Abstracts

Rationale: Panayiotopoulos Syndrome is one of the benign partial epilepsies of childhood with excellent prognosis. Febrile convulsions and family history of convulsive disorders are common. EEG with multifocal spikes and synchrony of independent occipital and frontopolar spikes have been recognized. Many studies have confirmed that spikes and seizures travel along existing anatomical pathways. The synchronous EEG phenomenon reflects the underlying neurophysiological mechanism involved in the transmission of epileptiform discharges. The synchrony is thought to be via the Cortico- cortical spread through the long association fibers and also via the subcortical spread. Intrahemispheric synchronizing epileptic phenomenon can be seen in posterior to anterior direction in some idiopathic epilepsies and latency between the occipital and frontopolar spikes can be measured. Objective: To recognize the Occipito ?" Frontopolar connectivity in a patient with Panayiotopoulos Syndrome. Methods: Case report 3.5 year old girl with history of left sided focal seizure with fever at the age of 2 years. Few months later she developed afebrile left focal seizure associated with vomiting and eye deviation during sleep. Product of full term pregnancy complicated by gestational diabetes. She has speech delay with normal hearing. Other milestones are appropriate. Parents are non- consanguinous. Normal neurological exam. Routine investigations and MRI brain are normal. Results: Scalp EEG study showing frequent moderate to high amplitude, synchronized spike-wave discharges at right frontopolar and occipital regions ( Fp-O spike) with projection at P3-O1 on bipolar montage. On referential montage maximal negativity was seen at Fp2 followed by O2 with dropping in the voltage gradient between the 2 electrodes. The measured latency between the O2 and Fp2 spike and wave activity was found to be 17 ms on topographic mapping ( Fig1 ) suggesting propagation from posterior to anterior region Frequent interictal epileptiform discharges (60 IIEDs per minute) were detected by the occipital, parietal and frontal sensors, predominantly from the right hemisphere. The neural sources of IIEDs were estimated using weighted minimum norm estimate (wMNE) and equivalent current dipole (ECD) model. wMNE showed the activity starting in the inferior parietal (angular gyrus) and superior occipital (superior occipital gyrus) cortices, and then within 5 to 10 ms propagating to the frontal cortex (orbital gyrus). (Fig2) Conclusions: The scalp EEG study suggested localization related epilepsy most likely early onset benign occipital lobe epilepsy (Panayiotopoulos syndrome). Further the EEG demonstrated the Intrahemispheric synchrony in posterior to anterior direction with a measured latency of 17 ms between occipital leads and the frontopolar leads in the right hemisphere. The MEG study done with a time interval of several months showed no shift in the epileptic focus. The results were concordant with the EEG result showing epileptic activity starting in the right hemisphere in the inferior parietal (angular gyrus) and superior occipital (superior occipital gyrus) cortices, and then within 5 to 10 ms propagating to the frontal cortex (orbital gyrus). This further demonstrates the Intrahemispheric synchrony. Funding: none