Objective: To identify lateralizing features during seizures in infants and assess their reliability.
Methods: Infants were included if they had video-EEG monitoring at our institution, and were seizure-free for at least 12 months after epilepsy surgery. Lateralizing signs and seizure symptomatology were classified based on blinded video review.
Results: We analyzed 100 seizures from 19 infants (1 to 32, mean 13 months of age) (1 to 14 seizures per patient). Potential lateralizing signs were seen in 58 seizures from 12 infants, including unilateral clonic jerking (8 patients); forced, sustained tonic version of the eyes to one side (7 patients); predominantly unilateral infantile spasms (5 patients); unilateral tonic stiffening of an arm and leg (2 patients); nystagmus (2 patients) and postictal hemiparesis (1 patient). Except for tonic eye version, each of the signs was contralateral to the hemisphere of seizure-onset in all but one patient who had predominantly ipsilateral spasms and clonic arm activity. Tonic eye version was contralateral in 3 patients, ipsilateral in 1 patient, and toward either side in different seizures in 3 patients.
Conclusion: Reliable lateralizing signs included focal clonic activity and predominantly unilateral spasms. Focal tonic activity, nystagmus and postictal hemiparesis were also consistently contralateral but were observed only in few patients. Tonic eye version was unreliable and could not be used to lateralize seizure onset. The sequence of eye and head version evolving to generalized tonic clonic convulsions was not seen in this age group.