Correlation between memory, proton magnetic resonance spectroscopy, and interictal epileptiform discharges in temporal lobe epilepsy related to mesial temporal sclerosis

Department of Neurology and Neurosurgery, Division of Neurology, Universidade Federal de São Paulo/UNIFESP, São Paulo, Brazil.
Epilepsy & Behavior (Impact Factor: 2.26). 11/2009; 16(3):447-53. DOI: 10.1016/j.yebeh.2009.08.032
Source: PubMed


The aim of the study described here was to examine the relationship between memory function, proton magnetic resonance spectroscopy ((1)H-MRS) abnormalities, and interictal epileptiform discharge (IED) lateralization in patients with temporal lobe epilepsy (TLE) related to unilateral mesial temporal sclerosis.
We assessed performance on tests of memory function and intelligence quotient (IQ) in 29 right-handed outpatients and 24 controls. IEDs were assessed on 30-minute-awake and 30-minute-sleep EEG samples. Patients had (1)H-MRS at 1.5 T.
There was a negative correlation between IQ (P=0.031) and Rey Auditory Verbal Learning Test results (P=0.022) and epilepsy duration; between(1)H-MRS findings and epilepsy duration (P=0.027); and between N-acetylaspartate (NAA) levels and IEDs (P=0.006) in contralateral mesial temporal structures in the left MTS group. (1)H-MRS findings, IEDs, and verbal function were correlated.
These findings suggest that IEDs and NAA/(Cho+Cr) ratios reflecting neural metabolism are closely related to verbal memory function in mesial temporal sclerosis. Higher interictal activity on the EEG was associated with a decline in total NAA in contralateral mesial temporal structures.

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Available from: Katia Lin, Jun 18, 2015
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    • "The absence of a correlation between frequency of seizures and memory deficits does not necessarily rule out the hypothesis that epileptic activity may play a role in memory impairment in these patients. For instance, interictal paroxysmal activity, not necessarily expressing as clinical seizures, might interfere with memory functioning (Mantoan et al., 2009). It is also possible to speculate that factors not specifically related to epileptic discharges might contribute to the memory impairments observed in both patients with TLE and patients with OLE with respect to controls. "
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    ABSTRACT: Objective: To compare cognitive profiles of occipital lobe epilepsy (OLE) and temporal lobe epilepsy (TLE) and to investigate whether impairment of visuospatial functions is a specific deficit of OLE. Method: Eighteen patients with OLE, 18 patients with TLE, and 18 controls underwent a neuropsychological battery assessing memory, visuospatial functions, and frontal/executive functions. Results: Multivariate analysis evidenced poorer performance of patients with TLE and patients with OLE relative to controls on tasks assessing verbal and non-verbal long-term memory, frontal functions, and visuospatial functions. Patients with OLE had poorer performance than patients with TLE on visuospatial tasks, whereas patients with TLE performed worse than patients with OLE on verbal long-term memory test. Discriminant analysis identified two canonical discriminant functions: The first explained 53.3% of the variance, and the second explained 46.7% of the variance. The first function included verbal and non-verbal memory tests distinguishing controls from both OLE and TLE, whereas the second factor including a visuoconstructional test distinguished OLE from TLE and controls. Conclusions: The results demonstrate that visuoconstructional dysfunction is related to OLE and support the idea that alterations of occipito-parietal stream may be specific to patients with OLE.
    Full-text · Article · Sep 2015 · Journal of Neuropsychology
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    • "Epileptic seizures might trigger neurodegenerative changes leading eventually to memory impairments (Helmstädter, 2002; Stefan and Pauli, 2008). However, the question whether TLE is a dementing disease due to seizure activity is under debate (Helmstaedter and Elger, 1999, 2009; Jokeit and Ebner, 1999, 2002; Dodrill, 2004; Elger et al., 2004; Mantoan et al., 2009; Gonzalez et al., 2012). The typical course of epilepsy includes in the early phase a long silent period after the brain insult before recurrent seizures start, which then allows an accurate diagnosis (see Najm et al., 2001, for a review on epidemiology and risk factors). "
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    ABSTRACT: Temporal lobe epilepsy (TLE) and mild cognitive impairment (MCI) are both subject to intensive memory research. Memory problems are a core characteristic of both conditions and we wonder if there are analogies which would enrich the two distinct research communities. In this review we focus on memory decline in both conditions, that is, the most feared psychosocial effect. While it is clear that memory decline in MCI is highly likely and would lead to the more severe diagnosis of Alzheimer's disease, it is a debate if TLE is a dementing disease or not. As such, like for MCI, one can differentiate progressive from stable TLE subtypes, mainly depending on the age of onset. Neuroimaging techniques such as volumetric analysis of the hippocampus, entorhinal, and perirhinal cortex show evidence of pathological changes in TLE and are predictive for memory decline in MCI. Several studies emphasize that it is necessary to extend the region of interest-even whole-brain characteristics can be predictive for conversion from MCI to Alzheimer's disease. Electroencephalography is increasingly subject to computational neuroscience, revealing new approaches for analyzing frequency, spatial synchronization, and information content of the signals. These methods together with event-related designs that assess memory functions are highly promising for understanding the mechanisms of memory decline in both TLE and MCI populations. Finally, there is evidence that the potential of such markers for memory decline is far from being exhausted. Similar structural and neurophysiological characteristics are linked to memory decline in TLE and MCI. We raise the hope that interdisciplinary research and cross-talk between fields such as research on epilepsy and dementia, will shed further light on the dementing characteristics of the pathological basis of MCI and TLE and support the development of new memory enhancing treatment strategies.
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    • "). Although a reduction of left-sided NAA/(Cho + Cr) ratio correlated with lower IQ scores in one study (Mantoan et al., 2009), other investigators could not confirm this correlation (Martin et al., 1999). In contrast to the previously mentioned 1 H - MRS studies , reduced right hippocampus NAA / ( Cho + Cr ) ratios have also been found to correlate with poorer verbal memory performance . "
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