A child with four episodes of recurrent reversible splenial lesions without an MYRF variant

Only a few cases of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) recur. The clinical findings of familial and/or MERS type 2 recurrent cases involving the myelin regulatory factor ( MYRF ) gene have recently been clarified, but it is unclear how the clinical findings of recurrent cases without an MYRF variant differ from those of cases with an MYRF pathogenic variant. A 5-year-old girl with healthy parents and no previous developmental problems experienced four episodes of reversible splenial lesions. Each episode was observed with three to six recurrent seizures and persistent disturbance of consciousness. Based on magnetic resonance imaging (MRI) findings, the diagnosis was MERS type 2 in two episodes, MERS type 1 in one episode, and MERS type 2 lesions in one episode. Recurrent seizures, nonfamilial occurrence, recurrent lesions of different types, isolated splenial lesions in the corpus callosum (CC), and limited spread of white matter lesions were the characteristics of this case. Recurrent lesions of different types and lesions that do not always involve the entire CC or both genial and splenial lesions in the CC may characterize recurrent MERS cases without an MYRF variant. Further comparative investigations should be conducted with a larger number of patients to clarify the differences in clinical findings.