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PubMed1990

CT, MR and SPECT imaging in temporal lobe epilepsy.

Cranial computed tomography (CT) with modified temporal lobe technique, 0.15T magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) were carried out on 30 patients with intractable temporal lobe epilepsy. Lateralising abnormalities were detected in 21/30 patients overall. Specific lesions were detected by CT in one patient and by MRI in seven patients (in one case bilateral). In addition CT detected asymmetry of the sylvian fissures or temporal horns in 10 patients, and MRI in eight patients. SPECT detected lateralising abnormalities in 19 patients (in five cases bilateral). It is concluded that low field MRI is superior to modified CT in demonstrating subtle structural lesions of the temporal lobe. Functional scanning with SPECT supports the evidence of origin of an epileptic focus in a substantial proportion of cases and may improve the selection of patients for surgery.

Adolescent↗
PubMed2006

Volumetric evidence of bilateral damage in unilateral mesial temporal lobe epilepsy.

PURPOSE: We sought to analyze the contralateral volumes of the temporal pole, posterior segment of the temporal lobe, amygdala, hippocampus, and parahippocampal gyrus in patients with temporal lobe epilepsy (TLE) due to histologically proven mesial temporal lobe sclerosis (MTLS), seizure free for >or=4 years of postsurgical follow-up. METHODS: Forty-six (23 male) TLE patients, operated on between 1996 and 2001, with histopathologic diagnosis of MTLS, and a postsurgical follow-up of >or=4 years, had their temporal lobe structures manually segmented, measured, and compared with those of 23 normal volunteers, paired as groups for sex, age, and handedness. RESULTS: The mean volumes of the contralateral temporal pole, hippocampus, and parahippocampal gyrus in TLE patients were significantly lower than those in controls. CONCLUSIONS: MRI volumetric data show that the damage in TLE due to MTS may be more widespread and bilateral, even in patients with unilateral TLE by clinical and neurophysiological criteria. Our results are relevant to the discussion of epileptogenic mechanisms in TLE.

Adolescent↗
PubMed1990

Seizure-induced miosis and ptosis: association with temporal lobe magnetic resonance imaging abnormalities.

Two patients with seizure-associated miosis and ptosis are described. In both there are magnetic resonance imaging abnormalities of the temporal lobe. In one patient, increased magnetic resonance imaging signal intensity is present in the temporal lobe contralateral to ptosis and miosis. In the other, there is temporal lobe asymmetry with the smaller temporal lobe ipsilateral to the miotic pupil and ptotic lid. The relevant human and experimental literature related to cortical control of pupil size and lid movement is reviewed. Based on the available literature and the findings in these two patients, it is proposed that the increased signal intensity in the temporal lobe of one patient represents an irritative stimulus causing contralateral miosis and ptosis, whereas the temporal lobe hypoplasia in the second patient permitted impulses from the contralateral normal temporal lobe to predominate, resulting in miosis and ptosis homolateral to the hypoplastic temporal lobe.

Adolescent↗
PubMed2002

The role of the temporal pole in the genesis of temporal lobe seizures.

Failure of selective amygdalo-hippocampectomy strongly suggests that the so-called mesio-temporal lobe seizures do not always arise from the sole amygado-hippocampo-parahippocampal complex. Studies in temporal lobe epilepsies have shown that even in the presence of hippocampal sclerosis, the temporo-polar region (TP) is often altered, both histologically, anatomically and functionally. These findings are in accordance with our last ten years experience in stereotactic intracerebral EEG recordings (SEEG), during which we frequently observed the simultaneous involvement of both the amygdala (A), the hippocampus (Hc) and the TP at the onset of temporal lobe seizures. Recently, we have reviewed the SEEG findings of 25 patients with a final diagnosis of temporal lobe epilepsy, in whom both mesial, lateral and polar temporal lobe structures were investigated. The analysis of the most representative seizure in each patient showed that a low voltage fast activity was recorded in the TP either initially or within the first 5 seconds in 13/25 patients (TP group, 52%), while in the remaining 12 cases, ictal discharges started in the Hc and/or amygdala with a later involvement of the TP (AH group, 48%). Preliminary results of a further study conducted in 48 patients have confirmed the high frequency of early TP involvement (2/3 of the cases) in temporal lobe seizures, the clinical characteristics of which did not differ from ictal clinical findings usually described in the mesio-temporal lobe epilepsy syndrome. History of prolonged febrile convulsions and diagnosis of Hc sclerosis were more frequent in the AH group, while early consciousness impairment during seizures and anterior temporal white matter changes on MRI were more frequently observed in TP patients. However a clear-cut distinction between the two groups remains rather difficult in the absence of intracerebral recordings.

Amygdala↗
PubMed1990

Supraspan learning in patients with unilateral anterior temporal lobe resections.

The present data addresses the role of the anterior temporal lobe in verbal and visual supraspan learning. Patient subjects had either a left or right standardized temporal lobe resection, which involved extensive removal of mesial temporal lobe structures. Neither patient group showed marked deficits on either the verbal or visual supraspan learning tasks, although an unexpected performance variation occurred. A tendency to mild depression of performance on the verbal supraspan learning task was observed among right temporal-lobectomy patients. Nevertheless, the overall results indicate that anterior temporal lobe structures are not independently critical for supraspan learning. These findings are consistent with a previous report that posterior brain regions are involved in mediating such tasks.

Adult↗
PubMed1991

Bilateral pathological damage in temporal lobe epilepsy.

Patients with drug-refractory temporal lobe epilepsy can be treated successfully with surgical resection of one temporal lobe, especially when the resection includes the hippocampus. Although intrahippocampal recordings usually localize seizure onsets to one hippocampus, there are bilaterally-independent interictal spikes, occasional contralateral seizure onsets and post-resection seizures that implicate contralateral damage and epileptogenicity. Post-mortem non-quantified studies of both hippocampi in epileptics have revealed incidences of bilateral hippocampal sclerosis, mostly being asymmetric. The present paper reports on two post-mortem cases of bilateral, asymmetric cell loss in patients with physiologically-verified hippocampal epilepsy. In one patient the damage was severe bilaterally, but only slightly greater damage in one hippocampus. In the second patient, damage in one hippocampus was as severe as in the first patient; however the contralateral hippocampus appeared undamaged. However, cell counts revealed losses of over 30% in three different hippocampal subregions, indicating a mild form of asymmetric bilateral damage in patient two.

Adult↗
PubMed1996

Interspike intervals during interictal periods in human temporal lobe epilepsy.

We recorded 259 single neurons from mesial temporal lobe structures of 21 patients with complex partial seizures. Interspike intervals within clusters of action potentials (clustered interspike intervals) recorded from cells in mesial temporal structures ipsilateral to seizure initiation were compared to clustered interspike intervals in the contralateral temporal lobe. 'Clusters' were defined as any group of three or more spikes separated by intervals of less than a defined maximum, or two spikes separated by less than half that maximum. The maximum interspike interval which defined a cluster was varied from 5 to 40 ms in 5-ms steps. Significantly smaller proportions of clustered spikes were discharged by neurons in the amygdala, hippocampus and entorhinal cortex from the temporal lobe commonly initiating seizures, compared to neurons in contralateral homotopic regions. When data from the same three structures were combined, significantly fewer cluster interspike intervals between 10 and 25 ms were recorded from cells on the side of seizure onset. Because clustered action potential discharge is a normal pattern of firing for cells that discharge endogenous bursts, the relative decrease in proportions of 10-25 ms clustered interspike intervals occurring in the temporal lobe initiating seizures might reflect a reduction in endogenous burst discharges from that side. Reduced endogenous bursting could be due to the loss of burst discharging neurons as a product of seizure-related excitotoxicity. The identification of decreased interictal single neuronal burst discharge in epileptogenic structures stresses the difference between the interictal and ictal states in patients with complex partial seizures, and the importance of the transition between those states.

Action Potentials↗
PubMed1993

Facial asymmetry, hippocampal pathology, and remote symptomatic seizures: a temporal lobe epileptic syndrome.

We performed a prospective study of neuroimaging studies and temporal lobe pathology in 13 patients with facial asymmetry and intractable partial epilepsy of temporal lobe origin. The 13 patients, derived from 50 consecutive patients with nonlesional medically refractory partial epilepsy, were deemed appropriate candidates for an anterior temporal lobectomy. The facial weakness occurred exclusively, or was most prominent, during emotional expression, ie, spontaneous smiling. The temporal lobe of seizure origin, demonstrated by ictal long-term EEG monitoring, was always contralateral to the side of weakness. All 13 patients had a history of early childhood neurologic disease, eg, complex febrile seizure or bacterial meningitis. Hippocampal formation atrophy was present in all the epileptic temporal lobes by MRI-based volume studies. Twelve of the 13 patients subsequently received an anterior temporal lobectomy, and mesial temporal sclerosis was present in all the surgically excised temporal lobes. Ten of the 12 patients have been seizure-free during short-term follow-up. Facial asymmetry may occur in patients with partial epilepsy related to remote symptomatic seizures and mesial temporal sclerosis.

Adolescent↗
PubMed1993

Olfactory information processing and temporal lobe epilepsy.

It has been suggested that olfactory information processing is impaired in patients with temporal lobe epilepsy. However, the existing evidence is not wholly in accordance with this notion. Patients with epileptogenic foci in the left temporal lobe, the right temporal lobe, or other brain regions were compared with normal control subjects in the identification and retention of common odors. All three patient groups were substantially and equally impaired in verbally labelling the odors in question. The patients with epilepsy associated with the left temporal lobe or with nontemporal regions showed no sign of any impairment on a test of immediate recognition memory for common odors. However, the patients with epilepsy associated with the right temporal lobe showed a specific disturbance in their retention of nameable odors. It is suggested that the latter patients were selectively impaired in their retrieval of the episodic memories which provide the context for the encoding of distinctive odors.

Adult↗
PubMed1992

Dystonia, clinical lateralization, and regional blood flow changes in temporal lobe seizures.

We analyzed the lateralizing value of ictal dystonia and head-turning in temporal lobe epilepsy, and sought the biologic basis of these clinical signs by studying the regional changes in perfusion with ictal single-photon emission computed tomography (SPECT). We identified unilateral temporal lobe epilepsy in 40 of 42 patients undergoing evaluation for temporal lobe surgery, and with ictal SPECT all 40 showed striking hyperperfusion of the epileptogenic temporal lobe. Twenty-five of the 40 patients showed unilateral or predominantly unilateral upper limb dystonia, which was opposite the epileptic temporal lobe in all cases. Analysis of regional count ratios in cases with ictal dystonia, compared with those without, showed significant changes only in the basal ganglia. Specifically, we found that ictal dystonia was associated with a relative increase in perfusion of the basal ganglia opposite the dystonic limb. Although we found 26 cases with head-turning, the sign was of no lateralizing value, even when only those with major or "tonic" versions (n = 11) were analyzed. Slight increases in cortical blood flow on the side opposite the direction of version were associated with head-turning, irrespective of the side of seizure focus. In clinical practice, ictal SPECT is a highly accurate aid in the lateralization of temporal lobe foci, in addition to providing a new method to investigate the pathophysiology of clinical signs in focal seizures.

Adolescent↗
PubMed1995

Age-related changes in brain: II. Positron emission tomography of frontal and temporal lobe glucose metabolism in normal subjects.

While many neuropsychological studies have demonstrated age-related performance alterations in tests thought to reflect frontal and temporal lobe function, there is little direct observation and comparison of these hypothesized brain changes in vivo. The cerebral glucose metabolism of frontal, temporal, and cerebellar regions was examined in 40 young (mean = 27.5 +/- 4.9) and 31 elderly (mean = 67.6 +/- 8.8) normal males using PET-FDG. Univariate analysis showed age-related metabolic reductions in all frontal and temporal lobe regions. The reductions ranged from 13%-24% with the greatest changes in the frontal lobes. Multiple regression analyses showed a stronger age relationship with frontal lobe than with temporal lobe metabolism. The dorsal lateral frontal lobe was the region that appears to change most within the frontal lobes. Examination of the temporal lobe showed that age contributed equally to the metabolic variance of both the lateral temporal lobe and hippocampus. These results suggest that age-related metabolic changes exist in both frontal and temporal lobes and that the frontal lobe change is greater.

Adult↗
PubMed1985

Diagnosis of temporal lobe epilepsy by positron emission tomography.

Temporal lobe epilepsy was studied by the 11C-glucose method of positron emission tomography. The temporal lobe at the level 25 mm above the orbitomeatal line showed the amygdala, hippocampus and hippocampal gyrus medially, and the T1, T2 and T3 neocortices laterally. The focus locations in these structures were divided into mesial, lateral and combined groups on the PECT images. This classification showed a close correlation between the clinical symptoms and the anatomical focus sites.

Adolescent↗
PubMed2006

Correlation of electrocorticographic to clinical seizure onset and interhemispheric propagation times in temporal lobe epilepsy.

This study was performed to test the hypothesis that, in human temporal lobe epilepsy, electrocorticographic time factors involved in the ictal EEG to clinical ictal transition (electrocorticographic to clinical seizure onset time, ECOT) and the interhemispheric propagation of epileptic activity (interhemispheric propagation time, IHPT), which are independently correlated with temporal lobe epileptogenicity and predictive of seizure-free outcome following temporal lobectomy, are correlated with one another in a quantitative fashion. A series of 37 patients with medically intractable temporal lobe seizures was studied with long-term subdural videoelectroencephalographic monitoring. Temporal lobe seizure interhemispheric propagation time (IHPT) was found to be a negative, exponential function of electrocorticographic to clinical seizure onset time (ECOT) (f(x)=8.201x10(-0.016x), r=0.347, d.f.=35, t=2.19, p<0.05, where f(x)=IHPT and x=ECOT). A small increase in ECOT was associated with a substantial decrease in IHPT and vice versa. The results suggest the electrophysiological time factor, ECOT, involved in the transition from ictal EEG seizure onset to clinical seizure onset, may determine the speed of interhemispheric propagation of established epileptic activity. The results suggest the interesting hypothesis that, in human temporal lobe epilepsy and, perhaps, under non-pathological circumstances, the human temporal lobe might possess a "time-labeling" function amenable to quantitative analysis.

Journal Article↗
PubMedDate not supplied

Temporal lobe, autism, and macrocephaly.

BACKGROUND AND PURPOSE: Because of increased prevalence of macrocephaly in autism, head size must be controlled for in studies that examine volumetric findings of the temporal lobe in autistic subjects. We prospectively examined temporal lobe structures in individuals with autism who were normocephalic or macrocephalic (head circumference > 97th percentile) and in control subjects who were normocephalic or macrocephalic or who had a reading disorder (unselected for head size). The rationale for the reading disorder group was to have control subjects with potential temporal lobe anomalies, but who were not autistic. METHODS: In individuals aged 7-31 years, autism was diagnosed on the basis of standardized interview and diagnostic criteria. Control subjects ranged in age from 7 to 22 years. All subjects were male. MR morphometrics of the major temporal lobe structures were based on ANALYZE segmentation routines, in which total brain volume and total intracranial volume (TICV) were calculated. Both group comparisons and developmental analyses were performed. RESULTS: No distinct temporal lobe abnormalities of volume were observed once head size (TICV) was controlled for. In autistic and control subjects, robust growth patterns were observed in white and gray matter that differed little between the groups. Although subtle differences were observed in some structures (ie, less white matter volume in the region of the temporal stem and overall temporal lobe), none was statistically significant. CONCLUSION: No major volumetric anomalies of the temporal lobe were found in cases of autism when IQ, TICV, and age were controlled. Temporal lobe abnormalities that may be associated with autism are likely to be more related to functional organization within the temporal lobe than to any gross volumetric difference.

Adolescent↗
PubMed1997

Human temporal lobe potentials in verbal learning and memory processes.

Animal experiments and lesion studies have shown the importance of temporal lobe structures for language and memory. We recorded intracranial cognitive potentials from the human lateral and medial temporal lobe in 26 patients with temporal lobe epilepsy undergoing presurgical evaluation, using a word- and a picture-recognition paradigm. Neuropsychological testing included word fluency, verbal reasoning, sustained attention and a verbal learning memory test (VLMT), which was an adapted version of the Rey auditory verbal learning test. Word-specific N400-potentials elicited in the middle temporal gyrus of the dominant left hemisphere (LTL-N400) predicted immediate recall performance after learning, whereas N400s, elicited by words but not pictures in the left anterior medial temporal lobe (AMTL-N400), predicted delayed recall. The number of words that were learned but forgotten after a 30-min delay correlated only with N400s elicited by words in the left anterior medial temporal lobe. Thus, intracranial recordings indicated that different electrophysiological responses in different temporal lobe structures were linked to memory scores from specific neuropsychological tests.

Adolescent↗
PubMed2000

[Executive cognitive alteration of prefrontal type in patients with mesial temporal lobe epilepsy].

This study examines the performance on executive function--classically considered as purported by the frontal lobes--in patients with temporal lobe epilepsy (TLE). Two groups of patients were evaluated: one consisted of 16 TLE patients and the other comprised 12 patients with primary generalised epilepsy (PGE). The Wisconsin Card Sorting Test (WCST) was used as a measure of executive function. Results demonstrated that performance on the WCST was remarkably defective in the TLE group, showing a pattern suggestive of frontal like executive dysfunction in a 75% of the patients, against the 17% of the PGE group (p < 0.001). Impairment was evident when number of categories achieved (p < 0.05), perseverative errors (p < 0.001) and perseverative responses (p < 0.001) were considered. Clinical and theoretical significance of these findings may reflex the executive dysfunction of the mesial temporal lobe region as part of the temporo-frontal circuit.

Adult↗
PubMed2001

Long-term alteration of calcium homeostatic mechanisms in the pilocarpine model of temporal lobe epilepsy.

The pilocarpine model of temporal lobe epilepsy is an animal model that shares many of the clinical and pathophysiological characteristics of temporal lobe or limbic epilepsy in humans. This model of acquired epilepsy produces spontaneous recurrent seizure discharges following an initial brain injury produced by pilocarpine-induced status epilepticus. Understanding the molecular mechanisms mediating these long lasting changes in neuronal excitability would provide an important insight into developing new strategies for the treatment and possible prevention of this condition. Our laboratory has been studying the role of alterations in calcium and calcium-dependent systems in mediating some of the long-term neuroplasticity changes associated with epileptogenesis. In this study, [Ca(2+)](i) imaging fluorescence microscopy was performed on CA1 hippocampal neurons acutely isolated from control and chronically epileptic animals at 1 year after the induction of epileptogenesis with two different fluorescent dyes (Fura-2 and Fura-FF) having high and low affinities for [Ca(2+)](i). The high affinity Ca(2+) indicator Fura-2 was utilized to evaluate [Ca(2+)](i) levels up to 900 nM and the low affinity indicator Fura-FF was employed for evaluating [Ca(2+)](i) levels above this range. Baseline [Ca(2+)](i) levels and the ability to restore resting [Ca(2+)](i) levels after a brief exposure to several glutamate concentrations in control and epileptic neurons were evaluated. Epileptic neurons demonstrated a statistically significantly higher baseline [Ca(2+)](i) level in comparison to age-matched control animals. This alteration in basal [Ca(2+)](i) levels persisted up to 1 year after the induction of epileptogenesis. In addition, the epileptic neurons were unable to rapidly restore [Ca(2+)](i) levels to baseline following the glutamate-induced [Ca(2+)](i) loads. These changes in Ca(2+) regulation were not produced by a single seizure and were not normalized by controlling the seizures in the epileptic animals with anticonvulsant treatment. Peak [Ca(2+)](i) levels in response to different concentrations of glutamate were the same in both epileptic and control neurons. Thus, glutamate produced the same initial [Ca(2+)](i) load in both epileptic and control neurons. Characterization of the viability of acutely isolated neurons from control and epileptic animals utilizing standard techniques to identify apoptotic or necrotic neurons demonstrated that epileptic neurons had no statistically significant difference in viability compared to age-matched controls. These results provide the first direct measurement of [Ca(2+)](i) levels in an intact model of epilepsy and indicate that epileptogenesis in this model produced long-lasting alterations in [Ca(2+)](i) homeostatic mechanisms that persist for up to 1 year after induction of epileptogenesis. These observations suggest that altered [Ca(2+)](i) homeostatic mechanisms may underlie some aspects of the epileptic phenotype and contribute to the persistent neuroplasticity changes associated with epilepsy.

Animals↗