Secondary
Vascular: SDH, ICH, CVST, pre-eclampsia
Infection: meningitis, encephalitis,
otitis media, sinusitis, optic neuritis
Trauma: head, neck
Autoimmune: GCA
Metabolic: hypoxia, hypercapnia, CO poisoning
Idiopathic: IIH, AACG, TMJ problems,
trigeminal neuralgia
Neoplastic: CNS cancer
Drugs: cocaine, alcohol, med overuse headache