Brachial plexus injuries

classification

Closed

      supraclavicular (roots and trunks)

      preganglionic (avulsion of roots)

      postganglionic (rupture of trunks)

      infraclavicular (cords and branches)

Open

Other

      obstetric

      Erb

      Klumpke

      postanaesthetic

      radiation

      tumour

      iatrogenic

Adult injuries

epidemiology

      closed injuries usually from MBA

      open injuries usually from

      stabbing

      gunshot

clinical features
General

      of patients with plexus injuries

      80% have have severe injury to whole body

      20% have rupture of subclavian artery or axillary vessels

      90% have fractures or dislocations in vicinity of plexus

      Narakasí rule of 7s

      70% MVA

      70% of those MBA

      70% associated other injuries (diagnosis frequently delayed)

      70% supraclavicular

      70% C8,T1 involvement

      70% root avulsions

      70% persistent pain

Patterns

Preganglionic supraclavicular

      root lesions

      severe pain

      tenderness and swelling in posterior triangle

      spinal cord injury

      esp. Brown-Sequard

      vascular injury

Upper roots (C5,6)

      features of upper trunk above PLUS deficits from branches from roots and trunk

      winging of scapula

      long thoracic n - serratus anterior

      paralysis of rhomboids

      dorsal scapular n

      loss of shoulder ER

      suprascapular n - infraspinatus

Lower roots (C8,T1)

      features of lower trunk PLUS Hornerís syndrome

Guide to loss of function

      C5 - supraspinatus and infraspinatus

      C6 - ECRL*, biceps, brachioradialis, pronator teres

      C7 - latissimus dorsi

Postganglionic supraclavicular

Upper trunk

      loss of shoulder abduction

      deltoid

      loss of elbow flexion

      biceps, brachialis, brachioradialis

      loss of forearm pronation

      pronator teres

      numb outer arm and forearm

Middle trunk

      loss of wrist and finger extensors

Lower trunk

      loss of wrist and finger flexion

      FCU, FDS, FDP

      loss of intrinsics

      numb ulnar forearm and hand

Infraclavicular

Lateral cord

      weakness of elbow flexion

      musculocutaneous - biceps

      weakness of pronation and radial wrist flexion

      lateral root of the medial nerve - FCR and pronator teres

      weakness of shoulder adduction with arm horizontal

      lateral pectoral nerve - clavicular head of pec. major

      numb anterolateral forearm

      lateral cutaneous n of forearm

Posterior cord

      weakness of shoulder internal rotation

      upper and lower subscapular nn - subscapularis andteres major

      weakness of shoulder adduction

      thoracodorsal - latissimus dorsi

      weakness of shoulder abduction and internal rotation

      axillary - deltoid and teres minor

      loss of elbow, wrist and finger extension

      radial - triceps, carpal and digit extensors

      numb lateral arm and snuffbox

      axillary n and radial n

Medial cord

      combined medial and ulnar nerve deficit

investigations
Screening

Chest x-ray

      elevation of diaphragm

      fracture or dislocation of 1st rib

Cervical x-ray

      avulsion of C7 transverse processes

Shoulder x-ray

      fracture of clavicle or scapula

      dislocation of shoulder, AC jt or SC jt

Preganglionic vs postganglionic

      based on fact that Wallerian degeneration does not occur in preganglionic lesions

      axons intact where lesion between cell body and spinal cord

Histamine test

Triple response

1.   red reaction

      due to capillary dilatation

      direct response of capillaries to pressure

2.   wheal

      due to fluid extravasation from increased permeability

      produced by histamine release

3.   flare

      due to arteriolar dilatation

      due to axon reflex in sensory nerve

      antidromic conduction leads to release of substance P near arterioles supplied by same sensory nerve

Histamine test

      intradermal injection of histamine causes triple response

      preganglionic lesion

      afferent axons remain intact

      normal triple response with flare seen

      postganglionic lesion

      sensory cell body and axon separated

      afferent axons degenerated

      redness and wheal but no flare response

      no longer routinely performed

Nerve conduction studies

      general

      muscle sampling of specific groups of interest

      denervation shows sharp waves and fibrillation potentials

      renervation shows polyphasic action potentials on volitional activity

      preganglionic lesion

      skin anaesthetic

      sensory action potentials persist

      cervical paravertebral muscles show denervation

      serratus anterior and rhomboids show denervation

      postganglionic lesion

      skin anaesthetic

      no sensory action potentials

CT-myelogram

      pseudomeningocoele

      from leakage of dye

      indicate root avulsion

      may have false negative early

      due to clotted blood

      should delay 6 weeks

MRI

      role still unclear

      not routine at present

Exploration

      definitive investigation

Early exploration

      within 2 weeks of injury

      becoming more popular in specialised hand units

      advantages

      easier as less scarring

      diagnostic and prognostic

      disadvantages

      if nerve intact but not functioning, could be neuropraxia or axonotmesis

Late exploration

      6-12 weeks

      traditional treatment

      advantages

      neuropraxia has resolved - if nerve intact but not functioning, is axonotmesis

treatment
Principles

Initial

      give priority to

      vascular compromise

      other life-threatening injuries

      associated fractures

Open

      may be amenable to direct repair

      ends may be cleanly divided

Sharp injury

      exploration and repair when

      patients condition permits

      facilities and expertise available

      if repair not feasible

      marking for later repair

Gunshot injury

      deficit may be due to nerve Ďconcussioní

      usually improves

      if no other major injury requiring surgery (pulmonary, vascular)

      observe for 3 months

      explore if no improvement or large residual deficit

Closed

      usually not amenable to repair

      extensive damage from traction

      initial exploration and repair not usually indicated

      occasionally performed in specialised centres

      treat initially with splinting and ROM

      perform electrical studies at 3 weeks

      consider exploration at 6 weeks if no improvement

      diagnostic tool

      better prognosis with

      infraclavicular cf. supraclavicular

      upper trunk cf. lower trunk

Aims

      restore

      elbow flexion (biceps)

      shoulder abduction and rotation (deltoid, supraspinatus, infraspinatus)

Indications

Indications for surgery

      patient fit

      C5,6 or upper trunk lesion

Contraindications to surgery

      patient unfit

      preganglionic C8 T1 lesion

      some function in all nerves or trunks

Types

Nerve repair

Indications

      tidy open injuries

      uncommon

Neurolysis

      exterrnal rather than internal

      indicated where there is

      neuroma in continuity

      scarring encompassing nerve

      may improve pain

Nerve graft

Indications

      postganglionic lesions

Donor

      sural nerve

      as cable graft

      ulnar nerve

      where there is a hopeless injury of C8T1

      use vascularised ulnar nerve for graft

      freeze-dried muscle

      promising technique

Repair

      suture

      laborious

      fibrin glue

      quick and effective

Nerve transfer

Indications

      C5,6,7 root avulsion with intact C8,T1

Aims

      reconstruct simple shoulder, elbow and wrist activity

      not for complex hand activity

Donors

      intercostal nerves

      2 or more used

      spinal accessory nerve

      no functional deficit as transected after 1st branch to trapezius

Transfers

      accessory to suprascapular

      intercostal to musculocutaneous

Approach

      Z-shaped incision

      longitudinal along posterior border of SCM

      transverse along inferior border of clavicle

      longitudinal in deltopectoral groove

      ligate

      external jugular v

      transverse cervical a

      suprascapular aa

      divide

      omohyoid

      protect

      accessory n

      may need to osteotomise clavicle

Specific lesions

C5

Preganglionic

      shoulder

      accessory nerve to suprascapular

      intercostal nerves to axillary

Postganglionic

      nerve graft

C5 C6

Preganglionic

      shoulder

      accessory nerve to suprascapular

      intercostal nerves to axillary

      serratus

      reinnervate with nerve to levator scapulae

      elbow flexion

      ulnar nerve to biceps

      wrist extension

      muscle transfer

      median nerve sensation

      ICN to lateral head of median n

Postganglionic

      nerve graft

C8 T1

      still a problem

      mainly tendon transfers

Pain

      common in pre-ganglionic injuries

      remains severe in 50%

      anti-epileptic drugs are of some value

      TENs useful

      successful nerve regeneration eases pain

      last resort is ablative CNS surgery

Salvage

Shoulder stability

Tendon transfers

      in form of trapezius to proximal humerus

      results not good

Arthrodesis

      indicated where

      total loss of shoulder control

      functioning serratus and trapezius to allow movement

      results inferior to those performed for isolated palsies

      widespread weakness with few donors

      extensive sensory loss

Elbow flexion

      bipolar latissimus dorsi transfer

      complete lat dorsi transfer on neurovascular pedicle

      attached proximally and distally to replace biceps

      triceps to biceps transfer

      Steindler flexorplasty

      transfer of common flexor origin to distal humerus

      Clark pectoralis major transfer

      transfer of sternocostal portion of pectoralis major

      free gracilis transfer

      innervated by intercostal nerves

Wrist stability

Arthrodesis

      indicated where

      wrist flexion and extension not possible

      stability will create functional hand

Amputation

      midhumeral

      occasionally performed

      indications

      flail limb

      back at work

      limb is a hazard

      should not be performed for pain relief

Results

Open

      direct repair effective in upper and middle trunks

      poor prognosis after lower trunk injury

Closed

      infraclavicular lesions improve in 80% after surgery

      supraclavicular lesions improve in 20%

Obstetric palsies

definition

      birth injury of brachial plexus

      usually caused by traction

epidemiology

      0.4 per 1000 live births

      increased risk with

      heavy baby

      shoulder dystocia

      forceps delivery

      breech

classification
Erb

      C5,6 lesion

      weakness of

      deltoid

      rotator cuff (abduction and external rotation)

      elbow flexion

      forearm supination

      wrist and hand extension

      sensation intact

      waiterís tip deformity

      shoulder adducted (by side) and internally rotated

      elbow extended

      forearm pronated

      wrist and elbow flexed

      best prognosis

Klumpke

      rare

      C8,T1 lesion

      weakness of

      wrist and finger flexors

      intrinsics

      loss of sensation in forearm and hand

      Hornerís syndrome if preganglionic

      poor prognosis

Total

      C5-T1

      flaccid arm and loss of sensation

      Hornerís syndrome if preganglionic

      worst prognosis

CLinical Course

      90% eventually recover

      most reliable indicator of recovery is return of biceps activity by 3rd month

      most recover within few days

      if no recovery by 3 weeks, degenerate injury

      if no recovery by 3 months, permanent defect

      if persisting complete lesion at 3 months, poor prospect for return of function

treatment
Early

      maintain full ROM by passive ranging

      no splinting

      perform EMG at 10 weeks if no recovery

      exploration indicated if

      no clinical evidence of recovery of biceps at 3 months

      no evidence of strong reinnervation on EMG

Operative

      performed in specialised unit

      intraoperative neurophysiological studies required

      may perform

      grafting

      neurotisation

Salvage

Early

      performed at about age 4

      in the form of

      muscle/tendon transfers

      release of contractures

      similar principles to polio surgery

Late

      in the form of osteotomies

      humerus

      forearm