Unihemispheric central nervous system vasculitis

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.