Researchers at University of Southampton, UK report an infant with focal seizures secondary to cortical dysplasia who presented at age 4 months with bilateral pinpoint pupils as first feature of right-sided clonic seizure. EEG recording during seizures showed ictal spiking over the left central region. ECG did not show bradycardia, and there were no signs of parasympathetic activation. MRI, obtained after relapse at 13 months of age with 30 seizures daily involving the right upper limb, revealed left frontal cortical dysplasia. A cortical electrographic grid and intracranial EEG demonstrated ictal fast spike activity within the left centroparietal region, over the middle parietal gyrus. The irritative zone was located at the margin and across the area of dysplasia. The child remained seizure-free at 3 years following excision of the lesion. The origin of ictal miosis is considered secondary to activation of a cortical pupillary constrictor zone as opposed to activation of the parasympathetic nervous system through the subcortical central autonomic network, usually resulting in mydriasis. [1]

COMMENT. Bilateral pupillary dilatation preceding, during, or after generalized convulsive or nonconvulsive seizures is common, but ictal pupillary miosis is rare. Autonomic disturbances during seizures (alterations in heart rate, blood pressure, gastrointestinal function) result from seizures within the largely subcortical and brainstem central autonomic network. The UK study demonstrates ictal miosis originating in the middle parietal gyrus juxtaposed by the superior anastomatic vein of Trolard, within the cortical central parietal region.