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Clinically mild encephalitis with a reversible splenial lesion (MERS) after mumps vaccination

Jun-Ichi Takanashi1, Takashi Shiihara2, Takeshi Hasegawa3

  • 1Department of Pediatrics, Tokyo Women's Medical University, Yachiyo Medical Center, Yachiyo, Japan.

Journal of the Neurological Sciences
|December 28, 2014
PubMed

Insights

Mild encephalitis with a reversible splenial lesion (MERS) after mumps vaccination is a potential concern. This condition presents with neurological symptoms and hyponatremia in young males post-vaccination.

Area of Science:

  • Neurology
  • Vaccinology
  • Pediatrics

Background:

  • Mumps vaccination is a routine pediatric immunization.
  • Encephalitis is a rare but serious complication of viral infections and vaccinations.

Observation:

  • Five male patients aged 1-9 years developed neurological symptoms 13-21 days post-mumps vaccination.
  • Initial symptoms included fever, vomiting, or headache, progressing to consciousness disturbance, seizures, or dysarthria.
  • All patients presented with hyponatremia and cerebrospinal fluid findings consistent with aseptic meningitis.

Findings:

  • Magnetic Resonance Imaging (MRI) revealed reversible splenial lesions in the corpus callosum.
  • Vaccine strain genome was confirmed in cerebrospinal fluid.
  • Electroencephalogram (EEG) showed abnormalities that normalized over time.

Implications:

  • Mild encephalitis with a reversible splenial lesion (MERS) following mumps vaccination may be underdiagnosed.
  • Suspected MERS in young males with neurological symptoms and hyponatremia post-mumps vaccination warrants MRI evaluation of the corpus callosum.
Keywords:
Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS)DiffusionHyponatremiaMRIMumps vaccinationSplenium

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