Study and compare clinico-epidemiological data and long-term outcomes in pediatric(<18yrs) and adult AIE patients  based on serostatus.

 India is a burgeoning hub for autoimmune diseases. Studies on AIE  comparing seropositive and seronegative outcomes in pediatric and adult population are lacking. We highlight age and serostatus  specific  approach in low resource country settings.

Retro-prospective study from Narayana Institute of Neurosciences, Bangalore(2016-2021) included AIE patients as per Autoimmune Encephalitis International Working Group and Autoimmune Encephalitis Alliance Clinicians Network. Serum and CSF autoimmune encephalitis panels, CSF meningitis panel was incorporated to exclude infections and other demyelinating disorders. With phone calls and outpatient follow ups(1-4yrs), results were statistically analyzed and compared based on age and serostatus.

Adult AIE was commoner than pediatric(75%vs25%,n=60) and seronegative than seropositive(56.7% vs43.3%) with overall male preponderance. NMDAR(11.7%), MOG(8.3%), LGI1 and GAD65(5% each) were common antibodies (MOG commoner than NMDAR in children; NMDAR, LGI1 and GAD 65 equally predominant in adults). Common presentations included seizures(75%) and memory disturbances(66.7%) independent of serostatus. There were no differences in MRI and EEG parameters based on age or serostatus. Methylprednisolone  mono-therapy(46.6%) was multitude than add on rescue immunosuppressants [IVIG(28.3%),rituximab(10%), PLEX & cyclophosphamide(3.3% each)]. Pediatric age, specific antibodies, status epilepticus and dysautonomia were markers requiring  aggressive immunotherapy. Oral steroids(61.7%),mycophenolate(8.3%)and azathioprine(6.7%) were maintenance immunosuppressants. 10% patients(mostly seropositive) had poor outcome with Modified Rankin Scale(MRS)>3. Deaths(all adults) though rare was slightly preponderant in seronegative type owing to lack of consent for aggressive immunosuppression. Clinical relapse was noted in 10%(mostly seropositive). 86% patients were weaned off maintenance immunosuppression(earlier in seronegative). 

Seronegative and pediatric AIE had better long term outcomes. Methylprednisolone mono-therapy is efficacious in majority of the cases when started early. Early recognition and aggressive management in high risk groups has pivotal role. Further multi-centric studies are needed to confirm these findings.