Although most patients in our case series showed pleocytosis or increased IgG index in CSF analysis, two patients had normal CSF findings in routine examination, as mentioned in some patients with anti-mGluR5 encephalitis in the previous study or other types of autoimmune encephalitis (e.g., mGluR1, NMDAR) (12, 14, 18). Here, GRM5 is linked to viral encephalitis.