Acute disseminated encephalomyelitis (ADEM)
MOG-IgG serum antibodies were first identified in a subset of children
with ADEM (28,29). Children with ADEM represent the most common
phenotype among all MOGAD patients and account for almost 50% of
paediatric MOGAD patients (2,24). Clinical presentation of ADEM includes
polyfocal neurological deficits and encephalopathy (i.e. behavioural
changes or altered consciousness), not explainable by fever (30). It has
recently been shown that up to 50% of all children with ADEM are
seropositive for MOG-IgG (31). In these patients, MOG-IgG seroprevalence
is associated with a higher risk for longitudinally extensive transverse
myelitis (LETM), but with resolution of brain lesions and a better
outcome compared to MOG-IgG negative ADEM patients (32). Relapses can
occur with further episode(s) of ADEM as multiphasic ADEM (MDEM), with
ON (ADEM-ON), or transverse myelitis (ADEM-TM) (33). Notably, persistent
seroprevalence of MOG-IgG is strongly associated with an increased risk
for relapsing disease (34,35).