Case Report: Four Cases of Cortical/Brainstem Encephalitis Positive for Myelin Oligodendrocyte Glycoprotein Immunoglobulin G

FLAIR Hyperintense Cortical Lesions in a 4-Year-Old Child with Myelin Oligodendrocyte Glycoprotein (MOG)-Associated Encephalitis and Seizures: A Case Report

Myelin oligodendrocyte glycoprotein (MOG)-IgG-associated disease (MOGAD) is a relatively uncommon autoantibody demyelinating disorder of the central nervous system (CNS) with heterogeneous clinical manifestations and magnetic resonance imaging (MRI) findings. In recent years, a rare MOGAD subtype characterized by distinct clinical and MRI findings has been described. Seizures and cortical hyperintensities best seen on MRI T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences, associated with headache and cerebral spine fluid (CSF) pleocytosis, are the most important characteristics of this MOGAD entity that is named FLAMES (FLAIR hyperintense cortical lesions in MOG-associated encephalitis with seizures). Because of its rarity and the peculiarities of the brain damage and clinical manifestations, it can be under-recognized and confused with focal viral encephalitis, meningitis, subarachnoid hemorrhage, CNS vasculitis, or mitochondrial cytopathy. We described the case of a 4-year-old previously healthy girl who was admitted for focal-onset, tonic-clonic seizures, fever, and headache, combined with optic neuritis. MRI was characterized by FLAIR imaging showing hyperintense cortical lesions, and a mild leukocytosis in the CSF was detected. Efficacy and rapid response to steroid therapy was observed, and no recurrences of neurological problems or further seizures were reported in the following 12 months. This case report can help in understanding FLAMES characteristics in pediatrics in order to favor early diagnosis and prompt therapy.

Two case reports and a systematic review of the literature on adult cerebral cortical encephalitis with anti-myelin oligodendrocyte glycoprotein antibody

Background and purpose

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) has gained recognition in recent years as an immune-mediated inflammatory demyelinating disease of the central nervous system. The clinical features and prognosis of MOGAD adult cerebral cortical encephalitis (adult CCE) have not been fully elucidated. This study aims to further characterize the clinical symptoms, magnetic resonance imaging (MRI) findings, and prognosis of CCE with anti-MOG antibody.

Methods

We present two adult cases of CCE with anti-MOG antibody and summarize the clinical symptoms, magnetic resonance imaging (MRI) findings, and prognosis of this phenotype as per a completed systematic review of the literature.

Results

We found a total of 39 cases of MOGAD adult CCE (36% females; average age of onset of 29 years). Among them, 85% had seizure, 82% had headache, 64% had cortical symptoms, 64% had fever, 54% had changes of consciousness, and 38% had ocular symptoms. All cases demonstrated cerebral cortical T2 fluid-attenuated inversion recovery (FLAIR) lesions on MRI. Of the 25 patients (with seizure or not) who had EEG reports, 76% of patients showed abnormal EEG. Cerebrospinal fluid (CSF) white blood cell count of 90% of patients and CSF total protein of 67% of patients were elevated. In 16 patients with available CSF cytology data, 11 (69%) had abnormal cytology findings with monocytic predominance. In the 15 cases for which MOG antibody IgG was tested in both serum and CSF, 14 (93%) demonstrated a higher positive MOG IgG titer in serum than CSF. The majority of patients were treated with immunosuppressive therapy (97% corticosteroids, 15% mycophenolate mofetil, 13% IVIg, 5% azathioprine, and 5% other). The majority of patients had a favorable prognosis after treatment, as exemplified by improved clinical symptoms and imaging. Two patients relapsed.

Conclusions

The clinical presentation and prognosis of adult CCE remain less understood in comparison to more common MOGAD phenotypes. It is important to consider MOGAD as an underlying etiology for adult CCE, as early detection and immunotherapy may improve outcomes.

[Absence of cortical lesions after the first seizure in a patient with anti-myelin oligodendrocyte glycoprotein-associated cortical encephalitis]

A 31-year-old man developed headache and generalized convulsions. At the time of the first seizure, there was no distinct MRI abnormality. He was admitted to the hospital with repeated seizures, left-sided hemiparesis, and left-sided neglect. He had a slight fever, elevated cerebrospinal fluid (CSF) pressure, and increased CSF cell count with predominance of mononuclear cells. A repeat MRI scan on day 8 after the recurrent seizure showed cortical edema in the right cerebral hemisphere on fluid-attenuated inversion recovery (FLAIR), abnormal high signal on DWI, and decreased apparent diffusion coefficient. The patient was diagnosed with aseptic meningoencephalitis and treated with antiviral drugs and methylprednisolone pulse therapy. Serum anti-myelin oligodendrocyte glycoprotein (MOG) antibody was subsequently detected, and prednisolone was added to treat the FLAIR-hyperintense lesions in anti-MOG antibody associated encephalitis with seizures (FLAMES). It is important to identify the clinical picture and typical images of FLAMES to allow early treatment.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD): A Review of Clinical and MRI Features, Diagnosis, and Management

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is the most recently defined inflammatory demyelinating disease of the central nervous system (CNS). Over the last decade, several studies have helped delineate the characteristic clinical-MRI phenotypes of the disease, allowing distinction from aquaporin-4 (AQP4)-IgG-positive neuromyelitis optica spectrum disorder (AQP4-IgG+NMOSD) and multiple sclerosis (MS). The clinical manifestations of MOGAD are heterogeneous, ranging from isolated optic neuritis or myelitis to multifocal CNS demyelination often in the form of acute disseminated encephalomyelitis (ADEM), or cortical encephalitis. A relapsing course is observed in approximately 50% of patients. Characteristic MRI features have been described that increase the diagnostic suspicion (e.g., perineural optic nerve enhancement, spinal cord H-sign, T2-lesion resolution over time) and help discriminate from MS and AQP4+NMOSD, despite some overlap. The detection of MOG-IgG in the serum (and sometimes CSF) confirms the diagnosis in patients with compatible clinical-MRI phenotypes, but false positive results are occasionally encountered, especially with indiscriminate testing of large unselected populations. The type of cell-based assay used to evaluate for MOG-IgG (fixed vs. live) and antibody end-titer (low vs. high) can influence the likelihood of MOGAD diagnosis. International consensus diagnostic criteria for MOGAD are currently being compiled and will assist in clinical diagnosis and be useful for enrolment in clinical trials. Although randomized controlled trials are lacking, MOGAD acute attacks appear to be very responsive to high dose steroids and plasma exchange may be considered in refractory cases. Attack-prevention treatments also lack class-I data and empiric maintenance treatment is generally reserved for relapsing cases or patients with severe residual disability after the presenting attack. A variety of empiric steroid-sparing immunosuppressants can be considered and may be efficacious based on retrospective or prospective observational studies but prospective randomized placebo-controlled trials are needed to better guide treatment. In summary, this article will review our rapidly evolving understanding of MOGAD diagnosis and management.