A case of anti-NMDA receptor encephalitis revealed by insular epilepsy

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder of the central nervous system that typically manifests predominantly as a psychiatric disorder. However, other manifestations such as epileptic seizures, abnormal movements, and memory or language complications are not unusual. Here, we report the case of a young man who presented with a new-onset epilepsy, with ictal semiology suggestive of insular involvement; this hypothesis was supported by a PET-CT study. Anti-NMDAR antibodies were found in the CSF, confirming the diagnosis of anti-NMDAR encephalitis. A review of the literature reveals that epilepsy can be the first manifestation of NMDAR encephalitis, with a clear male predominance. Despite its rarity, neurologists should consider this diagnosis for any young patient developing a new-onset epilepsy with temporal or insular features, particularly if the patient is male. Other cognitive or behavioural signs, even very subtle, should also prompt diagnosis.