Diagnostic challenge in primary angiitis of the central nervous system: altered consciousness with multifocal infarcts and haemorrhages

We present the case of a man in his late 50s who was admitted with an acute ischaemic stroke and subsequently developed rapidly progressive encephalopathy, multiple bilateral infarcts and intracranial haemorrhages. Despite initial suspicion of reversible cerebral vasoconstriction syndrome or posterior reversible encephalopathy syndrome, repeated neuroimaging, including high-resolution black-blood MRI, demonstrated vessel wall enhancement consistent with vasculitis. Extensive work-up excluded systemic vasculitis, infection, malignancy and cardioembolic sources. The clinical and radiological findings met the diagnostic criteria for probable primary angiitis of the central nervous system (PACNS). Definite diagnosis of PACNS requires histopathological confirmation by biopsy, which was not performed. Immunosuppressive therapy with high-dose corticosteroids and azathioprine was initiated, leading to a gradual improvement of the encephalopathic state although severe neurological deficits persisted. This case highlights the diagnostic challenges associated with PACNS and underscores the importance of repeated reassessment in patients with unexplained altered consciousness.