The gamma-aminobutyric acid-B receptor (GABAB) encephalitis: clinical manifestations and response to immunotherapy

Purpose: We report 11 patients diagnosed with GABAB receptor (GABABR) antibodies encephalitis in China and aim to analyze the clinical characteristics, laboratory and imaging findings, therapeutic modalities and outcomes.Methods: Clinical data from patients diagnosed with anti-GABAB receptor encephalitis in the Second Affiliated Hospital of Hebei Medical University from February 2016 to October 2016 January were retrospectively collected and evaluated.Results: Of the 11 patients, seven were males, and a mean age at presentation of 63 years (range: 47–79 years). The major clinical features include cognitive decline (9/11), epilepsy (10/11), mental and behavioral disorders (6/11), involuntary movement (4/11), sleep disorders (2/11), hearing loss (1/11), disturbance of consciousness (4/11) and fever (3/11). GABA-B receptor antibody was positive in serum and/or cerebrospinal fluid in 11 patients. Small-cell lung cancer was detected in five patients. Electroencephalogram monitoring demonstrated abnormal discharge in 10 cases. Epileptiform activities were found in five patients. Four patients showed abnormality in hippocampal region, parahippocampal gyrus, temporal and occipital lobe on magnetic resonance imaging. Ten patients accepted first-line immune therapy. Five patients with small-cell lung cancer received oncologic treatment. During a median follow-up of 11 months, eight patients showed a good outcome, two patients (cases 8 and 9) with tumors had a poor one and one patient (case 10) died of status epilepticus.Conclusion: Anti-GABAB receptor encephalitis is an uncommon autoimmune disease, which has been known to be often associated with cancer. Generally, patients associated with GABABR GABA-B receptor antibody encephalitis respond well to immunotherapy, especially if started early.