Antibodies against LGI1 (leucin-rich
glioma-inactivated 1
protein) are associated with
limbic encephalitis (LE), which is characterized by a favorable outcome following
immunotherapy. Here, we present two cases, where
antibodies against LGI1 were detected in the sera 36 and 53 months after acute LE, respectively, and none of the patients received
immunotherapy. LE showed characteristics of LGI1
encephalitis in both cases, including low
sodium content in the sera; disorientation,
hallucination, short-term memory loss; and epileptic
seizures. One patient had faciobrachial
tonic seizures. MRI indicated bilateral
inflammation of the hippocampus in one case. We reviewed longitudinal clinical and MRI data covering 53 and 36 months after LE without
immunotherapy, respectively. Both patients became seizure-free and spontaneously recovered with mild/moderate
cognitive impairment. No relapses have been observed. Follow-up brain MRI indicated early
hippocampal sclerosis and global brain
atrophy in one case characterized by more pronounced cognitive deficit. Memory and verbal fluency were affected most during the natural course of LGI1
encephalitis. LGI1
encephalitis had a monophasic course and spontaneously improved, suggesting that a relatively benign natural course may contribute to the favorable outcome observed after
immunotherapy. Our data also indicate that
LGI1 antibodies can be present in the sera without clinical disease activity.