Anti-NMDAR encephalitis with MOGAD overlap syndrome, isolated epilepsy, and unilateral thalamus changes: a case report and literature review

Abstract

Background Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an autoimmune brain disease mediated by antibodies and characterized by psychiatric symptoms, seizures, behavioral abnormalities, dyskinesia, and cognitive impairment. Recently, the co-existence of anti-NMDAR IgG and MOG IgG has been reported, and anti-NMDAR encephalitis has been found to occur concurrently or successively with demyelinating disease. With gradually increasing reports, the coexistence of anti-NMDAR-IgG and MOG-IgG has been noticed by scholars, and the combination of MOG antibody disease with anti-NMDAR encephalitis is called MOG antibody disease and anti-NMDAR encephalitis overlap syndrome (MNOS). MNOS is clinically rare, and due to its atypical clinical characteristics and its imaging manifestations, the disease is poorly understood, making clinical diagnosis difficult. Seizures are one of the most common atypical symptoms, and cases of mono antibody disease with bilateral thalamus symmetric involvement have also been reported, among which isolated seizures and MNOS cases of unilateral thalamus involvement have not been reported in the literature. Case presentation: A 29-year man was admitted to our hospital with isolated seizures, who had unilateral thalamic involvement and showed anti-NMDAR-IgG and MOG-IgG positivity in both cerebrospinal fluid and serum. His symptoms responded to immunotherapy and antiepileptic drugs with a good prognosis. To the best of our knowledge, this is the first case report of a double antibody-positive case with isolated seizures and unilateral thalamic involvement. Conclusions Our case is a reminder that we clinicians should think of MNOS when patients present with atypical clinical manifestations like epilepsy and test both serum and cerebrospinal fluid for multiple associated autoantibodies (including MOG antibodies) and viruses to avoid misdiagnosis, missed diagnosis, and impact on prognosis. In addition, it enriches the disease spectrum of MNOS syndrome.