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PubMed1991

Visual and quantitative analysis of interictal SPECT with technetium-99m-HMPAO in temporal lobe epilepsy.

Interictal 99mTc-HMPAO SPECT images were compared to ictal EEG localization in 51 patients with intractable temporal lobe epilepsy to determine their usefulness for preoperative seizure focus localization. Both quantified temporal lobe asymmetry and blinded visual detection of temporal lobe hypoperfusion were employed. Visual analysis detected ipsilateral hypoperfusion in 18 (39%) of the 46 patients with a unilateral focus and contralateral hypoperfusion in 3. None of the five patients with bitemporal foci had unilateral hypoperfusion. The positive predictive value of unilateral temporal lobe hypoperfusion was 86% (18/21). Quantified anterior temporal lobe asymmetry, greater than a previously derived normal range, correctly identified the focus in 22 (48%) but gave the wrong side in 5, resulting in a predictive value of 81%. The degree of asymmetry correlated inversely with age of seizure onset, but not with other clinical parameters, histology, or verbal and nonverbal memory. The usefulness of interictal 99mTc-HMPAO SPECT for pre-operative seizure focus localization is limited by low sensitivity when performed with a conventional rotating gamma camera. This suggests that ictal or immediate postictal imaging may be necessary for this purpose.

Adult↗
PubMed2005

Combined MEG/EEG analysis of the interictal spike complex in mesial temporal lobe epilepsy.

We studied the functional organization of the interictal spike complex in 30 patients with mesial temporal lobe epilepsy (MTLE) using combined magnetoencephalography (MEG)/electroencephalography (EEG) recordings. Spikes could be recorded in 14 patients (47%) during the 2- to 3-h MEG/EEG recording session. The MEG and EEG spikes were subjected to separate dipole analyses; the MEG spike dipole localizations were superimposed on MRI scans. All spike dipoles could be localized to the temporal lobe with a clear preponderance in the medial region. Based on dipole orientations in MEG, patients could be classified into two groups: patients with anterior medial vertical (AMV) dipoles, suggesting epileptic activity in the mediobasal temporal lobe and patients with anterior medial horizontal (AMH) dipoles, indicating involvement of the temporal pole and the anterior parts of the lateral temporal lobe. Whereas patients with AMV dipoles had strictly unitemporal interictal and ictal EEG changes during prolonged video-EEG monitoring, 50% of patients with AMH dipoles showed evidence of bitemporal affection on interictal and ictal EEG. Nine patients underwent epilepsy surgery so far. Whereas all five patients with AMV dipoles became completely seizure-free postoperatively (Class Ia), two out of four patients with AMH dipoles experienced persistent auras (Class Ib). This difference, however, was not statistically significant. We therefore conclude that combined MEG/EEG dipole modeling can identify subcompartments of the temporal lobe involved in epileptic activity and may be helpful to differentiate between subtypes of mesial temporal lobe epilepsy noninvasively.

Adult↗
PubMed1999

Anatomic asymmetries of the posterior superior temporal lobes: a postmortem study.

OBJECTIVE: To examine for structural asymmetries in the posterior superior temporal lobe at the microscopic level in an effort to explain the gross anatomical and functional asymmetries of this brain region. BACKGROUND: The posterior superior temporal lobe is typically larger on the left and damage to this area frequently results in an aphasia. This has led to the hypothesis that the structural asymmetry determines the functional asymmetry, but no definite confirmation of this hypothesis exists. METHODS: Sixteen men were studied at postmortem. Posterior superior temporal lobe dimensions, gray matter volume, white matter volume, SMI-32 immunopositive neuronal density, and glia cell volume were measured for both the left and right hemispheres. In a subset of eight subjects, myelin sheath and axon diameters were measured with electron microscopy. RESULTS: Posterior superior temporal lobe white matter volume was greater on the left (p = 0.003, t test for dependent samples). This asymmetry did not appear to be the result of an isolated proliferation of glia (p = 0.46, t test for dependent samples), nor the density of cortical to cortical projections neurons in the overlying cortex (p = 0.71, t test for dependent samples). In a subset of eight subjects studied with electron microscopy, axons of the left posterior superior temporal lobe were more thickly myelinated (57 nm [SD = 27] left, 46 nm [SD = 24], p < 0.001, ANOVA). CONCLUSIONS: As axons with thicker myelin sheaths conduct faster and require a greater volume, these results suggest asymmetry of myelination as an explanation for both a left hemisphere dominance for rapid sensory signal processing, leading to a functional asymmetry for language, and a larger left planum temporale.

Axons↗
PubMed2001

Distinguishing subtypes of temporal lobe epilepsy with background hippocampal activity.

PURPOSE: Two subtypes of temporal lobe epilepsy (TLE) can be defined through clinical observations and analysis of hippocampal tissue resected during surgical procedures for intractable TLE: (a) mesial temporal sclerosis (MTS), which is characterized by extensive changes to the hippocampus and good surgical outcome; and (b) paradoxical temporal lobe epilepsy (PTLE), which is characterized by minimal cell loss and comparatively poorer surgical outcome. Patients in both subtypes have seizures that appear to begin in the medial temporal lobe, but documented differences in substrate and outcome between these subtypes has defined a need to distinguish MTS and PTLE patients before surgery. This report describes a retrospective study to investigate the feasibility of doing so during intracranial monitoring. METHODS: Background EEG epochs, 5 min in duration, were recorded from the anterior hippocampus in 14 (10 MTS and four PTLE) patients with consistent localization of seizure onset to medial temporal structures. The power spectral density (PSD) of the EEG epochs was calculated by a Fourier spectral estimator, and the total signal power and power of the delta, theta, alpha, beta, and gamma frequency bands were submitted to group-to-group comparison. RESULTS: Spectral peaks were observed in the delta band in all PSD estimates and in the theta band in nine of 14 (seven MTS, two PTLE) estimates. The MTS and PTLE subtypes could be distinguished by the total signal power and delta band power. These power measurements were greater in the PTLE subtype. CONCLUSIONS: Both delta and theta spectral components are present in hippocampal background EEGs recorded from patients with TLE. The results indicate that group differences exist in spectral measures of background hippocampal signals recorded from MTS and PTLE subtypes. This suggests both that substrate differences in cellular composition and connectivity are reflected in hippocampal background EEGs and that spectral measurements of these signals may hold promise for tests to identify the group membership of individual patients.

Adult↗
PubMed2002

Clinical, EEG, and quantitative MRI differences in pediatric frontal and temporal lobe epilepsy.

OBJECTIVE: To examine the clinical, electrographic, and quantitative MRI differences between frontal lobe (FLE) and mesial temporal lobe epilepsy (MTLE) in children. METHODS: The population included children who underwent video-EEG monitoring between 1995 and 2000 who were classified as either FLE (n = 39) or MTLE (n = 17) according to the criteria of the International League Against Epilepsy. Clinical, EEG, and quantitative MRI data (including frontal cortical volumes) were compared between the two syndromes and a control group (n = 42). RESULTS: In FLE, seizures were significantly briefer, more frequent, and predominantly from sleep, and had differing motor characteristics. The rates of bilateral epileptiform interictal and ictal EEG abnormalities were significantly higher in FLE. A nonlesional MRI was significantly more common in FLE. Mean frontal cortical volume in FLE was significantly lower than MTLE and controls. Seizure freedom after surgery was lower in FLE. CONCLUSIONS: The clinical syndrome of FLE is clearly distinct from MTLE. The etiology of this disorder is unknown in the majority of cases despite extensive investigation. Because of a lack of a clearly defined etiology and frequent nonlateralizing EEG changes, few of these children are considered optimal surgical candidates. The demonstration of bilateral frontal cortical volume loss and bilateral EEG abnormalities suggests that FLE is a bilateral disease in a high proportion of patients. The outcome in those patients who were deemed surgical candidates was significantly worse than the MTLE cases.

Adolescent↗
PubMed2002

Mesial temporal lobe Cho to Cr(PCr) ratio asymmetry in chronic schizophrenics.

Proton magnetic resonance spectra (MRS) were acquired from 1.5 x 1.5 x 1.5-cm voxels in the left and right mesial temporal lobes of 20 schizophrenic patients and 20 non-psychiatric comparison subjects. Choline (Cho) to creatine (and phosphocreatine) (Cr(PCr)) ratios were estimated as were the percent gray matter, white matter and CSF contributing to the voxel. The Cho/Cr(PCr) metabolite ratio was significantly lower in the left temporal lobe than in the right temporal lobe for both the schizophrenia subjects and control group. This difference was greater in the schizophrenia subjects. Left temporal lobe gray matter voxel content was significantly higher and white matter content was significantly lower than in the right temporal lobe for both the schizophrenia subjects and control group. This difference was the same for the schizophrenia subjects and control group. Left voxel gray matter and white matter content correlated with Cho/Cr(PCr) metabolite ratios for the schizophrenic subjects but not for the control subjects. No such correlations were noted on the right side. No significant difference was found between Cho/Cr(PCr) in the left temporal lobe or in the right temporal lobe of the schizophrenia subjects vs. the control group.

Adult↗
PubMed2006

Compromised memory function in schizophrenia and temporal lobe epilepsy.

The purpose of this study was to investigate compromised memory function of schizophrenia patients in comparison with temporal lobe epilepsy patients, whose memory impairments result from a clear lesion. The authors hypothesized that schizophrenia patients would show poorer immediate and delayed recall performances in verbal and visual memory tasks. The study sample consisted of a healthy comparison group of 30 subjects and three patient groups comprising 76 schizophrenia patients, 93 left temporal lobe epilepsy patients, and 72 right temporal lobe epilepsy patients. The authors assessed immediate recall, delayed recall, and delayed retention. Tasks were subdivided into two categories (easy and difficult), and then patient memory dysfunction was compared among the memory tests. The authors observed material-specific memory impairment, where the left temporal lobe epilepsy group showed severe verbal memory impairment and the right temporal lobe epilepsy group showed severe visual memory impairment. A moderate impairment was found in immediate and delayed verbal memory in schizophrenia patients, and the impairment of visual memory was amplified with delayed recall. Such a result can be interpreted not only as a generalized cognitive deficit, but also as an integrative dysfunction involving the mesial temporal and frontal lobes in the left and right hemispheres, whereby the lesion site cannot be determined selectively. Our results show that the selection of a memory task that cannot be influenced by verbal mediation is very important for analyzing memory dysfunction in schizophrenia patients.

Adult↗
PubMed2003

Peri-ictal water drinking lateralizes seizure onset to the nondominant temporal lobe.

The authors describe seven patients with medically refractory temporal lobe epilepsy whose seizures were associated with peri-ictal water drinking behavior. Presurgical evaluation, including video-EEG monitoring, MRI, SPECT, and neuropsychological testing, revealed a seizure onset in the nondominant temporal lobe. All patients had an excellent outcome after epilepsy surgery. Peri-ictal water drinking may represent a lateralizing sign indicating seizure onset in the nondominant temporal lobe.

Adolescent↗
PubMed1993

Verbal recognition memory performance in unilateral temporal lobe epilepsy.

Recognition memory performance of 91 left and right unilateral temporal lobe epilepsy (TLE) patients was examined prior to and post anterior temporal lobectomy. The left TLE group showed more impaired response discrimination ability than the right TLE group; however, their false positive rate varied as a function of distractor type. Prior to temporal lobe resection, false positives were higher for semantically related distractors (novel or from an interference list) than for semantically unrelated items from an interference list, phonemic distractors, or unrelated errors. Following temporal lobe resection, only novel semantically related distractors in the left TLE group showed a significant increase in false positives, and they were also significantly higher than all other error types. The results of this study suggest that the left TLE patients have impaired individual item recollection in the context of intact information about basic semantic attributes.

Adult↗
PubMed1992

Auditory/verbal and visual/spatial memory in children with complex partial epilepsy of temporal lobe origin.

Two groups of epileptic children and a normal control group were administered a Comprehensive Children's Memory Scale (Experimental Edition) which is presently being developed by this author. The first experimental group consisted of 12 children having complex partial seizures of left temporal origin and the second group consisted of 12 children having partial complex seizures of right temporal lobe origin based upon clinical description and EEG/neuroimaging verification. Results indicated: (a) Children with left temporal lobe epilepsy demonstrated significantly lower performance than controls on auditory/verbal memory testing. (b) Children with right temporal lobe epilepsy demonstrated significantly lower performance than controls on visual/spatial memory testing. (c) For the most part, the right and left temporal lobe groups did not significantly differ from each other. However, their performance was in the expected direction; i.e., children with left temporal lobe epilepsy scored lower than right temporal lobe epileptics on auditory/verbal memory testing, and children with right temporal lobe epilepsy scored lower than left temporal lobe epileptics on visual/spatial memory testing.

Attention↗
PubMed1996

Temporal lobe morphology in childhood-onset schizophrenia.

OBJECTIVE: Neurodevelopmental models of schizophrenia imply that a more severe early brain lesion may produce earlier onset of psychotic symptoms. The medial temporal lobes have been proposed as possible locations for such a lesion. The authors tested this hypothesis in a group of children and adolescents with childhood-onset schizophrenia who had severe, chronic symptoms and who were refractory to treatment with typical neuroleptics. METHOD: Anatomic brain magnetic resonance imaging scans were acquired with a 1.5-T scanner for 21 patients (mean age=14.6 years, SD=2.1) who had onset of schizophrenia by age 12 (mean age at onset=10.2, SD=1.5) and 41 normal children. Volumes of the temporal lobe, superior temporal gyrus, amygdala, and hippocampus were measured by manually outlining these structures on contiguous 2-mm thick coronal slices. RESULTS: Patients with childhood-onset schizophrenia had significantly smaller cerebral volumes. With no adjustment for brain volume, no diagnostic differences were observed for any temporal lobe structure. Unexpectedly, with adjustment for total cerebral volume, larger volumes of the superior temporal gyrus and its posterior segment and a trend toward larger temporal lobe volume emerged for the patients with schizophrenia. These patients lacked the normal (right-greater-than-left) hippocampal asymmetry. CONCLUSIONS: These findings do not indicate a more severe medial temporal lobe lesion as the basis of very early onset schizophrenia.

Adolescent↗
PubMed2001

Enhanced but fragile inhibition in the dentate gyrus in vivo in the kainic acid model of temporal lobe epilepsy: a study using current source density analysis.

Temporal lobe epilepsy is related to many structural and physiological changes in the brain. We used kainic acid in rats as an animal model of temporal lobe epilepsy, and studied the neural interactions of the dentate gyrus in urethane-anesthetized rats in vivo. Our initial hypothesis was that sprouting of mossy fibers, the axons of the granule cells, increases proximal dendritic excitatory currents in the inner molecular layer of the dentate gyrus. Extracellular currents were detected in vivo using current source density analysis. Backfiring the mossy fibers in CA3 or orthodromic excitation of the granule cells through the medial perforant path induced a current sink at the inner molecular layer. However, the sink or inferred excitation at the inner molecular layer was not increased in kainic acid-treated rats and the sink actually correlated negatively with the degree of mossy fiber sprouting. It is inferred that the latter sink was mediated mainly by association fibers and not by recurrent mossy fibers. After kainic acid treatment, paired-pulse inhibition of the population spikes in the dentate gyrus was increased. In contrast, reverberant activity that involved looping around an entorhinal-hippocampal circuit was increased in kainic acid-treated rats, compared to control rats. The increase of inhibition in kainic acid-treated rats was readily blocked by a small dose of GABA(A) receptor antagonist bicuculline. The latter dose of bicuculline induced paroxsymal spike bursts in kainic acid-treated but not control rats, demonstrating that the increased inhibition in dentate gyrus was fragile. In conclusion, after kainic acid induced seizures, the dentate gyrus in vivo showed an increase in inhibition that appeared to be fragile. The hypothesized increase in proximal dendritic excitation due to mossy fiber sprouting was not detected. However, the fragile inhibition could explain the seizure susceptibility in patients with temporal lobe epilepsy.

Animals↗
PubMed1964

TEMPORAL LOBE EPILEPSY: A CLINICAL STUDY OF 47 CASES.

Clinical features of 47 cases of temporal lobe epilepsy are analyzed and treatment of this disorder is outlined. Twenty-four per cent of all cases of epilepsy seen by one of the authors over a two-year period were of this type. Fifteen of these 47 patients had a history of birth injury. Care must be taken to distinguish the symptoms of temporal lobe epilepsy from those of acute anxiety or hysteria and to differentiate the short-lived temporal lobe attack from centrencephalic petit mal.Interictal personality disturbances were identified in 11 of 24 persons with temporal lobe epilepsy, four of 35 with focal epilepsy from all other areas, and one of 17 with centrencephalic epilepsy. Personality deviations most frequently encountered were irritability, aggressiveness, bouts of depression, paranoid tendencies and exhibitionism. Medical or surgical treatment often improves the personality abnormalities concomitantly with control of seizures.

Adolescent↗
PubMed2002

LGI1 is mutated in familial temporal lobe epilepsy characterized by aphasic seizures.

Autosomal dominant lateral temporal lobe epilepsy previously has been linked to chromosome 10q22-q24, and recently mutations in the LGI1 gene (Leucine-rich gene, Glioma Inactivated) have been found in some autosomal dominant lateral temporal lobe epilepsy families. We have now identified a missense mutation affecting a conserved cysteine residue in the extracellular region of the LGI1 protein. The C46R mutation is associated with autosomal dominant lateral temporal lobe epilepsy in a large Norwegian family showing unusual clinical features like short-lasting sensory aphasia and auditory symptoms.

Aphasia↗
PubMed1996

Comparison of coronal sphenoidal versus standard anteroposterior temporal montage in the EEG recording of temporal lobe seizures.

Chronic sphenoidal electrodes were developed to facilitate the recording and localization of temporal lobe seizures during long term monitoring. Many reports demonstrate their utility in displaying temporal interictal epileptiform activity, but there have been few direct comparisons of sphenoidal electrodes and surface temporal recordings actually. We compared simultaneous portions of 74 EEG recordings of temporal lobe seizures (from 42 patients), with one portion including sphenoidal electrodes in a coronal montage and one with a standard anterior posterior temporal montage. Separated tracings were reviewed by readers blinded to the other portion of the tracing. The coronal sphenoidal montage allowed recognition of temporal lobe seizures inapparent with standard surface temporal electrodes in 19% of seizures and led to an earlier identification (usually by > or = 5 s) of the onset in 70% of seizures. Indwelling, flexible sphenoidal electrodes assist in ambulatory recording of temporal lobe seizures, both in demonstrating the presence of seizures and in determining the localization and time of seizure onset.

Electrodes↗
PubMed2002

Idiopathic familial temporal lobe epilepsy with febrile convulsions.

Efforts to duplicate the genetic and molecular breakthroughs of autosomal dominant frontal lobe epilepsy have lead to increased interest in familial temporal lobe epilepsy. In this report we describe three kindreds. The epilepsy syndrome described manifests after the teenage years and was generally mild and treatment responsive. The predominant seizure types were simple and complex partial seizures, typical of mesial temporal onset. Some family members had febrile convulsions only and others had epilepsy without preceding febrile convulsions. Three patients had both febrile convulsions and temporal lobe epilepsy. High-resolution quantitative and qualitative MRI was normal. The syndrome in these three kindreds is distinct from temporal lobe epilepsy due to mesial temporal sclerosis and febrile convulsions and is probably a form of idiopathic localization related epilepsy. Its relation to other familial temporal lobe epilepsy phenotypes is discussed.

Adolescent↗
PubMedDate not supplied

Value of single-voxel proton MR spectroscopy in temporal lobe epilepsy.

PURPOSE: To study the value of different parameters derived from single-voxel proton MR spectroscopy of the mesial temporal lobes in the lateralization of the epileptogenic zone in patients with temporal lobe epilepsy. METHODS: We studied 12 healthy volunteers and 21 patients with temporal lobe epilepsy refractory to medical treatment, which was clearly lateralized with electroencephalography (EEG) and MR imaging. The mesial temporal lobes were investigated with single-voxel proton MR spectroscopy using a point-resolved spectroscopic sequence with an echo time of 135 milliseconds. The normalized concentration of N-acetylaspartate (NAA), creatine (Cr), and choline-containing compounds (Cho), and the metabolite ratios NAA/Cho+Cr, NAA/Cr, Cho/Cr, and NAA/Cho were calculated from the spectra. Using these values and an asymmetry index, we assigned the patients to one of five lateralization categories. RESULTS: The most consistent MR spectroscopic parameter for clear lateralization was the NAA/Cho+Cr ratio, followed by the NAA ratio. But with an adequate asymmetry index, the epilepsy in 17 (81%) of 21 patients could be lateralized by EEG and MR imaging with both parameters concordantly. Symmetric bilateral abnormalities were found in four of the 21 patients with NAA/Cho+Cr and in only one of the 21 patients with NAA. With both parameters, no contradictory lateralization was found; however, this was indeed the case with the remaining ratios, NAA/Cr, Cho/Cr, and NAA/Cho, in two, three, and one of the patients, respectively. A statistically significant decrease in NAA was found on the epileptic side, but also on the contralateral side. CONCLUSION: With an adequate asymmetry index, NAA/Cho+Cr and NAA are equally sensitive in predicting the side of involvement in patients with unilateral temporal lobe epilepsy.

Adolescent↗