Isolated De Novo Headache as the Presenting Symptom of Listeria Meningitis: A Report of 2 Cases.

Headache is a frequent symptom at the onset of Listeria meningitis, accompanied by others such as fever, altered mental status and meningeal signs, but never reported so far as an isolated symptom.Two immunocompetent males, with no history of primary headaches, went to the emergency department because of headache. The first after a sudden severe, holocranial headache without other associated symptoms, and the second after a subacute, moderate oppressive headache in temples, which 8 days later added a mild left hemiparesis. None of them had fever or meningeal signs. The initial cranial CT was unremarkable in both cases. Lumbar puncture was diagnostic for Listeria meningitis serotype IVb.Listeria meningitis may present as an isolated headache, with different clinical patterns, which should be taken into account when evaluating de novo unclassified headaches according to the ICHD-3 criteria.