Elevated LGI1‐IgG CSF index predicts worse neurological outcome

To determine whether CSF leucine‐rich glioma‐inactivated 1(LGI1)‐IgG titer, index or IgG subclass has prognostic significance, we tested serum and CSF specimens collected concomitantly from 39 seropositive patients. LGI1‐IgG index was elevated (>1) in 21 patients (54%), suggesting intrathecal synthesis. Patients with worse outcome at last follow‐up (modified Rankin Scale >2) had significantly higher index (median 6.57 vs. 0.5, P = 0.048)...