A 26-year-old man presented with behavioral changes and blurry vision.  Examination showed impaired executive function and memory, paranoia and grandiose ideations. He had decreased visual acuity and optic disc edema bilaterally, with a right relative afferent pupillary defect, bidirectional nystagmus, pronator drift and ataxia in the left arm, generalized hyperreflexia and a left Babinski. MRI demonstrated multifocal, contrast-enhancing FLAIR hyperintensities involving the right pons, midbrain, thalami, and optic nerves. CSF revealed lymphocytic pleocytosis, hyperproteinorrhachia and oligoclonal bands. MOG antibody in the serum and anti-NMDA antibody in the CSF were positive. He received 5 days of high-dose steroids, plasmapheresis, intravenous immune globulin, followed by rituximab. Focal neurologic deficits improved, however cognitive and behavioral changes persisted.

NMDARe can present with clinical or radiological evidence of a demyelinating disorder, which can occur sequentially or simultaneously. The presence of mixed phenotypes suggest the coexistence of 2 simultaneous immune mechanisms. Although the initial treatment approach is similar, the prognosis and subsequent treatment differs. Our case demonstrated features atypical for NMDARe, such as demyelination on MRI and optic neuritis, as well as for MOG-AD, such as prominent psychiatric manifestations.