A case of myelin oligodendrocyte glycoprotein antibody-associated disease presenting with radiculopathies

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a demyelinating disease of the central nervous system (CNS). Recent reports suggest the peripheral nervous system (PNS) could also be involved, although the pathophysiology remains unclear. We report a 50-year-old woman who presented with acute cauda equina syndrome as the initial neurological manifestation of MOGAD. MOG antibodies were detected only in the cerebrospinal fluid (CSF). MRI showed a peripherally located small intramedullary lesion in the ventral spinal cord at the twelfth thoracic level. Leptomeningeal lesions were also present over the epiconus and conus. Despite treatment with corticosteroids and azathioprine, she experienced four relapses over years. During the fourth relapse, she developed left trigeminal neuralgia, and the MRI showed a small lesion at the entry zone of the trigeminal nerve. This case illustrates that leptomeningeal lesions can cause peripheral neuropathies in MOGAD in the absence of overt CNS signs. Testing for MOG antibodies in the CSF should be considered when there is a strong clinical suspicion of MOGAD or combined CNS and PNS involvement, even if serum results are negative.