The Clinical Features and Prognosis of Anti-NMDAR Encephalitis Depends on Blood Brain Barrier Integrity

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an autoimmune nervous system disease that has become increasingly recognized. This retrospective study is aimed to analyze the relations between clinical manifestations and blood brain barrier (BBB) integrity in anti-NMDAR encephalitis patients.

Anti-NMDAR encephalitis patients were admitted to the First Affiliated Hospital of Guangxi Medical University from April 2014 to April 2020. Patients were grouped by the normal BBB and damaged BBB groups according to the cerebrospinal fluid (CSF) albumin/serum albumin (QAlb). Neutrophil-to-lymphocyte ratio (NLR) in peripheral blood was used for estimating the inflammatory status. The modified Rankin Scale (mRS) was used to assess prognosis.

Seventy-three anti-NMDAR encephalitis patients were diagnosed based on the autoimmune encephalitis diagnosis criteria of 2016. Fifty-three (72.6%) patients were in the normal BBB group and twenty (27.4%) were in the BBB damaged group. There were no significant differences in gender, age, psychiatric disturbances, epilepsy, speech disorder, motor dysfunction, memory dysfunction, and autonomic dysfunction between the two groups (p>0.05). Nevertheless, the proportions of decreased consciousness, ICU admission, NLR, CSF protein and intrathecal IgG synthesis (IgGIF, IgGLoc) in the damaged BBB group were higher than that in the normal BBB group (p<0.05). Patients (79.2%) with normal BBB had good prognosis compared to patients with damaged BBB (50%) after 2 months follow-up. The median mRS before and after immunotherapy in the damaged BBB group were significantly higher than that in the normal BBB group (p<0.01, p<0.05, respectively). Additionally, QAlb increased was positively correlated with the quantitative intrathecal IgG synthesis (IgGLoc: r=0.66; IgGIF: r=0.433, all p<0.001).

The dysfunction of BBB can be helpful in evaluating its prognosis since QAlb showed associations with ICU admission, NLR, a higher CSF protein, intrathecal IgG synthesis (IgGLoc, IgGIF) and mRS score after 2 months follow-up.