Abstract
Purpose:
Epileptic seizures in children can be accompanied by oculomotor manifestations such as tonic gaze deviation, nystagmus and eyelid myoclonus. To date, not many studies on oculomotor manifestations in children exist, and neurophysiological mechanisms controlling these eye movements during seizures remain controversial. This study was designed to examine the pattern of oculomotor signs in children in relation to the epileptic focus in the EEG (electroencephalography).
Methods:
Seven patients (6 male, 1 female) aged 1.5 months to 15 years (median age: 1 year) were enrolled in this retrospective study. All patients had epilepsy associated with oculomotor manifestations. Simultaneous video-EEGs were recorded for a minimum of 24 hours. Gaze deviation, nystagmus and eyelid myoclonus recorded on the videos were analyzed in relation to the ictal epileptic activity in the EEG.
Results:
Etiology of epilepsy was diverse including epilepsy originating from occipital or frontocentral regions, epileptic encephalopathy and left-hemispheric epilepsy due to hemimegaloencephaly. On the video-EEG tonic gaze deviation was present in 5 patients. Nystagmus was observed in 3 patients and eyelid myoclonus in 2 patients. Three of the 5 patients with gaze deviation had a horizontal deviation that was directed to the contralateral hemisphere of the ictal epileptic discharges. Two patients had tonic up- or downgaze associated with bilateral epileptic discharges. The slow conjugate jerk nystagmus with large amplitude observed in 3 patients correlated with occipital epileptic activity. Nystagmus was horizontal in two of these children and beating contralateral to the main ictal epileptic discharges. Slow upbeat nystagmus in combination with tonic downgaze in the other child was associated with bilateral occipital epileptic activity. Eyelid myoclonus was only present in patients with gaze deviation.
Conclusions:
In this study, all patients with epileptic nystagmus showed an occipital focus in the EEG recording. Horizontal nystagmus and horizontal gaze deviation were always directed to the contralateral side of the main ictal discharges. In cases with upbeat nystagmus or vertical gaze deviation main epileptic activity involved both hemispheres. Associated eyelid myoclonus was only present in patients with frontal epileptic activity. In conclusion, oculomotor signs can help to localize the epileptic focus in children.
Keywords: 619 nystagmus •
523 eye movements: conjugate •
622 ocular motor control