French guidelines for the diagnosis and management of MOG antibody-associated disease.

MOG antibody-associated disease (MOGAD) is a new entity within the spectrum of autoimmune inflammatory diseases of the central nervous system. It is distinct from multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). Although they share certain clinical characteristics, these 3 diseases differ in terms of their pathophysiology, disease course and response to treatment. MOGAD is a rare disease affecting both adults and children, with a higher frequency in the latter. The clinical presentation of MOGAD varies depending on age: in children under the age of 10, presentations of acute disseminated encephalomyelitis (ADEM) are frequently described, whereas in children over the age of 10 and in adults, unilateral or bilateral optic neuritis or acute myelitis is more often observed. Other, rarer presentations have also been reported, including encephalitic presentations with seizures. Radiologic findings can sometimes help guide the diagnosis: extensive anterior optic nerve involvement, perineuritis, extensive lesions of the spinal cord with involvement of the conus medullaris, and involvement of the pons, for example. Diagnosis is confirmed by measuring anti-MOG antibodies in the serum. In case of diagnostic doubt, the result must be confirmed in a reference laboratory (currently available in Lyon and Le Kremlin Bicêtre in France). The disease course is usually monophasic in children, but relapses are possible. In adults, the frequency of relapses seems higher than in children, estimated at more than 40% after 5 years. Visual, bladder/sphincter, cognitive and, to a lesser extent, motor sequelae may occur, but much less frequently than in NMOSD. In children and adults, attacks are treated with high-dose IV corticosteroids, which are often very effective, followed by an oral taper. In certain situations, long-term immunoactive therapy may be proposed, particularly when a relapse occurs, after discussion with a reference or expert center for Inflammatory diseases of the central nervous system. Long-term follow-up is proposed at the reference/expert center at least once a year. In between these appointments, follow-up with the referring pediatric neurologist, pediatrician, treating physician or referring neurologist is carried out every 6 months. It is important to check for the occurrence of a new attack and the onset of complications but also, in the case of long-term therapy, adherence to and tolerance of the treatment. Multidisciplinary management is essential and involves a variety of healthcare professionals (neurologist or pediatric neurologist, ophthalmologist, physiatrist, physiotherapist, speech therapist, occupational therapist, psychologist and social worker).