Atypical manifestation of Anti-Gaba-Br autoimmune encephalitis

Abstract

Introduction: Anti-GABA-Br is an autoantibody associated with autoimmune encephalitis and small cell lung carcinoma. Clinical seizures, including status epilepticus, represent the most common feature of anti-GABA-Br related disorders. This case reports a previously healthy 40-year-old man with rapidly progressive dementia and Anti-GABA-Br positive cerebrospinal fluid (CSF). This is a case report based on retrospective analysis of a single patient’s medical record. Case report: From May 2019 to October 2020, the patient presented with dulling, decreased speech frequency and gait disturbance. He became unable to perform all basic and instrumental activities of daily living. Physical examination was marked by: pancerebellar dysfunction and impaired working memory. Brain magnetic resonance imaging (MRI) showed global brain volumetric reduction with bilateral T2/FLAIR (T2-weighted-Fluid-Attenuated Inversion Recovery) hypersignal in cortical regions of insula and mesial temporal lobes, without contrast enhancement. Analysis of CSF: 8.3 cells/ mm³ (96% lymphocytes) and protein 64 mg/ml. There was no evidence of: clinical/electroencephalographic seizures or pathological patterns on electroencephalograms. He received methylprednisolone for five days followed by cyclophosphamide infusions (one per month for seven months). Azathioprine started after tapering prednisone. On March 2022, the patient underwent a new MRI with hypersignal improvement although atrophy had persisted. CSF after treatment had no inflammatory changes and was antiGABA-Br positive. The patient presented a partial recovery and was still dependent on instrumental activities. Conclusion: Anti-GABA-Br encephalitis has a predilection for males, affects variable ages and is best characterized by generalized seizures with evolution to refractory status epilepticus although behavioral changes may occur. There are few reports of seizure free cases.