Autoimmune encephalitis in a South Asian population

Area of Science:

• Neurology
• Immunology
• Clinical Medicine

Background:

• Autoimmune encephalitis (AE) is a significant, treatable cause of encephalitis.
• AE is underreported in South Asia, necessitating regional studies.
• This study investigated AE in Sri Lanka, focusing on clinical characteristics, antibody status, and outcomes.

Purpose of the Study:

• To determine the clinical characteristics of autoimmune encephalitis in Sri Lanka.
• To investigate the association between antibody status and patient outcomes.
• To assess the prevalence of specific AE types, particularly NMDAR-antibody encephalitis (NMDARE).

Main Methods:

• Prospective recruitment of patients with suspected AE in Sri Lankan government hospitals over 12 months.
• Testing of sera and cerebrospinal fluid for key AE-associated antibodies (NMDAR, AMPAR, LGI1, CASPR2, GABARB) using cell-based assays.
• Comprehensive data collection on demographics, clinical presentation, and laboratory findings, with a 1-year follow-up.

Main Results:

• 142 patients were recruited; 65 (45.8%) had probable NMDARE and 6 (4.2%) had limbic encephalitis (LE).
• Common NMDARE symptoms included abnormal behavior (95.3%), seizures (81.5%), and movement disorders (69.2%).
• Antibody-negative NMDARE patients showed more frequent abnormal EEGs and higher likelihood of worse outcomes and death compared to antibody-positive cases.

Conclusions:

• NMDAR-antibody encephalitis (NMDARE) is the predominant form of AE in South Asians, consistent with global trends.
• Clinical presentations of antibody-positive and antibody-negative NMDARE patients are largely similar.
• Electroencephalogram (EEG) abnormalities may indicate an autoimmune basis for psychiatric symptoms in AE.