Brown-Séquard syndrome in a patient with spondyloarthritis after COVID-19 vaccine: a challenging differential diagnosis.

A 41-year-old woman with pre-radiographic axial and peripheric spondyloarthritis, taking adalimumab since 2010, started motor impairment of the right limbs and numbness of the left leg seven days after the administration of COVID-19 mRNA vaccine. Adalimumab was taken 47 days before clinical onset. A comprehensive study for infectious, autoimmune and neoplastic causes were unremarkable. MRI depicted an acute inflammatory lesion at C2 level with gadolinium enhancement. The patient started methylprednisolone with clinical improvement. Three scenarios should be considered: primary CNS inflammatory disorder or a secondary manifestation of the underlying rheumatologic disease; immune-mediated inflammatory lesion triggered by vaccine; demyelinating event due to adalimumab.