[Background] Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) can be alleviated without neurological sequelae. It is classified into three disease types by diagnostic imaging. In general, acute encephalopathy is caused by cytokine overproduction. However, there are few reports on the pathological analysis of MERS. In the present report, cytokines and chemokines analysis was performed by MERS type to elucidate its pathology.

[Material and method] The subjects were 3 boys, aged 9 (type 1), 13 (type 2), and 2 (type 3) years, who were admitted to our hospital. We analyzed cytokines and chemokines in the serum and cerebrospinal fluid (CSF) of the subjects. The levels of them were measured using 27-Plex Panel (Bio-Rad Laboratories, USA).

[Results] CSF interleukin (IL)-6, 8, 10 and interferon (IFN)-gamma were elevated in type 1. IL-6, 10 and 17 were elevated in type 2. IL-6, 17, Tumor Necrosis Factor (TNF)-alpha and IFN-gamma were elevated with low IL-10 in type 3.

[Conclusion] In both types 1 and 2, the anti-inflammatory cytokine IL-10 was also elevated, and the symptoms were improved early with a good prognosis. In type 3, IL-10 was low, with a large lesion, which may have been involved in the prolonged disturbance of consciousness after convulsions. Besides excitotoxicity, a pathological condition of MERS, inflammatory/anti-inflammatory cytokines variation may have influenced the prognosis.