Visual phenomena and anatomo-electro-clinical correlations in occipital lobe seizures

Abstract

Background: Occipital lobe seizure are underrepresented in epilepsy surgery cases series. This may reflect the fear for post-surgical functional deficits but also the doubt about the ability of anatomo-electro-clinical correlations to localize precisely the epileptogenic zone in occipital lobe seizure.

Methods: In this expert opinion paper, we review first the general clinical characteristics of occipital lobe seizures, describe the repertoire of visual phenomena and oculo-motor signes in occipital seizures, describe inter-ictal and ictal EEG and finally the possible schemes of epileptogenic zone organization.

Results: Visual and oculo-motor semiology points towards occipital onset seizures but is neither pathognomonic nor constant. Eyes version and unilateral ictal discharge have a strong lateralizing value but inter-ictal spikes as well as eyes version can be falsely lateralizing.

Conclusion: Although visual and oculo-motor phenomena are characteristic of occipital lobe seizures, they may be discrete, overlooked and should therefore be carefully assessed. There are no clear electro-clinical correlations of a sublobar organization of occipital seizures but the clinical pattern of propagation might help to differentiate complex occipito-temporal from occipito-parietal initial epileptogenic network.

Keywords: Drug resistant epilepsy; Epilepsy surgery; Occipital lobe seizures; Stereo-electroencephalography (SEEG); Video-EEG; Visual phenomena.