A severe, relapsing case of myelin oligodendrocyte glycoprotein IgG-associated CNS inflammation

A 55-year-old man presented in October 2004 with general unease, vomiting, and gait disturbance. Initially diagnosed with an inner ear infection, the patient's symptoms did not improve and he was evaluated further. MRI revealed a cerebellar lesion, which led to the suspicion of a posterior circulation stroke, and he was started on antiplatelet drugs. However, an angiogram suggested no vascular pathology. In March 2011, he had another episode of ataxia and MRI showed a right brainstem lesion. Cryptogenic stroke was reconsidered. In March 2013, the patient developed paraparesis with urinary and bowel symptoms. MRI revealed myelitis of the midthoracic spinal cord. Oligoclonal bands were present in both serum and CSF and steroids were begun. In February 2014, he was admitted with expressive aphasia and right hemiparesis. MRI (figure 1) confirmed a new T2-hyperintense lesion in the left frontal lobe and he was given IV methylprednisolone and subsequently underwent plasma exchange. Aquaporin 4 (AQP4) IgG was negative. The working diagnosis was tumefactive multiple sclerosis. He was started on glatiramer acetate in August 2014. A few months later, he developed right-sided weakness, left optic neuritis (ON), and confusion. MRI (figure 2) showed left occipital and left parietal cortical and subcortical white matter lesion spreading across the corpus callosum to the opposite side. There were changes bilaterally in the cerebellum, cerebral peduncles, and along the corticospinal tracts on the left side. Further scans showed swelling of the splenium of the corpus callosum. He was put back on prednisolone 60 mg. Markers for systemic inflammation (erythrocyte sedimentation rate, C-reactive protein) were normal and autoantibody testing (antinuclear antibodies, extractable nuclear antigen, paraneoplastic antineuronal antibodies) was negative. The diagnosis of fulminant seronegative NMO was re-entertained but AQP4 antibodies were negative. However, MOG antibodies returned positive (October 2014, live cell-based assay, John Radcliffe Hospital, Oxford, UK). Azathioprine 125 mg was begun in February 2015.