GABA-B Receptor Encephalitis Triggered by Enterovirus Encephalitis in a Patient With Small Cell Lung Cancer: A Case Report.

Seong Hoon Kim, Woojun Kim

The neurologist 2020 Jul

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Encephalitis with gamma-aminobutyric acid (GABA)-B receptor antibodies (GABA-B receptor encephalitis) is known to have underlying neoplastic condition in half of the cases; however, there could be an additional event that could work as a trigger factor. Here, we report a patient with GABA-B receptor encephalitis associated with small cell lung cancer, which was probably triggered by enterovirus encephalitis. A 53-year-old man was admitted for a seizure, following fever and headache for 3 days. Status epilepticus developed on the following day. Brain magnetic resonance imaging (MRI) was normal. Cerebrospinal fluid (CSF) study revealed lymphocyte-dominant pleocytosis, and enterovirus was detected by polymerase chain reaction test in CSF later. The patient recovered after 2 weeks of treatment. Another 2 weeks later, he showed confusion and seizure without fever. Follow-up CSF study revealed no abnormalities; however, MRI showed a lesion with vasogenic edema on the right posterior hippocampus. GABA-B receptor antibodies were found in the serum and CSF. The chest computed tomography revealed a mass on his right upper lung, which was confirmed as a small cell lung cancer. GABA-B receptor encephalitis associated with small cell lung cancer was diagnosed, and intravenous immunoglobulin and methylprednisolone were infused. Following treatment, seizures and delirium stopped, and the patient recovered to a near normal state. Follow-up MRI performed 2 months later showed that the hippocampal lesion had disappeared. In cases of infectious encephalitis with an atypical recurrent course, the possibility of newly onset autoimmune encephalitis should be considered.

Citation

Seong Hoon Kim, Woojun Kim. GABA-B Receptor Encephalitis Triggered by Enterovirus Encephalitis in a Patient With Small Cell Lung Cancer: A Case Report. The neurologist. 2020 Jul;25(4):106-108