Language lateralization by Wada test and fMRI in 100 patients with epilepsy

Structural and functional neuroimaging continue to play an increasing role in the presurgical evaluation of patients with epilepsy. In addition to their value for localizing the epileptogenic zone and eloquent cortex, neuroimaging is contributing to our understanding of mood comorbidity in epilepsy. Although the vast majority of research has focused on patients with temporal lobe epilepsy (TLE), neuroimaging studies of patients with frontal lobe epilepsy (FLE) and primary generalized epilepsy are increasing in number. In this review, structural and functional imaging modalities that have received considerable research attention in recent years are reviewed, along with an assessment of their strengths and limitations for understanding behavior in epilepsy. In addition, advances in multimodal imaging are discussed along with their potential application to the presurgical evaluation of patients with seizure disorders.

Section: Fmrimentioning

confidence: 94%

The use of neuroimaging to study behavior in patients with epilepsy

McDonald¹

2008

“…In recent years, several studies have compared fMRI and the IAP with respect to language lateralization, or evaluated the ability of fMRI to localize language functions in children and adults with epilepsy [12][13][14][15][16][17][18][19][20][21][22][23][24]. These and other authors used various language fMRI tasks including semantic decision [14,16,21,[25][26][27], verb generation/verbal fluency [13,19,20,23,[28][29][30], word generation [15,18,22,24], and sentence reading [17,31].…”

Section: Introductionmentioning

confidence: 99%

“…These and other authors used various language fMRI tasks including semantic decision [14,16,21,[25][26][27], verb generation/verbal fluency [13,19,20,23,[28][29][30], word generation [15,18,22,24], and sentence reading [17,31]. Some studies have also reported the use of more than one fMRI paradigm for language localization and lateralization [10,12,13,29,32,33], but the results of these studies have been mixed, with some tasks showing good and some poor correlation with the results of IAP.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive presurgical functional MRI language evaluation in adult patients with epilepsy

Szaflarski

Holland

Jacola

et al. 2008

112

137

Functional magnetic resonance imaging (fMRI) has the potential to replace the intracarotid amobarbital procedure (IAP) in presurgical evaluation of patients with epilepsy patients. In this study, we compared fMRI verb generation (VG) and semantic decision/tone decision (SDTD) tasks and the IAP in their ability to localize language functions in patients with epilepsy undergoing presurgical evaluation. We enrolled 50 healthy controls to establish normal language activation patterns for VG and SDTD tasks at 3 or 4 T, and to design language regions of interest (ROIs) that were later applied to 38 patients with epilepsy (28 of 38 also underwent the IAP). We calculated laterality indices (LIs) for each task for each subject based on the ROIs, and we used general linear modeling to analyze the fMRI data. All healthy and epileptic subjects activated language areas with both fMRI tasks. We found significant correlations in language lateralization between the fMRI tasks (r = 0.495, P ≤ 0.001) and between VG and IAP (r = 0.652, P < 0.001) and SDTD and IAP (r = 0.735, P < 0.001). The differences in LIs between SDTD and VG tasks were small and not affected by age, gender, epilepsy status, handedness, or performance. SDTD and VG tasks combined explained approximately 58.4% in the variability of the IAP/language. In the general linear modeling, only the SDTD task significantly contributed to the determination of language lateralization in patients with epilepsy undergoing presurgical evaluation. Results indicate a moderate convergent validity between both fMRI language tasks and between IAP and fMRI tasks. The results of this study indicate that either of these fMRI tasks can be used for language lateralization in patients with epilepsy undergoing presurgical evaluation, but that the SDTD task is likely to provide more information regarding language lateralization than the VG task.

“…Some newer methods include event-related brain potentials [4] and whole-head magnetoencephalography [5][6][7]. The other alternative activation techniques are based on hemodynamic responses to language activation, such as functional transcranial Doppler [8], single-photon-emission computed tomography [9], positron emission tomography [10], near-infrared spectroscopic mapping [11], and functional magnetic resonance imaging [12]. All of these newer methods have variable limitations, and none have yet supplanted the Wada test as the ''gold standard" for lateralizing cerebral language dominance.…”

Section: Introductionmentioning

confidence: 99%

Power spectral density changes and language lateralization during covert object naming tasks measured with high-density EEG recordings

Ramon

Holmes

Freeman

et al. 2009

a b s t r a c tOur objective was to study changes in EEG time-domain power spectral density (PSDt) and localization of language areas during covert object naming tasks in human subjects with epilepsy. EEG data for subjects with epilepsy were acquired during the covert object naming tasks using a net of 256 electrodes. The trials required each subject to provide the names of common objects presented every 4 seconds on slides. Each trial comprised the 1.0 second before and 3.0 seconds after initial object presentation. PSDt values at baseline and during tasks were calculated in the h, a, b, low c, and high c bands. The spatial contour plots reveal that PSDt values during object naming were 10-20% higher than the baseline values for different bands. Language was lateralized to left frontal or temporal areas. In all cases, the Wada test disclosed language lateralization to the left hemisphere as well.