Rarely a patient may develop acute disseminated encephalomyelitis (ADEM) following a vaccination.
Vaccines associated with ADEM:
(1) COVID-19
(2) influenza
(3) tetanus toxoid
Onset: usually 4 to 13 days after triggering event
The clinical course may be monophasic, recurrent, or multiphasic.
General symptoms may include:
(1) fever
(2) vomiting
(3) weakness
(4) headache
Neurological findings:
(1) change in behavior
(2) altered consciousness (lethargy, stupor, or coma)
(3) ataxia
(4) hemiparesis
(5) dystonia
(6) choreiform movements
(7) aphasia
(8) diplopia
(9) dyslexia
(10) cranial nerve palsy
(11) flaccid paralysis
(12) urinary retention and/or constipation
Brain CT shows multifocal areas that are irregular and poorly marginated mainly in cortical gray-white junction, best seen in T2-weighted and fluid-attenuated inversion recovery images.
Examination of the CSF shows absence of infection and absence of oligoclonal bands. Some patients may show anti-MOG antibodies.
The diagnosis requires exclusion of an infectious cause, which can be difficult.
