Electrophysiologic evaluation in Brachial Plexus lesion

1. 1st. International Meeting on Brachial Plexus Clínica Fausto Viterbo – Cirurgia Plástica FMUNESP Electrophysiologic evaluation in Brachial Plexuslesion José A Garbino - ILSL Botucatu - 2009

2. Summary • Routine electroneuromiography • Motor studies • Sensory studies • Electromyography • Expected results • Lesion localization • Severity • Dennervation and Reinnervation • Prognosis

3. routine electroneuromyography and its fundamentals

4. Nerve conduction – large fibers 1. Motor nerve conduction - parameters CMAP, Distal Latency, Conduction Velocity (CV m/s= distancy/L2-L1) and F wave (late latencies) 2 MU CMAP: Compound Motor Action Potential = sum of MU potentials = estimation of motor axons in one nerve

5. MNC- belly-tendon setting Active electrode in muscle belly and reference in tendon Isolated stimulation with hook electrodes and belly-tendon setting using needles How to do it in animal models?

6. Muscle fiber diameter X CMAP amplitude experimental data G5 G6 ↓ ↓ Brambilla, E. J. S. Dupla inervação muscular com neurorrafia término-lateral: estudo em ratos.Tese apresentada à FMB, UNESP, Curso Bases Gerais da Cirurgia, 2009.

7. 5 2 3B 1 Myelination, axon fiber diameter X nerve conduction (latency) G5 G6 ↓ ↓ Brambilla, E. J. S. Dupla inervação muscular com neurorrafia término-lateral: estudo em ratos.Tese apresentada à FMB, UNESP, Curso Bases Gerais da Cirurgia, 2009. 7 Figura 32 – Fibras do músculo tibial cranial direito. Cortes corados pela técnica de HE. (1) grupo G1; (2) grupo G2; (3) grupo G3; (4) grupo G4; (5) grupo G5; (6) grupo G6; (7) grupo G7. Microscopia óptica com aumento de 200 vezes.

8. Amplitudes CMAP (M wave) side to side comparison –crucialin prognosis and graduation ≥ 50% reduction <50% reduction = normal • Differences> 50% • 50-80%: SLIGHT • 80-90%: MODERATE NO RESPONSES: complete lesion • > 90%: PRONOUNCED

9. 2. sensory CV = distancy/ L1 m/s Action sensory potential (ASP) = sum of sensory fiber potentials = estimated number of sensory axons in one nerve

10. Sensory conduction normal and abnormal normal amplitude↓ latency↑ velocity ↓

11. SC: crucialin BP assessment - topographypre and post-ganglionic lesions pre-ganglionic post-ganglionic ← → Garbino pre-ganglionic post-ganglionic - myelinic post-ganglionic - axonal

12. MBS, male, 60 y, 27 days after Normal distal CB proximally complete axonal loss partial axonal loss complete axonal loss partial axonal loss conduction block - myelinic post – ganglionic lesions Complete axonal lesion: terminal reinnervation, 1mm/day Partial axonal lesion: collateral and terminal sprouting Myelinic lesion: remyelination/months

13. 3. Needle Electromyography a) resting muscle voluntary contraction b) voluntary contraction Motor unit potential: Shape, polyphasia, amplitude and duration will define the reinnervation patterns: collateral and terminal

14. Reinnervation patterns: collateral and terminal sprouting Garbino terminal collateral

15. Needle Electromiographyevaluation • Muscles mapping • spontaneus activities distribution in the target limb • Lesion localization: related to root, clavicle position and cords • Quantify the amount of spared motor units • Look for reinnervation signs plexus root

16. Electrophysiologicevaluation expected results

17. Expected results • NCS: suprascapularis, musculocutaneus, axillary radial superficialis (upper trunk), radial, posterior interosseus (middle trunk), medial cutaneous antebrachialis, median and ulnar nerves (lower trunk) • Determine: pre and post-ganglionic lesions, underline neuropathology, and severity • Electromyography: in the above nerve territories plus paraspinalis muscles • Determine: root lesions, supra and infra clavicular or, severity and reinnervation or not