IMPORTANCE Antibodies to myelin oligodendrocyte glycoprotein IgG (MOG-IgG) are increasingly detected in patients with non-multiple sclerosis-related demyelination, some of whom manifest a neuromyelitis optica (NMO) phenotype. Cortical involvement, encephalopathy, and seizures are rare in aquaporin 4 antibody (AQP4-IgG)-related NMO in the white European population. However, the authors encountered several patients with seizures associated with MOG-IgG disease. OBJECTIVE To compare incidence of seizures and encephalitis-like presentation, or both between AQP4-IgG-positive and MOG-IgG-positive patients. DESIGN, SETTING, AND PARTICIPANTS Retrospective case series of all patients who were seropositive for MOG-IgG (n = 34) and the last 100 patients with AQP4-IgG disease (NMO spectrum disorder) seen in the NMO service between January 2013 and December 2016, and analysis was completed January 4, 2017. All patients were seen in a tertiary neurological center, The Walton Centre NHS Foundation Trust in Liverpool, England. MAIN OUTCOMES AND MEASURES The difference in seizure frequency between the AQP4-IgG-positive and MOG-IgG-positive patient groups was determined. RESULTS Thirty-four patients with MOG-IgG disease (20 female) with a median age at analysis of 30.5 years (interquartile range [IQR], 15-69 years), and 100 AQP4-IgG-positive patients (86 female) with a median age at analysis of 54 years (IQR, 12-91 years) were studied. Most patients were of white race. Five of the 34 patients with MOG-IgG (14.7%) had seizures compared with 1 patient with AQP4-IgG (2-sided P < .008, Fisher test). On magnetic resonance imaging, all 5 MOG-IgG-positive patients had inflammatory cortical brain lesions associated with the seizures. In 3 of the 5 MOG-IgG-positive patients, seizures occurred as part of the index event. Four of the 5 presented with encephalopathy and seizures, and disease relapsed in all 5 patients. Four of these patients were receiving immunosuppressant medication at last follow-up, and 3 continued to take antiepileptic medication. In contrast, the only AQP4-IgG-positive patient with seizures had a diagnosis of complex partial epilepsy preceding the onset of NMO by several years and experienced no encephalitic illness; her magnetic resonance imaging results demonstrated no cortical, subcortical, or basal ganglia involvement. CONCLUSIONS AND RELEVANCE Patients with MOG-IgG-associated disease were more likely to have seizures and encephalitis-like presentation than patients with AQP4-IgG-associated disease.

BackgroundAntibodies to myelin oligodendrocyte glycoprotein (MOG) are being increasingly detected in patients with non-MS demyelination many of whom have the neuromyelitis optica spectrum disorders (NMOSD) phenotype. Cortical involvement or seizures are rare in AQP4 IgG NMO. Having encountered one MOG IgG+ve patient with seizures we systematically reviewed all our patients.MethodRetrospective review of the clinical and MRI data of all MOG IgG +ve cases (n=28) and 100 patients with AQP4 IgG+ve NMOSD for seizures and cortical lesions.ResultsOnly 1/100 NMOSD with AQP4 IgG had seizures (1%)-a 43-year old woman with epilepsy, her first seizure 5 years before the onset of NMOSD. Brain MRI was normal. 4/28 patients with MOG IgG had seizures (14%) that occurred along with an episode of demyelination. All 4 had cortical lesions and relapsing demyelination and are on immunosuppressants. 3 continue on antiepileptic drugs.ConclusionPatients with MOG IgG associated disease are more likely to have seizures (P<0.008, Fisher's test) and cortical MRI changes compared to AQP4IgG +ve cases. This may further support the view that the two are different diseases.

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.