The clinical significance and electrophysiologic findings of fixation-off and closure of the eyes sensitivity: Data from a prospective unselected population.

Purpose: Electroencephalography (EEG) findings related to the eye-closing motion can be defined in two ways: 'sensitivity to eyes closed' (SEC) and 'eye closure sensitivity (ECS).' Fixation-off sensitivity (FOS) is a different phenomenon induced by the elimination of central vision/fixation. The purpose of our study was to determine the frequencies of SEC, ESC, and FOS, and to analyze the relationship between eyes closure and the fixation-off phenomenon and clinical importance in an unselected population.

Methods: We prospectively evaluated 200 routine interictal EEGs by adding a standardized FOS examination protocol between June and September 2015. Goggles covered with semitransparent tape were used to evaluate FOS. We determined SEC when the epileptiform discharges appeared during eye closure and continued during the eye closed state, whereas ECS was defined as transient epileptic abnormalities following the closure of the eyes lasting for 1-4 sec. The patients were evaluated in terms of demographic characteristics, clinical features, and the relationship between SEC, ECS, and FOS.

Results: We detected SEC in 9 (4.4 %) and ECS in 11 (5.4 %) patients. FOS was detected in four (44.4 %) of the patients who showed SEC, all of whom had occipital epileptiform discharges. A statistically significant correlation was found between FOS and treatment resistance in the SEC group (p < 0.001). In logistic regression analysis, occipital lobe epilepsy (p < 0.001) and age under 20 years (p = 0.004) were found as risk factors for SEC. Another interesting finding was the suppression of epileptic discharges with fixation-off in three of 11 patients with ECS.

Conclusions: According to the results of our study, FOS is related to treatment resistance. Therefore, FOS should be evaluated in patients with SEC.