Cervical Myelitis Masquerading as Guillain-Barré Syndrome: A Case of Acute Flaccid Tetraplegia With a Sensory Level at the Third Cervical Dermatome

Acute flaccid tetraplegia with areflexia and respiratory failure is frequently attributed to Guillain-Barré syndrome in emergency practice. However, high cervical inflammatory spinal cord lesions may present with a similar clinical picture, leading to potential diagnostic delays and inappropriate initial management. A 26-year-old woman presented with sudden interscapular pain followed within hours by rapidly progressive weakness of all four limbs and acute respiratory distress. Neurological examination revealed generalized areflexia, absence of pyramidal signs, and a clearly defined sensory level at the third cervical dermatome. Cerebrospinal fluid examination was normal. Urgent spinal magnetic resonance imaging demonstrated an intramedullary inflammatory lesion extending from the second to the sixth cervical vertebrae, consistent with longitudinal extensive transverse myelitis. Extensive investigations for infectious, autoimmune, and demyelinating causes were inconclusive, and specific antibody testing was negative, limiting etiological characterization. The patient was treated with high-dose corticosteroids, plasma exchange, and rituximab. Despite partial radiological improvement, the neurological outcome remained unfavorable, with persistent severe motor deficit at follow-up. The presence of a sensory level in a patient with acute flaccid tetraplegia is a critical clinical sign that should prompt immediate spinal imaging. Early recognition of cervical transverse myelitis is essential to initiate timely immunotherapy and may influence neurological prognosis.