To study CSF Indices and their association with prognosis of autoimmune encephalitis.

Till date, there is no published data on use of CSF indices in diagnosing or prognosticating of autoimmune encephalitis.

This retrospective, single-center (AIMS, Kochi, India) cohort study included 60 adult patients with autoimmune encephalitis who were first admitted from August 2016 till November 2021. We used a univariate binary logistic regression for the entire cohort (n=60) or the cohort of seronegative cases (n=54) and a two-tailed Fisher’s exact test for a small group of seropositive cases (n=6). A Chi-square test was performed to describe the results in rare cases if logistic regression failed to work.

In the entire cohort (n=60) a statistically significant association was found between a good fast treatment response and a total count of cells in the CSF more than 4 cells/mm³ (OR 4.571, 95%CI 1.31–15.956, p=0.017), IgG Local Synthesis (OR 7.273, 95%CI 1.562–33.863, p=0.011), and Integrative Parameter of Local IgG Synthesis proposed by Ziadie M. et al. (OR 5.318, 95% CI 1.271–22.250, p=0.022). Good fast response was defined as an improvement with single agent from the first line therapy by mRS-9Q of at least 3 points in case of severe disease and at least 2 points in case of moderately severe disease at the time of discharge. Higher Albumin Index values associated with higher odds of having poor GCS Score­ (OR 1.165, 95%CI 1.011–1.343, p=0.035). In the cohort of seronegative cases (n=54) we obtained similar results. In the cohort of seropositive cases (n=6), none of the patients had a good fast response.

In our research, evidence of Local IgG Synthesis in CNS and CSF total cell count more than 4 cells/mm³ showed association with a good and fast treatment response in patients with autoimmune encephalitis. ­­­