A case of infantile mumps meningitis with acute cerebellar ataxia and MERS

Abstract

We report a patient with mumps meningitis and MERS (clinically mild encephalitis/encephalopathy with reversible splenial lesion) who exhibited flutter-like oscillations. A 7-year-old boy complaining of a headache, vomiting and dizziness consulted the Department of Pediatrics. Since he was positive for hemolytic streptococcus but did not exhibit cervical rigidity, an antibiotic was prescribed. He was brought back to the Department of Pediatrics after suffering from convulsions two days later. A high-intensity spot was found in the splenium of the corpus callosum on a diffusion-weighted magnetic resonance imaging (MRI) examination. The patient showed irregular horizontal eye movements and was referred to our department under a suspicion of peripheral vertigo. We found a horizontal pendular ocular movement with a small oscillation and a short duration and suspected flutter-like oscillations. No new lesions were found on a subsequent MRI examination, and the symptoms gradually improved without any additional treatment. The patient was discharged 20 days later. The diagnosis was mumps meningitis, acute cerebellar ataxia, and MERS based on a cerebrospinal fluid polymerase chain reaction (PCR) test and the MRI results. The patient's symptoms had disappeared at a follow-up examination performed in the outpatient department 47 days later.Flutter-like oscillations are an irregular ocular movement found in cases with an impaired brainstem or cerebellum. Flutter-like oscillations often occur with changes in fixation and are presumably caused by a malfunction in pause neurons in the brainstem.MERS is characterized by a reversible splenial lesion of high intensity on diffusion-weighted MRI in association with various diseases such as viral infection, epilepsy, renal failure and electrolyte imbalance. The cause is thought to involve inflammatory infiltrates or intramyelinic edema.The present report is thought to be the first description of a case of MERS exhibiting flutter-like oscillations. Since flutter-like oscillations may be confused with peripheral nystagmus, despite the distinctive ocular movement, a neurootologist consultation is desirable, especially in cases where central impairment is suspected.