Analysis of clinical and imaging characteristics of anti-GABABR encephalitis

ZHANG Jingliang; GUO Shougang

Abstract：Objective To investigate the clinical and imaging characteristics of anti-gamma-aminobutyric acid B receptor(GABABR)antibody encephalitis.Methods Data from 13 clinically confirmed cases of anti-GABABR antibody encephalitis treated at our hospital were retrospectively analyzed,including clinical manifestations,laboratory findings,electroencephalo-gram(EEG)results,and imaging features from Magnetic resonance imaging(MRI)and Fluorine-18 Fluorodeoxyglucose Posi-tron Emission Tomography/Computed Tomography(18F-FDG PET/CT).Results 1)Clinical manifestations:all 13 patients ex-perienced seizures,with 6 showing memory decline and psychiatric or behavioral abnormalities.One patient exhibited nausea,vomiting,limb numbness and weakness,while another presented with unsteady gait;2)Laboratory findings:anti-GABABR anti-bodies were positive in both serum and CSF in 12 patients.Two patients were positive for SOX-1 and Hu antibodies,and one case was positive for Hu,Ri,and Recoverin antibodies.Elevated CSF cell counts were noted in 8 cases,and increased protein levels were found in 6 cases.Abnormal EEG findings were observed in 10 patients,with epileptic discharges recorded in 3 cases;and 3)Imaging findings:Among the 13 patients,6 exhibited abnormal findings on cranial magnetic resonance imaging(MRI),including abnormal signals on T2-weighted imaging(T2WI)and fluid-attenuated inversion recovery(FLAIR)se-quences,involving the temporal lobe,hippocampus,frontal lobe,medulla oblongata,insula,occipital lobe,and basal ganglia,with no significant enhancement observed.Five patients underwent 18F-FDG PET/CT scans,and abnormalities were detected in four of them,all showing reduced glucose metabolism.Two patients had abnormalities on both MRI and 18F-FDG PET/CT,with the latter demonstrating a more extensive range of lesions compared to MRI.Conclusion The EEG of anti-GABABR antibody encephalitis mainly shows abnormal background rhythm and increased slow-wave activity.MRI often reveals unilateral or bilat-eral lesions in temporal lobe or hippocampus,while 18F-FDG PET/CT may be superior to MRI in identifying lesions,aiding in early diagnosis.