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PubMed2000

Profiles of cognitive performance associated with reading disability in temporal lobe epilepsy.

92 patients with temporal lobe epilepsy (TLE) were classified into reading deficient (RD; N = 41) and non-reading deficient (no-RD; N = 51) groups. A cutoff of 80 was used to further classify patients as having low average or better (AVG: IQ > 79) or below average (LOW: 69 < IQ < 80) intellectual ability. Differences between RD-AVG and no-RD-AVG patients in profiles of performance on cognitive tests were specific to verbal and non-verbal memory and verbal abilities, but not visuoconstructional and executive abilities. RD-LOW patients exhibited globally reduced abilities. Profiles of performance on cognitive tests were sensitive to side of seizure onset in the no-RD AVG group, but not the RD-AVG or RD-LOW groups. These data suggest that a group of patients with TLE and reduced academic achievement exhibit cognitive deficits suggestive of a language learning disability, and that cognitive tests are less sensitive to side of seizure onset in this group.

Adolescent↗

PubMed2003

A controlled quantitative MRI volumetric investigation of hippocampal contributions to immediate and delayed memory performance.

MRI volumetric TLE studies show inconsistent evidence of hippocampal involvement in memory. Prior studies have not dissociated hippocampal and temporal lobe contributions to memory. We measured hippocampal and temporal lobe volumes and immediate/delayed memory performances in 64 TLE patients. Regression was used to dissociate hippocampal from temporal lobe contributions to memory. Results revealed reliable evidence for dominant hippocampal involvement in delayed verbal recall across three separate measures and less consistent evidence for nondominant hippocampal involvement. The findings point to a consistent relationship of dominant hippocampal volumes to delayed verbal recall but no involvement of the temporal lobe or nondominant hippocampus in memory.

Adolescent↗

PubMed1991

Metabolic patterns associated with non-specific magnetic resonance imaging abnormalities in temporal lobe epilepsy.

We investigated the cerebral metabolic patterns associated with non-specific hyperintense T2-weighted image on Magnetic Resonance Imaging (MRI) in Temporal Lobe Epilepsy (TLE). Nineteen patients suffering from TLE with a normal CT scan underwent Positron Emission Tomography (PET) using 18F-fluorodeoxyglucose; 8 had hyperintense T2-weighted image on MRI in the epileptogenic temporal lobe and 11 had a normal MRI. Interictally, PET exhibited focal hypometabolism in all the patients with hyperintense T2-weighted image and in 8 of the 11 whose MRI was normal. The hypometabolic area was significantly more extensive in patients with hyperintense T2-weighted image in whom it always encompasses the site of the MRI abnormality. Moreover, these patients had higher metabolic asymmetry index in the temporal and parietal lobes than patients with a normal MRI. One patient with mesial temporal hyperintense T2-weighted image underwent an ictal PET, which showed that the focal hypermetabolism fitted remarkably with the site and size of the abnormal MR signal. Thus, non-specific hyperintense T2-weighted images are associated with particular interictal and ictal metabolic patterns which might suggest that these MRI abnormalities reflect an epileptogenic lesion.

Adolescent↗

PubMed1994

Relationship between atrophy of the amygdala and ictal fear in temporal lobe epilepsy.

Viscerosensory and affective manifestations are often elicited by temporal lobe seizure discharges. They have been reproduced by amygdaloid stimulation in awake patients during stereotaxic exploration or neurosurgical procedures. They are not exclusively reproduced by stimulation of the amygdala, though most commonly they are evoked from it. Ictal fear is frequently, but not invariably, associated with a rising epigastric sensation, palpitations, mydriasis and pallor. We studied 50 patients (mean age 33 years) with intractable temporal lobe epilepsy (TLE): MRI volumetric measurements of amygdala and hippocampus were performed using a protocol previously described by our group (Watson et al., Neurology 1992; 42: 1743-50). All patients had extensive EEG investigation and at least two seizures recorded by video-EEG monitoring. Seventeen patients (34%) had a clear history of fear accompanied by a rising epigastric sensation as the initial manifestation of their habitual attacks. The amygdala volumes in this group were significantly (P = 0.001) smaller (mean 2131.6 mm3) compared with the volumes of the 33 patients without these symptoms (mean 2561.5 mm3). Both patient groups had smaller mean amygdala volumes compared with normal controls (mean 2828.2 mm3). Postoperative pathology correlated well with volumetric atrophy. In addition, we found that patients with more pronounced amygdaloid atrophy more commonly had prolonged febrile convulsions in early childhood and also more frequently secondarily generalized seizures. Results support the finding that ictal fear is related to pathology of the amygdala and that it, like the hippocampus, is an important substrate of TLE.

Adolescent↗

PubMed1996

An analysis of clinical seizure patterns and their localizing value in frontal and temporal lobe epilepsies.

The differentiation of frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE) is a clinical problem of major theoretical and practical importance. Current electroclinical classification is based on retrospective studies of highly selected patients. When applied to the presurgical evaluation of patients, it has poor specificity. The current study adopts a different and prospective approach to the analysis of ictal clinical manifestations and their value in differentiating FLE and TLE. Two hundred and fifty-two patients with partial epilepsy were selected according to criteria of focal abnormality and imaging, ictal EEG or interictal EEG or highly focal clinical pattern. A witnessed seizure description was obtained for each of their habitual seizures and the sequence of manifestations encoded and entered into a statistical cluster analysis to form a clinical classification of the 352 seizures identified, which comprised 14 clinical groups. Neuroimaging abnormalities were measured, using a template technique, and graded 0-3 according to extent of involvement of each region in the lesion, using standard anatomical divisions. A chi 2 analysis of lesion location against seizure type was performed to assess the strength of association of seizure types with specific cerebral regions. The distribution of interictal EEG spikes and ictal EEG onsets were assessed qualitatively. An independent analysis was also performed, comparing clinical seizure manifestations associated with lesions restricted to either frontal or temporal lobes. Of the 14 clinical groups, four were predominantly related to temporal lobe abnormalities: fear/olfactory/gustatory; absence with no focal symptoms; experiential and visual. Within these groups, 45 out of 58 lesional cases involved the temporal lobes (P<<0.001). A minority of seizures in these groups were associated with frontal lesions and these seizures were significantly more likely to involve version/posturing, without an intervening absence phase, than the temporal cases (P<0.001). Two groups were related to perirolandic abnormalities; somatosensory and Jacksonian clonic with 22 out of 24 lesional cases involving this region (P<0.001). Two other groups were related to the frontal lobes; version/posturing and motor agitation. Early focal tonic activity or head turning were associated with lateral premotor lesions (P<0.001) and ictal and interictal EEG showed strong frontal predominance. Seizures characterized by general motor agitation were associated with lesions of the orbitofrontal (eight out of thirteen cases) and frontopolar (six out of thirteen cases) cortices (P<0.001). Location of interictal EEG spikes and ictal EEG onsets were generally consistent with lesion sites and where there were discrepancies, EEG localization tended to be more diffuse than lesion localization, rather than frankly discordant. Analysis of manifestations associated with pure frontal and pure temporal lesions supported the results of the cluster analysis and also showed a significant association of oro-alimentary automatisms with temporal lobe abnormalities. There were no consistent differences between groups with different localizations in terms of seizure frequency or other characteristics of seizure timing, although very high seizure frequencies were seen more often in association with frontal lesions. Only one combination of different seizure types in the same patient occurred with statistical significance: absence and generalized motor seizures and pseudo generalized epilepsy. The results of this study suggest that relatively few seizures can be localized reliably on clinical grounds and that even in those seizure types where there is a statistically significant association with specific cortical areas, an important minority do not share the same associations. Analysis of the seizure evolution as well as initial symptoms may be of value in localizing some cases, but even here wide variation occurs...

Cluster Analysis↗

PubMed1996

Source propagation of interictal spikes in temporal lobe epilepsy. Correlations between spike dipole modelling and [18F]fluorodeoxyglucose PET data.

Source localization methods were applied to interictal spikes from scalp EEGs and correlated with metabolic (PET scan) data in eight patients suffering from drug-resistant temporal lobe epilepsy (TLE). Dipolar sources, [18F]fluorodeoxyglucose (18FDG)-PET data and anatomical images (MRI) were projected into the same three-dimensional coordinates system. Averaged spikes were adequately modelled by two or three dipolar sources with different onset time of activation but overlapping activity (mean residual variance 3.4 +/- 2.1%). Although, in all patients, spike modelling demonstrated dipolar sources in both mesial and lateral temporal cortex, dipole propagation was consistent with the early involvement of only one of these two areas (mesio-temporal, five patients; lateral and polar neocortex, three patients). Six patients showed a unilateral interictal decrease in glucose uptake, as measured with 18FDG-PET, in the temporal lobe ipsilateral to the EEG spike focus. Temporal hypometabolism was bilateral in one patient and absent in the remaining case. When projected onto PET-scan slices, the dipolar sources of these patients were always included within the hypometabolic area. However, within the hypometabolic zone, the decrease in glucose uptake was not found to be more pronounced in regions containing dipoles. Therefore the spatio-temporal spread of neuronal hyperactivity underlying interictal spiking suggests the presence of preferential epileptogenic networks inside the hypometabolic temporal lobe. Fusion of bioelectric, metabolic and anatomical data proves to be a convenient way of summarizing multimodal information from non-invasive investigations in TLE patients entering an epilepsy surgery programme, and suggests that both interictal spike dipole modelling and 18FDG-PET data might be useful, as a complement to ictal electro-clinical data, in the presurgical evaluation of such patients.

Adult↗

PubMed2003

Olfactory short-term memory and related amygdala recordings in patients with temporal lobe epilepsy.

Olfactory short-term recognition memory was assessed with a delayed odour-matching task in 38 patients with unilateral temporal lobe epilepsy (TLE) and stereotactic electroencephalography (SEEG) recordings taken prior to surgical treatment. The amygdala SEEG activity associated with odorant stimulation was examined in 18 patients. Because the invasive SEEG procedure is only performed in a clinical framework, electrophysiological data obtained from these patients could not be analysed in comparison with data obtained from control subjects. Behavioural results (hits, false alarms, discrimination, bias scores) showed global impairment of odour recognition memory in patients when compared with controls. We also found lower discrimination and higher false alarm scores in left than in right TLE patients, and higher false alarm scores in male than in female patients. The hemisphere effect is discussed in terms of psychosocial trait differences between patients. Electrophysiological recordings collected from the amygdala demonstrated that odorant stimulation was associated with chemosensory evoked potentials (CSEPs). Analysis revealed that CSEPs obtained for target odorants had lower peak amplitudes and latencies than those obtained in response to sample odorants. The reduced peak amplitudes suggest a mechanism of repetition suppression--a process assumed to reflect neural activity related to high-level cognitive processes such as attention, memory and decision making. Latency modulations appear rather to be linked to early stages of information processing and may therefore reflect a facilitation process due to selective attention.

Adult↗

PubMed2004

Pre-operative verbal memory fMRI predicts post-operative memory decline after left temporal lobe resection.

Functional MRI (fMRI) of cognitive tasks depends on technology widely available in the clinical sphere, but has yet to show a role in the investigation of patients. We report here the first demonstration of a clinically valuable role for cognitive fMRI. Temporal lobe epilepsy (TLE) is commonly caused by hippocampal sclerosis and is frequently resistant to drug treatment. Surgical resection of the left hippocampus in this setting can cure seizures, but may produce significant verbal memory decline, which is hard to predict. We report 10 right-handed TLE patients with left hippocampal sclerosis who underwent left hippocampal resection. We compared currently used data for the prediction of post-operative verbal memory decline in such patients with a novel fMRI assessment of verbal memory encoding. Multiple regression analyses showed that fMRI provided the strongest independent predictor of memory outcome after surgery. At the individual subject level, the fMRI data had high positive predictive value for memory decline.

Adult↗

PubMed2003

Reelin controls granule cell migration in the dentate gyrus by acting on the radial glial scaffold.

Reelin, synthesized and secreted by Cajal-Retzius (CR) cells in the marginal zone of the cortex, is an extracellular matrix protein important for the development of cortical layers. In reeler mutant mice lacking Reelin, there are severe malformations of neocortical and hippocampal lamination. It has been assumed that Reelin acts as a stop signal for migrating neurons. Here we show, by using the dentate gyrus as a model in in vivo studies and in vitro assays, that Reelin exerts its effects, at least in part, by acting on the radial glial scaffold required for neuronal migration. Migration defects of dentate granule cells, reminiscent of those seen in reeler mutants, are observed in tissue from patients with temporal lobe epilepsy (TLE). The extent of granule cell dispersion in TLE was found to be inversely correlated with the number of reelin mRNA synthesizing CR cells and reelin mRNA expression as revealed in quantitative RT-PCR studies. These findings show that the Reelin signaling pathway is essential for the correct positioning of human hippocampal neurons and that a Reelin deficiency is involved in the pathological changes associated with epilepsy.

Adult↗

PubMed1999

Expression of cytochrome P450scc mRNA in the hippocampus of patients with temporal lobe epilepsy.

The hippocampus is one of the target areas of neurosteroidal action. Expression of cytochrome P450scc (P450scc, CYP11A1), one of the key enzymes in steroid metabolism, results in de novo synthesis of the neurosteroid pregnenolone. We used a competitive RT-PCR assay to quantify the amount of P450scc mRNA in hippocampal tissue specimens obtained at neurosurgery from patients with temporal lobe epilepsy (TLE). P450scc mRNA is expressed approximately 200 times lower in the hippocampus than in adrenal tissue known for high P450scc expression. P450scc mRNA concentrations were significantly higher in the hippocampus of women (1.72 +/- 0.36 aU, arbitrary units; mean +/- s.e.m.) than of men (0.92 +/- 0.15 aU, p < 0.004). Our data show for the first time the sex-dependent expression of P450scc mRNA in the hippocampus of patients with TLE.

Adrenal Glands↗

PubMed2002

Transcriptional profiling in human epilepsy: expression array and single cell real-time qRT-PCR analysis reveal distinct cellular gene regulation.

Highly parallel expression monitoring by microarrays is a powerful tool to study human brain disorders. In contrast to various nonneuronal tissues, the CNS is composed of a multitude of different cell types. Changed mRNA levels in neuropathological conditions may simply reflect altered tissue composition, rather than specific gene transcription regulation. Therefore, it is crucial, to supplement expression array data of histologically heterogeneous brain samples with a detailed analysis at the cellular level. Here, we have used a two-step approach to identify specific changes in hippocampal gene expression in patients with a hippocampal seizure focus (TLE) and marked neuronal damage. Using comparative expression array hybridization, 21 genes appeared to be differentially regulated. Expression alterations of a subset of these genes, i.e. (up-regulation of ataxin-3 and glial fibrillary acid protein (GFAP) as well as down-regulation of calmodulin) was confirmed in an extended series of individuals by real-time quantitative RT-PCR (qRT-PCR). In order to determine the cellular localization of these mRNAs, we performed real-time qRT-PCR of individual laser-microdissected neurons and glial cells. While ataxin-3 was expressed only in hippocampal neurons, GFAP was detected in reactive astrocytes. The differential calmodulin expression found on the tissue level was not observed in mRNA analyses from single neurons, suggesting that lower calmodulin mRNA levels are a consequence of segmental cell loss and do not indicate reduced cellular expression. Ataxin-3 has been related to neuronal maintenance. Its functional role for TLE has to be further evaluated.

Ataxin-3↗

PubMed1997

Frontopolar ictal epileptiform discharges on scalp electroencephalogram in temporal lobe epilepsy.

We report 3 patients with medically intractable complex partial seizures (CPS) arising from the temporal lobe judged by surgical outcome, in whom scalp electroencephalogram (EEG) showed ictal epileptiform discharges at the frontopolar region. In all patients, results of cranial magnetic resonance imaging (MRI), positron emission tomography (PET), and ictal single photon emission computed tomography (SPECT) were consistent with those of temporal lobe epilepsy (TLE). The epileptogenic area was defined in the temporal lobe by chronic subdural recording in 2 patients. After surgical treatment (amygdalohippocampectomy, anterior temporal lobectomy, and temporal lesionectomy, respectively), all 3 patients became seizure-free and the interictal frontopolar epileptiform discharges on scalp EEG disappeared. Patients with TLE may show ictal scalp EEG with frontopolar onset. This is most likely explained by direction of dipolar orientation of epileptiform discharges in 1 of our patients; rapid spread of ictal activity to the frontopolar area can also be considered in the 2.

Adult↗

PubMed1999

Temporal lobe microdysgenesis in epilepsy versus control brains.

Histopathologic evaluation of brain tissue derived from surgically treated patients with medically refractory temporal lobe epilepsy (TLE) frequently reveals structural brain lesions in the surgical specimen. While several of the most commonly encountered lesions such as low-grade neoplasms or vascular malformations are well established as structural substrates of epilepsy, the significance of subtle microscopic characteristics has remained controversial. Within the spectrum a broad range of microscopic features has previously been reported as "mild cortical dysplasia," "focal cortical dysplasia," or "microdysgenesis," including cortical laminar disorganization, columnar arrangement of cortical neurons, marked clustering of neurons throughout cortical layers II-VI, increased numbers of molecular layer neurons, marked perivascular clustering of oligodendroglia in the white matter, single heterotopic neurons in the deep white matter, glioneuronal hamartia, giant neurons, and balloon cell change. In this paper we report the frequency of these features in temporal lobe tissue of 47 surgically treated TLE-patients vs 29 normal autopsy controls. While most of them were found in both cases and controls, clustering of neurons throughout cortical layers II-VI, perivascular clustering of oligodendroglia in the white matter, increased single heterotopic white matter neurons, and glioneuronal hamartias predominated in tissue from patients with epilepsy (p < 0.05). A count of more than 10 white matter neurons/HPF was associated with a worse postoperative outcome (p < 0.05). These data suggest that certain microscopic characteristics are associated with the epileptic process, while others appear as normal variants.

Case-Control Studies↗

PubMed2005

Healthy life expectancy for selected race and gender subgroups: the case of Tennessee.

OBJECTIVE: To analyze healthy life expectancy (HLE) for major racial and gender subgroups, based on the diverse population of Tennessee and compared with the United States. MATERIALS AND METHODS: We use life table methodology and the HLE calculation model of the National Center for Health Statistics (NCHS), using two databases for 2001: NCHS National Vital Statistics Reports life tables and CDC Behavioral Risk Factor Surveillance System (BRFSS) survey. RESULTS: For Tennessee, although average total life expectancy (TLE) is 73.6 years at birth, only 61.1 years of "good" health are expected. Substantial racial and gender differences are found in both TLEs and HLEs with black males having the lowest and white females the highest. Although females have longer TLE, they spend more years in an unhealthy state than males. CONCLUSIONS: The findings raise new challenges for researchers and health policy makers for accomplishing the dual goals of longer life expectancy and elimination of health disparities among population subgroups.

Adolescent↗

PubMed2004

Unilateral hippocampal sclerosis with contralateral temporal scalp ictal onset.

PURPOSE: To investigate the clinical characteristics and surgical outcomes in patients with unilateral hippocampal sclerosis whose scalp ictal EEG recordings localize to the opposite temporal lobe. METHODS: We retrospectively reviewed the data of all adult patients who had undergone depth electrode implantation for suspected temporal lobe epilepsy (TLE) at UCLA (1993-2000) or the Montreal Neurological Institute (1991-1998) to identify patients who had (a) unilateral hippocampal atrophy, and (b) surface ictal recordings in which the majority of seizures appeared to initiate in the opposite temporal lobe, with few or none that were concordant with the hippocampal atrophy. RESULTS: Of 109 patients with suspected TLE who underwent depth electrode study at the two centers, five patients met the aforementioned criteria. Four of these five had very severe hippocampal atrophy, whereas the fifth had mild atrophy but extensive signal change on magnetic resonance imaging (MRI). Depth electrode recordings in four of the five patients yielded clear ictal onset in the mesial temporal lobe ipsilateral to the imaging abnormality (contralateral to apparent scalp ictal onset). One patient had an unusual bitemporal onset pattern, which was nonetheless suggestive of onset in the sclerotic hippocampus. No patient had intracranial ictal onset contralateral to the imaging abnormality. All patients underwent resection of the structurally abnormal temporal lobe. After follow-up of > or = 2 years, four (80%) of five patients were seizure free, while the fifth showed lesser improvement (class III). CONCLUSIONS: Some patients with severe hippocampal sclerosis (sometimes called a "burned-out hippocampus") have atypical spread of ictal discharges, resulting in apparent gross discordance between imaging and scalp ictal recordings. These patients nonetheless have excellent surgical outcomes on the whole. Whether such patients may forego intracranial recordings requires further study.

Adult↗

PubMed2004

Benign focal epileptiform discharges of childhood and hippocampal sclerosis.

PURPOSE: Benign focal epileptiform discharges of childhood (BFEDCs) are common EEG findings between ages 4 and 14 years. This epoch of maturational development overlaps with the age at presentation of temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) in children. METHODS: From our series of 17 preadolescent children who eventually underwent anteromesial temporal resection for medically refractory TLE due to HS, we identified two children, plus one thereafter, who were initially dismissed as candidates for epilepsy surgery because of abundant extratemporal sharp waves, which were bilateral in two cases. The sharp waves had the distinctive morphology, distribution, and sleep activation suggestive of BFEDCs, but the medical intractability and seizure symptoms were unusual for benign focal epilepsy of childhood. RESULTS: In each case, surgical candidacy was clarified when magnetic resonance imaging (MRI) showed unilateral HS and video-EEG demonstrated seizure onset in the ipsilateral anteromesial temporal region. The postoperative freedom from seizures in each case (follow-up, 2 to 4 years) confirmed that HS was the primary epileptogenic process, and that the BFEDCs were incidental or an atypical secondary manifestation. CONCLUSIONS: These cases illustrate the need for more extensive study of children with BFEDCs when medical intractability and seizure symptoms speak against a simple diagnosis of benign focal epilepsy of childhood. In addition, we observed that the BFEDCs in two of our children had an unusual bilateral occipitofrontal distribution, and we speculate that the coexistence of the BFEDCs in children with HS may not be an incidental finding.

Child↗

PubMed2004

Dystonic posturing associated with putaminal hyperperfusion depicted on subtraction SPECT.

PURPOSE: Dystonic posturing (DP) is one of the most reliable lateralizing indicators for temporal lobe epilepsy (TLE). We evaluated the ictal hyperperfusional areas in patients with DP by using ictal-interictal subtraction single-photon emission computed tomography (SPECT). METHODS: Ninety-seven patients were treated surgically for intractable TLE, and 39 patients underwent ictal and interictal SPECT studies with the same isotope. These patients were divided into three groups: group I with DP of the contralateral side extended to the epileptogenic focus, group II with elevated muscle tonus but without DP, and group III without DP or alteration of muscle tonus. Ictal, interictal SPECT and thin-slice magnetic resonance imaging (MRI) were overlaid by using the automatic multimodality registration program to construct ictal-interictal subtracted images of SPECT on MRI. RESULTS: Thirteen patients belonged to group I; 14, to group II; and 12, to group III. A statistically significant difference in hyperperfusion rate was observed in the putamen (10 patients in group I, three in group II and two in group III; p < 0.01) and mesial temporal lobe (10 patients in group I, seven in group II, and two in group III; p < 0.05) on the ipsilateral side of the epileptogenic focus. No statistically significant difference was observed for other ictal symptoms except ipsilateral upper-limb automatism (eight patients in group I, three in group II, and none in group III; p < 0.01). CONCLUSIONS: A strong correlation between DP and hyperperfusion in the putamen and mesial temporal lobe was demonstrated. Some patients showed a wide hyperperfusion area extending from the mesial temporal lobe to putamen, which may correspond to the propagation of epileptic discharges. Our results suggest a correlation between hyperperfusion of putamen and contralateral dystonic posturing.

Adolescent↗

PubMed2004

Intracranial EEG in temporal lobe epilepsy: location of seizure onset relates to degree of hippocampal pathology.

PURPOSE: To determine whether the specific location of electrographic seizure onset in the temporal lobe is related to hippocampal pathology in temporal lobe epilepsy (TLE). METHODS: Consecutive presurgical patients with scalp EEG-video evidence of TLE and no or mild hippocampal atrophy (HA) on magnetic resonance imaging (MRI) were prospectively studied by using depth and subdural strip electrode recordings to identify the site of the initial ictal discharge (IID). Thirty-four patients had either no or mild HA (HA- group). Four additional patients with moderate or marked HA (HA+ group) who required depth and strip electrodes served as a comparison group. Hippocampal pathology was assessed by MRI volumetrics and histopathologic grade of sclerosis (HS). RESULTS: Thirty-eight patients were investigated. In the HA- group, 10 patients had lobar ictal EEG onsets in the hippocampus (HF), medial paleocortex (MPC), and lateral neocortex (LNC); eight cases had regional IIDs in both HF and MPC; 12 persons had IIDs completely outside the HF; three cases lacked depth electrodes, and only one case (3%) had an IID confined to the HF. By contrast, three (75%) of four HA+ cases had IIDs confined to the HF (p = 0.002). Similarly, in 12 patients with low-grade HS, IIDs confined to the HF area were seen significantly less often than in six cases with high-grade HS (p = 0.025). CONCLUSIONS: In this study of a large number of patients with no to mild and a smaller group with moderate to marked HA and HS, the location of seizure onset in the temporal lobe was related to the degree of hippocampal pathology. Absence of HA and low-grade HS was each associated with IIDs in both the hippocampus and medial (with or without lateral) temporal cortex, or only the MPC or LNC. Marked HA and high-grade HS both were associated with IIDs restricted to the HF.

Atrophy↗