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Epilepsy and malformations of the cerebral cortex Volume 5, numéro 2, June 2003

Figure 1. Focal cortical dysplasia. Silver-stained section showing irregular arrangement of large neurons and ‘balloon cells’.

Figure 2. A â€“ Hemimegalencephaly involving the left hemisphere. MRI, T1-weighted axial section. The architecture of the whole left hemisphere is severely impaired. Note the enlarged appearance of the hemisphere, bulging across the midline, with thickened and smooth cortex and blurred boundaries between gray and white matter, especially in the frontal lobe. B â€“ Right frontal focal cortical dysplasia in a 14-year-old girl with intractable focal epilepsy. Coronal MRI scan. The cortex presents thickened gyri and is not clearly separated from the underlying white matter. C â€“ Tuberous sclerosis in a 22-year-old male patient with symptomatic generalised epilepsy and mental retardation. PD weighted axial MRI scan. Several subependymal calcified nodules are present along the ventricular walls. At least three hyperintense, subcortical lesions are clearly visible, one in the right and two in the left frontal lobe. They represent cortical tubers. A fourth lesion (tumoral) involves the right thalamus. D â€“ MRI, T2 weighted axial section. Left temporal DNET, visible as an area of enhanced signal is in the anteriomedial aspect of the left temporal lobe (arrows) in a six-year-old boy with drug-resistant, complex partial seizures. – MRI, T2-weighted axial section. Bilateral periventricular nodular heterotopia. Nodules of gray matter, presenting the same signal as the normal cortex, are lining the lateral ventricles. F â€“ Subcortical band heterotopia. MRI T2-weighted axial slice showing a thick, diffuse band of heterotopic cortex. Twenty-year-old woman with drug-resistant partial epilepsy and DCX gene mutation. G  â€“ XLIS lissencephaly. T1-weighted axial section. A simplified gyral pattern with severely thickened cortex is observed with a prominent frontal involvement. H  â€“ LIS1 lissencephaly. T1-weighted axial section showing a simplified gyral pattern and a thick cortex that is completely smooth particularly in the posterior brain. I – Unilateral open lip schizencephaly. T1-weighted coronal MRI. A large cleft in the right hemisphere spans from the subarachnoid space to the lateral ventricle. J â€“ Bilateral perisylvian polymicrogyria. T1-weighted axial section showing open sylvian fissures overlaid by an irregular and thick cortex. A sixteen-year-old male patient with facio-pharingo-glosso-masticatory diplegia, mild mental retardation and Lennox-Gastaut syndrome. K  â€“ Bilateral parasagittal parieto-occipital polymicrogyria. T1-weighted MRI showing irregular thickening and infolding of the cortex at the mesial parieto-occipital junction. L â€“ Bilateral frontal polymicrogyria. MRI, T1-weighted axial section. Polymicrogyric cortex with a irregular, bumpy aspect involves all the gyral pattern anterior to the precentral gyri. A 10-year-old boy with spastic quadriparesis, moderate mental retardation and partial epilepsy. Seizures have been in remission for some years. M â€“ Unilateral polymicrogyria. MRI, T1-weighted axial section. The right hemisphere is smaller than the left and the subarachnoid space overlying the right hemisphere is enlarged. The cortex on the right is irregular, with areas of thickening. An eight year-old boy with left hemiparesis, moderate mental retardation, atypical absences and partial motor seizures.

Figure 3. A â€“ Intracranial subdural recording from a 48-contact grid in a one-year-old boy suffering from symptomatic partial epilepsy due to focal cortical dysplasia involving the right parietal lobe. The drawing in the inset shows the position of the 48-contact grid overlying the right parietal lobe. Three additional six-contact strips overlay the right frontal lobe, the right temporal lobe and the right parieto-occipital junction. A ‘hypomotor’ seizure characterised by behavioural arrest starts at the time indicated by the single arrow. This is followed by a cluster of asymmetric spasms indicated by the double arrows. EEG shows a build-up of a rhythmic fast activity starting in the grid contacts that are shadowed in the schematic drawing.
B â€“ A similar seizure is recorded in the same patient with scalp EEG. The electrical onset of the seizure is difficult to pin-point on surface recording. An arrow indicates the clinical onset of the seizure. A clear cut build â€“ up of diffuse theta activity with a prominent sharp component on the parieto-occipital areas, bilaterally, is observed approximately 14 seconds after seizure onset. A cluster of asymmetric spasms, of which two are indicated by a double arrow, follows the initial ‘hypomotor’ episode. Each line represents a second (time).
Delt. = deltoid muscle; EOG = electro-oculogram; L. = left; R = right.





Figure 4. A â€“ Interictal recording during sleep in a 6-year-old boy with drug-resistant partial epilepsy and a left temporal DNET. The same patient as in figure 2D. Frequent left posterior sharp and slow waves that occasionally spread to the contralateral homologous regions. B  â€“ Ictal recording in the same patient. This seizure is characterized by behavioral arrest and retching. At onset, a diffuse, ill-defined, sharp and slow wave complex is observed; this is followed by rhythmic activity in the theta range that initially involves the posterior quadrants on both sides. However, sharper components are seen on the left.

Figure 5. â€“ Polygraphic recording in a 16-year-old boy with bilateral perisylvian polymicrogyria and Lennox-Gastaut syndrome. The same patient as in figure 2J. A generalized tonic seizure is recorded. The EEG shows an initial sharp, diffuse complex that is followed by electrodecremental activity, rapidly evolving to a discharge of polyspikes. EMG from bilateral deltoids shows a tonic contraction starting at approximately the same time on both sides. Delt. = deltoid muscle; L. = left; Neck = neck muscles; R = right.