The use of neuroimaging to study behavior in patients with epilepsy

McDonald, Carrie R.

doi:10.1016/j.yebeh.2007.10.016

Cited by 15 publications

(11 citation statements)

References 135 publications

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“…To that end, further work is needed to validate MSI language mapping studies as a guide for cortical resection by correlating MSI language maps with the results of electrocortical stimulation studies. We argue, along with others (McDonald, 2008), that there is a clear need to determine the contribution of MSI language data to the prediction of outcome following resection of cortex in or near language areas of the brain. These sorts of data will be the strongest determinates of the clinical utility of MSI.…”

Section: Discussionmentioning

confidence: 65%

Lateralizing language with magnetic source imaging: Validation based on the Wada test

et al. 2009

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SUMMARYPurpose: Magnetoencephalography (MEG)/magnetic source imaging (MSI) is a noninvasive functional neuroimaging procedure used to localize language-specific regions in the brain. The Wada test, or intracarotid amobarbital procedure (IAP), is the gold standard in determining speech/language lateralization for presurgical planning, although it is invasive and associated with morbidity. The purpose of this study is to provide further validation on the use of MSI for presurgical language lateralization by comparing results against the IAP. Methods: The sample consisted of 35 patients with epilepsy and/or brain tumor undergoing presurgical evaluation at the Minnesota Epilepsy Group. All patients received both an IAP and MSI to determine hemispheric language dominance. For MSI, a 148-channel MEG system was used to record activation of language-specific cortex by an auditory word-recognition task.Results: The MSI and IAP were concordant in determining language in the hemisphere to be treated in 86% of the cases with sensitivity and specificity values of 80% and 100%, respectively. Conclusions: The results from this study are consistent with prior research findings comparing functional neuroimaging procedures to the IAP in determining language lateralization in presurgical patients. The current study provides an important replication and support for Papanicolaou et al.'s findings in 2004 using a consecutive clinical sample from a different institution. An unusually high rate of atypical IAP language cases in this sample and differences between the two procedures are believed to explain the noted discrepancies. MSI is a viable noninvasive alternative to the IAP in the presurgical determination of language lateralization.

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Section: Discussionmentioning

confidence: 65%

Lateralizing language with magnetic source imaging: Validation based on the Wada test

et al. 2009

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“…This is despite years of research describing the importance of other MTL and LTL structures to memory [for recent reviews, see (Bell, Lin, Seidenberg, & Hermann, 2011; Hermann, Lin, Jones, & Seidenberg, 2009; McDonald, 2008)]. With new, advanced MRI measures more readily available and easier to integrate into clinical practice, we evaluated whether these newer measurements could enhance the prediction of memory impairments in TLE.…”

Section: Discussionmentioning

confidence: 99%

White matter microstructure complements morphometry for predicting verbal memory in epilepsy

McDonald

Leyden

Hagler

et al. 2014

Cortex

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Verbal memory is the most commonly impaired cognitive domain in patients with temporal lobe epilepsy (TLE). Although damage to the hippocampus and adjacent temporal lobe structures is known to contribute to memory impairment, little is known of the relative contributions of white versus gray matter structures, or whether microstructural versus morphometric measures of temporal lobe pathology are stronger predictors of impairment. We evaluate whether measures of temporal lobe pathology derived from diffusion tensor imaging (DTI; microstructural) versus structural MRI (sMRI; morphometric) contribute the most to memory performances in TLE, after controlling for hippocampal volume (HCV). DTI and sMRI were performed on 26 patients with TLE and 35 controls. Verbal memory was measured with the Logical Memory subtest of the Wechsler Memory Scale–III. Hierarchical regression analyses were performed to examine unique contributions of DTI and sMRI measures to verbal memory with HCV entered in block 1. In patients, impaired recall was associated with increased mean diffusivity (MD) of multiple fiber tracts that project through the temporal lobes. In addition, increased MD of the left cortical and bilateral pericortical white matter was associated with impaired recall. After controlling for left HCV, only microstructural measures of white matter pathology contributed to verbal recall. The best predictive model included left HCV and MD of the left inferior longitudinal fasciculus (ILF) and pericortical white matter beneath the left entorhinal cortex. This model explained 60% of the variance in delayed recall and revealed that MD of the left ILF was the strongest predictor. These data reveal that white matter microstructure within the temporal lobe can be used in conjunction with left HCV to enhance the prediction of verbal memory impairment, and speak to the complementary nature of DTI and sMRI for understanding cognitive dysfunction in epilepsy and possibly other memory disorders.

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“…Given the immediate aims of our study, we have yet to correlate our findings with long‐term functional language outcomes in the postoperative period. To date, this has been a limitation of all MEG studies of language lateralization 73…”

Section: Discussionmentioning

confidence: 99%

Dynamics of hemispheric dominance for language assessed by magnetoencephalographic imaging

Findlay

Ambrose

Cahn-Weiner

et al. 2012

Annals of Neurology

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Objective The goal of the current study was to examine the dynamics of language lateralization using magnetoencephalographic (MEG) imaging, to determine the sensitivity and specificity of MEG-imaging, and to determine if MEG-imaging can become a viable alternative to the intracarotid amobarbital procedure (IAP), the current gold-standard for preoperative language lateralization in neurosurgical candidates. Methods MEG was recorded during an auditory verb-generation task and imaging analysis of oscillatory activity was initially performed in 21 subjects with epilepsy, brain tumor, or arteriovenous malformation who had undergone IAP and MEG. Time-windows and brain regions-of-interest that best discriminated between IAP determined left or right dominant for language were identified. Parameters derived in the retrospective analysis, was applied to a prospective cohort of 14 patients and healthy controls. Results Power decreases in the beta-frequency band were consistently observed following auditory stimulation in inferior frontal, superior temporal, and parietal cortices; similar power decreases were also seen in inferior frontal cortex prior to and during overt verb generation. Language lateralization was clearly observed to be a dynamic process that is bilateral for several hundred milliseconds during periods of auditory perception and overt speech production. Correlation with the IAP was seen in 13 of 14 (93%) of prospective patients, with the test demonstrating a sensitivity of 100% and specificity of 92%. Interpretation Our results demonstrate excellent correlation between MEG imaging findings with the IAP for language lateralization, and provide new insights into the spatiotemporal dynamics of cortical speech processing.

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The use of neuroimaging to study behavior in patients with epilepsy

Cited by 15 publications

References 135 publications

Lateralizing language with magnetic source imaging: Validation based on the Wada test

Lateralizing language with magnetic source imaging: Validation based on the Wada test

White matter microstructure complements morphometry for predicting verbal memory in epilepsy

Dynamics of hemispheric dominance for language assessed by magnetoencephalographic imaging

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