JLE

Epileptic Disorders

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Paediatric epilepsy surgery in the posterior cortex: a study of 62 cases Volume 16, numéro 2, June 2014

Figure 1

Patient 5. Male, born 8/2003, with no significant family or personal antecedents. Neurological examination revealed no focal deficits, the presence of slight convergent strabismus of the right eye, and moderate global deficit regarding psychomotor development. Epilepsy onset at 17 months of age with infantile spasms was preceded by an ocular rotation or deviation to the right.

MRI showed a signal alteration involving the left occipital lobe, especially in the mesial part of the occipito-temporal junction (A). Interictal EEG showed slow waves and spike-waves on the left posterior region (B) with rapid diffusion to the anterior ipsilateral and posterior contralateral regions. Ictal EEG showed a bi-hemispheric rapid activity during spasms, slightly more rapid over the left occipito-parietal region (C). At 4 years of age, a tailored resection including the occipital mesial region (D) led to complete seizure freedom, causing a right HH, behaviourally demonstrated since a formal visual field examination was not possible.

Histopathological analysis revealed FCD IIA. Neuropsychological evaluation at last follow-up visit showed a positive evolution of psychomotor development.

Figure 2

Patient 13. Female, born 9/1994, with no family or personal antecedents. The patient had normal neurological and neuropsychological examination, and was right-handed. Epilepsy onset at 5 years of age with weekly seizures was characterised by amaurosis and visual illusions without lateralisation, and followed by intense headache and, frequently, vomiting. This semiology resulted in a diagnosis and treatment of migraine for nearly two years, and afterwards, the ictal episodes were enriched with an initial saccadic deviation of the eyes to the left and blinking.

Interictal EEG showed the presence of spikes and spike-waves over the right PTO region and ictal EEG showed a right posterior ictal onset, while MRI revealed the presence of three distinct signal alterations, suggesting dysplastic lesions, localised over the right occipital pole, the OT junction at the level of the O2-O3 (and T2-T3) sulcus, and the intraparietal sulcus (A).

An invasive evaluation with depth electrodes was performed in order to explore these malformative lesions, as well as the calcarine area, the posterior part of the hippocampus, the superior temporal gyrus, the parietal operculum, the hand area on the superior parietal region, and the inferior parietal lobule.

Interictal SEEG showed a sub-continuous spike activity intermingled with low-voltage fast discharges in the intermediate occipital contacts (see [B], where all the traces derived from the electrode V are displayed).

Ictal SEEG (one of the 13 spontaneous seizures recorded during invasive monitoring is presented in [C]) revealed the presence of an intermediate occipital and dorso-lateral occipito-temporal EZ, the tailored resection of which (D) at 16 years of age, led to complete seizure freedom (at two years follow-up) without post-surgical visual field deficits. Histopathological analysis revealed FCD II (legend continues at the bottom of next page with details on the Stereo-EEG scheme used).

SEEG scheme:

Electrode C: intermediate hippocampus, T1-T2 sulcus, middle temporal gyrus; Electrode D: para-hippocampal gyrus, fusiform gyrus, inferior temporal gyrus; Electrode E: anterior lingual gyrus, T2-T3 sulcus, posterior part of middle temporal gyrus; Electrode F: antero-inferior precuneus, middle temporal gyrus; Electrode I: antero-superior precuneus, superior parietal lobule; Electrode N: antero-superior precuneus, intraparietal sulcus, inferior parietal lobule; Electrode O: inferior calcarine cortex, middle occipital gyrus; Electrode P: splenium, intraparietal sulcus, superior parietal lobule; Electrode Q: parietal cingulate gyrus, angular gyrus; Electrode S: posterior insula, parietal operculum; Electrode V: superior calcarine cortex, superior occipital gyrus; Electrode W: postero-inferior insula, superior temporal gyrus; Electrode X: intermediate precuneus, intraparietal sulcus, superior occipital gyrus; Electrode Y: parietal cingulate gyrus, supramarginalis gyrus; Electrode Z: anterior cuneus, superior occipital gyrus.

Figure 3

Patient 61. Male, born 1/2000, with no significant family or personal antecedents. Neurological examination was normal. The patient was shown to have an inferior quadrant visual field defect, moderate neuropsychological deficits concerning discrimination of simple visual pattern, and reading abilities. Epilepsy onset occurred at 5 years of age with a secondary generalised seizure preceded by crying. Five days later, the child presented with focal seizures with a high frequency, characterised either by an isolated myoclonus of the left leg or, more commonly, by subjective symptoms consisting of a feeling of something “scary”; the child would cry and search for help, and afterwards, stare, with eyes wide open, mimicking fear. This was followed by agitation, crying, and repetitive and frantic movements with both arms and legs, over a duration of about 15-30 seconds, with no postictal deficits.

Interictal EEG showed spikes and sharp waves in the right temporal-parietal regions, intermixed with slow waves during slow sleep (A).

Ictal VEEG showed the presence of seizures characterised by a dystonic posturing of the left arm associated with motor automatisms, correlated with a right temporal-parietal flattening, followed by slow monomorphic activity.

MRI showed a possible structural alteration of the right intra-parietal sulcus (B).

SEEG (C), performed at 6 years of age, revealed the presence of interictal paroxysms localised in the superior parietal lobule and in the intraparietal sulcus, up to the mesial portion of the cuneus (D and E), the presence of hypermotor seizures and seizures with hypertonic/dystonic posturing, and an epileptogenic area involving the precuneus and the paracentral lobule (F). The resection was confined to the mesial portion of the parietal lobe in order to avoid a left hemiparesis (G). The child was seizure-free for about three years; afterwards, weekly seizures re-appeared, constituting an “electric-like” sensation in the left leg associated with pain, which could sometimes cause a fall. Histopathological analysis revealed FCD I and gliosis.

SEEG scheme:

Electrode P: precuneus, intraparietal sulcus, inferior parietal lobule; Electrode N: precuneus, sulcus in the superior parietal lobule, superior parietal lobule, inferior parietal lobule; Electrode L: precuneus, intraparietal sulcus, inferior parietal lobule; Electrode Q: mesial portion of cuneus, middle temporal gyrus; Electrode V: calcarine cortex, middle occipital gyrus; Electrode E: posterior portion of lingual gyrus, inferior occipital gyrus; Electrode W: superior portion of lingual gyrus, superior portion of middle temporal gyrus; Electrode K: superior parietal lobule; Electrode J: portion of cingulum inferior to the paracentral lobule, inferior portion of central sulcus, post-central gyrus; Electrode X: parietal cingulum, supramarginalis gyrus.

Figure 4

Patient 35. Male, born 1/2001, with no family or personal antecedents. Neurological examination revealed no focal deficits, mild psychomotor impairment, slight divergent strabismus of the right eye, and probable right hemianopic deficit. Epilepsy onset on the eighth day of life occurred with highly frequent seizures, characterised by horizontal nystagmus beating rapidly towards both sides, apparently without loss of contact. After several months, the ictal episodes constituted a sustained eye deviation to the right, followed by blinking and pendular horizontal nystagmus; sometimes the seizure continued with a postural hypertonia of the right limbs, while the child also presented with daily dialeptic seizures.

MRI revealed the presence of a vast TPO dysplastic lesion (A).

Interictal EEG showed the presence of left OT subcontinuous delta activity, intermixed with spikes and a short burst of fast activity, localised over the left OT region and diffused to the posterior temporal and, to a lesser degree, to the OP region (B), while ictal EEG showed a left O ictal onset (C). A partial lesionectomy consisting of a tailored OT resection (D) led to complete seizure freedom for nearly four years, associated with developmental gain. Afterwards, the seizures reappeared and were characterised by amaurosis, horizontal monocular nystagmus, head deviation to the right, blinking, lip corner deviation (“smile”), and hypertonia of the right limbs.

EEG showed rare spike-waves, localised over the left temporo-parietal region and a left parieto-occipital ictal onset with early temporal spread (E).

An SEEG investigation was performed in the left parieto-temporal region and showed: subcontinuous interictal parietal spikes (F; electrode Q7-8), an independent frequent infraclinical paroxysmal activity in the mesial temporal region (F; electrode C4-5), and an ictal onset over the intermediate mesial inferior parietal region (F; electrode Q2-3). The resection was extended to the inferior parietal region, but a complete disconnection of the temporal lobe was also performed in order to achieve complete posterior quadrant surgery (G). Histopathological examination revealed FCD IIA. The child was classified as Engel class Ia since 2007 and AEDs were definitively stopped in 2012. The neuropsychological evaluation at five years follow-up demonstrated a normal psycho-cognitive level.

Scheme SEEG:

Electrode N: parietal cingulate gyrus, inferior postcentral gyrus; Electrode B: anterior parahippocampic gyrus, hippocampus, anterior fusiform gyrus, intermediate part of inferior temporal gyrus; Electrode Q: posterior precuneus, posterior part of superior parietal lobule, posterior part of inferior parietal lobule; Electrode A: uncus, amygdala, middle temporal gyrus.

Electrode P: anterior precuneus, anterior part of inferior parietal lobule; Electrode X: cingulate gyrus (splenium), posterior precuneus, supramarginalis gyrus; Electrode M: posterior paracentral lobule, intermediate postcentral gyrus; Electrode C: parahippocampic gyrus, posterior hippocampus, posterior part of middle temporal gyrus; Electrode Z: posterior paracentral lobule, anterior part of superior parietal lobule; Electrode K: anterior precuneus, posterior part of superior parietal lobule; Electrode D: intermediate fusiform gyrus, posterior part of inferior and of middle temporal gyrus; Electrode U: intermediate part of superior temporal gyrus; Electrode W: transverse temporal gyrus, posterior part of superior temporal gyrus; Electrode S: lateral insula, central operculum.

Figure 5

Patient 38. Male, born 5/1998. The patient was adopted at 2 years and 7 months of age, with no clear medical information available before this age. The patient was born before term, with normal psychomotor development, and normal neurological and neuropsychological examination. The patient was left-handed, with right-foot preference, and exhibited the presence of a slight convergent strabismus of the right eye. Seizure onset occurred at 5 years, described as “absences” and characterised by loss of contact, with diffuse hypertonia and elevation of the arms, slightly predominant to the right, followed by saccadic deviation of the eyes towards the right, with possible automatic swallowing, and no postictal deficits. Seizure frequency was 300/month. Frequently, the seizure was preceded by the patient saying “Mom, I am having a spell”. A second, rare type of seizure was characterised by an isolated visual illusion (the patient saw his mother transforming into a monster) and an expression of fear.

MRI showed a smaller left hemisphere with a signal alteration of the TO region, suggesting a dysplastic or ulegyric lesion (A).

Interictal EEG revealed a normal background on the right and the presence of rather subcontinuous rhythmic spikes and polyspike-waves involving the left temporo-parieto-occipital (TPO) region (B). With time, interictal discharges progressively involved the posterior right region.

Ictal EEG showed a rapid ictal discharge on the left TPO area (C). At 7 years of age, a left occipital lobectomy was performed, associated with a functional disconnection of the temporal lobe and infero-posterior area of the parietal lobe (D). Histopathological analysis revealed the presence of gliosis. The child was classified as Engel class Ia. Neuropsychological and psychiatric evaluation at five years post-surgery was normal, with subtle difficulties in working memory and accuracy and speed of reading.