Forced normalization of Lennox-Gastaut syndrome using lacosamide: A case report

Forced normalization (FN) indicates psychotic episodes associated with seizure remission and disappearance of epileptiform activity on EEG. FN is likely to occur when frequent seizures are abruptly terminated by anti-epileptic drugs (AEDs) or epilepsy surgery.

We describe an atypical case of a patient with FN induced by lacosamide (LCM).

A 23-year-old female patient with Lennox-Gastaut syndrome (LGS) was administered AEDs for LGS and hospitalised with weight loss and abnormal behaviour. Her condition fulfilled the FN criteria, which was considered to be induced by LCM. After a reduction in LCM dose, her abnormal behaviour and appetite improved. During LCM use, the patient developed no seizures, and the high amplitude diffuse sharp and slow wave complexes that were frequently observed before LCM disappeared on EEG. The LCM dose was tapered to 150 mg per day, and she became calmer with socially appropriate behaviours, although a few mild focal seizures relapsed.

LCM was effective for treating LGS in this patient and induced FN. Initially, it was difficult to recognise FN in cases of psychiatric disorders, especially in patients with intellectual disability. Patients with FN induced by LCM are rare, and only four patients have been previously reported who were treated by antipsychotic drug for psychosis.