Background: Myelin oligodendrocyte glycoprotein (MOG) antibody–associated encephalitis is a new clinical phenotype of inflammatory demyelinating diseases. Some MOG antibody–positive patients with central nervous system demyelinating events present with isolated seizures. However, there are gaps in the epidemiological knowledge regarding seizures with MOG antibody–associated encephalitis in adults. This study characterized the clinical features and treatment of MOG antibody–positive patients with isolated seizures.
Methods: We reviewed all the patients admitted to Tianjin Huanhu Hospital between Jan. 1st 2017 and Jan. 1st 2022, to screen the MOG antibody–positive patients with isolated seizures, and collected the concerned patients’ information regarding epidemiology, clinical presentations, laboratory and radiological characteristics, electroencephalogram (EEG), treatments, and prognoses.
Results: We collected six MOG antibody–positive adult patients who had isolated symptomatic seizures. The mean age of the patients was 33 years (range, 29– 40 years), and five (83.3%) were men. All patients presented with motor seizures, five (83.3%) had cognitive dysfunction, and only one (16.7%) had status epilepticus. Five (83.3%) patients had a good response to immunotherapy and antiseizure medications; only one had a sequela. The cerebrospinal fluid or serum anti-MOG antibody test turned negative over time.
Discussion: The most common seizure type in patients with MOG antibody–associated encephalitis with isolated seizures was focal to bilateral tonic-clonic seizures, and most patients had a good prognosis. Adding antiseizure medications were beneficial for MOG antibody–positive patients with seizures. Relapses and sequelae were associated with low-dose, short-time, or delayed therapy, and wide-range demyelinating brain damage.

Plain Language Summary: We reported six adult patients with seizures (as the isolated symptom without any ophthalmoneuromyelitis symptom) associated with MOG antibodies. Focal to bilateral tonic-clonic seizures are the common seizure type in patients with myelin oligodendrocyte glycoprotein (MOG) antibodies. Antiseizure medications and immunotherapy are beneficial for treating MOG antibody–associated encephalitis with seizures. Many patients had good or complete recovery; low-dose, short-time, or delayed therapy is associated with relapses and sequelae. Emphasized the MOG antibodies testing should be relevant in patients with isolated seizures, particularly occurred in clusters, to guarantee the acute management timely.

Keywords: myelin oligodendrocyte glycoprotein, antibody-associated disease, seizure, clinical features, antiseizure medications