Neuralgic amyotrophy with hourglass-like constrictions: A case report.

Background: Neuralgic amyotrophy (NA) is a rare disease with sudden upper limb pain followed by affected muscle weakness. The most commonly affected area in NA is the upper part of the brachial plexus, and the paraspinal muscles are rarely affected (1.5%), making these cases difficult to distinguish from cervical radiculopathy.

Case summary: A 76-year-old male presented to the emergency department with left hip pain post-fall. After undergoing left femoral neck fracture surgery, he experienced sudden left shoulder pain for 10 days with subsequent left arm weakness. Cervical spine computed tomography revealed mild right asymmetric intervertebral disc bulging with a decreased C5-6disc space. Three weeks later, an electrodiagnostic study confirmed brachial plexopathy findings involving the cervical root. Magnetic resonance neurography was performed for a differential diagnosis. Contrast enhancement was identified at the upper trunk of the brachial plexus, including the C5 nerve root. A suprascapular nerve hourglass-like focal constriction (HLFC) was also identified, confirming NA. After being diagnosed with NA, the patient received 15 mg prednisolone, twice daily, for 3 weeks. Physical therapy was initiated, including left arm strengthening exercises and electrical stimulation therapy. Left shoulder muscle strength significantly improved one month after comprehensive rehabilitation.

Conclusion: NA's unique features like HLFC and paraspinal involvement are crucial for accurate diagnosis, avoiding confusion with cervical radiculopathy.