Role of High-Resolution Magnetic Resonance Imaging in the Diagnosis of Primary Angiitis of the Central Nervous System

BACKGROUND Primary angiitis of the central nervous system (PACNS) is a rare disorder and is often difficult to diagnose due to the lack of a confirmatory test. PACNS can generally be diagnosed based on typical angiographic findings. We describe herein a patient diagnosed with PACNS despite the presence of normal findings on conventional angiography. CASE REPORT A 44-year-old man with a recent history of ischemic stroke in the right posterior cerebral artery territory developed acute-onset vertigo. Diffusion-weighted imaging revealed an acute infarction within the left posterior inferior cerebellar artery. His medical history was unremarkable except for hyperlipidemia; the initial examination revealed mild gait imbalance. During the 10 days of hospital admission, the patient experienced four recurrent ischemic strokes within the posterior circulation territory (occipital lobe, pons, and cerebellum). He was diagnosed with recurrent cerebral infarctions due to PACNS. The basilar artery exhibited no demonstrable luminal stenosis, but there were direct imaging signs of central nervous system angiitis including wall thickening and contrast enhancement. High-dose intravenous steroid therapy followed by oral prednisolone was administered. There was no further stroke recurrence and follow-up imaging of the arterial walls showed normalization of their characteristics. CONCLUSIONS The present case emphasizes the importance of wall imaging in the diagnosis and treatment of PACNS.