Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) associated with bacteria meningitis caused by listeria monocytogenes: A case report

RATIONALE: Mild encephalitis/encephalopathy with a reversible splenial lesion is a clinico-radiological syndrome mainly triggered by viral infection. Bacteria, like listeria monocytogenes, are relatively rare pathogens. PATIENT CONCERNS: A two and a half years old girl with a 3-day history of fever and vomiting, complicated by a sudden seizure. She was in a coma after seizure. DIAGNOSES: Listeria monocytogenes was detected in cerebrospinal fluid cultures. Serum IL-6 remarkably elevated, and hyponatremia appeared on day 2 of hospitalization. Magnetic resonance imaging of the brain performed on day 3 of hospitalization showed right subdural effusion and a lesion in the central portion of the splenium of the corpus callosum. INTERVENTIONS: We administered antimicrobial therapy, intravenous mannitol and hypertonic fluid therapy. OUTCOMES: Her neurological symptoms improved gradually. The lesion in the splenium of the corpus callosum completely disappeared on magnetic resonance imaging on day 10 of hospitalization. LESSONS: We diagnosed this case as mild encephalitis/encephalopathy with a reversible splenial lesion caused by listeria monocytogenes. The patient recovered completely clinically and on imaging, without any specific immunomodulatory treatment. It also indicated IL-6 may play a role in the forms of hyponatremia in mild encephalitis/encephalopathy with a reversible splenial lesion.