The distinction of area postrema syndrome between MOGAD and NMOSD.

Background and objectives: Both myelin oligodendrocyte glycoprotein-IgG associated disorders (MOGAD) and neuromyelitis optica spectrum disorder (NMOSD) are demyelinating diseases of the central nervous system. They present similar clinical manifestations such as optica neuritis, myelitis and area postrema syndrome (APS). The distinctions of optica neuritis (ON) and myelitis between them have been elaborated to great length while their differences in APS remain to be elucidated. We aim to report the frequency of APS in patients with MOGAD as well as NNOSD patients, and to compare the characteristics of APS between patients with MOGAD and those with NMOSD. Methods: Seven MOG-IgG positive APS patients were retrospectively identified between 2017 and 2022. APS phenotypes have been previously described. The similarities and differences between MOGAD and NMOSD patients with APS was compared, including the frequency and duration of APS between the two diseases, and their incidences of accompanied subtentorial lesions have also been described and compared. Results: We reviewed a cohort of 218 MOG-IgG-positive patients, and 396 patients with NMOSD. 200 MOGAD patients and 332 NMOSD patients were included in this study. In the cohort, seven patients with MOG-IgG-positive antibody presented with APS were analyzed, four of whom had disease onset with APS. Of the 332 patients with NMOSD, 47 had APS attacks while 31 had APS at disease onset. In patients with MOGAD, 2 had nausea, 3 had vomiting, 5 had hiccups, and 1 patient presented with all three symptoms above. In patients with NMOSD, 70.2 % had nausea, vomiting and hiccups at the same time during APS attacks. Apart from the medulla oblongata, other subtentorial regions were also affected in 6/7 MOGAD patients while 14/47 NMOSD patients had other subtentorial regions involved. During an APS attack, the incidence of concomitant lesions in the brainstem and other regions was significantly greater in MOGAD than in the NMOSD cohort (P = 0.008*). Conclusion: APS is a rare, but not isolated clinical manifestation of MOGAD. APS happened more frequently with other supratentorial and subtentorial lesions in MOGAD. The symptoms of NVH (nausea, vomiting, hiccups) tended to happen respectively in MOGAD compared with NMOSD. The phenotype or mechanism of APS in MOGAD may differ from that in NMOSD.