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PubMed2002

Is the right amygdala involved in visuospatial memory? Evidence from MRI volumetric measures.

Quantitative MRI measurement of hippocampal sclerosis in patients suffering from temporal lobe epilepsy (TLE) have, as yet, failed to evidence any correlation between the right hippocampus and visuospatial memory. In this report, word learning and design learning tasks were carried out as well as MRI volumetric measurements of the hippocampus and amygdala in order to verify possible modality-specific correlations between function and structure. Delayed recall indices in our memory tasks provided significant results. Visuoverbal ratios differed between right and left TLE groups, as did laterality indices of hippocampal and amygdalar volumes. Furthermore, correlations were found between the left hippocampal volume and verbal memory, and between the right amygdala and visuospatial memory. We suggest that the difficulty encountered in establishing a correlation between right temporal structures and visuospatial memory could come both from the type of test employed and the structures considered.

Adult↗

PubMed2004

Absence of cortical gray matter abnormalities in psychosis of epilepsy: a voxel-based MRI study in patients with temporal lobe epilepsy.

The authors retrospectively explored cortical differences between 26 patients with temporal lobe epilepsy and psychosis of epilepsy (POE), 24 patients with temporal lobe epilepsy (TLE) alone, and 20 healthy comparison subjects. Using voxel-based morphometry based on statistical parametric mapping (SPM99), which is an unbiased and fully automated technique to test for morphometric differences, magnetic resonance imaging (MRI) 3D-datasets were acquired and analyzed. There were no significant cortical gray matter differences between the POE and the TLE group. Since cortical pathology is prominent in schizophrenia, POE may be a clinical entity separate from schizophrenia.

Adult↗

PubMed2006

The role of aura in psychopathology and dissociative experiences in epilepsy.

Cognitive auras seem to be associated with depression and anxiety, especially in patients with temporal lobe epilepsy (TLE). Dissociative symptoms may occur as an aura or in the context of psychiatric disorders such as depression, anxiety or schizophrenia. This is a cross-sectional study of 62 patients with TLE, using personality and dissociation measures to investigate their relationship with the presence of aura and its different subtypes. Our findings show no difference in psychopathology in patients with different types of aura and reveal that dissociative symptoms correlate with specific measures of anxiety, suggesting a possible link between these experiences and anxiety disorders.

Adult↗

PubMed2002

Reduced sensitivity of the N400 and late positive component to semantic congruity and word repetition in left temporal lobe epilepsy.

We studied 14 patients with well-characterized refractory temporal lobe epilepsy (TLE), 7 with right temporal lobe epilepsy (RTE) and 7 with left temporal lobe epilepsy (LTE), on a word repetition ERP experiment. Much prior literature supports the view that patients with left TLE are more likely to develop verbal memory deficits, often attributable to left hippocampal sclerosis. Our main objectives were to test if abnormalities of the N400 or Late Positive Component (LPC, P600) were associated with a left temporal seizure focus, or left temporal lobe dysfunction. A minimum of 19 channels of EEG/EOG data were collected while subjects performed a semantic categorization task. Auditory category statements were followed by a visual target word, which were 50% "congruous" (category exemplars) and 50% "incongruous" (non-category exemplars) with the preceding semantic context. These auditory-visual pairings were repeated pseudo-randomly at time intervals ranging from approximately 10-140 seconds later. The ERP data were submitted to repeated-measures ANOVAs, which showed the RTE group had generally normal effects of word repetition on the LPC and the N400. Also, the N400 component was larger to incongruous than congruous new words, as is normally the case. In contrast, the LTE group did not have statistically significant effects of either word repetition or congruity on their ERPs (N400 or LPC), suggesting that this ERP semantic categorization paradigm is sensitive to left temporal lobe dysfunction. Further studies are ongoing to determine if these ERP abnormalities predict hippocampal sclerosis on histopathology, or outcome after anterior temporal lobectomy.

Adult↗

PubMed2002

Spontaneous recurrent seizures and neuropathology in the chronic phase of the pilocarpine and picrotoxin model epilepsy.

In a recent publication, we have shown a potent interaction between the cholinergic and GABAergic systems in regard to seizure generation and developed the pilocarpine(pilo)/picrotoxin(PTX) model, in which combined injections of these agents have induced status epilepticus (SE) in rats. Here we report on the chronic features of this new animal model of epilepsy. Adult male Wistar rats were systemically injected with solutions containing 150/0.5 mg kg-1, 75/1.5 mg kg-1 and 50/2.0 mg kg-1 (pilo dose/PTX dose). Six epileptic and six control animals were observed for 120-131 days for the occurrence of spontaneous recurrent seizures (SRS). Electroencephalographic, neuropathologic and behavioral analyses were subsequently performed. Following SE, the animals went through a latent period and, subsequently, towards a state of 'chronic' epilepsy, characterized by the emergence of SRS. Animals that received 150/0.5 mg kg-1 presented a relatively short latent period, partial events as their most common initial seizure manifestations and a considerable subsequent progression towards generalization. The group injected with 75/1.5 mg kg-1 presented an extensive period during which the majority of the animals exclusively developed partial seizures (50 days). Animals injected with 50/2.0 mg kg-1 presented an average latent period of over 100 days. Only few animals within this group developed SRS. Our EEG, neuropathological and ictal behavioral findings, in conjunction with the fact that SE was required for the posterior development of SRS, suggest that our model parallels a human TLE condition. Even though diverse TLE models have been described, the pilo/PTX model has as a major feature the intriguing occurrence of disparities among these three groups in the chronic period, although no differences could be observed during SE induction. Future experiments conducted in this sense, might lead to important results in regard to the elucidation of mechanisms of epileptogenesis.

Acetylcholine↗

PubMed1987

Relationship between interictal psychopathology and the type of epilepsy. Results of a survey in general practice.

Psychiatric morbidity was assessed in a sample of 88 adult epileptic patients drawn from general practices in South London. Using the Clinical Interview Schedule, 48% emerged as psychiatric cases. When either total CIS score or caseness status was used for comparison, group differences were evident; patients with temporal lobe epilepsy and focal non-TLE did not differ, but each was significantly more impaired than those with primary generalised epilepsy. The groups also differed in their psychiatric symptom profiles. The results suggest that the increased prevalence of interictal psychopathology commonly associated with TLE may also be a feature of other forms of focal epilepsy.

Epilepsies, Partial↗

PubMed2003

Right hippocampal sclerosis is more common than left after febrile seizures.

Temporal lobe epilepsy (TLE) is frequently associated with hippocampal sclerosis (HS) and a history of febrile convulsions (HFC). The authors investigated 292 patients with TLE due to HS. Left HS occurred more frequently (57%) than right HS (43%, p = 0.01). Forty-seven percent of the patients had HFC. In patients with right HS, HFC occurred in 59.6%, whereas in patients with left HS, HFC was present in 37.5%, showing a highly significant lateralization difference.

Adolescent↗

PubMed2003

Very slow EEG responses lateralize temporal lobe seizures: an evaluation of non-invasive DC-EEG.

BACKGROUND: This study tested the idea that very slow EEG responses (direct current [DC] potential shifts) could be detected noninvasively during temporal lobe (TL) seizures, and that these shifts give lateralizing information consistent with that obtained by other methods. METHODS: Seven patients with TL epilepsy (TLE) were recorded with scalp DC-EEG technique at bedside. All recordings were performed simultaneously with conventional EEG (scalp in five, and intracranially in two; two patients with scalp recordings were recorded intracranially later). Seizures in five patients originated in the mesial TL. Ictal DC shifts were evaluated by comparing them to the temporal evolution of ictal discharges, and by comparing the laterality of these shifts to the side of seizure onset defined by routine EEG and other presurgical diagnostic tests. RESULTS: All seizures (35/35) were associated with negative DC shifts at temporal derivations (30 to 150 micro V relative to vertex), beginning at the electrical seizure onset, and lasting for the whole seizure. In eight seizures (five patients) with documented mesial TL onset, the polarity of the DC shift was initially positive followed by a negative one after lateral spread of seizure activity. In all cases, the side of the EEG shift agreed with other diagnostic tests, and, at times, was more clearly lateralized than the conventional scalp EEG. CONCLUSIONS: DC-EEG recordings are practical and achievable at the bedside. Ictal DC shifts are consistently observed in scalp recordings in TL seizures, and reliably lateralize them. This method may hold promise in reducing the need for invasive monitoring in patients with TLE where other noninvasive tests are equivocal.

Adult↗

PubMed2003

Hypertensive encephalopathy: antecedent to hippocampal sclerosis and temporal lobe epilepsy?

The authors describe three patients with refractory temporal lobe epilepsy (TLE) following an episode of hypertensive encephalopathy as their only identified antecedent event. All patients had typical MR features of hippocampal sclerosis (HS), and the two operated cases had typical HS histology and became seizure-free postoperatively. These cases suggest that hypertensive encephalopathy may be a rare form of initial precipitating injury, leading to TLE and HS.

Anterior Temporal Lobectomy↗

PubMed2003

Language lateralization by Wada test and fMRI in 100 patients with epilepsy.

Comparing the determination of language dominance using fMRI with results of the Wada test in 100 patients with different localization-related epilepsies, the authors found 91% concordance between both tests. The overall rate of false categorization by fMRI was 9%, ranging from 3% in left-sided temporal lobe epilepsy (TLE) to 25% in left-sided extratemporal epilepsy. Language fMRI might reduce the necessity of the Wada test for language lateralization, especially in TLE.

Adult↗

PubMed2004

Association of an ABCB1 gene haplotype with pharmacoresistance in temporal lobe epilepsy.

The multidrug transporter P-glycoprotein is suspected of contributing to pharmacoresistance in temporal lobe epilepsy (TLE). To assess the role of functional variations in its coding gene (ABCB1) the authors genotyped 210 patients with TLE who were stratified according to their degree of drug resistance. They identified a common haplotype that when present in the homozygous state significantly increased the risk for pharmacoresistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

Ictal neocortical slowing in temporal lobe epilepsy.

BACKGROUND: Temporal lobe epilepsy (TLE) may affect brain regions outside the temporal lobe, causing impaired neocortical function during seizures. METHODS: The authors selected 11 consecutive patients with mesial TLE and hippocampal sclerosis who underwent intracranial EEG monitoring and had no seizures during a follow-up period of at least 1 year after temporal lobe resection. Secondarily generalized seizures were excluded, and up to three seizures were analyzed per patient (31 seizures total). Electrode contacts were assigned to one of nine cortical regions based on MRI surface reconstructions. EEG during seizures was analyzed for specific patterns including low-voltage fast (LVF), rhythmic polyspike, spike-wave, irregular slowing, and postictal suppression. RESULTS: Mesial and lateral temporal contacts on the side of seizure onset showed significant increases in ictal patterns such as LVF and polyspike activity, followed by postictal suppression. Bilateral frontal and ipsilateral parietal cortex exhibited large amplitude irregular slow waves during seizures. This frontoparietal slowing persisted into the postictal period. Perirolandic and occipital cortex were relatively spared. These EEG patterns were accompanied by bland staring, minor automatisms, and unresponsiveness or amnesia in the majority of patients studied. CONCLUSIONS: Prominent irregular slowing occurs in bilateral frontal and ipsilateral parietal association cortex during and after temporal lobe seizures. EEG slowing in the frontoparietal association cortex may signify physiologic impairment that contributes to widespread altered cerebral function during partial seizures.

Adolescent↗

PubMed2005

Organization of receptive language-specific cortex before and after left temporal lobectomy.

OBJECTIVE: To examine brain activation associated with receptive language in patients with left temporal lobe epilepsy (TLE) before and after an anterior temporal lobectomy using magnetoencephalography (MEG), and to evaluate which patients were most likely to show a change in the lateralization and localization of the mechanisms supporting receptive language and if such changes were associated with neuropsychological function. METHODS: Twelve patients with left TLE underwent preoperative Wada testing, and pre- and postoperative neuropsychological testing and MEG language mapping. The anatomic location of receptive language-related activity sources observed with MEG was determined by coregistering MEG data with structural MRI scans. Language laterality indices were calculated based on the number of reproducible activity sources in each hemisphere. The proximity of language-specific activity sources to Wernicke's area was also examined. RESULTS: Although the small sample size precluded formal statistical analyses, patients with atypical (bilateral) hemispheric dominance preoperatively were more likely than patients with typical (left-hemisphere) dominance to show evidence of increased right hemisphere participation in language functions after surgery. Patients with left hemispheric dominance preoperatively were more likely to show intrahemispheric changes involving a slight inferior shift of the putative location of Wernicke's area. Patients with bilateral representation tended to perform worse on neuropsychological test measures obtained both pre- and postoperatively. CONCLUSION: Interhemispheric functional reorganization of language-specific areas may occur in patients undergoing left anterior temporal lobectomy. Intrahemispheric reorganization may take place even when the resection does not directly impinge upon Wernicke's area.

Amobarbital↗

PubMed2005

Gyratory seizures revisited: a video-EEG study.

PURPOSE: Gyratory seizures (GSs) have been rarely described in generalized as well as in focal epilepsies. They were defined as a rotation around the body axis during a seizure for at least 180 degrees. The mechanisms of generation are unknown and have been discussed controversially. The aim of this investigation was to further delineate seizure semiology and assess a possible lateralizing and localizing value of GSs. METHODS: The authors screened 277 consecutive patients with intractable epilepsies referred to a University Hospital for presurgical evaluation between 1998 and 2004 for GSs: 169 had temporal lobe epilepsy (TLE), 47 frontal lobe epilepsy (FLE), 38 generalized epilepsies (GE), and 23 had extratemporal or multifocal epilepsy. RESULTS: Twelve patients showed gyratory movements in 17 seizures. Eight had FLE and four TLE (p < 0.001). In 58% (7/12), the gyratory movement was initiated by a forced versive movement of the head followed by a rotation toward the contralateral side of seizure onset. In 42% (5/12), the gyratory movement was not preceded by a forced head version. In these seizures, the direction of the rotation was toward the side of seizure onset. CONCLUSIONS: The direction of rotation lateralizes seizure onset zone in focal epilepsy depending on the seizure evolution: 1) gyratory seizures (GSs) starting with a forced version of the head ensuing into a body rotation lateralize seizure onset zone contralateral to the direction of rotation. 2) In GSs without a preceding gyratory forced head version, the direction of rotation is toward the side of seizure onset. GSs occur more frequently in frontal lobe epilepsy than temporal lobe epilepsy, while none of our patients with GSs had generalized epilepsies.

Adult↗

PubMed2005

Progression in temporal lobe epilepsy: differential atrophy in mesial temporal structures.

OBJECTIVE: To determine the relationship between hippocampal, amygdalar, and entorhinal cortex atrophy and duration of epilepsy, presence of secondary generalized seizures, and prolonged childhood febrile convulsions in patients with pharmacologically intractable temporal lobe epilepsy (TLE). METHODS: Volumetric MRI of the hippocampus, amygdala, and entorhinal cortex were performed in 86 consecutive patients with TLE and 44 age- and sex-matched healthy control subjects. Linear regression analysis was used to explore the relation between the volumetric measurements and the clinical parameters. RESULTS: In simple regressions, duration of epilepsy but not age at seizure onset was related to hippocampal (r2 = 0.19, p < 0.001), entorhinal cortex (r2 = 0.11, p = 0.002), and amygdalar (r2 = 0.15, p < 0.001) atrophy ipsilateral to the seizure focus. Prediction of the regression function to time of onset of recurrent seizures (time = 0) resulted in a y intercept of < 0 for the hippocampus and the entorhinal cortex but was not different from 0 for the amygdala. Patients with a positive history of febrile convulsions had smaller hippocampal volumes ipsilateral to the seizure (p < 0.001). No relationship was found between febrile convulsions and entorhinal cortex and amygdalar volumes or between secondary generalization of seizures and any mesial temporal volume. CONCLUSION: Progressive volume loss in the mesial temporal lobe in relation to duration of epilepsy is not limited to the hippocampus but affects the entorhinal cortex and the amygdala.

Adolescent↗

PubMed1993

MRI volumetric measurement of amygdala and hippocampus in temporal lobe epilepsy.

We performed MRI volumetric measurements of the amygdala (AM), the hippocampal formation (HF), and the anterior temporal lobe in a group of 30 patients with intractable temporal lobe epilepsy (TLE) and in seven patients with extratemporal lobe foci. Measurements were analyzed with a semiautomated software program and the results compared with those of normal controls and correlated with the findings of all other investigations. In particular, we compared the results with the lateralization of epileptic abnormalities in the EEG. Volumetric studies of AM and HF showed lateralization of measurable atrophy consistent with that derived from extracranial and intracranial EEG examinations. The HF volumes were more sensitive and provided a lateralization in 87%. Combined measurements of AM and HF showed lateralization in 93%, always congruent with the results of EEG lateralization. This slight but important additional improvement in discrimination justifies using AM measurements in MRI volumetric studies of mesial temporal structures. Volumetric studies combined with other currently employed noninvasive techniques may diminish the need for invasive methods of investigation in patients with TLE.

Adult↗

PubMed1997

Relationship between mesial temporal seizure focus and elevated serum prolactin in temporal lobe epilepsy.

We evaluated the relationship between mesial temporal seizure focus and serum prolactin (PRL) in patients before and after they underwent anterior temporal lobectomy (ATL) for medically intractable temporal lobe epilepsy (TLE). These patients had a confirmed unilateral epileptogenic focus in mesial temporal structures, a postictal rise in serum PRL 15 to 20 minutes after onset of complex partial seizures, and were refractory for more than 2 years to antiepileptic drugs. Presurgical interictal serum PRL levels were significantly elevated (16.47 +/- 0.85 ng/mL, n = 62) and declined after ATL to normal values (patients, 9.63 +/- 0.55 ng/mL, n = 54; normal subjects, 8.99 +/- 0.57 ng/mL, n = 52). Serial evaluations indicated that normalization was seen 3 months after surgery (9.42 +/- 1.22 ng/mL, n = 9). The postsurgical reduction in serum PRL was similar in men and women, in patients with epileptogenic focus on either side of mesial temporal structures, and was unaffected by antiepileptic medication. We conclude that PRL is elevated following seizures and that a seizure focus in mesial temporal structures may exert a sustained excitatory influence on PRL release in patients with medically intractable TLE.

Adolescent↗

PubMed1998

Familial temporal lobe epilepsy: a clinically heterogeneous syndrome.

We describe the clinical characteristics of a group of patients with familial temporal lobe epilepsy (TLE) in 11 kindreds with 36 affected individuals identified and investigated at the Montreal Neurological Hospital. Seizure types were simple partial (n = 20), complex partial (n = 29), and rare generalized tonic-clonic. Simple and complex partial seizures were infrequent or well controlled by anticonvulsant medication in 17 of 29 patients (59%) and without optimal response to medical therapy in 12 of 29 patients (41%). Pedigree analysis suggested autosomal dominant inheritance with incomplete penetrance. The syndrome of familial TLE has heterogeneous clinical manifestations and is not always benign.

Adolescent↗