Identification of Abnormal Neuronal Metabolism Outside the Seizure Focus in Temporal Lobe Epilepsy

Mueller, S. G.; Laxer, Kenneth D.; Cashdollar, Nathan; Flenniken, Derek; Matson, Gerald B.; Weiner, Michael W.

doi:10.1111/j.0013-9580.2004.27603.x

Cited by 49 publications

(43 citation statements)

References 44 publications

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“…However, the number of participants in the vast majority of the published series is limited, since cases of unilateral MTS with no other pathology are relatively rare. 6,17,19,23,24,26 These limitations and technical weaknesses need to be taken into consideration in the clinical interpretation of our findings.…”

Section: Discussionmentioning

confidence: 98%

“…Several clinical investigators have demonstrated with the aid of proton MRS that in cases of MTS, the ipsilateral extrahippocampal temporal lobe may have altered metabolism. 6,[17][18][19]23,24,26 Meiners et al 17 reported their experience with a series of 11 patients with hippocampal sclerosis who underwent single-voxel extrahippocampal temporal lobe proton MRS (Table 3). They found that the white matter of the temporal lobe ipsilateral to the hippocampal sclerosis demonstrated decreased concentrations of NAA, marked increase in Cho concentrations, a slight increase in Cr concentrations, and decreased NAA/Cho and NAA/Cr ratios.…”

Section: Discussionmentioning

confidence: 99%

“…Likewise, Mueller et al 18,19 reported their experience with spectroscopic imaging of patients suffering TLE. They found that MTS is associated with extrahippocampal reduction of NAA concentration, increased Cho and Cr concentrations, and a decreased NAA/Cho+Cr ratio.…”

Section: Discussionmentioning

confidence: 99%

“…3,6,15,[17][18][19]23,24,26 Proton MRS is a noninvasive diagnostic tool that may provide valuable information regarding the biochemical profile and the metabolism of the brain. It has been extensively used in the preoperative evaluation of patients with medically intractable epilepsy, especially in cases of TLE, with varying specificity and accuracy rates.…”

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confidence: 99%

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Temporal pole proton preoperative magnetic resonance spectroscopy in patients undergoing surgery for mesial temporal sclerosis

Fountas

Tsougos

Gotsis

et al. 2012

FOC

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Object The purpose of this prospective study was to compare the results of proton MR spectroscopy (MRS) in temporal poles in patients with unilateral mesial temporal sclerosis (MTS) with the histopathological findings of the resected temporal poles. Methods A total of 23 patients (14 male and 9 female) with a mean age of 25.2 years (range 17–45 years) were included in this study, which was conducted over a 4-year period. All patients suffered medically refractory epilepsy due to unilateral, MRI-proven MTS, with no other imaging abnormalities. All participants underwent preoperative single-voxel proton MRS using a 3-T MRI unit. The hippocampi and temporal poles were examined bilaterally. The concentrations of N-acetyl-aspartate (NAA), choline (Cho), and creatine (Cr) were measured, and the NAA/Cho, NAA/Cr, and NAA/Cho+Cr ratios were calculated. All patients underwent anterior temporal lobectomy and ipsilateral amygdalohippocampectomy, and surgical specimens from the temporal poles were sent for histopathological examination. Comparisons of the spectroscopic and histopathological results of the resected temporal poles were performed. The modified Engel classification system was used for evaluating seizure outcome in the cohort. Results The preoperative spectroscopic profiles of the sclerotic hippocampi were abnormal in all patients, and the contralateral hippocampus showed altered spectroscopic findings in 12 patients (52.2%). Spectroscopy of the temporal poles demonstrated severely decreased concentrations of NAA, markedly increased concentrations of Cho, and increased concentrations of Cr in the temporal pole ipsilateral to the MTS in 15 patients (65.2%). Similarly, the NAA/Cho, NAA/Cr, and NAA/Cho+Cr ratios were severely decreased in the temporal pole ipsilateral to the MTS in 16 patients (69.6%). Histopathological examination of the resected temporal poles demonstrated ischemic changes in 5 patients (21.7%), gliotic changes in 4 (17.4%), demyelinating changes in 3 (13.0%), and microdysplastic changes in 1 patient (4.3%). Comparisons of the spectroscopic and histopathological findings showed that the sensitivity of proton MRS was 100%, its specificity was 80%, its positive predictive value was 87%, and its negative predictive value was 100%. The mean follow-up time in this study was 3.4 years. At the end of the 2nd postoperative year, 17 patients (73.9%) were in Engel Class I, 5 (21.7%) were in Class II, and 1 (4.3%) was in Class III. Conclusions Proton MRS detected altered ipsilateral temporal pole metabolism in patients with unilateral MTS. These metabolic changes were associated with permanent histological abnormalities of the temporal pole. This finding demonstrates that MTS may be a more diffuse histological process, and exact preoperative knowledge of its temporal extent becomes of paramount importance in the selection of the best surgical approach in these patients. Further validation of the observations is necessary for defining the role of temporal pole proton MRS in cases of temporal lobe epilepsy.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Temporal pole proton preoperative magnetic resonance spectroscopy in patients undergoing surgery for mesial temporal sclerosis

Fountas

Tsougos

Gotsis

et al. 2012

FOC

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“…Extratemporal abnormalities identified the hemisphere containing the epileptogenic focus in 78% of TLE with MTS but in only 17% of TLE without MTS. Therefore, temporal and extratemporal NAA/(Cr+Cho) reductions might be helpful for focus lateralization in TLE (41) . Because volumetric studies found no evidence for tissue atrophy beyond the ipsilateral temporal lobe (42) , it is reasonable that these NAA reductions probably also reflect neuronal dysfunction rather than actual neuronal loss.…”

Section: Naa In Brain Regions Secondarily Involved Seizure Spreadmentioning

confidence: 99%

N-Acetylaspartate as a Marker of Neuronal Injury in Neurodegenerative Disease

Schuff¹,

Meyerhoff²,

Mueller³

et al.

Advances in Experimental Medicine and Biology

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Considerable evidence suggests that normal aging is associated with gradual impairment of memory functioning [1]. The medial temporal lobe, especially the hippocampus, plays a central role in declarative memory processing [2]. However, magnetic resonance imaging (MRI) studies have produced controversial results concerning the age-related hippocampal volume loss, which could be due in part to the non-specificity of volume shrinkage as an indicator for neuron loss. In contrast to volume, NAA is generally considered a marker for viable neurons, because NAA reaches detectable concentrations only in neuronal tissue but not in other brain tissues, including glial cells. Using proton magnetic resonance spectroscopic imaging ( 1 H MRSI) and MRI together, we studied hippocampal metabolites and volumes in 24 healthy adults from 36 to 85 years of age. Our goals were to test whether NAA levels vary in the hippocampus as a function of normal aging and 2) to determine the relationship between hippocampal NAA and volume changes. We found NAA/Cho ratios decreased by 24% (r = −0.53, p = 0.01) and NAA/Cr ratios decreased by 26% (r = −0.61, p < 0.005) over the age range studied, while Cho/Cr remained stable, implying diminished NAA levels. In the same population, hippocampal volume shrank by 20% (r = −0.64, p < 0.05). The relationships of these measures with aging are depicted in Figure 1. Since NAA is considered a marker of neurons, these results provide stronger support for neuron loss in the aging hippocampus than volume measurements by MRI alone.Since contributions to the NAA signal may arise from both gray and white matter tissue, it is critical to differentiate between metabolite changes of gray and white matter, and other tissue types. One approach for differentiation is the use of linear regressions to predict the relationship between metabolite intensity changes and gray/white matter variations in MRSI voxels (4,(8)(9)(10)(11)(12). However, most previous MRSI studies that used linear regression averaged metabolite concentrations over different lobes of the brain, ignoring regional variations. In addition, tissues other than gray and white matter were ignored or not determined, such as white matter lesions, which occur frequently in the aged brain. We developed an approach for obtaining metabolite concentrations of gray, white matter, as well as of white matter lesions in different lobes of the brain using linear regression. We applied the new technique to measure NAA concentrations in the frontal and the parietal lobe in 40 normal elderly subjects (56 to 89 years, mean age 74 ± 8, 22 female, 18 male). NAA was about 15% lower in cortical gray matter and 23% lower in white matter lesions when compared to normal white matter. Cr was 11% higher in cortical gray than in white matter, and also about 15% higher in the parietal cortex compared to the frontal cortex. Cho was 28% lower in cortical gray matter than in white matter. Furthermore, NAA and Cr changes correlated with age. The results suggest that in addition to the hippo...

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EEG‐fMRI using z‐shimming in patients with temporal lobe epilepsy

Bagshaw

Torab

Kobayashi

et al. 2006

Magnetic Resonance Imaging

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Purpose: To use z-shimming, a technique that reduces signal loss due to susceptibility artifacts that can result in reduced or absent activation in electroencephalography (EEG) functional MRI (fMRI) sessions in patients with temporal lobe epilepsy (TLE), to determine whether it would result in an increased ability to detect significant regions of blood oxygenation level-dependent (BOLD) signal change. Materials and Methods:Eight patients with TL EEG spikes underwent an EEG-fMRI scanning session using z-shimming. The signal intensities in the z-shimmed images were compared with those in the standard images. BOLD activation maps were created from the two sets of images using the timings of the spikes observed on the EEG. Results:The mean signal increase in the TLs as a result of z-shimming was 45.9% Ϯ 4.5%. The percentage of TL voxels above a brain intensity threshold rose from 66.1% Ϯ 7.6% to 77.6% Ϯ 5.7%. This appreciable increase in signal did not lead to any significant differences in the statistical maps created with the two sets of functional images. Conclusion:The results suggest that loss of signal is not the limiting factor for the detection of spike-related BOLD signal changes in patients with TLE activity.

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Identification of Abnormal Neuronal Metabolism Outside the Seizure Focus in Temporal Lobe Epilepsy

Cited by 49 publications

References 44 publications

Temporal pole proton preoperative magnetic resonance spectroscopy in patients undergoing surgery for mesial temporal sclerosis

Temporal pole proton preoperative magnetic resonance spectroscopy in patients undergoing surgery for mesial temporal sclerosis

N-Acetylaspartate as a Marker of Neuronal Injury in Neurodegenerative Disease

EEG‐fMRI using z‐shimming in patients with temporal lobe epilepsy

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