electrophysiologic evaluation in brachial plexus lesion

Electrophysiologic evaluation in Brachial

Plexus lesion

José A Garbino - ILSL

José A Garbino - ILSL

1st. International Meeting on Brachial Plexus

Clínica Fausto Viterbo – Cirurgia Plástica FMUNESP

1st. International Meeting on Brachial Plexus

Clínica Fausto Viterbo – Cirurgia Plástica FMUNESP

Botucatu - 2009Botucatu - 2009

Summary

• Routine electroneuromiography– Motor studies– Sensory studies– Electromyography

• Expected results– Lesion localization– Severity– Dennervation and Reinnervation– Prognosis

routine electroneuromyograph

y 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 MU2 MU

MNC- belly-tendon setting

Active electrode in muscle belly and reference in tendonActive electrode in muscle belly and reference in tendon

How to do it in animal models?How to do it in animal models?

Isolated stimulation with hook electrodes and belly-tendon setting using needlesIsolated stimulation with hook electrodes and belly-tendon setting using needles

Muscle fiber diameter X CMAP amplitude experimental data

G5G5 G6G6

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.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.

↓↓

↓↓

Myelination, axon fiber diameter X nerve conduction (latency)

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.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.

G5G5 G6G6

↓↓↓↓

Amplitudes CMAP (M wave) side to side comparison – crucial in prognosis and graduation

<< 50% reduction = 50% reduction = normalnormal

≥ ≥ 50% 50% reductionreduction

Differences Differences > 50%> 50% 50-80%50-80%: SLIGHT : SLIGHT

80-90%80-90%: MODERATE : MODERATE NO RESPONSESNO RESPONSES: complete : complete lesionlesion

> 90%> 90%: PRONOUNCED: 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

GarbinoGarbino

pre-ganglionicpre-ganglionicpost-ganglionicpost-ganglionic

←←→→

MBS, male, 60 y, 27 days after

complete axonal losscomplete axonal loss

partial axonal losspartial axonal loss

conduction block - myelinicconduction block - myelinic

complete axonal losscomplete axonal loss

partial axonal losspartial axonal loss

Normal distal CB proximally Normal distal CB proximally

Complete axonal lesion: terminal reinnervation, 1mm/day

Partial axonal lesion: collateral and terminal sprouting

Myelinic lesion: remyelination/ months

Complete axonal lesion: terminal reinnervation, 1mm/day

Partial axonal lesion: collateral and terminal sprouting

Myelinic lesion: remyelination/ months

post – ganglionic lesionspost – ganglionic lesions

3. Needle Electromyography

Motor unit potential: Shape, polyphasia, amplitude and duration will define the reinnervation patterns: collateral and terminal

a) resting musclea) resting muscle

b) voluntary contractionb) voluntary contraction

voluntary contractionvoluntary contraction

Reinnervation patterns: collateral and terminal sprouting

collateralcollateral terminalterminal

GarbinoGarbino

• 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

plexusplexus

rootroot

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