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

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Presentation on theme: "Electrodiagnostic Evaluation of Brachial Plexus Injuries §William McKinley MD §Associate Professor PM&R §Virginia Commonwealth University."— 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: l Obstetrical: male = female, R > L l Ages 20-30, males (MVA, violence)

3 BP lesion localization §Know clinical ANATOMY!!! l Root/trunk/division/cord/branch (RTDCB) l Motor/sensory innervation §Comprehensive Edx eval l NCS & needle EMG l 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 l Supraclavicular (roots & trunks) l 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 l Traction injuries l Blunt trauma l Radiation l Tumor l Positioning l Brachial Neuritis §Open l GSW l Laceration l Surgical trauma l Injection needle

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

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

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

13 Thoracic outlet syndrome (TOS) §Somewhat controversial §sx represent vascular vs neurogenic compromise of: l C8 / T1 or lower trunk l 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) l Pancoast tumor (metastatic disease to the upper lobe of lung) l Lower trunk involvement l Horners syndrome

16 Radiation-induced §Related to total dosage & time-dependent l > 6000 Rads l 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 l Sternotomy (lower trunk / C8-T1) §Needle-induced l axillary angiography l regional anesthesia

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



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


23 Edx eval of BP Injury §Nerve Conduction Studies (NCS) l common (median, ulnar) (evaluates lower trunk & medial cord) l less common (radial, MC, Axillary, SS) l 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 l remains NL(on distal stim) if no axonal loss (cond block, demyelination) or with preganglionic BPI (SNAP NL) l 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 l Median, Ulnar, Radial, Axillary, MC l 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 l positive sharp waves, fibrillations l 7-10 days (paraspinal), 2-4 weeks (distal m’s) l 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) l Postganglionic-N9 Abnl (> 30% side-side diff.) l 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 l “Triple response” in light of clinical picture c/w BPI = lesion proximal to DRG (ie: preganglionic root avulsion & poor prognosis) l 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: l localizing pattern of involement l paraspinal m’s WNL (unless preganglionic) §NCS: l localizing pattern of involvement l amplitudes often most affected

41 Have a nice Weekend!!!

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