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Results for “Temporal Lobe”

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PubMed1991

Right-hemisphere language dominance in temporal lobe epilepsy: clinical and neuropsychological correlates.

Prior to and following temporal lobe surgery, patients with right-hemisphere language dominance and focal left temporal lobe epilepsy (RHLD-LTLSz) were compared to right-handed patients with left-hemisphere language dominance and either left temporal lobe epilepsy (LHLD-LTLSz) or right temporal lobe epilepsy (LHLD-RTLSz). The group of RHLD-LTLSz patients had a more consistent history of brain involvement before the age of 5 years and had a higher seizure frequency rating than did either LHLD patient group. Cognitively, RHLD-LTLSz patients did not show significant deficits in psychometric intellectural scores. In addition, they did not demonstrate comparable degrees of verbal memory loss as found either pre- or postoperatively in LHLD-LTLSz patients. The right-handed RHLD-LTLSz and the right-handed LHLD-LTLSz groups both appeared to exhibit bilaterally depressed fine-motor coordination. The left-handed RHLD-LTLSz patients did not show the same motor deficiencies. These latter findings suggest that hemispheric dominance for bilateral motor control may exist independent of language dominance, but not independent of handedness.

Adolescent↗

PubMed1990

Feasibility of subclassification of temporal lobe epilepsy (1989): an etiological overview.

Temporal lobe epilepsy with amygdalohippocampal seizures may have episodes of severe convulsions in childhood more frequently and the onset age is significantly lower compared to epilepsy with lateral temporal seizures. To the contrary, tumorous lesions are found more frequently in epilepsy with lateral temporal seizures. In view of the presumed known etiologies in relation to the localization of epileptogenic foci, the Classification of Epileptic Syndrome (1989), subdividing temporal lobe epilepsies into 2 groups, was found to be useful.

Adult↗

PubMed2003

[Development of automated segmentation method for the posterior portion of the temporal lobe on coronal MR images].

Brain MRI is an important method for examining the diseases caused by various cerebral pathologies, and the measurement of temporal lobe volume is useful for identifying dementia and temporal lobe abnormalities. However, no segmentation algorithm for the temporal lobe on coronal MR images has been established. Such an algorithm is needed because the shape of the temporal lobe on coronal images varies from area to area. The purpose of this research was to develop a segmentation method for the posterior portion of the temporal lobe on coronal MR images. The subjects were 11 normal patients, whose coronal T(1)-weighted images were selected for this study. The preprocessing algorithm for segmentation consists of smoothing, binarization, and thinning. The first step of the segmentation process consists of recognition techniques for the temporal lobe region on thinning images. The next step is distance transformation on identified thinning images. Finally, the temporal lobe was segmented by using the original images and distance transformation images and employing the newly developed algorithm. The rate of accuracy of automated recognition was over 74% for all cases, while the average rate of accuracy was 83.2+/-4.0%. These results suggest that this segmentation method can clearly segment the temporal lobe and has potential for clinical use. Based on this study, although it included only 11 normal patients, we have started applying this segmentation method to many patients, with or without temporal lobe disease.

Adult↗

PubMed2002

A short-echo-time proton magnetic resonance spectroscopic imaging study of temporal lobe epilepsy.

PURPOSE: We used short-echo-time proton magnetic resonance spectroscopy imaging (MRSI) to study metabolite concentration variation through the temporal lobe in patients with temporal lobe epilepsy (TLE) with and without abnormal MRI. METHODS: MRSI was performed at TE = 30 ms to study 10 control subjects, 10 patients with TLE and unilateral hippocampal sclerosis, and 10 patients with TLE and unremarkable MRI (MRI negative). We measured the concentrations of N-acetyl aspartate +N-acetyl aspartyl-glutamate (NAAt), creatine (Cr), choline (Cho), glutamate + glutamine (Glx), and myoinositol, in the anterior, middle, and posterior medial temporal lobe (MTL), and in the posterior lateral temporal lobe. Segmented volumetric T1-weighted MRIs gave the tissue composition of each MRSI voxel. Normal ranges were defined as the control mean +/- 3 SD. RESULTS: In the hippocampal sclerosis group, seven of 10 had abnormally low NAAt in the ipsilateral anterior MTL. In the MRI-negative group, four of 10 had low NAAt in the middle MTL voxel ipsilateral to seizure onset. Metabolite ratios were less sensitive to abnormality than was the NAAt concentration. Group analysis showed low NAAt, Cr, and Cho in the anterior MTL in hippocampal sclerosis. Glx was elevated in the anterior voxel contralateral to seizure onset in the MRI-negative group. Metabolite concentrations were influenced by voxel position and tissue composition. CONCLUSIONS: (a) Low NAAt, Cr, and Cho were features of the anterior sclerotic hippocampus, whereas low NAAt was observed in the MRI-negative group in the middle MTL region. The posterior temporal lobe regions were not associated with significant metabolite abnormality; (b) The two patient groups demonstrated different metabolite profiles across the temporal lobe, with elevated Glx a feature of the MRI-negative group; and (c) Voxel tissue composition and position influenced obtained metabolite concentrations.

Adult↗

PubMed2000

Electroencephalographic, volumetric, and neuropsychological indicators of seizure focus lateralization in temporal lobe epilepsy.

CONTEXT: Anterior temporal lobectomy is an effective treatment for medically intractable temporal lobe seizures. Identification of seizure focus is essential to surgical success. OBJECTIVE: To examine the usefulness of presurgical electroencephalography (EEG), magnetic resonance imaging (MRI), and neuropsychological data in the lateralization of seizure focus. DESIGN: Presurgical EEG, MRI, and neuropsychological data were entered, independently and in combination, as indicators of seizure focus lateralization in discriminant function analyses, yielding correct seizure lateralization rates for each set of indicators. SETTING: Comprehensive Epilepsy Program, Shands Teaching Hospital, University of Florida, Gainesville. PATIENTS: Forty-four right-handed adult patients who ultimately underwent successful anterior temporal lobectomy. Left-handed patients, those with less-than-optimal surgical outcome, and any patients with a history of neurological insult unrelated to seizure disorder were excluded from this study. MAIN OUTCOME MEASURES: For each patient presurgical EEG was represented as a seizure lateralization index reflecting the numbers of seizures originating in the left hemisphere, right hemisphere, and those unable to be lateralized. Magnetic resonance imaging data were represented as left-right difference in hippocampal volume. Neuropsychological data consisted of mean scores in each of 5 cognitive domains. RESULTS: The EEG was a better indicator of lateralization (89% correct) than MRI (86%), although not significantly. The EEG and MRI were significantly superior to neuropsychological data (66%) (P=.02 and .04, respectively). Combining EEG and MRI yielded a significantly higher lateralization rate (93%) than EEG alone (P<.01). Adding neuropsychological data improved this slightly (95%). CONCLUSIONS: The EEG and MRI were of high lateralization value, while neuropsychological data were of limited use in this regard. Combining EEG, MRI, and neuropsychological improved focus lateralization relative to using these data independently.

Adult↗

PubMed2002

Medial temporal lobe atrophy predicts Alzheimer's disease in patients with minor cognitive impairment.

OBJECTIVES: To investigate whether medial temporal lobe atrophy predicted outcome in patients with minor cognitive impairment and whether assessment of the medial temporal lobe could increase the predictive accuracy of age and delayed recall for outcome. Quantitative and qualitative methods of assessing the medial temporal lobe were also compared. METHODS: Patients with minor cognitive impairment older than 50 years (n=31) were selected from a memory clinic and were followed up for on average 1.9 years. The medial temporal lobe was assessed in three different ways: volumetry of the hippocampus, volumetry of the parahippocampal gyrus, and qualitative rating of medial temporal lobe atrophy (MTA). Outcome measures were Alzheimer type dementia or cognitive decline at follow up. Delayed recall was tested with a verbal learning test. RESULTS: Ten patients had experienced cognitive decline at follow up, of whom seven had probable Alzheimer type dementia. All medial temporal lobe measurements were associated with cognitive decline at follow up (p trend analysis between 0.001 (hippocampus) and 0.05 (parahippocampal gyrus)). Only the hippocampal volume and MTA score were associated with Alzheimer type dementia at follow up (p trend analysis respectively 0.003 and 0.01). All medial temporal lobe measurements increased the predictive accuracy of age and the delayed recall score for cognitive decline (p increase in predictive accuracy varied between <0.001 (hippocampus) and 0.02 (parahippocampal gyrus and MTA score)) and the hippocampal volume and the MTA score increased the predictive accuracy of age and the delayed recall score for Alzheimer type dementia (p= 0.02). CONCLUSIONS: The ability to detect patients at high risk for Alzheimer type dementia among those with minor cognitive impairment increases when data on age and memory function are combined with measures of medial temporal lobe atrophy. Volumetry of the hippocampus is preferred, but qualitative rating of medial temporal lobe atrophy is a good alternative.

Aged↗

PubMed2003

Interictal patterns of cerebral glucose metabolism, perfusion, and magnetic field in mesial temporal lobe epilepsy.

PURPOSE: To characterize the epileptogenic condition of patients with mesial temporal lobe epilepsy, the interictal patterns of glucose metabolism, perfusion, and magnetic field in the temporal lobe were evaluated by using [18F]fluorodeoxyglucose-positron emission tomography, [99mTc]-ethylcysteinate dimer-single photon emission computed tomography, and magnetoencephalography (MEG). METHODS: Twenty-one patients with mesial temporal lobe epilepsy related to hippocampal sclerosis were studied. The ictal-onset area was located by continuous video-EEG monitoring. Quantitative analysis of glucose metabolism and perfusion in the temporal lobe was performed, and the cerebral magnetic field was evaluated to measure the equivalent current dipole (MEG-ECD). RESULTS: Although hypometabolism and hypoperfusion in the temporal lobe were lateralized with the ictal-onset area in 16 (76.2%) and in 11 (52.4%) respectively, they were localized in diverse ways without any coupling. MEG-ECD was distributed in diverse ways unrelated to the ictal-onset area: ipsilateral medial temporal origin in five (23.8%), ipsilateral lateral temporal origin in two (9.5%), ipsilateral mixed (medial and lateral) temporal origin in six (28.6%), bilateral temporal origin in four (19.0%), and contralateral temporal origin in two (9.5%). CONCLUSIONS: MEG-ECD was distributed in varied ways with the disorder and uncoupling of glucose metabolism and perfusion in the temporal lobe. These results may help resolve the clinical controversy over the possibility that the cortical irritative area generating the interictal epileptic discharge is distinct from the ictal-onset area, and also may have some functional implications in identifying different brain compartments in the generation of metabolic signals.

Adolescent↗

PubMed1985

Autonomic responsiveness to affective visual stimulation in temporal lobe epilepsy.

Patients with temporal lobe epilepsy (TLE) have been posited by some to manifest a syndrome of interictal personality and behavioral change. Furthermore, this syndrome has been attributed to an underlying mechanism--enhanced affective responsiveness. The purpose of this investigation was to determine whether patients with TLE manifest increased emotional responsiveness relative to appropriate controls. Patients with TLE (n = 23) were compared with non-TLE (n = 7) and healthy controls (n = 16) as to their autonomic nervous system responsiveness to an emotionally stressing film. No differences were found among the groups. These results are related to the larger literature concerning epilepsy and psychopathology.

Adult↗

PubMed2002

Immature-like astrocytes are associated with dentate granule cell migration in human temporal lobe epilepsy.

In human temporal lobe epilepsy, a dispersion of dentate granule cells is frequently described in adults who had an early risk factor. To elucidate the role of glia in this phenomenon, we investigated neuronal dispersion, astrocyte organization and expression of intermediate filaments of mature and immature astrocytes (i.e. glial fibrillary acidic protein (GFAP) and vimentin, respectively) in seven subjects with early febrile seizures (F(+)) and five subjects with other etiologies than febrile seizures (F(-)). Compared to F(-) patients, a majority of F(+) subjects showed neuronal dispersion and vimentin expression in radial glia. However, in two patients with the maximal dispersion, radial processes expressed only GFAP. We suggest that granule cell migration that occurs in adult epileptic focus results from the transient occurrence of immature-like glia throughout the granular layer.

Adult↗

PubMed1993

Dormancy of inhibitory interneurons in a model of temporal lobe epilepsy.

In humans temporal lobe epilepsy (TLE) is characterized by recurrent seizures, neuronal hyperexcitability, and selective loss of certain neuronal populations in the hippocampus. Animal models of the condition indicate that a diminution of inhibition mediated by gamma-aminobutyric acid (GABA) accounts for the altered function, and it has been hypothesized that the diminution arises because GABAergic basket interneurons are "dormant" as a result of their being disconnected from excitatory inputs. In hippocampal slices, inhibitory postsynaptic potentials (IPSPs) were elicited in CA1 pyramidal cells by activation of basket cells; responses from an animal model of TLE were compared to those from control tissue. IPSPs evoked indirectly by activation of terminals that then excited basket cells were reduced in the epileptic tissue, whereas IPSPs evoked by direct activation of basket cells, when excitatory neurotransmission was blocked, were not different from controls. These results provide support for the "dormant basket cell" hypothesis and have implications for the pathophysiology and treatment of human TLE.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2004

Enlarged temporal lobes in Turner syndrome: an X-chromosome effect?

Gender differences in brain morphology have previously been reported in the temporal lobe and an 'X-chromosome dosage effect' has been described in Turner syndrome (45,X). To examine this further, we investigated temporal lobe morphology, metabolism and function in nine children with non-mosaic Turner syndrome using magnetic resonance imaging, (1)H magnetic resonance spectroscopy and neuropsychological testing and compared outcomes with results from nine age-matched control girls (46,XX). Turner subjects were found to have significantly larger superior temporal lobes (P = 0.004) and middle temporal lobes (P = 0.047) than controls. The size of the temporal lobe was found to correlate negatively with temporal lobe choline-containing compounds suggesting that increased temporal lobe size is associated with larger cells and/or decreased dendrites. This suggests a developmental failure to prune neurons. The degree of enlargement correlates negatively with functional performance on temporal-lobe associated tasks, suggesting that the enlargement may be a compensatory mechanism, or possibly causative in the case of semantic fluency performance. These temporal lobe abnormalities are discussed with reference to genes which are absent in Turner syndrome and to hormonal differences between Turner syndrome subjects and 46,XX controls.

Child↗

PubMed2003

Dissecting out conscious and unconscious memory (sub)processes within the human medial temporal lobe.

The human medial temporal lobe (MTL) system mediates memories that can be consciously recollected. However, the specific natures of the individual contributions of its various subregions to conscious memory processes remain equivocal. Here we show a functional dissociation between the hippocampus proper and the parahippocampal region in conscious and unconscious memory as revealed by invasive recordings of limbic event-related brain potentials recorded during explicit and implicit word recognition: Only hippocampal and not parahippocampal neural activity exhibits a sensitivity to the implicit versus explicit nature of the recognition memory task. Moreover, only within the hippocampus proper do the neural responses to repeated words differ not only from those to new words but also from each other as a function of recognition success. By contrast parahippocampal (rhinal) responses are sensitive to repetition independent of conscious recognition. These findings thus demonstrate that it is the hippocampus proper among the MTL structures that is specifically engaged during conscious memory processes.

Brain Mapping↗

PubMed2000

Surviving granule cells of the sclerotic human hippocampus have reduced Ca(2+) influx because of a loss of calbindin-D(28k) in temporal lobe epilepsy.

In mesial temporal lobe epilepsy (mTLE), the predominant form of epilepsy in adults, and in animal models of the disease, there is a conspicuous loss of the intracellular Ca(2+)-binding protein calbindin-D(28k) (CB) from granule cells (GCs) of the dentate gyrus. The role of this protein in nerve cell function is controversial, but here we provide evidence for its role in controlling Ca(2+) influx into human neurons. In patients with Ammon's horn sclerosis (AHS), the loss of CB from GCs markedly increased the Ca(2+)-dependent inactivation of voltage-dependent Ca(2+) currents (I(Ca)), thereby diminishing Ca(2+) influx during repetitive neuronal firing. Introducing purified CB into GCs restored Ca(2+) current inactivation to levels observed in cells with normal CB content harvested from mTLE patients without AHS. Our data are consistent with the possibility of neuroprotection secondary to the CB loss. By limiting Ca(2+) influx through an enhanced Ca(2+)-dependent inactivation of voltage-dependent Ca(2+) channels during prolonged neuronal discharges, the loss of CB may contribute to the resistance of surviving human granule cells in AHS.

Action Potentials↗

PubMed2002

Decrease of sympathetic cardiovascular modulation after temporal lobe epilepsy surgery.

In temporal lobe epilepsy (TLE), there is evidence of ictal and interictal autonomic dysregulation, predominantly with sympathetic overactivity. The effects of TLE surgery on autonomic cardiovascular control and on baroreflex sensitivity (BRS) have not been studied. To evaluate such effects, we monitored heart rate (HR), systolic blood pressure (BP(sys)) and respiration in 18 TLE patients 3-4 months before and after TLE surgery. We used Blackman-Tukey spectral analysis to assess sympathetic and parasympathetic modulation as powers of HR and BP(sys) oscillations in the low frequency (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.5 Hz) bands. BRS was determined as the LF transfer function gain between BP and HR. After surgery, HR, BP(sys), respiration and HF powers remained unchanged, while LF powers of HR (1.57 +/- 1.54 bpm(2)) and BP(sys) (2.19 +/- 1.34 mmHg(2)) and BRS (0.68 +/- 0.31 bpm/mmHg) were smaller than pre-surgical LF powers of HR (3.87 +/- 3.26 bpm(2)) and BP(sys) (4.80 +/- 3.84 mmHg(2)) and BRS (1.12 +/- 0.39 bpm/mmHg; P < 0.05). After TLE surgery, there is a reduction of sympathetic cardiovascular modulation and BRS that might result from decreased influences of interictal epileptogenic discharges on brain areas involved in cardiovascular autonomic control. TLE surgery seems to stabilize the cardiovascular control in epilepsy patients by reducing the risk of sympathetically mediated tachyarrhythmias and excessive bradycardiac counter-regulation, both of which might be relevant for the pathophysiology of sudden unexpected death in epilepsy patients (SUDEP). Thus, TLE surgery might contribute to reducing the risk of SUDEP.

Adrenergic Fibers↗

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↗

PubMed2003

Neocortical temporal FDG-PET hypometabolism correlates with temporal lobe atrophy in hippocampal sclerosis associated with microscopic cortical dysplasia.

PURPOSE: Medically intractable temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS), with or without cortical dysplasia (CD), is associated with atrophy of the hippocampal formation and regional fluorodeoxyglucose positron-emission tomography (FDG-PET) hypometabolism. The relation between areas of functional and structural abnormalities is not well understood. We investigate the relation between FDG-PET metabolism and temporal lobe (TL) and hippocampal atrophy in patients with histologically proven isolated HS and HS associated with CD. METHODS: Twenty-three patients underwent en bloc resection of the mesial and anterolateral neocortical structures. Ten patients were diagnosed with isolated HS; 13 patients had associated microscopic CD. Temporal lobe volumes (TLVs) and hippocampal volumes were measured. Magnetic resonance imaging (MRI) and PET were co-registered, and regions of interest (ROIs) determined as gray matter of the mesial, lateral, and anterior temporal lobe. RESULTS: All patients (HS with or without CD) had significant ipsilateral PET hypometabolism in all three regions studied (p < 0.0001). In patients with isolated HS, the most prominent hypometabolism was in the anterior and mesial temporal lobe, whereas in dual pathology, it was in the lateral temporal lobe. TLVs and hippocampal volumes were significantly smaller on the epileptogenic side (p < 0.05). The PET asymmetries ipsilateral/contralateral to the epileptogenic zone and TLV asymmetries correlated significantly for the anterior and lateral temporal lobes (p < 0.05) in the HS+CD group, but not in the isolated HS group. Mesial temporal hypometabolism was not significantly different between the two groups. CONCLUSIONS: Temporal neocortical microscopic CD with concurrent HS is associated with more prominent lateral temporal metabolic dysfunction compared with isolated HS in TL atrophy. Further studies are needed to confirm these findings and correlate the PET hypometabolic patterns with outcome data in patients operated on for HS with or without CD.

Adolescent↗

PubMed1996

Mesial atrophy and outcome after amygdalohippocampectomy or temporal lobe removal.

We studied 74 consecutive patients with temporal lobe epilepsy who were treated surgically and in whom the volumes of mesial temporal structures were determined preoperatively by magnetic resonance imaging. We divided the patients into three groups according to the volumetric findings: unilateral (63.5% of the patients), bilateral (23%), or no atrophy (13.5%) of the amygdala-hippocampal formation. Two distinct surgical approaches were used: selective amygdalohippocampectomy (n = 37) or anterior temporal lobe resection (n = 37). Outcome was assessed at least 1 year after surgery, according to Engel's modified classification. Patients with unilateral mesial temporal atrophy had significantly better results compared with the other two groups (p < 0.001): We found excellent results (class I or II outcome) in 93.6% of the patients with unilateral atrophy, in 61.7% of those with bilateral atrophy, and in 50% of the group with no significant atrophy of mesial temporal structures. The two different surgical techniques were equally effective, regardless of the pattern of atrophy. In conclusion, magnetic resonance volumetric studies in temporal lobe epilepsy proved to be an important preoperative prognostic tool for surgical treatment, but they did not provide guidance for selecting one surgical approach compared to the other.

Adult↗

PubMed2006

Idiopathic generalised epilepsy: a pilot study of memory and neuronal dysfunction in the temporal lobes, assessed by magnetic resonance spectroscopy.

BACKGROUND: The memory deficits in patients with temporal lobe epilepsy (TLE) are associated with epileptogenic lesions of the temporal lobes, especially hippocampal sclerosis. Memory deficits have been extensively studied in TLE, but the presence of pre-existing temporal lobe abnormality has confounded studies on the relationship between memory dysfunction and seizure activity. Idiopathic generalised epilepsy (IGE) is characterised by primary generalised seizures and is found to occur in the absence of any macroscopic brain abnormalities. IGE is therefore ideal for investigations on the effects of seizure activity on memory and cognition. AIM AND METHODS: Magnetic resonance spectroscopy (MRS) and neuropsychological testing were used to investigate the relationship between epileptic seizures, memory performance and neuronal dysfunction in the temporal lobes of a group of patients with IGE. 30 patients and 15 healthy controls participated in the study. RESULTS: Patients with IGE were found to perform worse than controls on tests of speed of information processing, general cognitive performance and a range of memory tests, including face recognition, word recognition, verbal recall and complex figure recall. The performance of the patient group on the visual recognition and verbal recall sections of the Doors and People Test was found to correlate with MRS ratios of N-acetyl aspartate:choline and N-acetyl aspartate:creatine in the temporal lobes. CONCLUSION: This result supports the hypothesis that memory deficits in epilepsy may be due to neuronal dysfunction secondary to epileptic activity itself in the absence of any macroscopic lesions in the temporal lobes.

Adult↗