Autoimmune glial fibrillary acidic protein astrocytopathy

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP‐A) was recently reported as a spectrum of autoimmune inflammatory central nervous system disorders characterized by the detection of immunoglobulin G (IgG) against GFAP in cerebrospinal fluid using tissue‐ and cell‐based testing. The most common phenotypes of GFAP‐A are meningoencephalitis with or without myelitis. Patients present with headache and fever followed by consciousness disturbance and meningeal signs. Movement disorders, ataxia, hyperreflexia and blurred vision related to optic disc edema are sometimes observed. Some patients with GFAP‐A have a neoplasm. The most commonly detected neoplasm is ovarian teratoma. Coexisting neural antibodies are also sometimes detected. N‐methyl‐D‐aspartate receptor (NMDA‐R)‐IgG is the most common coexisting antibody, and patients with coexisting N‐methyl‐D‐aspartate receptor‐IgG have a clinical course resembling N‐methyl‐D‐aspartate receptor encephalitis. Lymphocytic pleocytosis lasts for several months and brain linear perivascular radial gadolinium‐enhancement patterns, an imaging hallmark of GFAP‐A, are sometimes observed. A previous neuropathological study reported inflammatory infiltrates including T‐, B‐ and plasma cells surrounding blood vessels. Although the pathophysiological mechanisms of GFAP‐A remain to be elucidated, GFAP‐specific CD8+ T cells are likely effectors of this disorder. GFAP‐A is usually corticosteroid responsive in the acute stage. However, some patients are prone to relapse or even die. In relapsed or refractory patients, the administration of oral prednisolone or a steroid‐sparing agent might be necessary. Because the timing of corticosteroid therapy might affect patient prognosis, cerebrospinal fluid GFAP‐IgG should be examined in patients with meningoencephalitis with or without myelitis who present with characteristic clinical features.