1636 - When the Shoulder Isn’t the Source: Electrodiagnostic Confirmation of Rare C3–C4 Radiculopathy

Case Diagnosis: C3-C4 Radiculopathy

Case Description: A 66-year-old male was referred for evaluation of chronic left upper extremity pain to rule out cervical radiculopathy. Symptoms involved the lateral neck and scapular region, raising concern for possible shoulder pathology. Electrodiagnostic testing revealed median motor and sensory latency prolongation consistent with moderate carpal tunnel syndrome, but normal ulnar, radial, and axillary studies excluded diffuse neuropathy and mononeuropathy. Needle EMG demonstrated acute denervation in the levator scapulae and trapezius with chronic reinnervation changes in infraspinatus, rhomboid major, and pectoralis major. These findings confirmed acute C3–C4 radiculopathy, superimposed on chronic C5–C6 radiculopathy with mild C7 involvement.

Discussions: Upper cervical radiculopathy is uncommon and often misattributed to shoulder disorders due to overlapping pain distribution in the supraclavicular and scapular regions. Misdiagnosis may delay care or prompt unnecessary interventions. Key distinguishing features include pain aggravated by cervical motion with a relatively normal shoulder examination. Electrodiagnostic testing is key for localization in such cases, as it differentiates radiculopathy from brachial plexopathy or isolated peripheral nerve lesions. In this patient, abnormalities in proximal muscles innervated by the C4 root, along with preserved distal sensory responses, localized pathology to the upper cervical region. The concomitant presence of chronic lower cervical radiculopathy and carpal tunnel syndrome highlights the importance of comprehensive evaluation, as overlapping findings can obscure the primary diagnosis. Accurate identification of C3–C4 radiculopathy informs targeted rehabilitation, posture correction, and avoidance of unnecessary surgical procedures.

Conclusions: C3–C4 radiculopathy is uncommon but clinically significant. Electrodiagnostic confirmation, combined with imaging, is essential for accurate diagnosis when symptoms mimic shoulder pathology. This case underscores the need to include upper cervical radiculopathy in the differential diagnosis of refractory shoulder-region pain to improve patient outcomes.