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.