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PubMed1994

Temporal lobe epilepsy: the various MR appearances of histologically proven mesial temporal sclerosis.

PURPOSE: To determine the frequency of appearance of various MR signs in mesial temporal sclerosis, to determine the optimal scanning planes for their visualization, and to propose a histologic explanation for the diminished demarcation between gray and white matter in the temporal lobe, a frequent MR finding in patients with mesial temporal sclerosis. METHODS: MR scans of 14 surgically treated patients with epilepsy and histologically proven mesial temporal sclerosis were assessed for the presence of six features: feature 1, high signal intensity in the hippocampus; 2, reduced hippocampal size; 3, ipsilateral atrophy of the hippocampal collateral white matter; 4, enlarged temporal horn; 5, reduced gray-white matter demarcation in the temporal lobe; and 6, decreased temporal lobe size. RESULTS: Feature 1 was present in 14 patients and was best appreciated on the T2-weighted images in planes parallel to the long axes of the hippocampi. Feature 2, present in 12 patients, and feature 6, present in 9 patients, were optimally seen in the coronal planes and on the inversion-recovery sequences in particular. Feature 3, present in 12 patients, was optimally seen on the coronal T2-weighted images. Feature 4, seen in 11 patients, was equally well seen in all planes (transverse, coronal, and parallel to the long axes of the hippocampi). Feature 5, seen in 10 patients, was best appreciated on the T2-weighted images in the planes of the long axes of the hippocampi. Histologic investigation of the temporal lobe white matter in the 10 patients with feature 5 demonstrated on the MR scan showed abnormalities in 7 cases. Oligodendroglia cell clusters were found in 6, with concomitant corpora amylacea in 1 case and perivascular macrophages with pigment a sole finding in another case. CONCLUSION: Of the six features found in cases of mesial temporal sclerosis on MR, increased hippocampal signal intensity is the most consistent. A decreased gray-white matter demarcation in the temporal lobe parenchyma is also a frequent feature of this disease. A combination of multiple scanning planes results in an optimal demonstration of lesions.

Adolescent↗
PubMed1998

Memory, simple and complex language, and the temporal lobe.

Nineteen patients with intractable temporal lobe epilepsy who underwent anterior temporal lobectomy were given a highly specific memory battery (23 tests) pre- and post- (1 week; 1, 2, and 6 months; 1 and 2 years) resection. Sixteen of 23 tests revealed that memory performance of temporal lobe epilepsy patients was worse than normal controls prior to surgery (p < .001), while the most profound differences were seen in the remembering and generation of inferences from connected discourse. Almost no differences were observed in delayed nonmatching to sample tasks (recognition without language task). MRI results revealed that anterior, middle, and posterior hippocampal abnormality was extensive in 12 of 19 patients, and 12 also showed medial temporal lobe abnormalities and volume loss. Hippocampal damage was negatively correlated with extended delay memory performance for connected discourse: worse performance was associated with greater damage. Few differences in less complex memory performance were observed pre-postsurgery. While ordinary recognition functions were preserved, results demonstrated that dominant medial temporal lobe structures appeared heavily involved in language-generated memory, and hippocampus is heavily implicated in both simple and complex language.

Adult↗
PubMed2004

White matter fiber dissection of the optic radiations of the temporal lobe and implications for surgical approaches to the temporal horn.

OBJECT: The aim of this anatomical study was to define more fully the three-dimensional (3D) relationships between the optic radiations and the temporal horn and superficial anatomy of the temporal lobe by using the Klingler white matter fiber dissection technique. These findings were correlated with established surgical trajectories to the temporal horn. Such surgical trajectories have implications for amygdalohippocampectomy and other procedures that involve entering the temporal horn for the resection of tumors or vascular lesions. METHODS: Ten human cadaveric hemispheres were prepared with several cycles of freezing and thawing by using a modification of the method described by Klingler. Wooden spatulas were used to strip away the deeper layers of white matter progressively in a lateromedial direction, and various association, projection, and commissural fibers were demonstrated. As the dissection progressed, photographs of each progressive layer were obtained. Special attention was given to the optic radiation and to the sagittal stratum of which the optic radiation is a part. The trajectories of fibers in the optic radiation were specifically studied in relation to the lateral, medial, superior, and inferior walls of the temporal horn as well as to the superficial anatomy of the temporal lobe. In three of the hemispheres coronal sections were made so that the relationship between the optic radiation and the temporal horn could be studied more fully. In all 10 hemispheres that were dissected the following observations were made. 1) The optic radiation covered the entire lateral aspect of the temporal horn as it extends to the occipital horn. 2) The anterior tip of the temporal horn was covered by the anterior optic radiation along its lateral half. 3) The entire medial wall of the temporal horn was free from optic radiation fibers, except at the level at which these fibers arise from the lateral geniculate body to ascend over the roof of the temporal horn. 4) The superior wall of the temporal horn was covered by optic radiation fibers. 5) The entire inferior wall of the temporal horn was free from optic radiation fibers anterior to the level of the lateral geniculate body. CONCLUSIONS: Fiber dissections of the temporal lobe and horn demonstrated the complex 3D relationships between the optic radiations and the temporal horn and superficial anatomy of the temporal lobe. Based on the results of this study, the authors define two anatomical surgical trajectories to the temporal horn that would avoid the optic radiations. The first of these involves a transsylvian anterior medial approach and the second a pure inferior trajectory through a fusiform gyrus. Lateral approaches to the temporal horn through the superior and middle gyri, based on the authors' findings, would traverse the optic radiations.

Amygdala↗
PubMed2003

Use of an anteromedial subdural strip electrode in the evaluation of medial temporal lobe epilepsy. Technical note.

The temporal lobe is the most common site of partial epilepsy that is amenable to surgical therapy, and therefore ictal localization in this region is important. The authors describe the application of an anteromedial subdural strip electrode for the evaluation of epilepsy originating from the medial temporal lobe. This strip is advanced around the temporal pole and underneath the lesser wing of the sphenoid bone as it follows the medial temporal lobe contour. The advantages of this method of placement are the consistent path and reliable final position of the strip along the medial basal temporal lobe surface. This method allows adequate coverage of the parahippocampal gyrus along its long axis extending posterior to the level of the collicular plate. This technique has been used with no complications during intracranial monitoring of more than 100 patients with presumed temporal lobe epilepsy.

Anterior Thalamic Nuclei↗
PubMed1997

Decrease in somatostatin-immunoreactive neurons in the rat amygdaloid complex in a kindling model of temporal lobe epilepsy.

In human temporal lobe epilepsy, seizures can begin in the hippocampus, amygdala, or surrounding cortical areas. Histologically, the seizure-induced selective neuronal damage and synaptic reorganization are best documented in the hippocampus. Little information is available about the damage in the other temporal lobe structures or whether the distribution of damage depends on the location of the primary seizure focus. We used an amygdala-kindling model of temporal lobe epilepsy to study whether seizures of amygdaloid origin cause damage to the amygdala and hippocampus. All rats experienced five class 5 generalized seizures. Neuronal damage was assessed by counting the density of GABA-immunoreactive (GABA-ir) and somatostatin-immunoreactive (SOM-ir) neurons in the amygdala and hilus of the dentate gyrus six months after the last seizure. We found that the density of GABA-ir neurons did not differ from that in controls in the contralateral amygdala. The density of SOM-ir neurons was, however, decreased in the lateral (69% of neurons remaining, P < 0.01), basal (67% remaining, P < 0.05), and accessory basal (68% remaining, P < 0.05) nuclei. In the hilus, the densities of GABA-ir and SOM-ir neurons were similar to that in controls. According to our data, a few seizures of amygdaloid origin may cause more severe damage to SOM-ir neurons in the amygdala than in the hilus. Such decrease in SOM-ir neurons which form one subpopulation of GABAergic inhibitory interneurons may increase the local excitability in the amygdala and, therefore, contribute to epileptogenesis.

Amygdala↗
PubMed1993

Temporal lobe hypometabolism on PET: predictor of seizure control after temporal lobectomy.

To investigate the relationship of temporal lobe hypometabolism demonstrated on PET to surgical outcome and underlying pathology, we reviewed 30 consecutive epilepsy patients who underwent interictal PET studies with 18F fluorodeoxyglucose before temporal lobectomy. Two interpreters blindly reviewed the PET studies and graded them for degree, extent, and location of temporal lobe hypometabolism. Pathologic analysis of en bloc resected tissue showed mesial temporal sclerosis (n = 22), astrocytoma (n = 2), and no pathologic diagnosis (n = 6). Outcome (24 to 40 months' follow-up) was rated as seizure-free (21 patients), significantly improved (five patients), and not significantly improved (four patients). Both the degree and extent of the temporal lobe hypometabolism demonstrated on PET were strongly associated with subsequent seizure control. Pathologic findings, however, did not correlate with degree of PET hypometabolism or subsequent outcome. These data demonstrate that in patients judged to have temporal lobe epilepsy, the presence of temporal lobe hypometabolism is associated with a positive outcome after ipsilateral temporal lobectomy.

Adolescent↗
PubMed2004

[Prognostic factors in temporal lobe epilepsy surgery].

INTRODUCTION: Temporal lobe epilepsy surgery represents the majority of surgical interventions in patients with refractory epilepsy. In consequence, knowledge of prognostic factors in this type of epilepsy surgery is of major importance. The objective of this study is to study series of prognostic factors in a group of patients who underwent temporal lobe epilepsy surgery and to correlate Engel's Classification of Postoperative Outcome, now used in most epilepsy centers, and the Proposal for New Classification in regards to Epileptic Seizures Following Epilepsy Surgery of the International League Against Epilepsy (ILAE). METHODS: We analyzed 41 consecutive patients who underwent temporal lobe epilepsy surgery in the Epilepsy Surgery Program of the Epilepsy Unit in the Fundación Jiménez Díaz. The following prognostic factors were analyzed: age at surgery, time since the first seizure (excluding febrile seizures), risk factors for the development of epilepsy, presence of simple partial seizures, presurgical complex partial seizure frequency, findings in brain magnetic resonance imaging, interictal and ictal electroencephalogram, neuropsychological assessment, Wada test and neuropathological study of the surgical specimen. Two outcome classifications were used: Engel's classification of postoperative outcome and the proposal for a new classification of outcome in regards to epileptic seizures following epilepsy surgery of the ILAE. Statistical analysis was performed using non-parametric tests. RESULTS: The presence of temporal unilateral interictal epileptiform activity and the presence of less than 20 seizures complex partial seizures per month before surgery were associated with a better prognosis using both classifications. The electronencephalographic unilateral temporal ictal onset recording was associated with a better prognosis using Engel's classification but not ILAE's outcome classification. The presence of febrile seizures was associated with a better prognosis in regards to ILAE's outcome classification but not in regards to Engel's classification. The remaining factors were not associated with outcome. CONCLUSIONS: The following factors were associated with a good prognosis: presence of unilateral temporal interictal epileptiform activity, presurgery seizure frequency below 20 complex partial seizures per month, unilateral temporal ictal onset, and presence of febrile seizures. A good correlation was found between both outcome classifications in regards to most of the analyzed prognostic factors.

Adult↗
PubMedDate not supplied

Sequelae of temporal lobe herniation: MR imaging.

Acute temporal lobe herniation is a serious complication that may occur with an expanding temporal or parietal lobe mass. Temporal lobe herniation may produce further damage to intracranial structures due to compression or vascular compromise. Differentiation of clinical and imaging abnormalities due to the primary lesion from those related to temporal lobe herniation is essential for proper diagnosis and management. The CT and magnetic resonance findings in a 2 1/2-year-old child who survived severe temporal lobe herniation are reported.

Brain Neoplasms↗
PubMed1999

Recurrent seizures and hippocampal sclerosis following intrahippocampal kainate injection in adult mice: electroencephalography, histopathology and synaptic reorganization similar to mesial temporal lobe epilepsy.

Human mesial temporal lobe epilepsy is characterized by hippocampal seizures associated with pyramidal cell loss in the hippocampus and dispersion of dentate gyrus granule cells. A similar histological pattern was recently described in a model of extensive neuroplasticity in adult mice after injection of kainate into the dorsal hippocampus [Suzuki et al. (1995) Neuroscience 64, 665-674]. The aim of the present study was to determine whether (i) recurrent seizures develop in mice after intrahippocampal injection of kainate, and (ii) the electroencephalographic, histopathological and behavioural changes in such mice are similar to those in human mesial temporal lobe epilepsy. Adult mice receiving a unilateral injection of kainate (0.2 microg; 50 nl) or saline into the dorsal hippocampus displayed recurrent paroxysmal discharges on the electroencephalographic recordings associated with immobility, staring and, occasionally, clonic components. These seizures started immediately after kainate injection and recurrid for up to eight months. Epileptiform activities occurred most often during sleep but occasionally while awake. The pattern of seizures did not change over time nor did they secondarily generalize. Glucose metabolic changes assessed by [14C]2-deoxyglucose autoradiography were restricted to the ipsilateral hippocampus for 30 days, but had spread to the thalamus by 120 days after kainate. Ipsilateral cell loss was prominent in hippocampal pyramidal cells and hilar neurons. An unusual pattern of progressive enlargement of the dentate gyrus was observed with a marked radial dispersion of the granule cells associated with reactive astrocytes. Mossy fibre sprouting occurred both in the supragranular molecular layer and infrapyramidal stratum oriens layer of CA3. The expression of the embryonic form of the neural cell adhesion molecule coincided over time with granule cell dispersion. Our data describe the first histological, electrophysiological and behavioural evidence suggesting that discrete excitotoxic lesions of the hippocampus in mice can be used as an isomorphic model of mesial temporal lobe epilepsy.

Animals↗
PubMed2006

[Morphological characteristics from the insula's lobe in patients with medial temporal lobe epilepsy].

The temporal medial sclerosis (TMS) is characterized by hippocampal sclerosis in temporal and by distinguished grades of injury near to other neurological structures such as: amygdaloid nucleus, parahippocampal girus and entorhinal region. The study analyzed 40 patients with TMS and 40 people from the control cluster. All the cases were appreciated by one method for measurement of insula's cortex (E-Film) and another method to calculate the insula's volume (Neuroline). There is no variation statistical between the insula's volume and insula's measurement for the two clusters. This paper didn't show the insula's morphological variation when these two groups were compared.

Adolescent↗
PubMed1975

Outcome of surgery in 40 children with temporal-lobe epilepsy.

Temporal-lobe epilepsy commonly has its origins in childhood, particularly when the lesion involved is mesial temporal (Ammon's horn) Sclerosis. Evidence suggests that this lesion is probably a common cause of chronic epilepsy in adults and that often it is probably the result of a severe febrile convulsion in infancy. 40 children, fifteen years of age and younger, who had an anterior temporal lobectomy were followed up for one to twenty-four years. The findings confirm those already established in adults, that the best results of surgery, not only in seizure relief but also in behaviour, are obtained when mesial temporal sclerosis is the lesion found at operation, and also indicate that a severe febrile convulsion in infancy is often the chief provocative factor in the development of epilepsy.

Adaptation, Psychological↗
PubMed1995

Mesial temporal lobe epilepsy in Singapore.

Mesial temporal lobe epilepsy due to mesial temporal sclerosis is a distinctive syndrome and a surgically remediable form of epilepsy. We present 26 Singaporean cases of mesial temporal lobe epilepsy defined by clinical, electroencephalographic and MR features and validated by good surgical outcome (12 seizure free, 5 with two or fewer seizures) in all 17 patients who have so far undergone surgery and who have been followed up for at least 6 months. Sixty-five percent of patients experienced their first seizure in the setting of a febrile illness. Seventy-three percent of patients had seizure onset before the age of 10 years and the median interval between seizure onset and intractability of seizures was 3.75 years. 80.7% of patients had an aura and an equal number had at least one lateralizing sign during their seizures. Sixty-four percent of patients had predominantly unilateral anterior temporal interictal spikes. Eighty-eight percent of patients had seizures which were lateralised on scalp ictal EEG. MRI abnormalities were most frequently seen in the head and body of the hippocampal formation. Asymmetric hippocampal atrophy was more common than hippocampal T2 or T2* signal changes. There is much similarity in characteristics of mesial temporal lobe epilepsy in our population compared to what has been published regarding Caucasian subjects.

Adolescent↗
PubMed1995

The pathophysiologic relationships between lesion pathology, intracranial ictal EEG onsets, and hippocampal neuron losses in temporal lobe epilepsy.

In temporal lobe epilepsy (TLE) lesion patients the pathology, location of intracranial ictal EEG onsets, and hippocampal neuron losses were compared. Patients (n = 63) were classified into: (1) Tumors (n = 26, e.g. astrocytomas, gangliogliomas); (2) vascular (n = 9, e.g. cavernous and venous angiomas); (3) developmental (n = 17, e.g. cortical dysplasia, heterotopias); or (4) atrophic (n = 11, e.g. cortical or white matter encephalomalacia). Other variables were; (1) the location of the temporal lesion in the mesial to lateral, and anterior to posterior plane, (2) a clinical history of an initial precipitating injury (IPI) prior to the onset of TLE (e.g. prolonged first seizure, head trauma), (3) hippocampal neuron densities, (4) focal or regional location by intracranial depth EEG of ictal onsets, and (5) seizure outcomes. Results showed that severe hippocampal neuron losses were associated with two statistically significant findings. First, patients with mesial lesions in or adjacent to the body of the hippocampus had greater neuron losses compared to mesial lesions anterior or posterior to the hippocampus (P = 0.04). Second, lesion patients with an IPI history had greater Ammon's horn (AH) neuron losses compared to those without IPI histories (P = 0.0005), and the profile of loss was similar to hippocampal sclerosis (HS). Granule cell losses correlated in a complex manner in that; 1) by regression analysis densities decreased with longer intervals of TLE (P = 0.006), (2) tumor patients with IPIs had less granule cell loss compared to those without IPIs intervals of TLE (P = 0.006), (2) tumor patients with IPIs had less granule cell loss compared to those without IPIs (P = 0.05), and (3) developmental patients with IPIs had greater granule cell loss than patients without IPIs (P = 0.009). Mesial-temporal depth EEG electrodes were the first areas of ictal activity in 15 of 16 patients (94%), and greater hippocampal neuron losses were not associated with focal mesial-temporal EEG onsets. Seizure outcomes were worse in tumor patients compared to HS patients (P = 0.01), and patients with post-resection seizures had incomplete resections of their lesions and/or hippocampi. These results indicate that in TLE lesion patients the amount and pattern of hippocampal neuron loss depends on the location of the lesion, the pathologic classification, and a history of an IPI. Further, despite variable neuron losses, in temporal lesion patients the hippocampus was nearly always involved in the genesis or propagation of the chronic seizures.

Case-Control Studies↗
PubMed2000

Pediatric candidates for temporal lobe epilepsy surgery.

Temporal lobectomy is an under-valued and effective therapy for selected children with temporal lobe seizures. This article details three components of the identification and evaluation of such children. The ictal symptoms and signs remains an essential component. This includes an aura suggesting limbic system involvement, and the nature of automatisms and other motor phenomena which may have lateralising value. Electroencephalography continues to accurately identify a principally epileptogenic focus in children and adults. The value of high quality magnetic resonance imaging is emphasized. Invasive studies are required in only a minority of cases. Several studies have revealed that 73-100% of carefully selected children receive benefit from this procedure whereas significant neurosurgical complications rarely occur.

Child↗
PubMed1977

The measurement of emotional concepts in patients with temporal lobe epilepsy.

Eleven temporal lobe epileptics, implanted with depth electrodes, 21 post-lobectomy epileptics, and 24 orthopedic controls were given a semantic differential test, which measured responses along 4 scales (evaluative, potency, activity, and danger) of 18 emotional and 1 non-emotional concepts. Results showed that post-lobectomy females thought of themselves as more dangerous than did orthopedic control females. Both post-lobectomy and implantation patients found the anger-hostility and fear-anxiety concepts less bad, potent, active, and dangerous than did the orthopedic controls. The post-lobectomy and implantation patients found the concept "sexual intercourse" and other non-sexual love-related concepts to be worse and more dangerous, but less potent and active than did the orthopedic controls.

Adolescent↗
PubMed2006

Memory and language impairments and their relationships to hippocampal and perirhinal cortex damage in patients with medial temporal lobe epilepsy.

Chronic medial temporal lobe epilepsy (MTLE) is associated with memory loss due to damage in the hippocampal system. To investigate the relationship between volume of medial temporal lobe structures and performance on neuropsychological tests, we studied 39 consecutive patients with MTLE and unilateral hippocampal atrophy (HA) determined by volumetric magnetic resonance imaging (MRI). Structures of interest comprised hippocampus, amygdala, and entorhinal, perirhinal, parahippocampal, and temporopolar cortices. The findings indicated that (1) performance was significantly worse in the group with left HA as compared with the group with right HA on general memory, verbal memory, delayed recall, and verbal fluency tests and the Boston Naming Test (BNT), and (2) the volume of the left hippocampus and also the degree of asymmetry of perirhinal cortex volume were significant and independent predictors of performance on general memory, verbal memory, and verbal fluency tests and the BNT in patients with MTLE.

Adolescent↗
PubMed2005

Correlations between granule cell physiology and bioenergetics in human temporal lobe epilepsy.

Human temporal lobe epilepsy (TLE) is associated with bioenergetic abnormalities including decreased phosphocreatine (PCr) normalized to ATP. The physiological consequences of these metabolic alterations have not been established. We hypothesized that impaired bioenergetics would correlate with alterations in physiological functions under conditions that strongly activate neural metabolism. We correlated several physiological variables obtained from epileptic human dentate granule cells studied in slices with hippocampal PCr/ATP measured using in vivo magnetic resonance spectroscopy. The physiological variables included: the ability to fire multiple action potentials in response to single stimuli, the inhibitory postsynaptic potential (IPSP) conductance and the responses to a 10 Hz, 10 s stimulus train. We noted a significant negative correlation between the ability to fire multiple spikes in response to single synaptic stimulation and PCr/ATP (P < 0.03) and a positive correlation between the IPSP conductance and PCr/ATP (P < 0.05). Finally, there was a strong correlation between PCr/ATP and the recovery of the membrane potential following a stimulus train (P < 0.01), with low PCr/ATP being associated with prolonged recovery times. These data suggest that the bioenergetic impairment seen in this tissue is associated with specific changes in excitatory and inhibitory neuronal responses to synchronized synaptic inputs.

Adenosine Triphosphate↗