Auto-immune encephalitides involve auto-antibodies targeting the central nervous system, and particularly the synapse and its structure, such as protein CASPR2.

CASPR2 antibody-associated auto-immune encephalitides lead to an inflammation of the limbic system and generate focal temporal seizures and cognitive impairment. Most patients are initially hospitalized because of the temporal seizures (Joubert et al., JAMA Neurology 2016). However, many already show at that time cognitive impairment, which has failed to elicit the appropriate investigations, therefore delaying the diagnosis.

The study will hence investigate precisely the initial, sometimes neglected, clinical symptoms and those leading to the diagnosis, in the cohort of patients suffering from a CASPR2 antibody-associated encephalitis, from the French reference center on paraneoplastic neurological diseases and autoimmune encephalitis.

This way, the study aims to delineate the symptoms that should trigger suspicions of a CASPR2 antibody-associated encephalitis

Inclusion Criteria:

• Positive CASPR2-Ab in serum and/or CSF tested by immunohistochemistry on mouse brain slices and confirmed by cell-based assay (CBA) of HEK293 cells expressing CASPR2.
• Diagnosis and follow-up in France
• From 18 to unlimited age

Exclusion Criteria:

• Patients CASPR2-IgG negative in serum and CSF
• Foreign follow-up

Patients with a CASPR2 antibody-associated auto-immune encephalitis