Characteristics and medical practices of hospitalized patients with anti-N-methyl-D-aspartate receptor encephalitis associated with ovarian teratoma in Japan: a retrospective cohort study

Abstract Background The incidence of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis and the proportion of patients with ovarian teratoma with complications are unclear. The proportion of those who become severely ill and the percentage of those undergoing medical treatment for severe cases are also unknown. Therefore, in this study, we aimed to investigate the characteristics and medical practice of hospitalized patients with ovarian teratomas complicated by NMDAR encephalitis in Japan. Results Patients with ovarian teratoma and encephalitis had a lower median age than those without encephalitis. The group with ovarian teratoma complicated with anti-NMDAR encephalitis was more likely to be transported by ambulance and had more transfers from other hospitals than the group without the complication. Among the target hospitalized patients, the 15 − 19 age group had the highest incidence rates. The median age was lower for steroid pulse therapy, intravenous immunoglobulin therapy, and plasma exchange therapy in that order. Additionally, younger patients underwent more invasive treatments. Conclusion Anti-NMDAR encephalitis associated with ovarian tumors often occurs in young people in their late teens and 20s, and younger patients are more likely to be severely ill.