradialisECRLECRBSuperficialSupinatorRadial sensExt DigitAbd Pol LongusPost InterosseousExt Pol LongusExt Pol BrExt Indicies

Bilateral radial nerve palsies at the spiral (radial) groove related to fractures

Examples

Superficial radial neuropathy secondary to handcuffs

Axillary Neuropathy in the Axilla

C6 Radiculopathy secondary to a herniated discOn exam :Weakness of shoulder abductionWeakness of elbow flexionMild weakness of pronationSensory loss in her lateral forearm and thumb both posteriorly and anteriorly

Ulnar neuropathy at the wrist Ulnar sensory loss in an ulnar lesion proximal to the midforearm

Ulnar nerveElbowFlexor carpi ulnaris Flex Dig Prof III/IV Dorsal uln cutWristAdductor PollicusAbductorFlex Pollicus BrOpponens Digiti MinimiFlexorDorsal/palmarInterosseous3rd/4th lumbricals

Related to Trauma

Dislocation of the Shoulder

Mostly Anterior > 95 % of dislocations

Posterior Dislocation occurs < 5 %

True Inferior dislocation (luxatio erecta) occurs < 1%

Habitual Non traumatic dislocation may present as Multi directional dislocation due to generalized ligamentous laxity and is Painless

Anterior Shoulder dislocation

Usually also inferiorUsually Indirect fall on Abducted and extended shoulder

May be direct when there is a blow on the shoulder from behind

Clinical PicturePatient is in painHolds the injured limb with other hand close to the trunkThe shoulder is abducted and the elbow is kept flexedThere is loss of the normal contour of the shoulder

Clinical PictureLoss of the contour of the shoulder may appear as a step

Anterior bulge of head of humerus may be visible or palpable

A gap can be palpated above the dislocated head of the humerus

X Ray anterior Dislocation of Shoulder

Associated injuries of anterior Shoulder DislocationInjury to the neuro vascular bundle in axilla ( rare )

Injury of the Axillary or Circumflex Nerve ( Usually stretching leading to temporary neuropraxia )

Associated fracture

Axillary Nerve InjuryAlso called circumflex nerveIt is a branch from posterior cord of Brachial plexusIt hooks close round neck of humerus from posterior to anteriorIt pierces the deep surface of deltoid and supply it and the part of skin over it

Axillary nerve injury

Management of Anterior Shoulder DislocationIs an EmergencyIt should be reduced in less than 24 hours or there may be Avascular Necrosis of head of humerusFollowing reduction the shoulder should be immobilised strapped to the trunk for 3-4 weeks and rested in a collar and cuff

Methods of Reduction of anterior shoulder DislocationHippocrates Method ( A form of anesthesia or pain abolishing is required )

Stimpsons technique ( some sedation and analgesia are used but No anesthesia is required )Kochers technique is the method used in hospitals under general anesthesia and muscle relaxation

Hippocrates MethodStimpsons techniqueKochers Technique

Complications of anterior Shoulder Dislocation Neuro vascular injury ( rare )Axillary nerve injuryAssociated Fracture of neck of humerus or greater or lesser tuberosities Avascular necrosis of the head of the Humerus (high risk with delayed reduction)Heterotopic calcification ( used to be called Myositis Ossificans )Recurrent dislocation

Fractures of The HumerusProximal Humerus (includes surgical and anatomical neck )Shaft of HumerusDistal humerus ( includes Supra Condylar fracture in children )Commonly Indirect injuryIndirect injury results in Spiral or Oblique fracturesDirect injuries results in transverse or comminuted fractureMay be associated with Radial Nerve injury

Fracture Proximal and Shaft Humerus

Radial Nerve InjuryResults in Wrist drop

Associated with fracture humerus in up to 12% of fractures

2/3 ( 8%) of Radial injury are Neuropraxia

1/3 ( 4%) are nerve lacerations or transection

Sciatic NerveComposed from roots of L4 to S3.Peroneal and tibial components differentiate early, sometimes as proximal as in pelvis.Passes posterior to posterior wall of acetabulum.Generally passes inferior to piriformis muscle, but occasionally the piriformis will split the peroneal and tibial components

Hip Dislocation: Mechanism of InjuryAlmost always due to high-energy trauma.Most commonly involve unrestrained occupants in MVAs.Can also occur in pedestrian-MVAs, falls from heights, industrial accidents and sporting injuries.

Posterior DislocationGenerally results from axial load applied to femur, while hip is flexed.Most commonly caused by impact of dashboard on knee.

Type of Posterior Dislocation depends on:Direction of applied force.

Position of hip.

Strength of patients bone.

Clinical Management: Emergent TreatmentDislocated hip is an emergency.Goal is to reduce risk of AVN Evaluation and treatment must be streamlined.Allows restoration of flow through occluded or compressed vessels.Literature supports decreased AVN with earlier reduction.Requires proper anesthesia.Requires team (i.e. more than one person).

Sciatic Nerve InjuryOccurs in up to 20% of patients with hip dislocation.

Nerve stretched, compressed or transected.

With reduction: 40% complete resolution25-35% partial resolution

If No Improvement after 34 Weeks:EMG and Nerve Conduction Studies for baseline information and for prognosis.

Allows localization of injury in the event that surgery is required.For Foot Drop:Splinting (i.e. ankle-foot-orthosis):

Improves gaitPrevents contracture

SURGERYNERVE GRAFTNERVE TRANSFER

REHABILITATIONBrace or SplintsElectrical StimulatorPhysical and Occupational therapy

U Shaped slab

Functional brace Fracture Shaft of Humerus

Questions?

CONCLUSIONWhen present in open fractures ; immediate exploration and repairIn closed injuries treated conservatively after close reduction-immobilization of the bone ; initial management is doing Nerve Conduction Studies ( NCS ) and Electromyography ( EMG ) and awaiting for spontaneous recoveryRecovery usually starts after few days but may take up to 9 months for full recoveryIf No spontaneous recovery occurs in 12 weeks confirmed by NCS and EMG ;then exploration of the nerve should be carried out