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Atypical language organization in temporal lobe epilepsy revealed by a passive semantic paradigm.

Miró J, Ripollés P, López-Barroso D, Vilà-Balló A, Juncadella M, de Diego-Balaguer R, Marco-Pallares J, Rodríguez-Fornells A, Falip M - BMC Neurol (2014)

Bottom Line: Sometimes, these paradigms are too complex and may result in patient underperformance.Furthermore, we observed that the atypical right-lateralization patterns in LMTLE patients was associated to earlier age at epilepsy onset.These results are in line with the idea that early onset of epileptic activity is associated to larger neuroplastic changes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cognition and Brain Plasticity Group [Bellvitge Biomedical Research Institute]- IDIBELL, L'Hospitalet de Llobregat, Barcelona 08907, Spain. jmiro@bellvitgehospital.cat.

ABSTRACT

Background: Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy in adults and can be successfully cured by surgery. One of the main complications of this surgery however is a decline in language abilities. The magnitude of this decline is related to the degree of language lateralization to the left hemisphere. Most fMRI paradigms used to determine language dominance in epileptic populations have used active language tasks. Sometimes, these paradigms are too complex and may result in patient underperformance. Only a few studies have used purely passive tasks, such as listening to standard speech.

Methods: In the present study we characterized language lateralization in patients with MTLE using a rapid and passive semantic language task. We used functional magnetic resonance imaging (fMRI) to study 23 patients [12 with Left (LMTLE), 11 with Right mesial temporal lobe epilepsy (RMTLE)] and 19 healthy right-handed controls using a 6 minute long semantic task in which subjects passively listened to groups of sentences (SEN) and pseudo sentences (PSEN). A lateralization index (LI) was computed using a priori regions of interest of the temporal lobe.

Results: The LI for the significant contrasts produced activations for all participants in both temporal lobes. 81.8% of RMTLE patients and 79% of healthy individuals had a bilateral language representation for this particular task. However, 50% of LMTLE patients presented an atypical right hemispheric dominance in the LI. More importantly, the degree of right lateralization in LMTLE patients was correlated with the age of epilepsy onset.

Conclusions: The simple, rapid, non-collaboration dependent, passive task described in this study, produces a robust activation in the temporal lobe in both patients and controls and is capable of illustrating a pattern of atypical language organization for LMTLE patients. Furthermore, we observed that the atypical right-lateralization patterns in LMTLE patients was associated to earlier age at epilepsy onset. These results are in line with the idea that early onset of epileptic activity is associated to larger neuroplastic changes.

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Whole brain fMRI activations for the three groups. Results are shown over an MNI template, at a p < 0.05 FDR-corrected threshold with 20 voxels of cluster extent using neurological convention. A. Healthy participants B. LMTLE patients. C. RMTLE patients. PSEN, Passive Listening to Pseudo Sentences; SEN, Passive Listening to Sentences; L, Left hemisphere; R, Right hemisphere.
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Figure 2: Whole brain fMRI activations for the three groups. Results are shown over an MNI template, at a p < 0.05 FDR-corrected threshold with 20 voxels of cluster extent using neurological convention. A. Healthy participants B. LMTLE patients. C. RMTLE patients. PSEN, Passive Listening to Pseudo Sentences; SEN, Passive Listening to Sentences; L, Left hemisphere; R, Right hemisphere.

Mentions: Task vs. rest contrasts (SEN vs. rest, PSEN vs. rest) thresholded at p < 0.001 uncorrected with 20 voxels of cluster extent and elicited clear activations in the STG and MTG bilaterally in all patients and controls (42 subjects in total, see Figure 2 and Tables 2,3 and4 for descriptions of each contrast of interest per group and Figure 3 for single case examples). The contrast between SEN vs. PSEN failed to show significant activations in any cortical region in 4 out of 11 (36%) RMTLE patients, 5 out of 12 (42%) LMTLE patients and in 8 out of 19 (42%) controls and thus was not analyzed any further.


Atypical language organization in temporal lobe epilepsy revealed by a passive semantic paradigm.

Miró J, Ripollés P, López-Barroso D, Vilà-Balló A, Juncadella M, de Diego-Balaguer R, Marco-Pallares J, Rodríguez-Fornells A, Falip M - BMC Neurol (2014)

Whole brain fMRI activations for the three groups. Results are shown over an MNI template, at a p < 0.05 FDR-corrected threshold with 20 voxels of cluster extent using neurological convention. A. Healthy participants B. LMTLE patients. C. RMTLE patients. PSEN, Passive Listening to Pseudo Sentences; SEN, Passive Listening to Sentences; L, Left hemisphere; R, Right hemisphere.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4017227&req=5

Figure 2: Whole brain fMRI activations for the three groups. Results are shown over an MNI template, at a p < 0.05 FDR-corrected threshold with 20 voxels of cluster extent using neurological convention. A. Healthy participants B. LMTLE patients. C. RMTLE patients. PSEN, Passive Listening to Pseudo Sentences; SEN, Passive Listening to Sentences; L, Left hemisphere; R, Right hemisphere.
Mentions: Task vs. rest contrasts (SEN vs. rest, PSEN vs. rest) thresholded at p < 0.001 uncorrected with 20 voxels of cluster extent and elicited clear activations in the STG and MTG bilaterally in all patients and controls (42 subjects in total, see Figure 2 and Tables 2,3 and4 for descriptions of each contrast of interest per group and Figure 3 for single case examples). The contrast between SEN vs. PSEN failed to show significant activations in any cortical region in 4 out of 11 (36%) RMTLE patients, 5 out of 12 (42%) LMTLE patients and in 8 out of 19 (42%) controls and thus was not analyzed any further.

Bottom Line: Sometimes, these paradigms are too complex and may result in patient underperformance.Furthermore, we observed that the atypical right-lateralization patterns in LMTLE patients was associated to earlier age at epilepsy onset.These results are in line with the idea that early onset of epileptic activity is associated to larger neuroplastic changes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cognition and Brain Plasticity Group [Bellvitge Biomedical Research Institute]- IDIBELL, L'Hospitalet de Llobregat, Barcelona 08907, Spain. jmiro@bellvitgehospital.cat.

ABSTRACT

Background: Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy in adults and can be successfully cured by surgery. One of the main complications of this surgery however is a decline in language abilities. The magnitude of this decline is related to the degree of language lateralization to the left hemisphere. Most fMRI paradigms used to determine language dominance in epileptic populations have used active language tasks. Sometimes, these paradigms are too complex and may result in patient underperformance. Only a few studies have used purely passive tasks, such as listening to standard speech.

Methods: In the present study we characterized language lateralization in patients with MTLE using a rapid and passive semantic language task. We used functional magnetic resonance imaging (fMRI) to study 23 patients [12 with Left (LMTLE), 11 with Right mesial temporal lobe epilepsy (RMTLE)] and 19 healthy right-handed controls using a 6 minute long semantic task in which subjects passively listened to groups of sentences (SEN) and pseudo sentences (PSEN). A lateralization index (LI) was computed using a priori regions of interest of the temporal lobe.

Results: The LI for the significant contrasts produced activations for all participants in both temporal lobes. 81.8% of RMTLE patients and 79% of healthy individuals had a bilateral language representation for this particular task. However, 50% of LMTLE patients presented an atypical right hemispheric dominance in the LI. More importantly, the degree of right lateralization in LMTLE patients was correlated with the age of epilepsy onset.

Conclusions: The simple, rapid, non-collaboration dependent, passive task described in this study, produces a robust activation in the temporal lobe in both patients and controls and is capable of illustrating a pattern of atypical language organization for LMTLE patients. Furthermore, we observed that the atypical right-lateralization patterns in LMTLE patients was associated to earlier age at epilepsy onset. These results are in line with the idea that early onset of epileptic activity is associated to larger neuroplastic changes.

Show MeSH
Related in: MedlinePlus