Secondary
Vascular: ICH, EDH, SDH, CVST, malignant HTN
Infection: meningitis, encephalitis, cerebral abscess
Trauma: head, C-spine
Autoimmune: GCA
Metabolic: hypoxia, hypercapnia, CO poisoning
Idiopathic: IIH, AACG, trigeminal neuralgia
Neoplastic: CNS cancer
Functional: somatisation disorder