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PubMed2006

Face memory in MRI-positive and MRI-negative temporal lobe epilepsy.

PURPOSE: Effects of MRI-positive (MRI(+)) as compared to MRI-negative (MRI(-)) temporal lobe epilepsy (TLE) on face memory are not yet known. METHODS: We studied 24 MRI(-) (11 right/13 left) and 20 MRI(+) (13 right/7 left) TLE patients, 12 generalized epilepsy patients, and 12 healthy subjects undergoing diagnostic workup with 24-72-h Video-EEG-monitoring. Twenty faces were shown, and had to be recognized from 40 faces immediately and after a 24-h delay. RESULTS: MRI(+) and MRI(-) right TLE (RTLE) patients showed deficits in face recognition compared to controls or generalized epilepsy, consistent with right temporal lobe dominance for face recognition. MRI(+) RTLE patients had deficits in both immediate and delayed recognition, while MRI(-) RTLE patients showed delayed recognition deficits only. The RTLE groups showed comparable delayed recognition deficits. Separate analyses in which the MRI(+) group included patients with hippocampal sclerosis only, did not alter results. Furthermore, MRI(-) RTLE had a worse delayed recognition than MRI(-) left TLE (LTLE). On the other hand, MRI(+) RTLE did not differ from MRI(+) LTLE in delayed recognition. Combining MRI(-) and MRI(+) TLE groups, we found differences between RTLE and LTLE in delayed, but not immediate face recognition. CONCLUSIONS: Our results suggest that a delayed recognition condition might be superior to immediate recognition tests in detecting face memory deficits in MRI(-) RTLE patients. This might explain why former studies in preoperative patients did not observe an immediate face recognition dominance of the right temporal lobe when combining MRI(-) and MRI(+) TLE patients. Our data further point to an important role of the right mesial temporal region in face recognition in TLE.

Epilepsy, Temporal Lobe↗

PubMed2006

Measuring inequalities in health: the case for healthy life expectancy.

OBJECTIVE: To evaluate healthy life expectancy (HLE) as a measure of health inequalities by comparing geographical and area-based deprivation-related inequalities in healthy and total life expectancy (TLE). DESIGN: Life table analysis based on ecological cross-sectional data. SETTING AND POPULATION: Council area quarters and postcode sector-based deprivation fifths in Scotland. MAIN OUTCOME MEASURES: Expectation of life in good self-assessed general health, or free from limiting long-term illness, and TLE, for females and males at birth. RESULTS: Women in Scotland have a life expectation of 70.3 years in good health, 61.6 years free from limiting long-term illness, and a TLE of 78.9 years. Comparable figures for men are 66.3, 58.6 and 73.5 years. TLE and HLE decrease with increasing area deprivation. Differences are substantially wider for HLE. A 4.7-year difference is seen in TLE between women living in the most and least deprived fifth of areas. The difference in HLE is 10.7 years in good health and 11.6 years free from limiting long-term illness. The degree of deprivation-related inequality in HLE is 2.5 times wider for women and 1.8 times wider for men than in TLE. CONCLUSIONS: Differences in TLE underestimate health inequalities substantially. By including morbidity and mortality, HLE reflects the excess burden of ill health experienced by disadvantaged populations better. Inequalities in length of life and health status during life should be taken into account while monitoring inequalities in population health.

Adolescent↗

PubMed2001

Temporal lobe epilepsy: qualitative reading of 1H MR spectroscopic images for presurgical evaluation.

PURPOSE: To study the feasibility and clinical potential of visual inspection of hydrogen 1 magnetic resonance (MR) spectroscopic metabolite images for the lateralization of unilateral nonlesional temporal lobe epilepsy (TLE). MATERIALS AND METHODS: MR imaging and 1H MR spectroscopic imaging were performed of the temporal lobes in 50 patients with TLE and 23 age-matched healthy volunteers. N-acetylaspartate (NAA) and creatine plus choline metabolite images were read by two neuroradiologists who determined lateralization according to the side of lower NAA signal intensity. Quantitative estimates of NAA were calculated by using an automated fitting program. RESULTS: Agreement in lateralization between readers was significant with a kappa score of 0.53 for all patients with TLE and 0.63 for patients displaying mild or marked NAA asymmetry. Among the 50 patients with TLE, lateralization was determined correctly by reader 1 in 38 (76%) patients and by reader 2 in 31 (62%) patients. If limited to patients with mild or marked NAA asymmetry, correct lateralization improved to 30 (77%) of 39 and 16 (80%) of 20 patients, respectively. Combined qualitative reading and quantitative spectral fitting enabled lateralization in 34 (85%) of 40 patients with TLE for reader 1 and 30 (77%) of 39 for reader 2, including nine of 14 patients with TLE with negative MR images. CONCLUSION: Reading of metabolite images is a feasible and fast means for noninvasive evaluation of patients with TLE who are candidates for surgery and enables lateralization in some patients with negative MR images.

Adult↗

PubMed1997

Brain morphometric comparison of first-episode schizophrenia and temporal lobe epilepsy.

BACKGROUND: Converging evidence has suggested that the abnormalities in brain morphology observed in schizophrenia are similar to those seen in temporal lobe epilepsy (TLE). The purpose of this study was to compare the features of these groups directly with measures of the brain using magnetic resonance (MR) morphometry. METHOD: Morphometric measures of ventricular and hippocampal volumes obtained from FLASH MR images were studied in 32 patients with first-episode schizophrenia (FES), 39 patients with TLE (21 left, 18 right), and 42 healthy controls. RESULTS: Ventricular volumes in the FES and TLE groups were both significantly larger that those seen in controls and did not differ from each other. The FES group showed significantly larger temporal horns, while the TLE group had relatively larger frontal horns. Analyses of hippocampal volumes revealed a significant group by hemisphere effect. The FES group showed relative reductions in left hippocampal volume that were comparable only to TLE patients with seizures originating from the left hemisphere. CONCLUSION: The results indicate that FES and TLE groups both show evidence of ventricular enlargement. Lateralised morphological abnormalities of the hippocampal formation in FES and left TLE are comparable, and may be specific to temporolimbic regions.

Adult↗

PubMed2003

GABA(B) receptor 1 polymorphism (G1465A) is associated with temporal lobe epilepsy.

BACKGROUND: Dysfunction of gamma-aminobutyric acid (GABA) (B) receptors has been implicated in the pathogenesis of temporal lobe epilepsy (TLE). OBJECTIVE: To evaluate the genetic contribution of cloned human GABA(B) receptors to TLE. METHODS: The authors genotyped 141 patients (78 women and 63 men; mean age = 49.1 +/- 18.0 years) with nonlesional TLE and 372 age- and sex-matched normal individuals for the known polymorphism G1465A in the human GABA(B) receptor 1 [GABA(B[1])] gene. RESULTS: There was a highly significant overrepresentation of the G1465A heterozygote in patients with TLE compared with controls. The A/G genotype was found in 17% of the 141 patients with TLE and in only 0.5% of the 372 controls (p < 0.0001). The authors also found that patients carrying the A allele had a significantly higher risk (p = 0.003, OR = 6.47, 95% CI = 2.02 to 20.76) of developing drug-resistant TLE. Furthermore, the age at onset of seizures tended to be lower in patients with A/G genotype, but the difference was not significant. CONCLUSIONS: The results of this study indicate that the GABA(B[1]) polymorphism (G1465A) confers a highly increased susceptibility to TLE. Moreover, it seems to influence the severity of this common epileptic disorder.

Age of Onset↗

PubMed1999

Entorhinal cortex in temporal lobe epilepsy: a quantitative MRI study.

BACKGROUND: The entorhinal cortex (EC) is a distinct anatomic and functional region of the anterior parahippocampal gyrus, which plays a role in seizure generation and propagation in temporal lobe epilepsy (TLE). In tissue resected from TLE patients, cell loss in the EC has been described. OBJECTIVES: To develop a standardized protocol for identifying the anatomic boundaries of the EC using high-resolution MRI and to examine morphologic changes of the EC in TLE. METHODS: We performed T1-weighted MRIs in 20 patients (7 males) with TLE (mean age 34 years) and 18 normal controls (mean age 26 years). Eleven patients had a left and 9 a right epileptic focus as defined by history, video-EEG, and surgical outcome. The volumes of the EC, the hippocampus, and the amygdala were measured using a standardized MRI protocol. Analysis of variance (ANOVA) was used to examine the effect of seizure focus lateralization and hemisphere on these volumes. An asymmetry ratio [A (%) = 100 x (R-L)/(R+L)/2] was also compared between groups using ANOVA. RESULTS: In normal controls the volume of the right EC was 1,247 +/- 127 mm3 (mean +/- standard deviation), and that of the left EC was 1,215 +/- 135 mm3 (p > 0.05). We found a bilateral reduction in the volume of the EC in TLE patients compared with controls (p < 0.05). Examination of the asymmetry ratios showed that the reduction in volume of the EC was greater ipsilateral to the epileptic focus (p < 0.05). The volumes of the hippocampus and the amygdala were smaller on the side of the focus in TLE patients compared with controls (p < 0.05). CONCLUSIONS: With a standardized protocol for the quantitative assessment of the EC, patients with unilateral TLE show bilateral reduction in the volume of the EC. However, this reduction is more severe ipsilateral to the epileptic focus.

Adolescent↗

PubMed2002

The localizing value of the abdominal aura and its evolution: a study in focal epilepsies.

OBJECTIVE: To evaluate the localizing value of abdominal aura and its evolution into other seizure types. METHODS: The seizures of 491 consecutive patients with focal epilepsies were prospectively classified according to a recently introduced semiologic seizure classification. All patients underwent prolonged EEG video monitoring and MRI scan. Two hundred twenty-three patients (45%) had temporal lobe epilepsies (TLE); 113 patients (23%) had extratemporal epilepsies; and for 155 (32%) patients, the epilepsy could not be localized to one lobe. RESULTS: Abdominal auras were more frequent with TLE (117 of 223 patients, 52%) than in extratemporal epilepsy (13 of 113 patients, 12%, p < 0.0001) and more frequent in mesial TLE (70 of 110 patients, 64%) than in neocortical TLE (16 of 41 patients, 39%, p = 0.007). No preponderance to one side existed. Abdominal auras were followed by ictal oral and manual automatisms (automotor seizure) in at least one seizure evolution in all patients with TLE (117 patients, 100%). In contrast, only two patients with extratemporal epilepsy (2 of 13 patients, 15%, p < 0.0001) had abdominal auras evolving into automotor seizures. An abdominal aura is associated with TLE with a probability of 73.6%. The evolution of an abdominal aura into an automotor seizure, however, increases the probability of TLE to 98.3%. CONCLUSIONS: These results demonstrate that evolution of abdominal aura into automotor seizure permits differentiation between temporal lobe epilepsy and extratemporal epilepsy, showing that analysis of seizure evolution provides more localizing information than does the frequency of particular seizure types.

Abdomen↗

PubMed1997

The effect of early versus late onset of temporal lobe epilepsy on hemispheric memory laterality: an intracarotid amobarbital procedure study.

Thirty-three temporal lobe epilepsy (TLE) patients, 19 left TLE and 14 right TLE, underwent an intracarotid amobarbital procedure. For each patient, hemispheric memory laterality was determined by measuring the relative magnitude of recognition memory following left versus right hemisphere injection of sodium amobarbital. The patients were divided into early and late seizure onset groups, based on the median age (13 yrs) of seizure onset of the total sample. Early-onset left TLE was associated with a greater tendency toward right hemispheric representation of both verbal and visual memory compared with late-onset left TLE. Early-onset right TLE was associated with a greater tendency toward left hemispheric representation of visual, but not verbal, memory compared with late-onset right TLE. These findings indicate that interhemispheric plasticity for memory is greater in early than in late life, bidirectional, and at least partially material-specific.

Adolescent↗

PubMed2001

MR volumetry of the entorhinal, perirhinal, and temporopolar cortices in drug-refractory temporal lobe epilepsy.

BACKGROUND AND PURPOSE: The occurrence of damage in the entorhinal, perirhinal, and temporopolar cortices in unilateral drug-refractory temporal lobe epilepsy (TLE) was investigated with quantitative MR imaging. METHODS: Volumes of the entorhinal, perirhinal, and temporopolar cortices were measured in 27 patients with unilateral drug-refractory TLE, 10 patients with extratemporal partial epilepsy, and 20 healthy control subjects. All patients with TLE were evaluated for epilepsy surgery and underwent operations. RESULTS: In left TLE, the mean volume of the ipsilateral entorhinal cortex was reduced by 17% (P <.001 compared with control subjects) and that of the ipsilateral temporopolar cortex by 17% (P <.05). In right TLE, the mean ipsilateral entorhinal volume was reduced by 13% (P < or =.01), but only in patients with hippocampal atrophy. Asymmetry ratios also indicated ipsilateral cortical atrophy. When each patient was analyzed individually, the volume of the ipsilateral hippocampus was reduced (> or = 2 SD from the mean of controls) in 63% and that of the entorhinal cortex in 52% of patients with TLE. Furthermore, ipsilateral entorhinal (left: r = 0.625, P <.001; right: r = 0.524, P < or =.01), perirhinal (left: r = 0.471, P <.05), and temporopolar (right: r = 0.556, P <.01) volumes correlated with ipsilateral hippocampal volumes. There was no association, however, with clinically or pathologically identified causes of epilepsy, duration of epilepsy, or age at onset of epilepsy. Mean cortical volumes were unaffected in extratemporal partial epilepsy. CONCLUSION: Subpopulations of patients with unilateral TLE have ipsilateral damage in the entorhinal and temporopolar cortices. The damage is associated with hippocampal damage.

Adolescent↗

PubMed2003

[Qualitative and quantitative MRI findings in temporal lobe epilepsy].

PURPOSE: Mesial temporal sclerosis is the most common pathological finding in temporal lobe epilepsy (TLE). Accurate identification and localization of this pathology before surgery is obligatory for a good prognosis after the operation. In this study we compared the results of qualitative and quantitative MR findings of the hippocampus in TLE. MATERIALS AND METHODS: The study group consisted of 42 patients with the definitive diagnosis of temporal lobe complex partial seizure and 42 control subjects. Extrahippocampal lesions had been detected in 10 patients. Qualitative evaluation was performed by T2-weighted FSE, fast FLAIR, T1-weighted fast IR sequences on coronal plane. We also performed volumetric measurements of the hippocampus in 32 patients with TLE and compared the results with those of the control group. The mesial temporal lobes were investigated with SVS-proton MR spectroscopy using a PRESS sequence with an echo time of 135 milliseconds and T2 relaxation values. RESULTS: Hippocampal pathology was detected on paracoronal plane at T1-weighted fast IR (84%), T2-weighted FSE (60%) and fast FLAIR (88%) images. On comparing the hippocampal volumes of the patient and control groups, the hippocampal of the control group were found to be significantly larger (p < 0.05). Considering the right-left volume differences, 28 patients (88%) were found to have unilateral hippocampal atrophy. The most consistent MR spectroscopic parameter for definite lateralization was the NAA/Cho + Cr ratio (100%). Accurate epileptic focus lateralizations were made in 27 subjects (84%) by using hippocampal T2 relaxation time, and in 12 subjects (33%) by using temporal white matter T2 relaxation time. CONCLUSION: MR imaging is highly sensitive in detecting and locating abnormalities in the temporal lobe and hippocampus in patients with TLE. Implementation of FLAIR and T1 IR sequences in the routine MR examination of patients with TLE is recommended. With adequate asymmetry index, NAA/Cho + Cr ratio is sensitive in predicting the side of involvement in patients with TLE. For medically intractable TLE patients MRS is a very important guiding tool prior to surgery.

Adolescent↗

PubMed1992

Morphological changes in the dentate gyrus in human temporal lobe epilepsy.

Multiple morphological and neurochemical changes are found in the dentate gyrus of humans with temporal lobe epilepsy (TLE). Three basically different types of changes will be discussed and some interrelationships considered. Neuronal loss in several regions of the hippocampal formation in human TLE has been recognized for many years, but only recently have the polymorph or hilar neurons been evaluated as a distinct group of neurons, and cell loss in this region is now being documented in many cases with severe TLE. Reorganization of afferents within the molecular layer of the dentate gyrus is also found in a high percentage of TLE specimens. The apparent reorganization of mossy fibers from the dentate granule cells is particularly striking, and aberrant innervation of the inner part of the molecular layer by zinc- and dynorphin-containing mossy fibers has been reported in human tissue by several groups of investigators. In a subpopulation of TLE specimens, there is also disorganization of the granule cell layer. Rather than being arranged in the compact, highly organized layer that is characteristic of control tissue, the granule cell bodies in some TLE cases are dispersed. In some additional cases, a bilaminar pattern of granule cells is observed. Each of these changes could contribute to altered circuitry within the dentate gyrus of humans with TLE, and such alterations could influence seizure susceptibility within the hippocampal formation.

Afferent Pathways↗

PubMed2005

MR volumetric analysis of the piriform cortex and cortical amygdala in drug-refractory temporal lobe epilepsy.

BACKGROUND AND PURPOSE: The assessment of patients with temporal lobe epilepsy (TLE) traditionally focuses on the hippocampal formation. These patients, however, may present structural abnormalities in other brain areas. Our purpose was to develop a method to measure the combined volume of the human piriform cortex and cortical amygdala (PCA) by using MR imaging and to investigate PCA atrophy. METHODS: The definition of anatomic landmarks on MR images was based on histologic analysis of 23 autopsy control subjects. Thirty-nine adults with chronic TLE and 23 age-matched control subjects were studied. All underwent high-spatial-resolution MR imaging at 1.5T, including a tilted T1-weighted 3D dataset. The PCA volumes were compared with the control values and further correlated with hippocampal, amygdala, and entorhinal cortex volumes. RESULTS: The normal volume was 530 +/- 59 mm(3) (422-644) [mean +/- 1 SD (range)] on the right and 512 +/- 60 mm(3) (406-610) on the left PCA (no asymmetry, and no age or sex effect). The intraobserver and interobserver variability were 6% and 8%, respectively. In right TLE patients, the mean right PCA volume was 18% smaller than in control subjects (P < .001) and 15% smaller than in left TLE (P < .001). In left TLE, the mean left PCA volume was 16% smaller than in control subjects (P < .001) and 19% smaller than in right TLE (P < .001). Overall, 46% (18/39) of the patients had a greater than 20% volume reduction in the ipsilateral PCA. There was bilateral atrophy in 18% (7/39). Patients with hippocampal volumes of at least 2 SDs below the control mean had an 18% reduction in the mean PCA volume compared with patients without hippocampal atrophy (P < .001). Ipsilaterally, hippocampal (r = 0.756, P < .01), amygdaloid (r = 0.548, P < .01), and entorhinal (r = 0.500, P < .01) volumes correlated with the PCA volumes. CONCLUSION: The quantification of PCA volume with MR imaging showed that the PCA is extensively damaged in chronic TLE patients, particularly in those with hippocampal atrophy.

Adolescent↗

PubMedDate not supplied

MR imaging volumetry of subcortical structures and cerebellar hemispheres in temporal lobe epilepsy.

BACKGROUND AND PURPOSE: There is mounting evidence of extratemporal volume changes associated with medically refractory temporal lobe epilepsy (TLE). This MR imaging study aimed to characterize volume changes in subcortical structures and cerebellar hemispheres with respect to lateralization of the seizure focus, onset and duration of epilepsy, and frequency of generalized tonic-clonic seizures (GTCS). METHODS: Amygdalar, hippocampal, thalamic, caudate head, and cerebellar volume measurements were obtained in the preoperative MR images of 40 patients with TLE (20 right, 20 left), who underwent temporal lobe resection with good outcome, and in 20 right-handed control participants. All 3D MR images were spatially aligned and normalized before measurements were obtained. Standardized volumes and right-to-left volume ratios (VRs) were compared between control participants and right and left TLE groups. Multiple regression analyses were performed to study the effects of epilepsy onset and duration and GTCS frequency on ipsilateral-to-contralateral VRs with respect to the resected seizure focus. RESULTS: Thalamic volumes were smaller bilaterally in patients with TLE. Hippocampal volumes were smaller ipsilateral to the seizure focus, but there was no significant volume loss involving the amygdala, caudate, or cerebellum. Hippocampal and amygdalar right-to-left VRs differed significantly between right and left TLE groups and controls, whereas thalamic right-to-left VRs differed only between the TLE groups. Thalamic ipsilateral-to-contralateral VRs were correlated positively with epilepsy onset and negatively with epilepsy duration. Caudate ipsilateral-to-contralateral VRs were positively, whereas amygdalar and cerebellar VRs were negatively, correlated with GTCS frequency. CONCLUSIONS: Unilateral amygdalar and bilateral thalamic volume loss, in the absence of caudate head atrophy, is likely to reflect seizure-induced injury due to TLE. Correlations of VRs affecting the amygdala, caudate, and cerebellum with GTCS frequency may also reflect injury or a prediposition for secondary generalization. Potential effects of complex partial seizures, febrile seizures, or antiepileptic medications on subcortical structures need to be evaluated in future studies.

Cerebellum↗

PubMed2006

Composite SISCOM perfusion patterns in right and left temporal seizures.

OBJECTIVE: To compare composite subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance imaging (also known as SISCOM) patterns between right and left medial temporal-onset seizures to document neuroanatomical involvement in perfusion patterns. DESIGN: A retrospective comparative survey. SETTING: Epilepsy monitoring unit in a tertiary care referral center. PARTICIPANTS: Subjects with temporal lobe epilepsy (TLE) who underwent ictal single-photon emission computed tomography studies. MAIN OUTCOME MEASURES: Comparison of ictal perfusion pattern changes in subjects with right and left temporal seizures. RESULTS: Composite subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance images showed similar regions of hyperperfusion change in the ipsilateral anteromedial temporal-corpus striatum-insula region in both groups. In the midbrain reticular formation, there was a significant difference in hyperperfusion between the left and right TLE groups. In addition, the right, but not the left, TLE group shows contralateral hypoperfusion of the temporoparietal junction. CONCLUSIONS: While anteromedial temporal-corpus striatum-insula perfusion patterns are similar, there are brainstem and hemispheric perfusion pattern differences in right and left TLE seizures, confirming pathophysiological differences between the groups. These findings help define neuronal network involvement in TLE seizures, and may explain the differences in clinical symptoms of right and left TLE seizures.

Adult↗

PubMed1999

Short echo time single-voxel 1H magnetic resonance spectroscopy in magnetic resonance imaging-negative temporal lobe epilepsy: different biochemical profile compared with hippocampal sclerosis.

Single-voxel proton magnetic resonance spectroscopy (1H MRS) has shown abnormalities in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). Many TLE patients, however, do not have HS or other lesions on quantitative magnetic resonance imaging (MRI) (MRI-negative). Fifteen control subjects, 15 patients with unilateral HS, and 15 MRI-negative TLE patients underwent 1H MRS at an echo time of 30 msec on a 1.5-T GE Signa scanner. Voxels were tailored to the individual hippocampi. N-Acetylaspartate (NAA), creatine, choline, total glutamate plus glutamine (Glx), and myo-inositol (Ins) were quantitated by using an external standard and LCModel, a user-independent quantitation method. Normal ranges were defined as the control mean +/- 2.5 SD. In HS patients, 12 of 15 had abnormally low NAA in sclerotic hippocampi; 3 of these 12 also had abnormally low NAA contralaterally. Abnormally low NAA/Ins ratios lateralized the side affected by HS in 7 of 15 patients, without any bilateral abnormalities. In 15 MRI-negative TLE patients, 4 had abnormally low hippocampal NAA ipsilateral to seizure onset, 1 of whom had abnormally low NAA bilaterally. Analysis of groups of subjects showed a bilateral decrease in NAA, most marked in patients with HS and on the side of seizure onset. The mean NAA/Ins ratio was lower in patients with HS than in control subjects and in MRI-negative patients. The concentration of Glx was higher ipsilateral to seizure onset in MRI-negative patients than in HS patients. Quantitative short echo time 1H MRS identified abnormalities in 87% of patients with HS and 27% of MRI-negative TLE patients in concordance with other lateralizing data. In individual and group comparisons, 1H MRS described a metabolite profile in the hippocampi of MRI-negative TLE patients that was different from patients with HS, with an increase in Glx and a less marked decrease in NAA than was seen in HS.

Adult↗

PubMed2007

Temporal lobe interictal epileptic discharges affect cerebral activity in "default mode" brain regions.

A cerebral network comprising precuneus, medial frontal, and temporoparietal cortices is less active both during goal-directed behavior and states of reduced consciousness than during conscious rest. We tested the hypothesis that the interictal epileptic discharges affect activity in these brain regions in patients with temporal lobe epilepsy who have complex partial seizures. At the group level, using electroencephalography-correlated functional magnetic resonance imaging in 19 consecutive patients with focal epilepsy, we found common decreases of resting state activity in 9 patients with temporal lobe epilepsy (TLE) but not in 10 patients with extra-TLE. We infer that the functional consequences of TLE interictal epileptic discharges are different from those in extra-TLE and affect ongoing brain function. Activity increases were detected in the ipsilateral hippocampus in patients with TLE, and in subthalamic, bilateral superior temporal and medial frontal brain regions in patients with extra-TLE, possibly indicating effects of different interictal epileptic discharge propagation.

Auditory Cortex↗

PubMed2000

T2 relaxometry can lateralize mesial temporal lobe epilepsy in patients with normal MRI.

In unselected patients with intractable temporal lobe epilepsy (TLE), approximately 15% do not have detectable hippocampal atrophy on MRI. The purpose of this study was to evaluate whether T2 relaxometry can identify hippocampal pathology and lateralize the epileptic focus in patients with intractable TLE, who do not demonstrate hippocampal atrophy on volumetric MRI (MRIV). We selected 14 patients with unilateral TLE who had unilateral atrophy and 11 patients with unilateral TLE who had no evidence of atrophy on MRIV. Images were acquired on a 1.5 T MR scan using a dual echo sequence with 23 contiguous oblique coronal slices in all patients and in 14 healthy subjects. Fitting a single exponential decay equation to the imaging data generated T2 maps. Averages of six slices containing the head, body, and tail of the hippocampus were used to calculate hippocampal T2 relaxation times (HT2). The epileptic focus was defined by history, video-EEG, and surgical response. All TLE patients with hippocampal atrophy and 9/11 (82%) patients with normal MRI had abnormally high HT2 ipsilateral to the epileptic focus. Bilateral abnormal HT2 were found in 6/14 (43%) of patients with unilateral hippocampal atrophy and 2/11 (18%) of patients with normal MRI. However, this increase was always greater ipsilateral to the epileptic focus. Qualitative hippocampal pathology showed gliosis and neuronal loss in 10/14 operated patients with hippocampal atrophy on MRIV and in 5/7 operated patients with normal MRI. In conclusion, hippocampal T2 mapping provides evidence of hippocampal damage in the majority of patients with intractable TLE who have no evidence of atrophy on MRI and can correctly lateralize the epileptic focus in most patients.

Adult↗

PubMed1990

The effects of lateralized temporal lobe dysfunction on formal and semantic word fluency.

Word fluency performance was studied in 32 patients with unilateral temporal lobe epilepsy (TLE) and 25 healthy dextral controls. Two word fluency tasks were administered conforming to either formal-based criteria or semantic-based criteria. Performance for TLE patients was assessed both pre-operatively and approximately 1 week following anterior temporal lobectomy. Both formal and semantic word fluency decreased regardless of resection laterality. Left TLE patients performed significantly worse at both pre- and post-operative assessments compared to the right TLE patients, while right TLE patients performed significantly poorer than controls on all verbal fluency criteria at pre- and post-operative assessments. In addition, both TLE and control groups produced significantly fewer formal and semantic words during the second 30-sec portion of each task. These findings are discussed in terms of temporal lobe contributions to word fluency production and lexical semantic processing.

Adult↗