A rare, medium or small vessel vasculitis characterized by focal and/or diffuse neurologic symptoms due to a documented arteritic process in the central nervous system, in the absence of other identified underlying cause (infectious, systemic, other neurologic diseases, etc.). It presents with non-specific symptoms of headache, stroke or transient ischemic attacks with cognitive impairment, hemiplegia, weakness, and rarely, with cranial nerve involvement, seizures and ataxia. [from
ORDO]