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PubMed1995

Neuronal recordings in human lateral temporal lobe during verbal paired associate learning.

The temporal lobe has a role in memory and learning. The objective of this study was to assess the activity of neurons in the temporal cortex of humans during learning. Single neuron activity was recorded with extracellular microelectrodes in adults undergoing awake craniotomies for resections for medically intractable epilepsy. Participants were administered control tasks of overt reading, silent reading, nonword visual controls and a recent verbal memory task with distracters followed by a verbal paired associates (PA) paradigm. Forty-nine neurons were identified and characterized by their relationship to language and memory. Neurons related to overt speech (Type A neurons) showed increased activity during learning in patients who were good learners compared to patients who were poor learners. Neurons not related to language or to memory (Type D neurons) showed increased activity with exposure to unlearned word pairs in poor learners compared with those who were good learners. Activity in all groups diminished with practice. Levels of activity in specific types of neurons in human temporal lobe differ in patients who learn word pairs rapidly or poorly.

Craniotomy↗

PubMed2001

[Is visual assessment of MRI adequate in the investigation of patients with temporal lobe epilepsy? Evaluation of the diagnostic accuracy of the visual assessment of MRI in mesial temporal sclerosis].

INTRODUCTION: Is visual assessment of MRI adequate in patients with temporal lobe epilepsy? Visual versus quantitative MRI assessment of mesial temporal sclerosis (hippocampal gliosis (HG) and hippocampal atrophy (HA)). MATERIAL AND METHODS: The MRIs of 25 patients with temporal lobe epilepsy were assessed visually by three radiologists with different levels of neuroradiological MRI experience (expert, trained, and inexperienced). Diagnosis obtained earlier by T2-relaxometry and volume measurements were considered to be the gold standard. RESULTS: The diagnostic accuracy of visual assessment was high for unilateral HA, but low for bilateral HA and unilateral and bilateral HG, and it was not better for the expert eye than for the inexperienced. Interobserver agreement on the visual diagnosis of HG and HA (Cohen's Kappa coefficient): 0.49 (HG) and 0.84 (HA). Intraobserver reliability for the expert/trained/inexperienced observer for visual diagnosis (Kappa): 0.83/0.64/0.47 (HG) and 0.88/0.69/0.73 (HA). DISCUSSION: Reproducibility and diagnostic accuracy of visual assessment varied unacceptably from the quantitative MRI-based diagnosis. Quantitative measurements are recommended in patients suspected of MTS.

Atrophy↗

PubMed2000

Prognostic value of proton magnetic resonance spectroscopic imaging for surgical outcome in patients with intractable temporal lobe epilepsy and bilateral hippocampal atrophy.

The objective of this study was to assess which features of temporal lobe proton magnetic resonance spectroscopic imaging (1H-MRSI) are associated with satisfactory surgical outcome in patients with intractable temporal lobe epilepsy and bilateral hippocampal atrophy. We studied 21 patients with intractable temporal lobe epilepsy and bilateral hippocampal atrophy defined by magnetic resonance imaging volumetric measurements who underwent surgical treatment. 1H-MRSI was used to determine the relative resonance intensity ratio of the neuronal marker N-acetylaspartate to creatine + phosphocreatine (NAA/Cr) for mid and posterior temporal lobe regions of the left and right hemisphere, as well as an asymmetry index. Values lower than 2 SDs below the normal mean were considered abnormal. We used Engel's classification to assess surgical outcome with respect to seizure control. Eleven patients (52%) were in class I-II and 10 (48%) were in class III-IV. All 21 were operated on the side of maximal electroencephalographic (EEG) lateralization. Concordant lateralization of decreases in NAA/Cr to the side of surgery and normal NAA/Cr values in the contralateral posterior-temporal region were significantly associated with good surgical outcome: 11 (69%) of 16 patients with 1H-MRSI abnormalities concordant with EEG lateralization and none of the 5 patients with nonconcordant 1H-MRSI had a good outcome (class I-II); 10 (77%) of 13 patients with normal NAA/Cr contralateral to the EEG lateralization versus 1 (12.5%) of 8 of those with NAA/Cr reduction contralateral to EEG lateralization were in class I-II. Regression correlation analysis showed significant linear correlation between the midtemporal NAA/Cr relative asymmetry ratio and surgical outcome; the greater the asymmetry, the better the outcome. We conclude that discriminant 1H-MRSI features associated with favorable surgical outcome in patients with temporal lobe epilepsy and bilateral hippocampal atrophy were (1) concordant 1H-MRSI lateralization, (2) a greater side-to-side asymmetry of NAA/Cr, and (3) an absence of contralateral posterior NAA/Cr reduction.

Adolescent↗

PubMed2005

Model based prognosis of postoperative object naming in left temporal lobe epilepsy.

Epilepsy surgery in the left temporal lobe is associated with a high risk of naming decline. In the present study, in 45 patients with left temporal lobe epilepsy (TLE) and confirmed left hemisphere language dominance, 13 (29%) patients demonstrated postoperative decrement >or=5 naming failures in the Boston Naming Test (BNT). Multivariate discriminant analysis with age at onset of epilepsy, age at first risk, age at operation and preoperative naming performance as predictors indicated that 12 (92%) patients with later naming decline could be identified preoperatively. Univariate group comparisons revealed that specifically patients with seizure onset later than 14 years without preceding risk factors (e.g., febrile seizures) are in danger of postoperative dysnomia. It is hypothesized, that there is a strong connection between stable naming performance and deviant intrahemispheric speech representation as a result of early brain damage and/or chronic seizures.

Adult↗

PubMed2003

Decreased left temporal lobe volume of panic patients measured by magnetic resonance imaging.

Reported neuroimaging studies have shown functional and morphological changes of temporal lobe structures in panic patients, but only one used a volumetric method. The aim of the present study was to determine the volume of temporal lobe structures in patients with panic disorder, measured by magnetic resonance imaging. Eleven panic patients and eleven controls matched for age, sex, handedness, socioeconomic status and years of education participated in the study. The mean volume of the left temporal lobe of panic patients was 9% smaller than that of controls (t21 = 2.37, P = 0.028). In addition, there was a trend (P values between 0.05 and 0.10) to smaller volumes of the right temporal lobe (7%, t21 = 1.99, P = 0.06), right amygdala (8%, t21 = 1.83, P = 0.08), left amygdala (5%, t21 = 1.78, P = 0.09) and left hippocampus (9%, t21 = 1.93, P = 0.07) in panic patients compared to controls. There was a positive correlation between left hippocampal volume and duration of panic disorder (r = 0.67, P = 0.025), with recent cases showing more reduction than older cases. The present results show that panic patients have a decreased volume of the left temporal lobe and indicate the presence of volumetric abnormalities of temporal lobe structures.

Adult↗

PubMed2006

A site directed fMRI approach for evaluating functional status in the anterolateral temporal lobes.

Functional magnetic resonance imaging (fMRI) is increasingly being used for neurosurgical planning. One potential application relates to identifying eloquent cortex in regions immediately adjacent to epileptogenic foci in temporal lobe epilepsy (TLE). While medial temporal structures, such as the hippocampus and amygdala, are typically removed during surgery, it is often difficult to determine whether nearby cortical regions in the anterolateral temporal lobe should be spared. An essential first step is to identify a method of activating these regions in healthy individuals. The purpose of this study was to develop a site directed fMRI approach for evaluating functional status in the anterolateral temporal lobes. A picture-word matching task, with object category and level of abstraction factors, was used to characterize temporal lobe activation. Whole brain analysis at the group level confirmed the involvement of the temporal poles as well as adjacent superior, middle and inferior temporal gyri within a larger object recognition network. A region-of-interest analysis on the anterolateral temporal lobe demonstrated that activation varied across conditions and regions for individuals. Importantly, it was possible to detect activation in one or more conditions and/or regions for all individuals--demonstrating that it is possible to evaluate functional status. The findings provide the foundation for a novel fMRI approach in neurosurgical planning for TLE.

Adolescent↗

PubMed1999

MRI temporal lobe volume measures and neuropsychologic function in Alzheimer's disease.

The authors performed quantitation of the temporal lobes using magnetic resonance imaging in 20 patients with mild-to-moderate Alzheimer's disease, 20 age-matched aged control subjects, and 26 healthy young volunteers. Compared to young subjects, aged controls showed volume reductions in amygdala (17%, p = 0.02), hippocampus (15%, p = 0.0001) and temporal lobe (22%, p = 0.0001). Compared to aged controls, Alzheimer's subjects showed further volume reductions in amygdala (33%, p = 0.0001) and hippocampus (20%, p = 0.006) but not temporal lobe (7%, p = 0.15). In Alzheimer's subjects, left temporal lobe volume correlated strongly with the Mini Mental State (MMSE) score (adjusted r2 = 0.46, p = 0.0006) whereas right amygdala volume correlated inversely with the noncognitive ADAS score (adjusted r2 = 0.46, p = 0.0006). The authors conclude that significant volume changes occur in the temporal lobe in aging and in Alzheimer's disease, with the greatest percentage reductions in the amygdala in Alzheimer's disease. Temporal neocortical atrophy and temporal limbic atrophy might be associated with different patterns of performance and behavior in Alzheimer's patients.

Adult↗

PubMed2003

Development of malignant glioma 15 months after anterior temporal lobectomy in a patient with temporal lobe epilepsy.

We report a 36-year-old woman, who had previously undergone anterior temporal lobectomy for intractable temporal lobe seizures; fifteen months later, magnetic resonance (MR) images showed a space-occupying lesion in the temporal lobectomy cavity. After a second operation, a histopathological examination showed a grade III astrocytoma. The fortuitous co-occurrence of temporal lobe epilepsy and a tumour was suspected, but histopathological and immunohistochemical examination of original resected temporal lobe parenchyma did not show evidence of neoplasm. The patient had not undergone postoperative radiotherapy and had not experienced viral infections. We propose that two factors possibly associated with the development of glioma were chemical exposure from anticonvulsant agents and trauma from resection of the anterior temporal lobe during initial surgery.

Adult↗

PubMed1997

The medial temporal lobe in schizophrenia.

Evidence from diverse avenues of research has highlighted abnormalities in the anatomy, physiology, and function of medial temporal lobe structures in schizophrenia. Clinical similarities between schizophrenia and psychotic disorders associated with temporal lobe lesions have been recognized for decades. Neuropsychological studies have found selective impairments in learning and memory in schizophrenia consistent with medial temporal lobe dysfunction. Neuroimaging studies have identified medial temporal lobe abnormalities that have been correlated with clinical features. Postmortem findings in the hippocampus and entorhinal cortex have included differences in neuron density, size, and arrangement; abnormalities in synapse-related proteins; alterations in monoaminergic and glutamatergic innervation and receptor distribution; and abnormalities in the expression of cytoskeletal proteins. These findings appear most consistent with models of aberrant development of medial temporal lobe structures in schizophrenia.

Animals↗

PubMed2000

Radiation-induced temporal lobe changes: CT and MR imaging characteristics.

OBJECTIVE: This article documents the CT and MR imaging characteristics of patients with temporal lobe changes after radiation therapy for nasopharyngeal carcinoma. These characteristics may serve to differentiate radiation-induced changes from intracranial tumor recurrence. MATERIALS AND METHODS: We reviewed the imaging records of 1916 patients with nasopharyngeal carcinoma examined over a 5-year period. Forty-seven patients (2.5%) had temporal lobe changes. Thirty-four patients underwent CT (55 examinations), and 26 patients underwent MR imaging (32 examinations). Thirteen patients underwent CT and MR imaging. These studies were independently analyzed according to imaging technique and were categorized as follows: location of lesions, characteristics of gray or white matter changes, and patterns of late changes. RESULTS: On CT, 12 patients (35%) had unilateral temporal lobe changes, and 22 patients (65%) had bilateral temporal lobe changes. The following patterns were noted: ill-defined contrast enhancement in 27 patients (79%); solid enhancement in six patients (18%); and ring enhancement in one patient (3%). On MR imaging, 11 patients (42%) had unilateral lesions, and 15 patients (58%) had bilateral lesions. Simultaneous gray and white matter lesions were noted in 17 patients (65%), and nine patients (35%) had lesions localized to the gray matter. Three patients (6%) had cerebral atrophy, and two patients (4%) had encephalomalacia. CONCLUSION: The temporal lobes show characteristic CT and MR imaging features after radiation injury. Familiarity with these changes may assist in differentiating temporal lobe changes from progressive nasopharyngeal carcinoma.

Adult↗

PubMed2002

Long-term amygdalohippocampal stimulation for refractory temporal lobe epilepsy.

Short-term deep brain stimulation (DBS) recently has been shown to be efficacious in refractory temporal lobe epilepsy. We (1) evaluated long-term DBS in medial temporal lobe structures in patients with normal magnetic resonance imaging (MRI) findings and (2) investigated the use of chronic DBS electrodes for the localization of the ictal onset zone before DBS. In three patients with complex partial seizures (CPSs), DBS electrodes were implanted in the amygdalohippocampal region to identify and subsequently stimulate the ictal onset zone. CPSs were compared before and after chronic DBS. Side effects were carefully monitored. DBS electrodes yielded high-quality electroencephalogram recordings showing unilateral seizure onset in medial temporal lobe structures. For all patients, unilateral amygdalohippocampal stimulation was performed. After a mean follow-up of 5 months (range, 3-6 months), all patients had a greater than 50% reduction in seizure frequency. In two patients, antiepileptic drugs could be tapered. None of the patients reported side effects. This open study demonstrates the feasibility of consecutive electroencephalographic recordings and DBS in medial temporal lobe structures using DBS electrodes. These results prompt further studies in a larger patient population to establish the efficacy and safety of chronic DBS as an alternative treatment for refractory temporal lobe epilepsy.

Adult↗

PubMed2004

Simple partial seizures (isolated auras) in medial temporal lobe epilepsy.

We analysed whether the medial temporal lobe epilepsy (MTLE) with isolated auras makes any difference in the clinical picture in comparison with MTLE in which only complex partial seizures (CPS) occur. We included 100 patients (aged 16-59 years) with unilateral medial temporal lobe lesions who consecutively underwent presurgical evaluation due to intractable MTLE and who became completely aura- and seizure-free after the anterior temporal resection. Preoperatively, isolated auras were present in 70 patients. These patients were categorised into the IA group. The remaining 30 patients in whom the auras preceded seizures were categorised into the NIA group. We found no difference between the two groups for the age at onset, epilepsy duration or aura types. Conversely, a right-sided epileptogenic region (61%) occurred more frequently in the IA group than in the NIA group (27%, P = 0.001). Conclusively, isolated auras show affinity to the right hemisphere. One explanation may be that seizures stop more quickly in the right hemisphere. Another hypothesis is that consciousness can be disturbed much easier by the ictal activity in left temporal seizures: auras evolve more frequently to CPS due to the disturbance of consciousness.

Adolescent↗

PubMed2001

[Clinical study on epileptic aura in children with temporal lobe epilepsy].

We studied the clinical characteristics of epileptic aura with temporal lobe epilepsy (TLE) in children, by retrospectively reviewing medical records of 33 patients whose first seizures developed under 15 years of age. The diagnosis of TLE was made by interictal EEG and head MRI/SPECT, both of which demonstrated a temporal lesion. The patients were classified into 24 with mesial TLE syndrome, 3 with a temporal lobe tumor, 3 with temporal lobe dysplasia and 3 with other causes. The epileptic aura was not recognized in 5 patients (15%). The age at onset of aura ranged from 4 to 10 years with a median age at 7. In patients older than 10, it was always followed by impairment of consciousness. It was manifested with nausea in 14 patients (42%), vertigo, a sense of fear, palpitation and heating sensation on the back in three patients (9%) each. Thus, clinical manifestations of epileptic aura in children with TLE were largely identical to those of adult patients. Detailed history taking about the aura may provide a clue to the diagnosis of TLE even in children.

Adolescent↗

PubMed1999

Neocortical temporal lobe epilepsy: intracranial EEG features and surgical outcome.

Patients with neocortical temporal lobe epilepsy (NTLE) may have less favorable outcome with anterior temporal lobectomy than those with mesial temporal foci. The authors analyzed ictal intracranial electroencephalograms (EEGs) in patients with NTLE to identify features that predict surgical outcome. The following intracranial ictal EEG features in 31 consecutive medically intractable NTLE patients were studied: Frequency (i.e., low-voltage fast [>20 Hz], recruiting ictal-onset spikes, ictal-onset rhythms less than 5 Hz, ictal-onset rhythms with repetitive sharp waves between 5 and 20 Hz); extent of ictal onset (focal, sublobar, and lobar); localization within the temporal lobe (anterior, posterior, or regional); and the time to seizure spread outside the temporal lobe (rapid, intermediate, and slow). The average follow-up period was 36.7 months (range, 18 to 60 months). Findings between two outcome groups were compared: class I group (seizure-free) and class II to IV group (persistent seizures). Twenty-one (66.7%) of 31 patients with NTLE were seizure-free. Intracranial EEG features which were significantly associated with seizure-free outcome were focal or sublobar onset, anterior temporal onset, and slow propagation time (P < 0.05). There was a trend for patients with ictal onset morphologies of slow ictal-onset rhythm and repetitive sharp waves to be seizure-free (P = 0.07). Intracranial EEG is helpful in predicting surgical outcome in NTLE patients.

Adult↗

PubMed1996

Temporal lobe epilepsy subtypes: differential patterns of cerebral perfusion on ictal SPECT.

PURPOSE: We studied cerebral perfusion patterns in the various subtypes of TLE, as determined by pathology and good outcome after temporal lobectomy (as confirmation of temporal origin). METHODS: We studied clinical features and ictal technetium 99m hexamethyl-propyleneamineoxime (99mTc-HM-PAO) single-photon emission-computed tomography (SPECT) in four subgroups of patients with intractable temporal lobe epilepsy (TLE) treated with surgery: hippocampal sclerosis (group 1, n = 10), foreign-tissue lesion in mesial temporal lobe (group 2, n = 8), foreign-tissue lesion in lateral temporal lobe (group 3, n = 7), and normal temporal lobe tissue with good surgical outcome (group 4, n = 5). RESULTS: No major clinical differences in auras, complex partial seizures or postictal states were identified among the groups. Ictal SPECT showed distinct patterns of cerebral perfusion in these subtypes of TLE. In groups 1 and 2, hyperperfusion was seen in the ipsilateral mesial and lateral temporal regions. In group 3, hyperperfusion was seen bilaterally in the temporal lobes with predominant changes in the region of the lesion. Hyperperfusion was restricted to the ipsilateral anteromesial temporal region in group 4. Ipsilateral temporal hyperperfusion in mesial onset seizures can be explained by known anatomic projections between mesial structures and ipsilateral temporal neocortex. Bilateral temporal hyperperfusion in lateral onset seizures can be explained by the presence of anterior commissural connections between lateral temporal neocortex and the contralateral amygdala. CONCLUSIONS: We conclude that the perfusion patterns seen on ictal SPECT are helpful for subclassification of temporal lobe seizures, whereas clinical features are relatively unhelpful. These perfusion patterns provide an insight into preferential pathways of seizure propagation in the subtypes of TLE.

Adolescent↗

PubMed1999

Visual assessment of medical temporal lobe atrophy in demented and healthy control subjects: correlation with volumetry.

The present study evaluated the validity of visual rating of medial temporal lobe atrophy on coronal magnetic resonance imaging scans in a population of demented and non-demented individuals. Medial temporal lobe atrophy in 194 subjects was visually rated from hard copies, using a 0-4 rating scale, and a comparison was made with the absolute volumes (ccm) of the medial temporal lobe as estimated with volumetry, using a stereological method. We found a highly significant correlation between the estimated and stereologically measured volumes. There was a 10-fold difference in time spent on rating medial temporal lobe atrophy (1-2 min) vs. time spent calculating the medial temporal lobe volume (10-12 min) on a single subject. The diagnostic accuracy of both methods showed that visual rating was more efficient than volumetry in differentiating Alzheimer's disease from control subjects, We conclude that visual rating is a reliable and fast method to estimate medial temporal lobe atrophy in demented subjects in a clinical setting.

Adult↗

PubMed2002

Deficits of musical timbre perception after unilateral temporal-lobe lesion revealed with multidimensional scaling.

Thirty patients with unilateral temporal lobe excisions and 15 normal control subjects were tested in a task involving judgements of timbre dissimilarity in single tone and melodic conditions. Perceptual correlates of spectral and temporal parameters resulting from changing the number of harmonics and rise-time duration, respectively, were investigated by using a multidimensional scaling technique. The results of subjects with left temporal lobe lesion suggest that they were able to use the spectral and temporal envelopes of tones independently in making perceptual judgements of single tones. In the melodic condition, their results were significantly different from those of normal control subjects, suggesting that left temporal lesions do affect subtle aspects of timbre perception, despite these patients' preserved ability to make discrimination judgements using traditional paradigms. The major finding of this study concerns perceptual ratings obtained by subjects with right temporal lobe lesion, which revealed a disturbed perceptual space in both conditions. The most distorted results were obtained with single tones, in which the temporal parameter was less prominent. Tones were grouped according to their spectral content, but the results did not reflect a coherent underlying perceptual dimension. In general, the data from both patient groups (left lesions and right lesions) showed that the extraction of temporal cues was easier in the melodic than in the single tone condition, suggesting that the different durations and frequencies heard in a musical phrase enhance the importance of certain physical parameters. The findings of the present study replicate and extend previous results showing that timbre perception depends mainly upon the integrity of right neocortical structures, although a contribution of left temporal regions is also apparent. These data also demonstrate that multidimensional techniques are sensitive to more subtle perceptual disturbances that may not be revealed by discrimination paradigms.

Acoustic Stimulation↗

PubMed2000

Affective aggression in patients with temporal lobe epilepsy: a quantitative MRI study of the amygdala.

Recurrent episodes with interictal affective aggression are a rare but well-recognized problem in patients with temporal lobe epilepsy. They are referred to as episodic dyscontrol or, more precisely, as intermittent explosive disorder (IED). The amygdala play a crucial role in the affective evaluation of multimodal sensory input and the neurobiological mediation of aggressive behaviour. With hippocampal sclerosis, in the context of mesial temporal lobe sclerosis, being the most common cause of temporal lobe epilepsy, we hypothesized that the amygdala might be affected by the same pathogenic process in aggressive patients. We investigated 50 patients with temporal lobe epilepsy: 25 with and 25 without a history of IED. Data from clinical, electrophysiological, neuropsychological and psychometric investigations were obtained, as well as MRI scans for the quantitative assessment of possible amygdala pathology. We found no evidence of a higher prevalence of amygdala sclerosis in the aggressive patients. Hippocampal sclerosis was significantly less common in patients with temporal lobe epilepsy and IED. However, a significant subgroup of patients (20%) with temporal lobe epilepsy and aggressive behaviour had severe amygdala atrophy in the context of a history of encephalitis. Another subgroup of aggressive patients (28%) had different left temporal lesions affecting either the amygdala or periamygdaloid structures. IED was associated with left-sided or bilateral EEG and MRI abnormalities, low IQ and high scores in depression and anxiety.

Adolescent↗