Primary angiitis of the central nervous system presenting as unilateral optic neuritis.

A middle-aged woman who experienced recurrent episodes of unilateral vision loss and eye pain. On presentation, magnetic resonance imaging (MRI) demonstrated left optic nerve enhancement with patchy hyperintensities in the white matter of both frontal lobes and ill-defined enhancement in a lenticulostriate distribution. Ophthalmologic examination revealed left optic disc edema with a macular scar consistent with neuroretinitis. Her subsequent clinical course was notable for 2 episodes of painful vision loss, without associated neurologic symptoms, which resolved with intravenous and oral steroids. More than 1 year after her initial presentation, the patient developed right facial weakness and slurred speech, and shortly thereafter suffered a fatal intracerebral hemorrhage. Histopathology on autopsy confirmed a diagnosis of primary angiitis of the central nervous system (PACNS). This is an unusual case of PACNS presenting with recurrent unilateral optic neuritis. The vascular enhancement pattern on MRI suggesting inflamed cerebral blood vessels is a rarely described pattern, which likely reflects intracerebral extension of the ocular pathology. The combination of neuroretinitis and perivascular MRI enhancement pattern may represent a subtype of PACNS.