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Electrodiagnostic Evaluation of Brachial Plexus Injuries

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Presentation on theme: "Electrodiagnostic Evaluation of Brachial Plexus Injuries"— Presentation transcript:

1 Electrodiagnostic Evaluation of Brachial Plexus Injuries
William McKinley MD Associate Professor PM&R Virginia Commonwealth University

2 Incidence 10% of all peripheral nervous system injuries
14% of UE neurological injuries Bimodal distribution: Obstetrical: male = female, R > L Ages 20-30, males (MVA, violence)

3 BP lesion localization
Know clinical ANATOMY!!! Root/trunk/division/cord/branch (RTDCB) Motor/sensory innervation Comprehensive Edx eval NCS & needle EMG Consider less common motor/sensory NCS


5 BP Anatomy Anterior (ventral) rami C5-T1
R/T/D/C/B ( ) “Palindrome” BP extends from vert column to axilla clavicle separates R/T from C/B Supraclavicular (roots & trunks) Infraclavicular (cords & branches) Cords named in relation to Axillary artery Lateral (C5,6,7) Posterior (C5-T1) Medial (C8-T1)


7 Types of Neural Injury Stretch / traction - most common
Contusion - energy dissipation Laceration - fiber disruption Compression - ischemia / mechanical Ischemia - decreased nutrients


9 Etiologies Closed Open Traction injuries Blunt trauma Radiation Tumor
Positioning Brachial Neuritis Open GSW Laceration Surgical trauma Injection needle

10 Differential Dx Proximal mononeuropathies Radiculopathy
radial, axillary, suprascapular, musculocutaneous (vs upper / post cord involvement) Ulnar & median (vs lower trunk / medial cord injury) Radiculopathy

11 Neuralgia Amyotrophy “Brachial plexopathy”, “Parsonage-Turner syndrome” Sx - Acute pain, proximal (upper trunk) /shoulder innervation involvement SS, long thoracic, axillary often affected Good prognosis Recovery (year 1- 35%, year %)

12 Obstetrical-related Risk factors: heavy birth weight
long, difficult labor breech presentation short maternal stature

13 Thoracic outlet syndrome (TOS)
Somewhat controversial sx represent vascular vs neurogenic compromise of: C8 / T1 or lower trunk NCS findings can include abnormalities of median motor, ulnar sensory & motor

14 Sports-related injuries
“Burners” or “stingers” Traction of shoulder / head (upper trunk) Sx: paresthesias (rarely weakness)

15 Neoplastic Primary tumors - schwannomas, neurofibromas
Secondary tumors (more common) Pancoast tumor (metastatic disease to the upper lobe of lung) Lower trunk involvement Horners syndrome

16 Radiation-induced Related to total dosage & time-dependent
> 6000 Rads between 6-24 months favors upper trunk involvement “myokymia” on needle EMG Ddx: recurrent tumor

17 Peri-operative / Post-anesthetic
Positioning, straps, traction, pressure Usually upper plexus, good prognosis Sternotomy (lower trunk / C8-T1) Needle-induced axillary angiography regional anesthesia

18 Classifications of BP injuries
Open vs Closed (etiology) Supraclavicular (R/T) vs infraclavicular (C/B) Supraclavicular is more common Preganglionic vs postganglionic Upper (Erbs) vs middle vs lower (Klumpke) trunks Complete vs incomplete



21 Preganglionic Injury Nerve root avulsion
dorsal & ventral rootlets invested by pia mater / dural funnel etiology: traction (occasionally missile, knife) Significant traction causes dural rupture / root vulnerability ventral > dorsal root (esp C8-T1) at higher risk POOR Prognosis!


23 Edx eval of BP Injury Nerve Conduction Studies (NCS)
common (median, ulnar) (evaluates lower trunk & medial cord) less common (radial, MC, Axillary, SS) proximal NCS (C5-6, Erbs point) (technically possible, difficult, uncomfortable) Needle EMG (recruitment, abnl spont pot’s) Late-responses (H-reflex, F wave)- may be abnormal but ? less useful

24 Motor/Sensory NCS Distal latency & NCV are not helpful
Amplitude is “key” parameter remains NL(on distal stim) if no axonal loss (cond block, demyelination) or with preganglionic BPI (SNAP NL) look for decreased side-side > 50% motor day 4-7 (NMJ fragmentation) sensory day 8-10

25 Localizing NCS involement
Terminal branches of Brachial Plexus Median, Ulnar, Radial, Axillary, MC sensory & motor travel to and from the CNS thru the various roots, trunks, divisions & cords in a fairly consistent “pattern”

26 Sensory NCS Localization

27 Motor NCS Localization

28 Needle EMG Abnormal spontaneous potentials
positive sharp waves, fibrillations 7-10 days (paraspinal), 2-4 weeks (distal m’s) Important: follow “pattern” of BP innervation Paraspinal M’s WNL! (distal to Post rami) Decreased recruitment (voluntary MUAP)

29 Adjunctive tests Xrays (C-spine, clavicle, humerus, 1st rib)
Myelography - w/i 2-3 weeks, nerve root avulsion forms diverticulum c/w SA space MRI (>CT)

30 Somatosensory Evoked Potential (SSEP)
Supraclav. Fossa / Erbs pt. (N9) / cervical spine (N13) / contra somatosensory cortex (N19) sensory fibers / post column / thalamus Considerations (less than ideal agreement) Postganglionic-N9 Abnl (> 30% side-side diff.) Preganglionic- Nl N9 w/ Abnl N13



33 Axon reflex testing To evaluate pre vs post ganglionic lesion
1% SQ histamine normally leads to a vasodilation, wheal & flare due to reflex between DRG & cutaneous receptors “Triple response” in light of clinical picture c/w BPI = lesion proximal to DRG (ie: preganglionic root avulsion & poor prognosis) Loss of flare = postganglionic (better prognosis)

34 Case Study Hx: MVC Clinical exam: Prox UE wk (Sh Fl/Abd, EF), numbness lateral arm/forearm/hand What NCS & needle exam abnormalities will assist in localizing the site of injury?


36 Sensory Nerve Localization


38 Motor NCS Localization


40 Brachial Plexus Injuries (Summary)
Know your ANATOMY!!! Needle EMG: localizing pattern of involement paraspinal m’s WNL (unless preganglionic) NCS: localizing pattern of involvement amplitudes often most affected

41 Have a nice Weekend!!!

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