2025 Workshop Handout Bundle-W45FC Cervical Radiculopathy Brachial Plexopathy

W45FC Cervical Radiculopathy Brachial Plexopathy - Hayat

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This document provides a comprehensive overview of the electrodiagnostic (EDX) evaluation of cervical radiculopathies and brachial plexopathies, authored by Drs. Mark A. Ferrante and Ghazala Hayat. The EDX exam combines nerve conduction studies (NCS)—sensory and motor—and needle electrode examination (NEE) to assess peripheral nerve and muscle function.<br /><br />Anatomically, the brachial plexus consists of five roots (C5-T1), three trunks, six divisions, three cords, and five terminal nerves, with each component having specific motor and sensory fiber compositions. Cervical nerve roots C5-T1 primarily innervate the upper extremities. Radiculopathies often stem from root compression, with C7 radiculopathy being most common. Because sensory nerve action potentials (SNAPs) evaluate postganglionic fibers and dorsal root ganglia (DRG) are proximal to the lesion in radiculopathies, sensory NCS typically remain normal despite sensory symptoms. Motor NCS abnormalities depend on lesion severity and root involvement but are often subtle due to partial nerve damage and collateral reinnervation. NEE detects denervation changes, such as fibrillation potentials and neurogenic motor unit action potentials, aiding lesion localization and chronicity assessment.<br /><br />Brachial plexopathies are categorized by location: supraclavicular (roots, trunks), retroclavicular (divisions), and infraclavicular (cords, terminal nerves). The supraclavicular plexus divides further into upper, middle, and lower plexuses associated with different roots and trunks. Upper plexus injuries are more common and often traumatic but tend to have better prognoses.<br /><br />A regional, stepwise EDX approach is recommended: start with sensory NCS (superficial radial, median, ulnar nerves) due to their high sensitivity for axon loss and lesion localization; proceed to motor NCS to assess severity and pathophysiology; and perform NEE last for detailed lesion characterization. Sensory NCS help distinguish preganglionic (radiculopathy) from postganglionic (plexopathy) lesions by revealing abnormalities only in the latter. Comprehensive NEE includes multiple muscles innervated by different roots or plexus segments to improve detection sensitivity.<br /><br />The document emphasizes that normal EDX findings do not exclude radiculopathy, due to limitations like isolated preganglionic involvement or minimal axonal loss. Nevertheless, EDX is valuable for confirming diagnosis, guiding treatment (e.g. surgery, injections), monitoring progression, and differentiating mimics such as motor neuron disease.<br /><br />Tables and figures provide detailed innervation maps and domains of SNAP, CMAP, and NEE findings for various brachial plexus components, facilitating targeted testing and lesion localization.<br /><br />In summary, the electrodiagnostic assessment of cervical radiculopathies and brachial plexopathies requires an understanding of peripheral nerve anatomy and pathophysiology, a strategic testing approach prioritizing sensory NCS, followed by motor NCS and needle EMG, to accurately localize, characterize, and monitor these complex disorders.

Keywords

electrodiagnostic evaluation

cervical radiculopathies

brachial plexopathies

nerve conduction studies

ncs

needle electrode examination

brachial plexus anatomy

sensory nerve action potentials

motor nerve conduction studies

denervation changes

electrodiagnostic localization