Acquired, nMS, central nervous system (CNS) demyelinating disorders are categorized into monophasic demyelinating event (MDE) or clinically isolated syndrome (CIS), aquaporin 4 antibody (AQP4) associated  Neuromyelitis optica spectrum disorder (AQP4-NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody associated demyelinating disorder (MOGAD).  MDE/CIS includes optic neuritis (ON), transverse myelitis (TM), acute disseminated encephalomyelitis (ADEM), posterior fossa syndrome (PFS), and encephalitis without ADEM features. These are rare and not well understood in children. An infectious trigger to  immune response causing demyelination has been hypothesized.

Retrospective chart review spanning 11 years. Data was collected from Kaleida Health’s medical records with discharge diagnoses of MOGAD, AQP4-NMOSD, ADEM, encephalitis, ON, and TM. Clustering of cases means maximum number of events, in total and individually, over certain months and years.

Out of 313 patient records’, only 36 ( 12%)  fulfilled our inclusion criteria. Twenty eight (78%) had an acute infectious occurrence with initial event while only one (3%) received a vaccine 2 weeks prior. 31% events were reported each during summer and winter while 19%  each in spring and fall. 14% (5/36) seen in August, 11% (4/36)  each in January, February, May, July and September, 8% (3/36) in December, 5.5% (2/26) each in April, June and October, and 3% (1/36) each in March and November. Total 3 events (8%) were found in 2011, and 2 (5.5%) each in 2014, 2017 and 2020. ADEM clustering was noticed in 2011 and 2014, followed by 2013, 2015 and 2019, MOGAD during 2020, and optic neuritis during 2011 and 2012.

Our study described link of seasonal infectious triggers to the initial events of pediatric nMS acquired demyelinating  disorders. However, smaller data size precluded to see distinct patterns by year.