HSV encephalitis triggered anti-NMDAR encephalitis: a case report

Background Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis (AE) is a common cause of nonviral infectious encephalitis, which can be triggered by herpes simplex virus infection. Previous studies have shown that approximately 27% of herpes simplex encephalitis (HSE) patients produce anti-NMDAR antibodies within 3 months. Immunotherapy is recommended in this situation, but some symptoms usually remain in the 1-year follow-up. Case presentation A previously healthy 23-year-old Chinese young woman developed epileptic attack followed by psychiatric symptoms of confusion and irritation as well as cognitive deficits. Brain MRI showed hyperintense lesions of the right temporal lobe on DWI and T2 without contrast enhancement effects. Twenty-one days of acyclovir was administered based on the primary diagnosis of HSE. The anti-NMDAR antibody (IgG) was detected positively on day 11 after disease onset. She had improved cognitive function but suffered another grand mal epilepsy after the first course of intravenous immunoglobulin (IVIG) therapy combined with 1000 mg intravenous methylprednisolone. After discussion, another course of IVIG was started for 5 days. Her symptoms were well controlled with only mild cognitive deficits at the 1-year follow-up (mRS = 1). Conclusions Our case indicated that anti-NMDAR antibodies could develop earlier after HSE compared with previous data from adults. We suggested detecting AE antibodies simultaneously with each CSF analysis. Meanwhile, the second course of IVIG therapy was reasonable when symptoms were not controlled after the first course of IVIG combined with IV steroid treatment.