Initially, this case was thought to be fairly typical of ADEM with a cluster of lesions which evolve at variable rates during the one period. 

The presence of basal ganglia high T2 signal suggests that this is indeed post-streptococcal acute disseminated  encephalomyelitis (ADEM) as basal ganglia involvement (with auto-reactive antibasal ganglia antibodies (ABGA)) is far more common (80%) in post-strep ADEM than in non-post-strep ADEM (18%) ¹. 

Unfortunately on further follow-up additional new lesions developed (over one year after the initial presentation) suggesting that in fact this was, or had gone on to become, a relapsing form of ADEM (relapsing disseminated encephalomyelitis (RDEM) and multiphasic disseminated encephalomyelitis - MDEM). The demarcation between these, however, and relapsing-remitting multiple sclerosis is contentious.

Overall when the diagnosis of ADEM is made, progression to MS is not uncommon, reported in up to 35% of cases.