Case reportUnihemispheric central nervous system vasculitis

•Primary central nervous system vasculitis (PCNSV) can manifest with multiple lesions confined to a single hemisphere.•The response to immunosuppressive therapy for unihemispheric PCNSV varies in different reported cases as shown in Table 1.•In our case, the unihemispheric PCNSV shows a very good response to the immunosuppressive therapy.

Patients with primary central nervous system vasculitis (PCNSV) usually manifest with multiple enhancing bilateral hemispheric lesions. We presented an extremely rare clinical course and follow-up of a patient with PCNSV affecting only a single (right) hemisphere. A 33-year-old previously healthy man presented with a left hand clonic seizure followed by a secondary generalized tonic-clonic seizure and dysarthria. MRI brain revealed multiple hyperintense lesions confined to only the right hemisphere with contrast enhancement, involving both white and grey matters. He was treated with a methylprednisolone for 5 days followed by prednisone for suspected acute disseminated encephalomyelitis without improvements. He was presented again with left-sided weakness, transient dysarthria and black objects in left visual field. MRI brain was unchanged. MR angiogram and conventional cerebral angiogram were normal. Autoimmune work-ups were all negative. A brain biopsy showed evidence of PCNSV. He was then successfully treated with intravenous cyclophosphamide followed by oral azathioprine. On a follow-up 3 years later, he remains asymptomatic on azathioprine and a repeat MRI showed all areas of enhancement were gone.