Neurophysiological methods of photosensitivity identification in juvenile myoclonic epilepsy (review)

Abstract

To date, it has been shown that juvenile myoclonic epilepsy (JME) is a common form of genetic (idiopathic) generalized epilepsy. The study of neurophysiological factors that inhibiting and provocating photosensitivity on the electroencephalogram (EEG) in JME expands our understanding of this disease, which is important for diagnosis, treatment and prognosis.The purposeof this review is to analyze neurophysiological techniques that inhibiting and provocating photosensitivity on EEG in patients with JME.Materials and methods. We searched for full-text publications in Russian and English over the past two decades in the databases eLibrary, PubMed, Web of Science, OxfordPress, Springer, Clinicalkeys using keywords: juvenile myoclonic epilepsy (JME), diagnostics, neurophysiology, electroencephalography (EEG), eye opening, photostimulation, eye closure sensitivity, photoparoxysmal response (PPR), epilepsy.Results. Currently, visual triggers such as eye closure, eye closure sensitivity (ECS)/fixation-off sensitivity, other than photosensitivity, are routinely used for EEG in patients with JME, but are rarely scientifically investigated for this pathology. However, it has been shown that ECS is present in 15–25 % of patients with JME. Trigger photostimulation is most effective for detecting photosensitivity in JME compared to intermittent (rhythmic) photostimulation. The frequency of photosensitivity in patients with JME is variable — from 30 % to 54 %. The exact mechanisms of these phenomena are still unknown. It is assumed that ECS and photosensitivity are expressions of hyperexcitability of the occipital cortex in JME.Conclusion. The analyzed neurophysiological and electroclinical studies indicate positive changes in the diagnosis of JME and changes in our understanding of this disease. The mechanism of ECS and photosensitivity in JME is unknown, which is a reason for future research to clarify their consequences, including their impact on the prognosis of the disease and their role in the development of pharmacoresistance. However, despite the characteristic clinical picture and the progress of modern neurophysiological research methods, the question of the role of photosensitivity in this form of epilepsy remains a problem for practicing neurologists, and the proposed EEG protocols need to be modified and more widely implemented in real clinical practice. Variable light and color patterns in broadcast or video game material with a high rate of image change of high-contrast stimulation (more than 3 repetitions per second) can cause seizures in some patients with JME. This requires changing approaches to the neurophysiological diagnosis of photosensitivity in JME and the use of combined triggers for video EEG monitoring.