A 59-year-old, right-handed woman had a paroxysmal polyoptic
visual illusion, in which multiple copies of the object she saw spread horizontally in the left hemi-visual field.
Polyopsia appeared for a few seconds. Neurological examination was normal. Magnetic resonance imaging (MRI) showed a
tumor-like lesion involving the cortical and subcortical matters in the right mesial temporal regions. An interictal EEG showed frequent spikes in the right mesial temporal area and intermittent theta waves in the right fronto-temporal area. Video-EEG monitoring using the sphenoidal
electrodes showed the seizure discharges originating in the right sphenoidal lead accompanying the polyoptic
visual illusion. The seizure discharges were restricted within the right mesial temporal lobe. Paroxysmal
visual illusion disappeared after administration of anti-epileptic drugs. EEG showed rare spikes in the right mesial temporal area.
Polyopsia in this patient presumed to be associated with right mesial
temporal lobe epilepsy because
polyopsia and seizure activities on the ictal EEG were coupled and
polyopsia ceased after administration of anti-epileptic drugs.
Polyopsia is recognized as visual perseveration in space and a rare
visual illusion. The lesion causing
polyopsia has been reported to be mostly within posterior cerebral areas including occipital, parietal and temporal regions. This patient whose ictal
polyopsia associated with mesial
temporal lobe epilepsy is a very rare case because most reported cases presenting ictal
polyopsia are neocortical
temporal lobe epilepsy. The precise mechanism of
polyopsia remains unknown. The mesial temporal lobe includes the hippocampus and parahippocampal formation that have been reported to receive information from the diverse association cortex and work as memory controllers. Ictal
polyopsia may result from dysfunction of the visual association cortex or visual memory systems induced by the epileptic activities in the mesial temporal lobe.
Polyopsia is a rare ictal semeiology of mesial
temporal lobe epilepsy and may be one of the important ictal symptoms.