Gq1b IgG-positive myeloradiculoneuropathy with spinal cord demyelination and autonomic dysfunction

Here, we present a case of a 43-year-old woman who developed acute-onset progressive weakness in both lower limbs, with a distinct sensory level at D3-D4, and bowel/bladder incontinence, demonstrating an unusual overlap of central and peripheral nervous system involvement. Magnetic resonance imaging (MRI) revealed linear hyperintensities from C6 to D3 spinal levels while nerve conduction studies confirmed peripheral demyelination, creating a diagnostic challenge. Serological testing identified strongly positive GQ1b IgG antibodies with equivocal GQ1D reactivity, while comprehensive panels ruled out neuromyelitis optica, myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and paraneoplastic aetiologies. The patient showed dramatic improvement following IVIG therapy, supporting an antibody-mediated pathophysiology affecting both spinal cord and peripheral nerves. This case showcases the heterogeneity of presentation of GQ1b-associated disorders by demonstrating its potential to cause concurrent central demyelination and peripheral neuropathy. Our findings underline the importance of considering atypical presentations in anti-ganglioside antibody disorders, where immunotherapy may be effective. This type of presentation of anti GQ1b reactive disease is rarely documented in the existing literature.