Seizure incidence among neuromyelitis optica spectrum disorder patients

Neuromyelitis optica spectrum disorders (NMOSDs) are a group of neuroinflammatory diseases, which mainly affect the optic nerve and spinal cord. NMOSD is an astrocytic channelopathy involving the aquaporin-4 (AQP4) water channels in the central nervous system. Patients can present with seizure attacks as a first manifestation or relapse. However, compared with multiple sclerosis (MS) or myelin oligodendrocyte glycoprotein encephalomyelitis (MOG-EM), seizure attacks are less frequent in NMOSD. In this study, we aimed to find out the incidence of seizure attacks during the disease course of 137 NMOSD patients who were registered in our centre from January 2011 till January 2020. Furthermore, we reviewed the literature for NMOSD cases with seizure attacks during their follow-up, in order to investigate the reason for this low incidence of seizures. Only one of our patients (0.72%) experienced an episode of generalised tonic-clonic seizure during his follow-up. Reviewing the literature revealed that although seizures are rare in NMOSD, AQP4 disruption possibly increases the risk of seizure attacks. We therefore concluded that the role of AQP4 in seizures is controversial and needs more investigation.