Forced normalization syndrome (Landolt phenomenon) as an unusual side effect of antiepileptic therapy. Literature review and clinical cases

In general, mental disorders are 2–3 times more common in epilepsy than in the general population without epilepsy and can be caused by a combination of factors, including the side effects of antiepileptic drugs. However, only in rare cases is the development of mental disorders in epilepsy associated with significant improvement in the course of epilepsy and the onset of seizure remission due to the high efficacy of antiepileptic therapy or epilepsy surgery. This article discusses forced normalization syndrome (Landolt phenomenon), which can be considered an unusual side effect of antiepileptic therapy. It provides a definition, history of study, proposed pathogenesis, clinical and electroencephalographic presentation, diagnostic criteria for Landolt syndrome, and patient management strategies for this condition. A detailed review of the current literature and descriptions of clinical cases of patients observed by us are presented. More than 1,000 years after its first description, this phenomenon remains a mystery to clinicians. Informing physicians about the possibility of Landolt syndrome is of practical importance, as the syndrome is likely more common than recognized and is often underdiagnosed. However, awareness of the possibility of this complication of drug therapy for epilepsy allows for timely discontinuation of the offending medication, which interrupts the progression of mental disorders and promotes mental stabilization.