FLAIR-hyperintense lesions in anti-MOG associated encephalitis with seizures (FLAMES) is a clinicoradiographic sub-entity of MOGAD comprising seizures and FLAIR-hyperintensities on MRI, particularly involving the cerebral cortex ^1,2.

Epidemiology and treatment are covered in a general discussion of myelin oligodendrocyte glycoprotein​ antibody-associated disease (MOGAD).

Clinical presentation

As the name suggests, the clinical presentation includes:

• seizure, with additional symptoms including ³:

  • headache

  • fever

  • specific focal neurological deficits referable to the cortical lesions

CSF samples reveal a pleocytosis and elevated proteins with normal glucose ratios are described ³.

Radiographic features

MRI

FLAMES is characterised by high T2/FLAIR signal cortical lesions that are usually unilateral, although bilateral involvement has been described ^2,3. These lesions can have high signal on DWI ^2,3. There may be mild gyral swelling ².

Additionally, leptomeningeal abnormalities can be seen with sulcal FLAIR-hyperintensity and leptomeningeal contrast enhancement ². Occasionally these can be the dominant features with minimal to no cortical involvement, and in these cases the term FLAIR-variable unilateral enhancement of the leptomeninges (FUEL) has been suggested ⁴.  

Differential diagnosis

Due to the clinical and radiographic presentation of FLAMES possible differential diagnoses are:

• infectious encephalitis

• hemiplegic migraine

• postictal changes

• ischaemia

• mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS)