We present a case report of a patient with abrupt right fronto-temporal headache and neck pain that persisted for 13 days, followed by first-time generalized tonic-clonic seizures, weakness, neglect, and encephalopathy. She was ultimately diagnosed with FLAIR-hyperintense lesions in anti-MOG-associated Encephalitis with Seizures (FLAMES), which resolved with IV methylprednisolone.

We discuss a case of a 25-year-old previously healthy Asian woman, not on home medications, who experienced abrupt onset of right fronto-temporal headache and neck pain, which persisted for 13 days. She saw her primary care doctor four days prior to admission who recommended continuing ibuprofen. Brain imaging was not obtained at that time. She subsequently developed generalized tonic-clonic seizures with acute left sided weakness, neglect, and encephalopathy, which prompted presentation to the hospital. 

Video EEG showed right sided lateralized rhythmic delta activity (LRDA), as well as diffuse slowing. Lumbar puncture was performed: OP of 22 mm H20, W108 (35% PMNs, 55% lymphocyte), R 20, P 63.4, G 58.7, CSF culture was negative. CSF MOG antibody was positive at 1:100 and serum MOG antibody was positive at 1:320. Antivirals and antibiotics were stopped when infectious workup returned negative, and she began a five-day course of IV methylprednisolone with dramatic improvement.

FLAIR-hyperintense lesions in anti-MOG-associated Encephalitis with Seizures (FLAMES) should be included in the differential diagnosis of new, sudden-onset, severe, and persistent headache. Recommendations include early imaging and treatment with corticosteroids.