Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the central nervous system (
4) and encompasses post-infectious and post-vaccination encephalomyelitis ( 1). The incidence rate of ADEM is 0.8 in 100000 people, and post-vaccination ADEM accounts for < 5% of all the ADEM cases ( 4). It has been associated with several vaccines such as rabies, diphtheria, tetanus, pertussis, influenza, small pox, measles-mumps-rubella, Japanese encephalitis, polio, and hepatitis B vaccines. The clinical presentation of ADEM comprises fever, altered consciousness, and multifocal neurological deficits, which typically appear within 1 day to 3 weeks after immunization. The CSF examination usually reveals lymphocytic pleocytosis, raised protein levels, and myelin basic protein. The CT and MRI of the brain in ADEM can be normal, but they often show multifocal or extensive white matter or deep gray matter lesions (thalamus and basal ganglia) within 5 to 14 days of the symptom onset ( 5).
Meningococcal vaccine is used to help prevent meningitis. Mencevax ACWY meningococcal polysaccharide vaccine can be used in adults and children over 2 years of age, but it confers protection only against meningitis caused by the four
Neisseria meningitidis serogroups of A, C, W-135, and Y. This vaccine is recommended for individuals in close contact with those infected by A, C, W-135, and Y serogroups of meningococcal disease. In addition, individuals travelling to countries where the disease is endemic or highly epidemic are advised to receive the vaccine. Moreover, individuals with inherited defects of properdin or complement or functional or anatomical asplenia are at increased risk of meningococcal infection.
The side effects of Mencevax ACWY meningococcal polysaccharide vaccine include tenderness, pain or discomfort, redness, itching around the injection site, headache, dizziness, weakness or fatigue, serious allergic reactions, and fever (> 38°C) and/or chills. Neurological reactions (reactions involving the nervous system) are rare but can be serious (
6). In our patient, given the likelihood of neurological reactions to Mencevax, the plausible time relationship between the clinical event and the vaccine administration, and the absence of other possible etiologies, the diagnosis of post-vaccination ADEM was very likely. The main therapeutic options for ADEM are high-dose corticosteroids, plasma exchange, and intravenous immunoglobulin ( 1). In our patient, high-dose steroid therapy had a good outcome insofar as the treatment was successful without any complications.
We herein presented a possible case of post-vaccination encephalitis due to Mencevax ACWY meningococcal polysaccharide vaccine. This case report highlights the possibility of adverse neurological events following immunization with this vaccine. We would, therefore, recommend that ADEM be considered in the differential diagnosis of a patient with altered consciousness and fever after recent vaccination.