Gaze deviation from contralateral pseudoperiodic lateralized epileptiform discharges (PLEDs)

Pseudoperiodic lateralized epileptiform discharges (PLEDs) usually produce "negative" neurologic findings. This contrasts with seizures which typically induce cortical activation with "positive" clinical manifestations. Gaze preference may arise from ipsilateral frontal eye fields (FEFs) damage because of the unopposed action of an intact contralateral FEF. Epileptic nystagmus (EN) and gaze deviation (GD) can also occur with focal temporo-parieto-occipital or hemispheric seizures in awake or obtunded patients. A patient with old right frontal and parieto-temporal cerebral infarctions manifested leftward gaze preference and deviation (without nystagmus) while alert and talking. Digitized EEG demonstrated PLEDs at ∼1 Hz over the right fronto-central region, without electrographic seizures. This report illustrates that PLEDs without seizures may excite frontal regions proximate to the FEFs to produce contraversive gaze preference in an awake patient, and discusses putative mechanisms. Gaze deviation, in this case, was the principal clinical feature of PLEDs.