Aetiology

ADEM is predominately considered a post-infectious disease of the CNS. An identifiable infection or immunization has been reported in 50% to 85% of cases (1)

ADEM often follows an upper respiratory or gastrointestinal viral infection, viral exanthems (measles, rubella, chickenpox, etc.) or immunisation with viral vaccines - live or killed; influenza, rabies. ADEM is seen in adults and children approximately 8 to 21 days following immunization. The rabies vaccine is the most commonly reported vaccine associated with ADEM.

The frequency of ADEM occurring after vaccination has decreased in recent years, likely related to different methodologies in vaccine production (2)

Reference

1. Paolilo RB, Deiva K, Neuteboom R, Rostásy K, Lim M. Acute Disseminated Encephalomyelitis: Current Perspectives. Children (Basel). 2020 Nov 03;7(11)
2. Karussis D, Petrou P. The spectrum of post-vaccination inflammatory CNS demyelinating syndromes. Autoimmun Rev. 2014 Mar;13(3):215-24.