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Brachial Plexus Injuries

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Topic updated on 05/26/14 7:20pm
Introduction
  • Traumatic brachial plexus injuries (BPIs) can involve any degree of injury at any level of the plexus
    • more severe injury such as rupture of plexal segments or root avulsions are associated with higher energy trauma
  • Brachial Plexus injuries include
    • traumatic injury (this topic)
    • obstetric brachial plexus injury topic
      • Erb's palsy
      • Klumpke palsy 
    • burners and stingers topic
    • Parsonage-Turner Syndrome topic
  • Epidemiology
    • supraclavicular injuries
      • complete involvement of all roots is most common
        • 75%-80% of traumatic BPIs
      • C5 and C6 upper trunk (Erb palsy)
        • 20%-25% of traumatic BPIs
      • C8, T1 or lower (Klumpke palsy)
        • 0.6%-3.0% of traumatic BPIs
  • Mechanism
    • high speed vehicular accidents (mostly motorcycle)
      • 83% of traumatic BPIs
    • caudally forced shoulder
      • predominantly affect upper brachial plexus  
      • with high enough energy all roots can be affected
    • forced arm abduction (as in grabbing onto something while falling)
      • predominantly affects lower roots
  • Prognosis
    • recovery of reconstructed plexus can take up to 3 years
    • nerve regeneration occurs at speed of 1mm/day
    • infraclavicular plexus injuries have better prognosis than supraclavicular injuries
    • upper plexus injuries have improved prognosis
      • preservation of hand function
    • root avulsion (preganglionic injuries) have worst prognosis
      • not repairable
    • other surgeries such as arthrodesis and tendon transfers may be needed
Anatomy
  • Anatomy
    • brachial plexus motor and sensory innervation
Classification
  • Preganglionic vs. postganglionic
    • preganglionic
      • avulsion proximal to dorsal root ganglion
        • involves CNS which does not regenerate – little potential recovery of motor function (poor prognosis)
      • lesions suggesting preganglionic injury:
        • Horner’s syndrome
          • disruption of sympathetic chain
        • winged scapula medially
          • loss of serratus anterior (long thoracic nerve) rhomboids (dorsal scapular nerve) leads to medial winging (inferior border goes medial)
        • presents with motor deficits (flail arm)
        • sensory deficits
        • absence of a Tinel sign or tenderness to percussion in the neck
        • normal histamine test (C8-T1 sympathetic ganglion)
          • intact triple response (redness, wheal, flare)
        • elevated hemidiaphragm (phrenic nerve
        • rhomboid paralysis (dorsal scapular nerve)
        • supraspinatus/infraspinatus (suprascapular nerve)
        • latissimus dorsi (thoracodorsal)
      • evaluation
        • EMG may show loss of innervation to cervical paraspinals
    • postganglionic
      • involve PNS, capable of regeneration (better prognosis)
      • presentation
        • presents with motor deficit (flail arm)
        • sensory deficits
      • evaluation
        • EMG shows maintained innervation to cervical paraspinals
        • abnormal histamine test
          • only redness and wheal, but NO flare
  • Classification based on location
Upper Lesion: Erb's Palsy (C5,6) 
Introduction
Physical Exam
  • Most common obstetric brachial plexopathy
  • Results from excessive displacement of head to opposite side and depression of shoulder on same side producing traction on plexus
  • Occurs during difficult delivery in infants or fall onto shoulder in adults
  • Best prognosis
  • Clinically, arm will be adducted, internally rotated, at shoulder; pronated, extended at elbow (“waiter’s tip”)
  • C5 deficiency
    • axillary nerve deficiency (weakness in deltoid, teres minor)
    • suprascapular nerve deficiency (weakness in supraspinatus, infraspinatus)
    • musculocutaneous nerve deficiency (weakness to biceps)
  • C6 deficiency
    • radial nerve deficiency (weakness in brachioradialis, supinator)
Lower Lesion: Klumpke Palsy (C8,T1)
  • Rare in obstetric palsy
  • Usually avulsion injuries caused by excessive abduction (person falling from height clutching on object to save himself)
  • Other causes may include cervical rib, or lung mets in lower deep cervical lymph nodes
  • Frequently associated with a preganglion injury and Horner's Syndrome
  • Poor prognosis
  • Deficit of all of the small muscles of the hand (ulnar and median nerves)
  • Clinically, presents as “claw hand”
    • wrist  held in extreme extension because of the unopposed wrist extensors
    • hyperextension of MCP due to loss of hand intrinsics
    •  flexion of IP joints due to loss of hand intrinsics
Total Palsy (C5-T1)
  • A form of brachial plexopathy
  • Worst prognosis
  • Leads to a flaccid arm
  • Involves both motor and sensory
 
Presentation
  • History
    • high energy injury
  • Physical exam
    • Horner's syndrome
      • features include
        • drooping of the left eyelid
        • pupillary constriction
        • anhidrosis
      • usually show up three days after injury
      • represents disruption of sympathetic chain via C8 and/or T1 root avulsions
    • severe pain in anesthetized limb
      • correlates with root avulsion
    • important muscles to test
      • serratus anterior (long thoracic nerve) and rhomboids (dorsal scapular nerve)
        • if they are functioning then it is more likely the C5 injury is postganglionic
    • pulses
      • check radial, ulnar and brachial pulses
        • arterial injuries common with complete BPIs
Imaging
  • Radiographs
    • chest radiograph
      • recommended views
        • PA and lateral
      • fractures to the first or second ribs suggest damage to the overlying brachial plexus
      • evidence of old rib fractures can be important in case intercostal nerve is needed for nerve transfer
      • inspiration and expiration can demonstrate a paralyzed diaphragm (indicates upper nerve root injury)
    • cervical spine series
      • recommended views
        • AP and lateral
      • transverse process fracture likely indicates a root avulsion
    • scapular and shoulder series
      • recommended views
        • at least AP and axillary (or equivalent) 
      • scapulothoracic dissociation is associated with root avulsion and major vascular injury
    • clavicle
      • recommended views
        • orthogonal views
      • fracture may indicate brachial plexus injury
  • CT myelography
    • indications
      • gold standard for defining level of nerve root injury
    • avulsion of cervical root causes dural sheath to heal with meningocele
    • scan should be done 3-4 weeks after injury 
      • allows blood clot in the injured area to dissipate and meningocele to form
  • MRI
    • indications
      • suspect injury is distal to nerve roots
        • can visualize much of the brachial plexus
        • CT/myelogram demonstrates only nerve root injury
    • findings 
      • traumatic neuromas and edema
      • mass lesions in nontraumatic neuropathy of brachial plexus and its branches
      • consistent with injury include
      • pseudomeningocele (T2 highlights water content present in a pseudomeningocele )
      • empty nerve root sleeves (T1 images highlight fat content nerve roots and empty sleeves)
      • cord shift away from midline (T1 highlights fat of cord)
Studies
  • Electromyography (EMG)
    • tests muscles at rest and during activity
    • fibrillation potentials (denervation changes)
      • as early as 10-14 days following injury in proximal muscles
      • as late as 3-6 weeks in distal muscles
    • can help distinguish preganglionic from postganglionic
      • examine proximally innervated muscles that are innervated by root level motor branches
        • rhomboids
        • serratus anterior
        • cervical paraspinals
  • Nerve conduction velocity (NCV)
    • performed along with EMG
    • measures sensory nerve action potentials (SNAPs)
      • distinguishes  preganglionic from postganglionic
      • SNAPs preserved in lesions proximal to dorsal root ganglia
        • cell body found in dorsal root ganglia
      • if SNAP normal and patient insensate in ulnar nerve distribution
        • preganglionic injury to C8 and T1
      • if SNAP normal and patient insensate in median nerve distribution
        • preganglionic injury to C5 and C6
  • Nerve action potential (NAPs)
    • often intraoperative
    • tests a nerve across a lesion
    • if NAP positive across a lesion
      • preserved axons 
      • or significant regeneration
    • can detect reinnervation months before EMG
      • NAP negative-neuropraxic lesion
      • NAP positive- axonotmetic lesion
  • Sensory and Motor Evoked Potential 
    • more sensitive than EMG and NCV at identifying continuity of roots with spinal cord (positive finding)
      • a negative finding can not differentiate location of discontinuity (root avulsion vs. axonotmesis)
    • perform 4-6 weeks after injury to allow for Wallerian degeneration to occur
    • stimulation done at Erb's point and recording done over cortex with scalp electrodes (transcranial)
Treatment
  • Nonoperative
    • observation alone waiting for recovery
      • indications
        • most managed with closed observation
        • guns shot wounds (in absence of major vascular damage can observe for three months)
      • signs of neurologic recovery
        • advancing Tinel sign is best clinical sign of effective nerve regeneration

  • Operative
    • immediate surgical exploration (< 1 week)
      • indications
        • sharp penetrating trauma (excluding GSWs)
        • iatragenic injuries
        • open injuries
        • progressive neurologic deficits
        • expanding hematoma or vascular injury
      • techniques
        • nerve repair
        • nerve grafting
        • neurotization
    • early surgical intervention (3-6 weeks)
      • indicated for near total plexus involvement and with high mechanism of energy
    • delayed surgical intervention (3-6 months)
      • indications
        • partial upper plexus involvement and low energy mechanism
        • plateau in neurologic recovery
        • best not to delay surgery beyond 6 months
      • techniques
        • usually involves tendon/muscle transfers to restore function
Surgical Techniques
  • Direct nerve repair
    • rarely possible due to traction and usually only possible for acute and sharp penetration injuries
  • Nerve graft
    • commonly used due to traction injuries (postganglionic)
    • preferable to graft lesions of upper and middle trunk
      • allows better chance of reinnervation of proximal muscles before irreversible changes at motor end plate
    • donor sites include sural nerve, medial brachial nerve, medial antebrachial cutaneous nerve
    • vascularized nerve graft includes ulnar nerve when there is a proven C8 and T1 avulsion (mobilized on superior ulnar collateral artery)
  • Neurotization (nerve transfer)
    • transfer working but less important motor nerve to a nonfunctioning more important denervated muscle
    • use extraplexal source of axons
      • spinal accessory nerve (CN XI)
      • intercostal nerves
      • contralateral C7
      • hypoglossal nerve (CN XII)
    • intraplexal nerves
      • phrenic nerve
      • portion of median or ulnar nerves
      • pectoral nerve
      • Oberlin transfer
        • ulnar nerve used for upper trunk injury for biceps function
  • Muscle or tendon transfer
    • indications 
      • isolated C8-T1 injury in adult (reinervation unlikely due to distance between injury site and hand intrinsic muscles)
    • priorities of repair/reconstruction
      • elbow flexion (musculocutaneous nerve)
      • shoulder stability (suprascapular nerve)
      • brachial-thoracic pinch (pectoral nerve)
      • C6-C7 sensory (lateral cord)
      • wrist extension / finger flexion (lateral and posterior cords)
      • wrist flexion / finger extension
      • intrinsic function
    • technique
      • gracilis most common free muscle transfer

 

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Qbank (3 Questions)

TAG
(SBQ07.29) A 21-year-old collegiate football player has been diagnosed with a left superior trunk brachial plexus injury following a tackle. Which of the following would most likely be normal on physical exam? Topic Review Topic

1. Sensation over the lateral aspect of shoulder
2. Biceps reflex
3. Shoulder abduction
4. Sensation over radial aspect of forearm
5. Finger abduction

PREFERRED RESPONSE ▶
TAG
(OBQ13.115) A 26-year-old male sustains a traction injury to his left arm after a motorcycle crash with resulting weakness in this left upper extremity. An electromyography (EMG) done shows normal cervical paraspinal muscle activity. Which of the following statements is true regarding this injury? Topic Review Topic

1. The injury has likely resulted in the avulsion of several nerve roots
2. Physical exam would likely reveal drooping of his left eyelid and anhidrosis
3. Intact paraspinal musculature on EMG is suggestive of a post-ganglionic lesion
4. Immediate surgical intervention with neurotization would eliminate weakness and restore function
5. The patient would show a normal histamine test

PREFERRED RESPONSE ▶
TAG
(OBQ08.272) A patient sustains a transection of the posterior cord of the brachial plexus from a knife injury. This injury would affect all of the following muscles EXCEPT? Topic Review Topic

1. Subscapularis
2. Latissimus dorsi
3. Supraspinatus
4. Teres minor
5. Brachioradialis

PREFERRED RESPONSE ▶
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