A hemicrania continua‑like headache as an early signal of anti‑NMDA receptor encephalitis: a case report

Trigeminal autonomic cephalalgia (TAC) syndromes, although rare in the spectrum of headache disorders, are of great importance to recognize, because they can be debilitating and may be linked to potentially serious underlying causes. We present a patient with a TAC-like headache, where the diagnostic workup revealed a new secondary cause for TAC syndromes. A 62-year-old male patient has been referred with a complaint of experiencing a new-onset severe headache located in the left orbitofrontal region. Each episode lasted 15 min and was repeated 3 to 4 times a day with mild continuous pain between episodes. Severe pain was associated with psychomotor agitation and ipsilateral cranial autonomic symptoms. Brain and vascular imaging showed mild pachymeningeal enhancement. Cerebrospinal fluid pressure and analysis were normal except for a high protein level. Further investigation for a secondary cause revealed a positive result for serum anti-N-methyl D-aspartate (NMDA) receptor antibody. The headaches were resolved after 5 days of intravenous methylprednisolone followed by oral prednisolone. There are various etiologies for secondary TACs. Most of them are structural lesions, especially in the sella turcica region, and vascular disorders such as dissection or aneurysm. To our knowledge, this is the first case of TAC associated with autoimmune encephalitis antibodies that responded significantly to corticosteroids. This patient, along with cases of Neuromyelitis Optica-Spectrum Disorder (NMO-SD) with TAC presentation, highlights the role of autoimmunity in TAC syndromes.