An 81-year old man presented with a sudden right ataxic hemiparesis. Brain CT scan showed a left anterior choroidal artery territory infarction. Biological signs of inflammation were present without any evidence of infection or neoplasm. The patient's clinical status deteriorated with fever, loss of weight and confusion. Muscle biopsy showed characteristic abnormalities of polyarteritis nodosa (PAN). Oral corticosteroids plus monthly pulse intravenous cyclophosphamide were started. A rapid clinical improvement was observed as well as the resolution of inflammation within one month. Twenty months later, the patient had recovered normal cognitive function and was able to carry out all usual activities. We describe the CNS complications of PAN and the therapeutic options.