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PubMed1996

Interictal mood and personality disorders in temporal lobe epilepsy and juvenile myoclonic epilepsy.

BACKGROUND: Mood disorders have been described as the commonest psychiatric disorders in patients with temporal lobe epilepsy. Secondary depression in temporal lobe epilepsy could be interpreted either as an adjustment reaction to a chronic disease or as a limbic dysfunction. To clarify this issue, a controlled study of psychiatric disorders was conducted in different forms of epileptic and non-epileptic chronic conditions. METHODS: Twenty outpatients with temporal lobe epilepsy, 18 outpatients with juvenile myoclonic epilepsy--a primary generalised seizure disorder--20 matched type I diabetic patients, and 20 matched normal controls were assessed by a structured interview (SADS) and by self rating scales (Beck depression inventory (BDI) and the state and trait anxiety scales STAIX1 and STAIX2). RESULTS: Sixteen (80%) patients with temporal lobe epilepsy fulfilled the criteria for a psychiatric diagnosis at the SADS interview with a significantly higher frequency than patients with juvenile myoclonic epilepsy (22%) and diabetic patients (10%) (P < 0.0001). The most frequent disorder in temporal lobe epilepsy was a mood disorder: 11 (55%) patients with temporal lobe epilepsy had depression compared with three patients with juvenile myoclonic epilepsy and two diabetic patients (P < 0.001). Eight patients with temporal lobe epilepsy with an affective disorder also had a comorbid personality or anxiety disorder. Patients with temporal lobe epilepsy scored significantly higher on BDI, STAIX1, and STAIX2 than the three control groups (P < 0.001, P < 0.01, P < 0.001). CONCLUSIONS: Patients with temporal lobe epilepsy have a higher incidence of affective and personality disorders, often in comorbidity, than patients with juvenile myoclonic epilepsy and diabetic patients suggesting that these psychiatric disorders are not an adjustment reaction to a chronic disease but rather reflect a limbic dysfunction.

Adult↗
PubMed1998

Absence of normal activation of the left anterior fusiform gyrus during naming in left temporal lobe epilepsy.

Patients with left temporal lobe epilepsy (TLE) often have impaired naming. We studied 13 patients with left TLE and 10 healthy control subjects with [(15)O]H2O PET during visual confrontation naming. Statistical mapping detected multiple regions of significant cerebral blood flow increases within individuals. The left fusiform gyrus was activated in nine healthy subjects, but only in two patients with TLE (a significant difference, p < 0.001). Other activation sites were more variable in healthy subjects and those with TLE. Impaired naming ability may be associated with a lack of increased cerebral blood flow in the left fusiform gyrus in TLE.

Adolescent↗
PubMed1992

Hippocampal volumetric and morphometric studies in frontal and temporal lobe epilepsy.

The most common temporal lobe pathology is Ammons Horn sclerosis (AHS), and several different imaging techniques have been utilized to detect this with varying success. We describe the clinical application of magnetic resonance imaging (MRI) using a three-dimensional volume technique which allows total hippocampal volume to be measured and symmetry evaluated. Hippocampal surface area was calculated in sequential 1.5 mm thick contiguous images, using a GE IC workstation. Total volumes and surface areas were calculated. The cross-sectional surface area at 1.5 mm intervals was displayed graphically, permitting morphometric analysis of the hippocampus throughout its length. Focal atrophy within any part of the hippocampal formation (HF) and its extent could thus be assessed. Patients with well-lateralized temporal lobe epilepsy (TLE) (n = 20) and well-defined frontal lobe epilepsy (FLE) (n = 20) were studied, and volumes compared with normal values derived from 10 neurologically normal controls. Asymmetric hippocampal volume loss was demonstrated in all 20 patients with clinically typed TLE, but not in normal controls or patients with FLE. Volume loss distribution was anterior in 12 patients, posterior in one patient and widespread in seven patients. Secondarily generalized seizures were strongly associated with widespread loss. This method of surface area and volumetric analysis of the hippocampus in TLE can demonstrate asymmetry and focal involvement, and help distinguish between hippocampal and frontal pathologies.

Adult↗
PubMed1993

Interictal metabolic anatomy of mesial temporal lobe epilepsy.

OBJECTIVE--To examine patterns of temporal and extratemporal regional interictal glucose hypometabolism in individual patients with unilateral mesial temporal lobe epilepsy (TLE). Previous reports disagree on which extratemporal areas can be hypometabolic in TLE. DESIGN--Case series of patients with TLE who underwent interictal fludeoxyglucose F 18 positron emission tomography, compared quantitatively with normal positron emission tomography. SETTING--Patients referred for surgical treatment of medically refractory complex partial seizures. PATIENTS AND OTHER PARTICIPANTS--Ten normal volunteers; 27 patients with TLE selected to exclude seizures of bilateral temporal or extratemporal onset. RESULTS--Regional hypometabolism occurred in 25 patients. Hypometabolic regions were ipsilateral to seizure onset and included lateral temporal (in 78% of patients), mesial temporal (70%), thalamic (63%), basal ganglial (41%), frontal (30%), parietal (26%), and occipital (4%). Specific patterns of temporal and extratemporal hypometabolism varied considerably across the TLE group. CONCLUSIONS--Any of the previously reported anatomic areas of hypometabolism can occur in individual patients with TLE. The prevalence of thalamic hypometabolism suggests a pathophysiologic role for the thalamus in initiation or propagation of temporal lobe seizures or in the interictal cognitive dysfunction of TLE.

Adult↗
PubMed1998

Temporal lobe epilepsy in infants and children.

Temporal lobe epilepsy in adults and adolescents is a fairly homogeneous syndrome, both in terms of seizure semiology and in terms of its pathology, and it has been studied extensively. Temporal lobe epilepsy in infants and young children has begun to receive increasing attention in recent years, and a different clinico-pathological picture has emerged. Clinically, the concept of complex partial seizures, which may be useful in adults, is difficult to apply to infants, since it is often not possible to assess impairment of consciousness in this age group. The main distinctive features of complex partial seizures of temporal lobe origin in infants are (1) a predominance of behavioral arrest with possible impairment of consciousness, (2) no identifiable aura, (3) automatisms that are discrete and mostly orofacial, (4) more prominent convulsive activity, and (5) a longer duration (more than 1 min). In addition, seizures of temporal lobe origin in infants may appear clinically generalized, such as infantile spasms or generalized tonic seizures, or can occasionally represent a benign syndrome. The neuropathological findings of temporal lobe epilepsy in infants differ even more than the clinical seizure semiology. In contrast to adult and adolescent patients, mesial temporal sclerosis is a rare finding in infants, in whom the pathological abnormalities associated with seizures of temporal lobe origin consist mostly of dysplasias, migrational disorders, hamartomas, and low-grade tumors such as gangliogliomas. Mesial temporal sclerosis is seen more often in older children than in infants, and its pathogenesis remains a subject of controversy.

Child, Preschool↗
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

Extratemporal hypometabolism on FDG PET in temporal lobe epilepsy as a predictor of seizure outcome after temporal lobectomy.

We investigated the relationship between the presence of extratemporal hypometabolism on fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) and seizure outcome after temporal lobectomy in patients with medically intractable temporal lobe epilepsy (TLE). In 47 patients with intractable unilateral mesial TLE, regional metabolic changes on FDG PET images obtained during the 2 months preceding anterior temporal lobectomy were compared with postoperative seizure outcome. Postoperative seizure outcome was evaluated with a mean follow-up period of 6.1+/-0.6 years (range 5.2-7.2 years). Forty-two (89%) of the 47 patients achieved a good postoperative seizure outcome (Engel class I or II). All patients had hypometabolism in the temporal cortex ipsilateral to the epileptogenic region on FDG PET scans. Fourteen (78%) of the 18 patients with hypometabolism only in the ipsilateral temporal cortex were completely seizure free (Engel class Ia) after surgery. In contrast, five (45%) of the 11 patients with extratemporal cortical hypometabolism confined to the ipsilateral cerebral hemisphere and only four (22%) of the 18 patients with hypometabolism in the contralateral cerebral cortex were completely seizure free after surgery. The postoperative seizure-free rates were significantly different across the three groups of patients with different cortical metabolic patterns ( P<0.005). Furthermore, all of the nine patients with a non-class I outcome (Engel class II-IV) had extratemporal (including contralateral temporal) cortical hypometabolism. Thalamic hypometabolism was noted in 20 (43%) of the 47 patients (ipsilateral in 12, bilateral in 8). Sixteen (59%) of the 27 patients with normal thalamic metabolism were completely seizure free after surgery, while only seven (35%) of the 20 patients with thalamic hypometabolism became completely seizure free ( P<0.05). Multivariate analysis revealed that among variables including clinical, EEG, magnetic resonance imaging, pathological and FDG PET metabolic findings, only cortical metabolic pattern was an independent factor for the prediction of postoperative seizure outcome ( P<0.005). It is concluded that extratemporal cortical hypometabolism outside the seizure focus, in particular hypometabolism in the contralateral cerebral cortex, may be associated with a poorer postoperative seizure outcome in TLE and may represent underlying pathology that is potentially epileptogenic. Thalamic hypometabolism, which was associated, but not independently, with a higher likelihood of postoperative seizures, may be secondary to extratemporal or temporal pathology.

Adolescent↗
PubMed1997

Longitudinal distribution of hippocampal atrophy in mesial temporal lobe epilepsy.

Patients with mesial temporal lobe epilepsy (MTLE) have asymmetric hippocampal volumes with atrophy that sometimes by visual inspection appears to favor different regions along the longitudinal axis of the affected hippocampus. Histological studies suggest that cell loss may affect the anterior hippocampus preferentially, and that hippocampal sclerosis (HS) limited to the anterior of the hippocampus may indicate better surgical outcome. We used volumetric magnetic resonance imaging (MRI): (1) to objectively describe the distribution of volume loss in HS; and (2) to relate this distribution to outcome of temporal lobectomy. Hippocampal volumes and anterior and posterior subvolumes (AHV, PHV) were measured from MP-RAGE MRI in 43 temporal lobectomy patients with MTLE determined by pathological findings of HS and compared to 23 age-matched controls. Atrophy was defined as 'anterior', 'diffuse', 'posterior', or 'normal' depending on position of AHV and PHV relative to the mean +/- 2 S.D. of regional volumes of control hippocampi. Anterior to posterior ratios (APR = AHV/PHV) were also calculated. Mean APR of hippocampi ipsilateral to lobectomy cannot be distinguished from hippocampi contralateral to lobectomy or from controls. AHV and PHV from hippocampi contralateral to temporal lobectomy were smaller than controls but larger than hippocampi ipsilateral to lobectomy. Surgical outcome was independent of longitudinal distribution of atrophy. We determined that overall volume loss in HS is diffuse, neither clearly favoring the head nor body-tail. Surgical outcome for MTLE is not related to the longitudinal distribution of atrophy revealed by volumetric MRI.

Adult↗
PubMed2003

Quantification of hippocampal signal intensity in patients with mesial temporal lobe epilepsy.

BACKGROUND: Refractory mesial temporal lobe epilepsy (MTLE) is frequently associated with hippocampal atrophy (HA) and an abnormal hippocampal signal (Hsig) on magnetic resonance imaging (MRI). OBJECTIVE: To quantify Hsig on MRI using a simplified technique. METHODS: The authors included 15 patients with refractory MTLE who underwent surgery and had preoperative MRI with hippocampal volumetry. Hsig was quantified on preoperative coronal T1-weighted and T2-weighted MRI using the NIH-Image program. Hsig was determined for the head, tail, and entire hippocampal extension. Abnormal Hsig was defined when values were above (for T2) or below (for T1) 2 standard deviations from the mean of normal control group. RESULTS: The lateralization of abnormal Hsig values was concordant with electroencephalograms and HA in all patients. There was a significant difference in ipsilateral T2 Hsig between patients and controls (P < .0001), but not for contralateral T2 Hsig. T1 Hsig showed bilateral abnormalities more frequently, whereas T2 Hsig could lateralize better hippocampal abnormalities. Overall, there were no differences when comparing T2 Hsig for the entire hippocampus, head, or tail only. However, there were some individual differences. T2 Hsig abnormalities involved the entire hippocampus in most patients but were restricted to the head in one patient and to the tail in another. CONCLUSIONS: This simplified method for the quantification of Hsig using NHI-Image is an efficient method for the identification and quantification of hippocampal abnormalities in patients with MTLE. The assessment of the entire extension of the hippocampal formation may provide important additional data, compared to T2 relaxometry maps limited to one segment of the hippocampus.

Adult↗
PubMed2006

Degree of hippocampal atrophy is related to side of seizure onset in temporal lobe epilepsy.

BACKGROUND AND PURPOSE: Temporal lobe epilepsy (TLE) is associated with pathologic changes in hippocampal physiology and morphology. Our aim was to quantify volume reduction of the right and left hippocampus in patients with TLE and to investigate whether the degree of hippocampal atrophy is related to the side of seizure onset. METHODS: The volume of the right and left hippocampus was estimated for 50 controls and 101 patients with TLE, by applying the unbiased Cavalieri method on MR images. RESULTS: Pairwise comparisons, within a multivariate analysis of variance and adjusted by using the Bonferroni correction, revealed that both right and left hippocampal volumes were, on average, significantly smaller in patients with right-sided seizure onset (R-patients) relative to those of controls (P < .001 and P = .04, respectively). Furthermore, left hippocampal volume was significantly smaller in patients with left-sided seizure onset (L-patients) compared with controls (P < .001), but the right-sided hippocampal volume was not significantly smaller (P = .71). Moreover, a correlation analysis revealed that the strong linear association between the right and left hippocampal volumes existing in the control population (r = 0.73) is partially lost in patients with TLE (r < or = 0.48), and this loss in correlation appears to be more pronounced in L-patients than in R-patients. CONCLUSION: Our MR imaging results suggest that although the major damage in patients with TLE is located in the hippocampus ipsilateral to the side of seizure onset, R-patients are more likely to have bilateral hippocampal volume reduction. These findings support the hypothesis that cerebral hemispheres may not only differ in their functionality organization but also in their vulnerability to a neurologic insult.

Adult↗
PubMed2002

[A case of medial temporal lobe epilepsy associated with occult focal cortical dysplasia in the lateral temporal neocortex].

A 29-year-old male with medial temporal lobe epilepsy(MTLE) was revealed to have "occult" focal cortical dysplasia(FCD) in the lateral temporal neocortex. He had no history of febrile convulsion and developed complex partial seizure at the age of 14 year, which became intractable. Although MRI failed to reveal structural abnormality in the temporal lobe, even retrospectively, the findings of non-invasive preoperative examination, such as video-EEG monitoring and interictal ECD-SPECT and FDG-PET, were consistent with those of the left MTLE. Intraoperative electrocorticography(ECoG) demonstrated almost continuous paroxysmal activities on the anterior part of the inferior temporal gyrus(ITG). Anterior temporal lobectomy(ATL) with hippocampectomy was performed. Histological examination revealed FCD in the small area with 0.8 mm in diameter of the resected ITG. In the ATL without preoperative invasive examination such as chronic subdural electrode recording, intraoperative ECoG recording is mandatory.

Adult↗
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↗
PubMed2003

[Temporal lobe epilepsy associated with cystic lesion in the temporal lobe and middle cranial fossa].

Four patients out of 52 patients with temporal lobe epilepsy (TLE), who underwent epilepsy surgery in our hospital since September of 1994, had cystic lesions in the temporal lobe and middle cranial fossa. Case 1 had old hematoma cavity in the inferior temporal gyrus and chronic subdural electrode recording revealed the ictal onset zone to be localized in the ipsilateral medial temporal region. Case 2 had cystic ganglioglioma in the temporal tip, and intraoperative electrocorticography demonstrated independent paroxysmal activities from medial temporal region and temporal tip near the cyst. Both area were resected and the patients became seizure free. Case 3 and 4 had arachnoid cysts in the middle cranial fossa. Chronic subdural electrode recording revealed that the ictal onset zone was localized in the ipsilateral inferior temporal gyrus (that had microdysgenesis) in Case 3 and contralateral medial temporal region (that had hippocampal sclerosis) in Case 4, respectively. These finding suggest that co-existence of extra-axial cyst such as Case 3 and 4 is incidental and that arachnoid cyst is less epileptogenic. However, intra-axial cyst such as Case 1 and 2 is epileptogenic and complicated physiological mechanism such as kindling phenomenon or secondary epileptogenesis may effect on the hippocampus. Comprehensive presurgical evaluation including electrocorticography is needed in the surgical treatment of TLE with cystic lesion.

Adolescent↗
PubMed2006

MRI evidence of mesial temporal sclerosis in sporadic "benign" temporal lobe epilepsy.

OBJECTIVE: To determine whether there is MRI-detectable mesial temporal sclerosis (MTS) in patients with sporadic benign temporal lobe epilepsy (BTLE). METHODS: Brain MRIs were obtained from 101 consecutive, unrelated patients (51 women; mean age 37.3 +/- 17.5 years; range 10 to 83 years) with BTLE, who reported rarely or never having had seizures at the time of long-term (> 2 years) follow-up. The mean age at seizure onset was 22.3 +/- 17.4 years; the mean duration of epilepsy was 16.4 +/- 14.1 years. MRI diagnosis of MTS was based on the occurrence of hippocampal formation atrophy on T1 slices, an increased mesial temporal signal intensity alteration on fluid-attenuated inversion-recovery (FLAIR) or T2 images, or both. RESULTS: Thirty-nine of 101 patients (38.6%) had MRI evidence of unilateral MTS (19/39 left MTS, 20/39 right MTS), which correlated with the epileptiform activity. Hyperintense FLAIR and T2 signal with or without atrophy was observed in 24 of 39 individuals. There was no difference between patients with or without MRI-detected MTS in age at onset and duration of epilepsy. Family history of epilepsy or febrile convulsions (FCs) was more frequent in patients with MRI-detected MTS (36%) as compared with patients with normal MRI (22.7%), but the difference was not significant. Antecedent FCs were more frequent (p = 0.03) in patients with MRI-detected MTS (9/39; 23%) vs those with normal MRI (5/62; 8%). CONCLUSIONS: MRI-detected mesial temporal sclerosis is often encountered in patients with sporadic benign temporal lobe epilepsy.

Adolescent↗
PubMed2000

Sleep influence on seizures and epilepsy effects on sleep in partial frontal and temporal lobe epilepsies.

OBJECTIVES: A reciprocal effect is observed between sleep and epilepsy. Sleep effect on epilepsy is protective and facilitating. Reciprocally epilepsy alters sleep organization and microarchitecture. This interelationship is well established for some epilepsies but remains undefined for cryptogenic and symptomatic frontal and temporal lobe epilepsies. In order to research sleep influence on seizures and epilepsy effects on sleep we carried out two studies in patients with cryptogenic/symptomatic frontal or temporal lobe epilepsies. METHODS: The occurrence of seizures in relation to the state of alertness was analyzed in patients with (1) mesial temporal and frontal lobe epilepsy, and (2) in patients with mesio-lateral temporal and mesial temporal lobe epilepsy in several conditions. Sleep analysis (organization and microarchitecture) was realized. RESULTS: We found: (1) a precise relationship between sleep and seizures in frontal lobe epilepsy (FLE); (2) a precise relationship between wakefulness and seizures in temporal lobe epilepsy (TLE); (3) sleep organization was normal in FLE and altered in TLE; (4) alterations of sleep microarchitecture in FLE and TLE. CONCLUSIONS: Seizure occurrence was mainly in relation to sleep for FLE and to wakefulness for TLE. Sleep organization appeared more altered for TLE than FLE. These results allow practical applications to localize and study FLE and TLE.

Brain↗
PubMed2000

Temporal lobe epilepsy: a clinicopathological study with special reference to temporal neocortical changes.

The number of patients undergoing surgical treatment for pharmacoresistant temporal lobe epilepsy is rapidly increasing. While there have been many clinicopathological studies concerning the medial structures of the temporal lobe in temporal lobe epilepsy, its lateral structures have received little attention. To examine the nature and frequency of lateral temporal lobe abnormalities that occur in temporal lobe epilepsy, 22 patients who underwent standard anterior temporal lobectomy with hippocampectomy for intractable temporal lobe epilepsy were studied. The mean ages at the onset of seizure and at surgery were 15.9 years and 27.7 years, respectively. The electroclinically determined epileptogenic zones were the medial structures of the temporal lobe in 16 patients and the lateral in six. There was histologic evidence of hippocampal sclerosis in 12 of the 16 patients with medial onset seizures and in three of the six patients with lateral onset seizures. The lateral structures of the temporal lobe showed variable degrees of histological abnormalities in 21 patients. Among these abnormalities, heterotopic white matter neurons were observed in six of the 16 medial patients and in all the lateral patients. Glial changes were also common abnormalities, and often glial fibrillary acidic protein (GFAP)-positive astrocytes were present over the entire temporal lobe. In addition to hippocampal sclerosis, cerebral microdysgenesis and gliosis in the lateral structures of the temporal lobe may have a significant role in epileptogenesis of temporal lobe epilepsy.

Adolescent↗
PubMed2000

Temporal lobe epilepsy: when are invasive recordings needed?

Temporal lobe epilepsy (TLE) is the most common type of medically intractable partial epilepsy amenable to surgery. In the majority of cases, the underlying pathology in temporal lobe epilepsy is mesial temporal sclerosis (MTS). Whereas historically invasive recordings were required for most epilepsy surgeries, indications have dramatically changed since the introduction of high-resolution MRI, which uncovers structural lesions in a high percentage of cases. No invasive recordings are required to perform a temporal lobectomy in patients with intractable epilepsy who have structural imaging suggesting unilateral MTS and concordant interictal and ictal surface EEG recordings, functional imaging, and clinical findings. Invasive testing is needed if there is evidence of bitemporal MTS on structural imaging and/or electrophysiologically, and additional information from functional imaging, neuropsychology, and the intracarotid amobarbital (Wada) test also does not help to lateralize the epileptogenic zone. Depth electrodes can be particularly helpful in this setting. However, no surgery is indicated, even without invasive recordings, if bitemporal-independent seizures are recorded by surface EEG and all additional testing is inconclusive. Other etiologies of TLE such as a tumor, vascular malformation, encephalomalacia, or congenital developmental abnormality account for about 30% of all patients who undergo epilepsy surgery. Epilepsy surgery is indicated after limited electrophysiologic investigations if neuroimaging and electrophysiology converge. However, approaches for resection in lesional temporal lobe epilepsy vary among centers. Completeness of resection is crucial and invasive recordings may be needed to guide the resection by mapping eloquent cortex and/or to determine the extent of the non-MRI-visible epileptogenic area. Specific approaches for the different pathologies are discussed because there is evidence that the relationship between the lesions visible on MRI and the epileptogenic zone varies among lesions of different pathologies, and therefore variable surgical strategies must be applied.

Adolescent↗