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

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

routine electroneuromyography and its fundamentals

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

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

Muscle fiber diameter X CMAP amplitude experimental data G5G6 Brambilla, E. J. S. Dupla inervação muscular com neurorrafia término-lateral: estudo em ratos.Tese apresentada à FMB, UNESP, Curso Bases Gerais da Cirurgia, ↓ ↓

Myelination, axon fiber diameter X nerve conduction (latency) 1 2 3B3B 5 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. Brambilla, E. J. S. Dupla inervação muscular com neurorrafia término-lateral: estudo em ratos.Tese apresentada à FMB, UNESP, Curso Bases Gerais da Cirurgia, G5G6 ↓ ↓

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

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

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

SC: crucial in BP assessment - topography pre and post-ganglionic lesions pre-ganglionic post-ganglionic - myelinic post-ganglionic - axonal Garbino pre-ganglionic post-ganglionic ← →

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

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

Reinnervation patterns: collateral and terminal sprouting collateral terminal Garbino

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 Needle Electromiography evaluation plexus root

Electrophysiologic evaluation expected results

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