Characteristics of the synchronous occipital and frontopolar spike phenomenon in Panayiotopoulos syndrome
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Published on: December 18, 2016
Harumi Yoshinaga1, Katsuhiro Kobayashi, Yoko Ohtsuka
1Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan. magenta@md.okayama-u.ac.jp
Insights
Frontopolar-occipital (Fp-O) spikes in Panayiotopoulos syndrome (PS) originate from posterior brain areas and rapidly spread forward. This pattern is distinct from other childhood epilepsies, supporting PS as a distinct syndrome.
Area of Science:
- Neurology
- Epileptology
- Neurophysiology
Background:
- The frontopolar-occipital (Fp-O) spike is a characteristic EEG finding in Panayiotopoulos syndrome (PS).
- This spike pattern can also be observed in other childhood epilepsies, necessitating differentiation.
- Investigating the spatiotemporal characteristics of Fp-O spikes aids in understanding epilepsy origins.
Purpose of the Study:
- To investigate the electrophysiological characteristics of Fp-O spikes in Panayiotopoulos syndrome (PS).
- To compare Fp-O spike patterns in PS with those in symptomatic localization-related epilepsy (SLE) in childhood.
- To differentiate PS from other epilepsy types using dipole analysis and sequential mapping.
Main Methods:
- Sequential topographical mapping of Fp-O spikes in 7 PS patients and 6 SLE patients.
- Analysis of averaged and individual spikes from 40 ms before to 40 ms after the negative peak.
- Equivalent current dipole localization software used for source analysis.
Main Results:
- Occipital negative peaks preceded frontal peaks in all PS patients, but only in 2 of 6 SLE patients.
- Dipole locations for PS patients were consistently posterior, while SLE patients showed more anterior and scattered locations.
- Fp-O and occipital spike sources showed similar positions and orientations in PS patients.
Conclusions:
- Fp-O spikes in PS result from rapid posterior-to-anterior epileptic activity spread.
- PS patients exhibit a uniform topographical pattern and dipole location for Fp-O spikes.
- The homogeneity of Fp-O spike characteristics supports the classification of PS as a distinct syndrome.
Purpose:
The synchronous appearance of an occipital and frontopolar spike (the Fp-O spike) is characteristic of Panayiotopoulos syndrome (PS). This phenomenon is also seen in various other types of epilepsy, particularly those that occur in childhood. Using dipole analysis and sequential mapping, we investigated the characteristics of the Fp-O spike observed in seven patients with PS and six patients with symptomatic localization-related epilepsy in childhood (SLE).
Methods:
We analyzed both one averaged spike and 20 manually selected successive individual Fp-O spikes for each patient through sequential topographical mapping with steps of 10 ms from 40 ms before to 40 ms after the negative maximum peak of each spike. For dipole analysis, a period of 40 ms before the maximum negative peak of the averaged spike in each patient was examined using equivalent current dipole localization software.
Results:
Sequential mapping revealed that occipital negative peaks preceded frontal negative peaks in all of the PS patients, as well as in two of the six SLE patients. The four remaining SLE patients did not exhibit preceding occipital peaks. In all of the patients with PS, representative dipole locations were in the posterior area, whereas in SLE patients they were scattered over more anterior areas. The estimated sources of the Fp-O and O spikes appeared to have the same position and orientation in the two PS patients.
Conclusion:
We conclude that Fp-O spikes in PS occur as the result of a rapid spread of epileptic activity from the posterior areas to the anterior areas of the brain. Fp-O spikes in PS patients show a uniform topographical pattern and dipole location, whereas those in other patients show more heterogeneity in these features. These findings support the homogeneity of PS and thus its designation as a syndrome.
