PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Temporal Lobe”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
PubMed1998

Single-voxel proton MR spectroscopy and positron emission tomography for lateralization of refractory temporal lobe epilepsy.

PURPOSE: We compared the metabolic information obtained from single-voxel proton MR spectroscopy and positron emission tomography (PET) in patients with temporal lobe epilepsy. METHODS: Twenty-nine patients with temporal lobe epilepsy were screened for metabolic abnormalities with both proton MR spectroscopy and PET. Lateralization with MR spectroscopy was possible by using NAA/(Cho+Cr) and an asymmetry index. Hypometabolism as determined by PET was classified as typical or complex. RESULTS: Twenty-four (96%) of 25 patients whose seizure onset could be lateralized to one temporal lobe showed ipsilateral lateralization with either MR spectroscopy or PET, whereas concordant lateralization with both techniques was possible only in 14 (56%) of the 25 patients. MR spectroscopy showed 42 abnormal temporal lobes whereas PET showed only 25 lobes with decreased metabolism. All temporal lobes with hypometabolism at PET also had a low NAA/(Cho+Cr). Five patients (20%) with negative PET studies had seizures lateralized correctly with MR spectroscopy. CONCLUSION: Proton MR spectroscopy is more sensitive in depicting metabolic abnormalities than is PET in patients with temporal lobe epilepsy. Patients with negative PET studies will benefit from MR spectroscopy for the purpose of lateralization.

Adolescent↗
PubMed2006

Global/local scoring modifications for the Rey-Osterrieth Complex Figure: relation to unilateral temporal lobe epilepsy patients.

Observation of figural reproductions of right temporal lobe epilepsy (RTLE) patients have revealed overall configuration errors, whereas in left temporal lobe epilepsy (LTLE) patients, the global aspect of performance is generally preserved. This study compared performance of individuals with temporal lobe epilepsy (LTLE, n=83; RTLE, n=63) on a global/local modification of the Rey-Osterrieth Complex Figure Test (RCFT). In Phase I, neuropsychologists (n=6) and neuropsychology fellows (n=3) completed a survey identifying the global and local aspects of the RCFT. Questionnaire responses were used to categorize a list of global and local items (five global, five local) for re-scoring the protocols of TLE patients during study Phase II. Results showed that the RTLE and LTLE groups were not differentiated according to the global or local indices F(1,141) = .385; p = not significant. There were lower local scores for both groups in the copy F(1,142) = 5.23; p = .024, immediate F(1,142) = 445.26; p < .001, and delay trials F(1,142) = 427.82; p < .001, indicating less retention of local information over time. Results suggest general declines in figural memory for local stimulus properties in both unilateral TLE groups. However, this relationship was weakened after controlling for global and local item verbalizability.

Adult↗
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↗
PubMed2007

The value of interictal diffusion-weighted imaging in lateralizing temporal lobe epilepsy.

BACKGROUND: A subgroup of patients with nonlesional temporal lobe epilepsy (TLE) has no evidence of hippocampal sclerosis on standard temporal lobe protocol MRI. OBJECTIVE: To investigate whether interictal diffusion-weighted imaging adds lateralizing information in patients with TLE with and without lateralizing conventional MRI. METHODS: We studied 22 patients (9 right, 13 left TLE) who had undergone temporal lobectomy and 18 control subjects. We measured hippocampal volumes on high- resolution coronal magnetization-prepared rapid gradient echo scans. Apparent diffusion coefficients (ADCs) for the entire hippocampus and three arbitrarily defined areas of interest within the hippocampal head, body, and tail were measured from the coregistered ADC map. Pathology was reviewed and correlated with imaging findings. RESULTS: Fourteen of 22 patients had hippocampal atrophy on MRI (defined as volume asymmetry greater than 2 SDs compared with asymmetry in the control group). Overall, resected hippocampi (n = 22) were significantly smaller than contralateral hippocampi as well as ipsilateral hippocampi in controls. ADCs were significantly higher in resected hippocampi than contralateral hippocampi as well as ipsilateral hippocampi in controls. These differences were also observed within the three areas of interest. ADCs in the hippocampi contralateral to the epileptogenic zone (n = 22) were also higher than in ipsilateral hippocampi in controls. In the subgroup of eight patients with nonlateralizing conventional MRIs, ADCs of resected hippocampi were not significantly different compared with the contralateral side. Pathology in these patients revealed gliosis only without apparent neuron loss. CONCLUSION: Interictal apparent diffusion coefficients confirm lateralization in patients with hippocampal atrophy on standard temporal lobe protocol MRI. However, they do not provide lateralizing information in patients with nonlateralizing conventional MRI.

Adolescent↗
PubMed1991

[A case of adult pilocytic astrocytoma in the right temporal lobe].

A case of adult pilocytic astrocytoma in the right temporal lobe is reported here. The patient was a twenty-four year old man, who came to the neurological division of our hospital on October 6, 1987 because of repeated consciousness-loss attacks accompanied with uncinate fit. He had no neurological deficits. However, an EEG revealed spike-and-wave complexes in the right temporal region, and a CT scan showed a small cystic lesion in the right temporal lobe. A diagnosis of psychomotor seizure was made, and the administration of anticonvulsants was started. The incidence of attack then decreased, but after approximately two years of drug therapy the attacks increased again. A CT scan was again performed, and revealed that the lesion in the right temporal lobe was enlarging. Also a noticeable enhanced lesion, identified as a mural nodule was found in the post-contrast enhancement study. A brain tumor was then suspected, and he was admitted to the neurosurgical division on October 11, 1989. He had no neurological deficits on admission. An MRI showed a low intensity lesion in the T1 weighted image, and a high intensity lesion in the T2 weighted image. A cystic lesion with a marked enhanced mural nodule was also found in the base of the right temporal lobe, according to the Gd enhancement study. Perifocal edema was not recognized. Cerebral angiography showed no positive findings. Positron emission tomography (PET), using H2(15)O, revealed low perfusion at or around the lesion, and PET using [11C]-methionine revealed an accumulation of methionine at the lesion. A diagnosis of low-grade glioma was made, and a right temporal craniotomy, for the purpose of totally removing the tumor was performed on October 26, 1989.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Quantitative magnetic resonance imaging in temporal lobe epilepsy: relationship to neuropathology and neuropsychological function.

Magnetic resonance images (MRIs) were obtained from 25 patients with medically refractory epilepsy of temporal lobe origin (12 on the left, 13 on the right) and 14 right-handed control subjects. The hippocampi and temporal lobes were traced by computer on successive coronal images and the resulting measurements of area were summed for each region. The left and right hippocampi were symmetrical in the control subjects; however, for patients the hippocampus was smaller on the side of the seizure focus. Moreover, the left-right hippocampal ratio significantly differentiated the control subjects from each patient group. The left temporal lobe was significantly smaller than the right in control subjects. The epileptics' temporal lobes were smaller on the side of the seizure focus, compared to the temporal lobes in the control subjects. MRI hippocampal measurements were compared to hippocampal neuronal densities obtained postoperatively. Significant correlations were obtained between the ratio (side ipsilateral to focus/side contralateral to focus) of MRI hippocampal measurements and neuronal densities in all hippocampal subfields except CA2. Prior to surgery, patients were administered the Wechsler Memory Scale and the verbal Selective Reminding Test. Significant correlations existed between MRI measurements of the left hippocampus and the Wechsler logical memory percent retention scores and between the left temporal lobe measurements and the verbal Selective Reminding Test scores for patients with seizure foci in the left temporal lobe.

Adolescent↗
PubMed1992

Neurotransmitters and their receptors in human temporal lobe epilepsy.

Patients with medically intractable temporal lobe epilepsy (TLE) undergo medial temporal lobectomy with hippocampectomy for one of two reasons. (1) A lesion (tumor or arteriovenous malformation) adjacent to, but not invasive of, the hippocampus, results in the removal of the lesion and adjacent hippocampus in order to ensure a tumor-free margin. This group will be referred to as tumor-related TLE (TTLE) patients. (2) The operation is performed when depth electrode recordings and other evaluative techniques point to the hippocampus as the focus of seizure initiation. This group will be referred to as cryptogenic TLE (CTLE) patients. Analysis of the hippocampi of these two groups of patients reveals that the TTLE hippocampus is quite similar to that of autopsy subjects in its chemical neuroanatomy. However, the dentate gyrus of the CTLE patients shows considerable morphological and cytochemical reorganization. This reorganization is characterized by a number of features. (1) There is a loss of granule cells which occurs either as a patchy loss and/or a thinning of the granule cell layer. (2) Remaining granule cells which contain dynorphin appear to produce recurrent collaterals into the inner molecular layer of the dentate gyrus. (3) In the subgranular region of the hilus (the polymorphic layer) there is a selective loss of interneurons immunoreactive for somatostatin, neuropeptide Y and substance P. (4) There appears to be an increase in fibers immunoreactive for somatostatin and neuropeptide Y which extend throughout the dentate molecular layer. Somatostatin fibers being less numerous than neuropeptide Y fibers (5). The distributions of a number of neurotransmitter receptors also show striking reorganization in the dentate gyrus of the CTLE hippocampus. (6) Second messenger systems protein kinase C and adenylate cyclase, and Na+, K(+)-ATPase activity, as determined by ouabain binding, is increased in the molecular layer of CTLE. This remodeling of the CTLE hippocampus may hold the key to the mechanisms of hyperexcitability of the granule cells in the hippocampus of this group, and consequently the generation of seizures. The removal of the hippocampus in CTLE patients results in good control of seizures, whereas removal of hippocampi that do not show such reorganization, in a group of patients classified as atypical CTLE patients, results in inadequate seizure control. These findings suggest a complex series of processes in converting the properly regulated granule cells into hyperexcitable ones.

Afferent Pathways↗
PubMed2004

Quantitative proton MR spectroscopic imaging of the mesial temporal lobe.

PURPOSE: To evaluate variations in regional metabolite concentrations in the anterior mesial temporal lobe (ATL), and compare metabolite concentrations between the allocortex and neocortex using quantitative proton MR spectroscopic imaging (MRSI). MATERIALS AND METHODS: Metabolite concentrations and ratios were measured in 20 healthy young subjects with the use of a multislice spin-echo (SE) sequence (TR/TE=2300/280 msec). Quantitation of MRSI data was performed by means of the phantom replacement methodology. RESULTS: The highest choline (Cho) concentration (4.1 +/- 1.1 mM) was found in the ATL (P=0.0015 compared to the middle mesial temporal lobe (MTL), and P=0.0008 compared to the posterior mesial temporal lobe (PTL)). The ATL also had a higher Cho/creatine (Cr) ratio and a lower N-acetyl aspartate (NAA)/Cho ratio compared to other examined regions (P <0.0001 and P < or = 0.052, respectively). In the allocortical regions, the average Cho concentration (3.5 +/- 0.8 mM) was 68% higher, and the NAA concentration (9.5 +/- 1.8 mM) was 13% lower than in the neocortex (P <10(-6) and P <0.008, respectively). Cho/Cr was 64% higher, NAA/Cr 14% lower, and NAA/Cho 47% lower in the allocortex than in the neocortex (P <10(-6), P=0.013, and P <10(-6), respectively). CONCLUSION: The mesial temporal lobe shows high levels of Cho, which presumably reflect a difference in cellular composition between the allocortex and neocortex. Regional metabolite variations must be considered when pathological conditions involving the mesial temporal lobe are evaluated.

Adult↗
PubMed1999

Directed forgetting deficits in patients with temporal lobe epilepsy: an information processing perspective.

Although mesial temporal lobe brain damage is frequently associated with memory loss, it is unclear whether the deficit results entirely from a disruption in the processing of relevant information or whether it also reflects interference from irrelevant information. Directed forgetting is one procedure that can be used, along with standard tests of memory, to investigate this distinction. Seventeen patients with a diagnosis of complex-partial seizures of temporal lobe origin and 17 healthy volunteers were compared on lexical decision, free recall, and recognition tests in a directed-forgetting paradigm. These tests created a memory profile to measure the influence of task relevant and irrelevant information in implicit and explicit memory. Compared with healthy volunteers, the patients were significantly impaired on the memory tasks overall [F(5,25) = 5.01, p < .01]. Specifically, directed forgetting in lexical decision and recognition both discriminated between the groups [stepdown F(1,26) = 6.84, eta 2 = .26, p < .05 and stepdown F(1,25) = 5.36, eta 2 = .13, p < .05, respectively]. The results suggest that interictal memory performance in temporal lobe epilepsy may be disrupted in part because of a deficit in the differential processing of task relevant and task irrelevant information, particularly at retrieval.

Adolescent↗
PubMedDate not supplied

Temporal and spatial characteristics of intracerebral seizure propagation: predictive value in surgery for temporal lobe epilepsy.

We examined the prognostic value of spatial and temporal characteristics of intracerebral propagation of seizures during temporal lobe epilepsy (TLE) surgery. Seven TLE patients resistant to standard anterotemporal lobectomy who had no known causes of resistance [e.g., extratemporal (ET), lesions, multifocal epilepsy] were matched with 7 seizure-free patients and 7 others who were almost seizure-free after operation. Intracerebral ictal propagation pathways were not different in the three groups. Propagation was multidirectional, most frequently to the frontal lobes and sometimes to the contralateral temporal lobe (CTL). ET propagation delays were significantly shorter in resistant patients than in markedly improved patients. The resistant group also had more frequent propagation delays < 1.0 s, but propagation times > 1.0 s were equally likely in all groups. The extent of ET propagation and frequency of focal onsets were not different among the groups. Results suggest that very short propagation times predict reduced efficacy of operation, and that long propagation times are not related to surgical success.

Electroencephalography↗
PubMed2005

Loss of memory for auditory-spatial associations following unilateral medial temporal-lobe damage.

The goal of the present experiment was to determine the role of medial temporal-lobe structures in episodic memory of auditory-spatial associations. By using a two-alternative forced choice paradigm in which an association between eight different sounds and their spatial location must be recognized, learning abilities over 10 learning sessions were tested in 19 patients who had undergone a right or a left medial temporal-lobe resection for the relief of intractable seizures as well as in nine normal control participants. The data demonstrated that significant learning took place over the successive sessions for all the participants. In addition, the results showed that patients with left but not right medial temporal-lobe lesion were impaired in this learning task as compared to normal participants, suggesting the predominant implication of left medial temporal-lobe structures in auditory-spatial associative learning. The predominant role of left hemisphere structures in this memory task could be explained by a spatial categorical coding, which was enhanced by the use of eight loud-speakers. This result also suggests that the ability to store an episodic event associated with a rich spatial (or temporal) context depends on the left medial temporal-lobe structures. Thus, this finding provides an interesting parallel with data obtained in the visual modality by documenting for the first time the role of the left medial temporal-lobe in episodic learning of auditory-spatial associations.

Adult↗
PubMed2005

Pathophysiology of posttraumatic temporal lobe lesions.

BACKGROUND: Posttraumatic parenchymal lesions in the temporal lobe may cause neurologic deterioration. An analysis was made of the natural evolution of this type of lesion, with emphasis on its 2 components: hemorrhage (hyperdense on computed tomography [CT]), and edema and necrosis (hypodense on CT). The clinical repercussions were studied, and the factors that might influence such evolution were investigated. METHODS: Forty head-injured patients with temporal lobe lesions admitted within 12 hours after the injury were selected in a prospective manner. Computed tomography scans were systematically repeated within the first 36 hours and at 7 and 30 days postinjury. Factors such as interval between injury and the first CT scan, age, velocity of the injury, alcohol consumption, coagulation abnormalities, and the presence of decompressive measures were compared between the patients that had enlargement of the hemorrhage and those who did not. Increase in hypodensity was compared with that in hyperdensity. RESULTS: Fourteen patients showed enlargement of the hemorrhage. In all cases but one, the interval between injury and admission was 3 hours or less. Other factors had no statistical significance as predisposing causes for such enlargement. In approximately half of the cases, the hypodense component increased in the first 36 hours and continued increasing until the end of the first week. Evolution of the hypodense component was not dependent on behavior of the hemorrhage, surgical drainage, or diameter of the hemorrhagic lesion. CONCLUSIONS: The natural evolution of the hyperdense component of temporal lobe lesions was to enlarge within the first few hours after the injury. Edema and necrosis developed more slowly and with no significant clinical manifestations.

Age Factors↗
PubMed2004

Contralateral motor automatisms in neocortical temporal lobe epilepsy.

BACKGROUND: The lateralizing value of the motor automatisms is generally doubted in most patients with temporal lobe epilepsy. However, subgroup analysis of the seizures of temporal lobe origin suggests a role for motor automatisms in discriminating seizures of neocortical versus mesial temporal lobe origin. METHODS: Video-EEG of a patient with well-defined neocortical temporal lobe epilepsy was reviewed to assess the localizing value of motor automatisms. RESULTS: We report a patient with left upper extremity motor automatisms and clonic movements of the proximal left lower extremity with altered awareness as the sole manifestations of right temporal neocortical seizures. CONCLUSION: Early onset unilateral motor automatisms without dystonic posturing can localize the seizure origin to the contralateral temporal lobe neocortex.

Automatism↗
PubMed2004

The anatomy of semantic knowledge: medial vs. lateral temporal lobe.

Semantic knowledge (e.g., long-established knowledge about objects, facts, and word meanings) is known to be severely impaired by damage to the anterolateral temporal lobe. For example, patients with semantic dementia have prominent atrophy in anterolateral temporal cortex and also have significant damage within the medial aspect of the temporal lobe. However, there is uncertainty about the contribution of medial temporal lobe damage, including perirhinal cortex damage, to impaired semantic knowledge. Drawing largely on published material from multiple sources, we compared the performance of severely amnesic patients with large medial temporal lobe lesions and patients with semantic dementia on nine tests of semantic knowledge and two tests of new learning ability. On the tests of semantic knowledge, the amnesic patients performed markedly better than the patients with semantic dementia. By contrast, on the tests of new learning, the patients with semantic dementia performed markedly better than the amnesic patients. We conclude that medial temporal lobe damage impairs the formation of declarative memory, and that semantic knowledge is impaired to the extent that damage extends laterally in the temporal lobe. Reports that the extent of atrophy in perirhinal cortex correlated with the severity of impaired semantic knowledge may be understood by supposing that the extent of damage in many temporal lobe areas is intercorrelated in this progressive disease, and that the extent of atrophy in perirhinal cortex is a proxy for the overall severity of dementia.

Aged↗
PubMed1994

Do dichotic word listening asymmetries predict side of temporal lobe seizure onset?

Dichotic word listening asymmetries are thought to be useful in predicting side of temporal lobe dysfunction. However, little direct evidence exists to support this assumption in practice, especially in patients with subtle epileptogenic lesions. To determine if word listening ear asymmetries are valid predictors of side of temporal lobe seizure onset, we examined the preoperative dichotic word listening performance of 80 patients with either left (N = 41) or right (N = 39) temporal lobe (TL) seizure foci. On a group level, patients showed a statistically significant 'lesion effect' as evidenced by a relative deficit in the ear contralateral to the side of lesion. Prediction of side of seizure focus in individual cases, however, was poor: depending upon the criteria used, 61% to 80% of epileptics with unilateral temporal lobe foci did not show the expected contralateral ear deficit. Results suggest that caution be exercised when inferring side of temporal lobe seizure focus through dichotic word listening asymmetries in individual temporal lobe epilepsy cases.

Adult↗
PubMed1995

Characterization and localization of [125I]RTI-121 binding sites in human striatum and medial temporal lobe.

Dopamine Transporter (DAT) binding sites in medial temporal lobe structures are much less dense than in striatum and have been difficult to image and quantitate. The recently synthesized compound [125I]RTI-121 ([125I]2 beta-carboxylic acid isopropyl ester-3 beta-(4-iodophenyl)tropane) has demonstrated high specificity and affinity for the DAT in preliminary animal studies. The present experiments were designed to delineate the pharmacological and anatomical characteristics of [125I]RTI-121 binding sites in the striatum and medial temporal lobe of normal humans. A series of saturation experiments performed with striatal membrane preparations generated a one-site model with a KD averaging 1.49 +/- 0.06 nM, and a Bmax that was comparable to those of earlier reports. Competition experiments confirmed the selectivity of [125I]RTI-121 for DAT binding sites. After the assay conditions for autoradiography were optimized, [125I]RTI-121 binding was visualized, pharmacologically characterized and quantitated in human temporal lobe structures. In the hippocampus, specific binding was distributed in the CA4 and CA3 pyramidal cell layers, the outer stratum radiatum and the dentate molecular layer, but not in the dentate granule cells or outer pyramidal cells. In the amygdala specific binding was limited to the basolateral nuclei. Dopamine nerve terminals, as identified with [125I]RTI-121 binding, also displayed a discrete and homologous innervation pattern in the amygdala and hippocampus of several other mammalian species. In summary, the kinetic, saturation, competition and autoradiographic experiments demonstrated that [125I]RTI-121 can be used to identify DAT binding sites and to assess their functional state in post mortem human brain samples.

Animals↗
PubMed1999

Electrical stimulation of the contralateral mesial temporal structure induces an ipsilateral seizure pattern in mesial temporal lobe epilepsy.

PURPOSE: We examined the mode of seizure development induced by electrical stimulation in patients with mesial temporal lobe epilepsy. METHODS: Of 25 patients undergoing intracranial EEG evaluation and electrical stimulation ipsilateral to the presumed site of habitual seizure origin, 17 patients had additional stimulation studies on the contralateral temporal lobe. RESULTS: Fourteen of the 25 patients had seizures induced with ipsilateral stimulation, and two of the 17 patients had seizures with contralateral stimulation. Seizures induced by ipsilateral stimulation started in the ipsilateral temporal lobe, whereas those induced by contralateral stimulation originated from the ipsilateral temporal lobe structure and were identical to the habitual seizures. CONCLUSIONS: Electrical stimulation of the temporal lobe structure opposite the site of habitual seizure origin is said to induce a seizure rarely. However, according to our preliminary results, if contralateral stimulation elicits a habitual seizure in the ipsilateral temporal lobe, it might be considered additional confirmatory evidence of seizure lateralization.

Adult↗