NERVE CONDUCTION STUDY - BRACHIAL PLEXUS
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Upper trunk
C5/C6
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Middle trunk
C7
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Lower trunk
C8/T1
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|---|---|---|---|
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Accessory motor (trapezius) Long thoracic motor (serratus anterior) |
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| Lateral fascicle | |||
| Posterior fascicle | |||
| Medial fascicle |
NEEDLE EMG - BRACHIAL PLEXUS
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Upper trunk
C5/C6
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Middle trunk
C7
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Lower trunk
C8/T1
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|---|---|---|---|
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Pre-plexus muscles |
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| Lateral fascicle | |||
| Posterior fascicle | |||
| Medial fascicle |
Copies checked nerves/muscles as a list ready for the report Methods section.
NCS and EMG checklist in brachial plexopathy
Structured checklist of nerve conduction studies and EMG by trunk (upper, middle, lower) in brachial plexopathy workup. Helps standardize reporting and avoid missing key nerves.
· Ferrante MA. Brachial Plexopathies: Classification, Causes, and Consequences. Muscle Nerve. 2004;30(5):547–568.
· Rubin DI. Brachial and Lumbosacral Plexopathies: A Review. Clin Neurophysiol Pract. 2020;5:173–193.
· Nunes, KF NCS AND EMG IN BRACHIAL PLEXUS PRACTICE. EMG/NCS 2025 Targeted Teaching.
Anatomic and clinical classification
Brachial plexopathy (BP) may be traumatic, inflammatory (Parsonage-Turner), neoplastic (Pancoast) or iatrogenic. Localization by trunk (upper C5–C6, middle C7, lower C8–T1) guides expected electrophysiologic patterns. Upper BP (Erb-Duchenne) → shoulder/biceps weakness; lower BP (Klumpke) → intrinsic hand + possible Horner if T1.
Nerve conduction strategy
Assess nerves crossing each trunk: upper — axillary, musculocutaneous, suprascapular; middle — median (C7), radial; lower — median/ulnar (C8–T1). Record distal latency, CMAP/SNAP amplitude and velocity. Temporal conduction block or dispersion favors focal demyelination; reduced amplitudes without block suggest axonotmesis. Compare affected vs contralateral side.
EMG strategy
EMG is mandatory for axonal localization, chronicity and differentiation from multilevel radiculopathy. Sample one spinal level per trunk: C5 deltoid/infraspinatus; C6 biceps/brachioradialis; C7 triceps/pronator teres; C8 FCU/FDI; T1 intrinsic hand muscles. Increased insertional activity and neuropathic MUAPs confirm axonal injury. Reinnervation MUAPs indicate recovery or chronic lesion.
Differential diagnosis and pitfalls
- Multilevel radiculopathy: myotomal pattern; spinal imaging correlates.
- Multiple mononeuropathy: isolated nerves without trunk pattern.
- CTS + C6–C7 radiculopathy: isolated median — do not confuse with middle trunk BP.
- Parsonage-Turner: initial severe pain then weakness; EMG shows denervation without early conduction block.
Use this checklist to track nerves and muscles assessed before finalizing the report.
Frequently asked questions
Which nerves to assess in brachial plexopathy?
By suspected trunk: median, ulnar, radial, axillary, musculocutaneous, suprascapular, long thoracic, spinal accessory, among others.
Is EMG mandatory in plexopathy?
Yes for axonal localization, chronicity and differentiation from multilevel radiculopathy vs plexus lesion.
References
· Ferrante MA. Brachial Plexopathies. Muscle Nerve. 2004;30(5):547–568.
· Rubin DI. Brachial and Lumbosacral Plexopathies. Clin Neurophysiol Pract. 2020;5:173–193.
· Nunes KF. NCS AND EMG IN BRACHIAL PLEXUS PRACTICE. EMG/NCS 2025 Targeted Teaching.