Abnormal visual sensitivity in eyelid myoclonia with absences: Evidence from electrocortical connectivity and non-linear quantitative analysis of EEG signal.

PURPOSE

Eyelid myoclonia with absences (EMA) is an epileptic syndrome characterized by eyelid myoclonia with or without absences, eyes closure-induced EEG paroxysms and photosensitivity. Pathophysiological mechanisms of visual sensitivity in EMA are not-fully understood. The objective of the present study was to analyze the electrophysiological dynamics implicated in the visual sensitivity in patients with EMA.

METHODS

We analyzed data of 10 subjects with diagnosis of EMA and of 10 healthy control subjects. For both patients and controls, 4-seconds artifacts-free electroencephalographic signal epochs recorded were analyzed, during resting state, eyes-opened and eyes-closed tasks. Resting state networks in EEG have been computed using independent components analysis (ICA) LORETA. Moreover, the power law exponent β was obtained for each coordinate as minus the slope of the power spectrum versus frequency in a Log-Log scale.

RESULTS

Using LORETA ICA, patients during resting state showed significant differences as compared to controls with a reduction of the physiological alpha activity over the occipital lobe and of the physiological beta activity over the frontal lobe. Immediately after eye closure, a significant increase of beta activity over the frontal lobe was found in the group of patients compared to controls. Power law exponent β analysis showed a significant increase of β over the frontal regions in patients as compared to controls during resting-state and an increase of β over the parieto-occipital regions after eye closure.

CONCLUSION

Abnormal occipital and frontal cortex activities seem to be related with the visual sensitivity and eyelid myoclonia observed in patients with EMA.