Epilepsy rarely presents as psychosis; this is reportedly more common in temporal lobe epilepsy, particularly mesial temporal lobe sclerosis (MTLS). in first psychotic episodes, epilepsy is often a neglected diagnosis. Also, distinguishing ictal behavioral manifestations from postictal psychosis may be troublesome, hindering adequate management.

26-year-old female without known psychiatric or neurological disorder, brought to the emergency department due to rapidly progressive behavioral disturbance, with Capgras and persecutory delusions, marked aggressiveness and disorientation. Hallucinations were absent. According to her mother, she experienced several “fits” during the previous 2 days, and she also invariably sustains these every month, around “the full moon days”. Blood and urine tests and a brain CT scan were normal. She was treated with risperidone and lorazepam, with symptom remission in two days. Further exploration revealed a two year history of undiagnosed partial complex and generalized seizures; MRI disclosed right MTLS. Interictal EEG and video-EEG were normal (with a negative psychogenic induction trial). the symptoms are successfully controlled with oxcarbazepine.

Although the EEG was not carried out acutely, this seems to be a case of postictal psychosis; this diagnosis is also supported by the clinical progression. the differential diagnoses include toxic psychosis and non-convulsive status epilepticus; a brief review of epilepsy-related psychosis will be conducted. A low suspicion threshold must be kept in these situations, and a meticulous multidisciplinary approach seems advisable.