see also:

• encephalopathy
• progressive multifocal leukoencephalopathy (PML)
• encephalitis
• leukoencephalopathy (ADEM)
• acute necrotising encephalopathy of childhood (ANEC)
• Subacute sclerosing panencephalitis (SSPE)

• a rare form of autoimmune encephalitis associated with IgG autoantibodies that target GFAP in astrocytes, which leads to an eventual loss of astrocytes
• first described by Boyan Fang, Vanda Lennon, and colleagues from the Mayo Clinic in their 2016 seminal paper

• rare

• the autoantibodies may have a paraneoplastic or parainfectious aetiological basis
• 1/3rd of cases are associated with an ovarian teratoma or an adenocarcinoma

• broad spectrum of clinical features but usually consistent with meningo-encephalitis clinical features

• cerebrospinal fluid (CSF)
  • usually elevated protein levels, pleocytosis and positive for GFAP antibodies
• co-existing autoantibodies (e.g. NMDAR antibody, AQP4 antibody) may also be present especially in patients with ovarian teratoma ¹⁾
• MRI brain:
  • T2/FLAIR
    • up to 75% have hyperintense, diffuse, confluent, periventricular white matter lesions
  • other findings - see https://radiopaedia.org/articles/autoimmune-glial-fibrillary-acid-protein-gfap-astrocytopathy

• leukoencephalopathy (ADEM)
• encephalitis
• a range of other differentials of the MRI findings - see https://radiopaedia.org/articles/autoimmune-glial-fibrillary-acid-protein-gfap-astrocytopathy

• high dose IV steroids