The Classical Pathways of Occipital Lobe Epileptic Propagation Revised in the Light of White Matter Dissection.

Francesco Latini,Håkan Aldskogius,Mats Ryttlefors,Mats Hjortberg

doi:10.1155/2015/872645

Francesco Latini, Håkan Aldskogius + Show 2 more

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https://doi.org/10.1155/2015/872645

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Abstract

The clinical evidences of variable epileptic propagation in occipital lobe epilepsy (OLE) have been demonstrated by several studies. However the exact localization of the epileptic focus sometimes represents a problem because of the rapid propagation to frontal, parietal, or temporal regions. Each white matter pathway close to the supposed initial focus can lead the propagation towards a specific direction, explaining the variable semiology of these rare epilepsy syndromes. Some new insights in occipital white matter anatomy are herein described by means of white matter dissection and compared to the classical epileptic patterns, mostly based on the central position of the primary visual cortex. The dissections showed a complex white matter architecture composed by vertical and longitudinal bundles, which are closely interconnected and segregated and are able to support specific high order functions with parallel bidirectional propagation of the electric signal. The same sublobar lesions may hyperactivate different white matter bundles reemphasizing the importance of the ictal semiology as a specific clinical demonstration of the subcortical networks recruited. Merging semiology, white matter anatomy, and electrophysiology may lead us to a better understanding of these complex syndromes and tailored therapeutic options based on individual white matter connectivity.

Highlights

IntroductionDescribed in 1879 in a patient with a parieto-occipital tumour [1], occipital lobe epilepsy (OLE) is still nowadays considered a rare condition that represents less than 2–13% of extratemporal epilepsies [2,3,4,5]
Described in 1879 in a patient with a parieto-occipital tumour [1], occipital lobe epilepsy (OLE) is still nowadays considered a rare condition that represents less than 2–13% of extratemporal epilepsies [2,3,4,5].Typical symptoms of OLE are visual auras and/or elementary visual hallucinations (EVHs), ictal blindness, contralateral eye and head deviation, eye movement sensations, blinking, and eyelid fluttering [6,7,8,9]
The pia mater, arachnoid membrane, and vascular structures were carefully removed under microscopic magnification and the hemispheres were frozen at −15∘C–−20∘C for 6–10 days and slowly defrosted for 12 hours

Summary

Introduction

Described in 1879 in a patient with a parieto-occipital tumour [1], occipital lobe epilepsy (OLE) is still nowadays considered a rare condition that represents less than 2–13% of extratemporal epilepsies [2,3,4,5]. Typical symptoms of OLE are visual auras and/or elementary visual hallucinations (EVHs), ictal blindness, contralateral eye and head deviation, eye movement sensations, blinking, and eyelid fluttering [6,7,8,9]. Despite this commonly accepted semiology, the diagnosis remains a problem in some cases. The epileptic propagation tends to spread rapidly to other regions in the brain up to 50% of the cases [10, 11], especially towards temporal and frontal areas [7, 12, 13], and for this reason (the semiology) is sometimes misinterpreted.

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