To investigate the clinical manifestations, imaging characteristics, and prognosis of recurrent severe anti-NMDAR encephalitis combined with MOGAD.

This study reports the clinical characteristics and prognosis of a patient with severe recurrent anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis combined with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) who was successfully treated with efgartigimod.

A 26-year-old male  patient was admitted due to recurrent memory decline and abnormal mental behavior for 2 years, with recurrence accompanied by drowsiness for 1 month. Two years ago, he experienced memory decline, abnormal mental behavior, vision loss, and cognitive dysfunction. Comprehensive examinations revealed positive NMDAR antibodies in both blood and cerebrospinal fluid, and positive MOG antibodies in blood. He was diagnosed with anti-NMDAR encephalitis combined with MOGAD and showed improvement after high-dose steroid pulse therapy without taking immunosuppressants. One month ago, he experienced a recurrence of cognitive dysfunction, consciousness disturbance, status epilepticus, and respiratory failure. Laboratory tests showed cerebrospinal fluid NMDAR antibody 1:100, serum NMDAR antibody 1:1000, and positive blood MOG antibody. Brain MRI showed abnormal signals in both hippocampi. After high-dose steroid pulse therapy, plasma exchange (5 times), immunoglobulin, and multiple antiepileptic drugs, his symptoms did not significantly improve. After treatment with Efgartigimod 800mg,the patient's state of consciousness improved on the second day  and one week later, Efgartigimod 400mg was used. At present, the patient's consciousness was clear, he could close his eyes and move his limbs as instructed, and the seizures stopped.

Neuroimmune overlap syndrome has complex clinical manifestations, severe conditions, and a tendency to recur. For patients with poor response to first-line treatments, the new drug FcRn antagonist efgartigimod may be effective.