Meningoencephalitis-like onset of post-infectious AQP4-IgG-positive optic neuritis complicated by GM1-IgG-positive acute polyneuropathy.

Fifteen days after a respiratory infection, a 45-year-old woman presented with paresthesias in the hands and feet, bilateral loss of vision, fever, headache, and impairment of consciousness. Magnetic resonance imaging (MRI) showed predominant lesions in the optic tracts, optic chiasm, and hypothalamus. Cerebrospinal fluid analysis revealed elevated protein level, and lymphocytic pleocytosis. Neurophysiological studies disclosed a demyelinating sensorimotor polyneuropathy. Serum anti-Mycoplasma pneumoniae immunoglobulin (Ig)M, anti-GM1 IgG, and anti-AQP4 IgG were positive. This case, which is remarkable for post-infectious meningoencephalitis-like onset, MRI picture, and dysimmunity to central and peripheral nervous system autoantigens, underpins the pivotal diagnostic role of anti-AQP4-IgG, and expands the list of clinico-pathological findings that can associate with neuromyelitis optica spectrum disorders.