ABSTRACT
Objective To investigate the clinical manifestations, laboratory and imaging features, treatments and prognosis of anti GABA-B receptor encephalitis. Methods We performed a retrospective analysis of the clinical data of five cases with anti GABA-B receptor encephalitis diagnosed by cerebrospinal fluid immunological examination. Results Five cases had acute onset. The initial clinical symptom was epileptic seizure. After epileptic attack, patients developed different degrees of cognition dysfunction, mental and behavioral disorders. Neuroimaging showed that the lesions mainly involved medial temporal lobe and hippocampus. The lesions ware equal or low density shadows in CT scan and long T 1 and T2 signals, T2 high signals on Flair, equal or high signals on DWI in MRI scan. Cranial MRI enhancement showed lesions with no enhancement in two tested cases. One case took PET-CT and data showed a low density shadow of temporal lobe and hippocampus with increased metabolism. CSF and blood immunological examinations showed CSF GABAB-R-AB positive (+), blood GABAB-R-AB positive (+). Five cases were associated with increased NSE. EEG was nonspecific and related to the conscious state of the patient. Lung CT showed enlarged mediastinal lymph nodes in 5 tested cases. Central lung cancers were found in five cases including three cases at onset and two cases during three month follow-up. Bronchoscopic biopsy identified small cell lung cancer in two examined cases. Conclusion Epileptic seizure is the most frequent initial symptoms of anti GABA-B encephalitis. Inflammatory response signals in the medial temporal lobe and hippocampus are image features of anti GABA-B encephalitis. The disease is closely related to lung cancer (Especially c small cell lung cancer, SCLC). Immunological examination of cerebrospinal fluid and the above characteristics are helpful for diagnosis.