Anti-NMDAR encephalitis in Southeast Asia - A single-centre, longitudinal study.

Aims: To describe the clinical features and outcomes of anti-NMDA receptor encephalitis (ANMDARE) in Southeast Asian (SEA) patients.

Method: SEA patients diagnosed and treated for ANMDARE at Singapore General Hospital between January 2010 and June 2020 were included in this observational study, in which their clinical features and outcomes were retrospectively analysed.

Results: We studied 20 patients: 11 Chinese, 3 Tagalogs, 2 Malays, 2 Indians, 1 Eurasian and 1 Javanese. Their median age was 28 years. 15 were females, amongst whom teratomas were demonstrated in 13 (12 ovarian, 1 mediastinal). Delirium and seizures were the two commonest events leading to their presentation at our facility. 1 male had biliary neuroendocrine tumour. Comparison between genders revealed a strong male predilection for early seizures and insomnia; females were four times likelier than males to develop movement disorders or have underlying neoplasms. Patients with dysautonomia required longer ICU stay beyond 14 days, but their outcomes at 1 year did not differ. When reviewed at 1 year, none had clinical relapses, and outcomes were favourable (mRS 0-2) in nearly two-thirds.

Conclusions: SEA patients with ANMDARE frequently present with delirium and seizures. Underlying neoplasms are very common in females. Differences in clinical characteristics may exist between the two genders. Recognition of these can facilitate diagnosis, and permit earlier initiation of appropriate treatment strategies, and thus improve outcomes of SEA patients.