Anti-GAD Antibodies as an Etiology of Cerebral Cortical Encephalitis: 2 Case Reports

Abstract

Introduction: Cerebral cortical encephalitis (CCE) has been recently described as an entity associated with anti-MOG antibodies and, in some cases, of anti-GABA_AR encephalitis. No clear association with other antibodies has been reported to date. We describe two cases of patients presenting clinical and radiological features of diffuse cortical encephalitis associated with anti-GAD antibodies.

Method: In two patients with CCE, screening for the presence of anti-GAD and other antibodies was performed, along with a complete workup for alternative diagnoses.

Results: Two patients showing clinical and radiological features of CCE were tested positive for anti-GAD antibodies. MRI scan revealed multiple bilateral areas of cortico-subcortical FLAIR hyperintensities. They were both tested negative for anti-MOG, anti-NMDAr, and anti-GABA_AR antibodies. An ovarian teratoma was discovered in patient 1. Clinical and radiological evolution was favorable in both patients after cumulated therapies in the acute phase.

Discussion: CCE could be a new manifestation of anti-GAD antibodies, with distinct features compared to anti-MOG antibodies related to CCE. We recommend screening for anti-GAD antibodies in the context of CCE, especially in case of atypical features for MOG antibodies-associated disease (MOGAD).

Keywords: CCE; anti‐GAD antibodies; autoimmune encephalitis; cerebral cortical encephalitis.

FIGURE 1

MRI images of patient 1 (A1–A3) and 2 (B1–B3) showing cortico‐subcortical FLAIR hyperintensities (A1, B1) with areas of restricted apparent diffusion coefficient (ADC) (A3, B3) and without contract enhancement (A2, B2). PET‐scan of patient 1 (A4) reveals alternance of hyper and hypometabolism in the cortex. Coregistrated ASL‐FLAIR image of patient 2 (B4) shows elevated perfusion in areas with cortical FLAIR hyperintensity.