Limits...
Ictal depth EEG and MRI structural evidence for two different epileptogenic networks in mesial temporal lobe epilepsy.

Memarian N, Madsen SK, Macey PM, Fried I, Engel J, Thompson PM, Staba RJ - PLoS ONE (2015)

Bottom Line: MRI analysis found reduced cortical thickness correlated with longer duration of epilepsy.One, identified by HYP ictal onsets, chiefly involves hippocampus and is associated with excellent outcome after standardized anteromedial temporal resection, while the other also involves lateral temporal and orbitofrontal cortex and a seizure-free surgical outcome occurs less after this procedure.These results suggest that a more extensive tailored resection may be required for patients with the second type of MTLE.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States of America.

ABSTRACT
Hypersynchronous (HYP) and low voltage fast (LVF) activity are two separate ictal depth EEG onsets patterns often recorded in presurgical patients with MTLE. Evidence suggests the mechanisms generating HYP and LVF onset seizures are distinct, including differential involvement of hippocampal and extra-hippocampal sites. Yet the extent of extra-hippocampal structural alterations, which could support these two common seizures, is not known. In the current study, preoperative MRI from 24 patients with HYP or LVF onset seizures were analyzed to determine changes in cortical thickness and relate structural changes to spatiotemporal properties of the ictal EEG. Overall, onset and initial ipsilateral spread of HYP onset seizures involved mesial temporal structures, whereas LVF onset seizures involved mesial and lateral temporal as well as orbitofrontal cortex. MRI analysis found reduced cortical thickness correlated with longer duration of epilepsy. However, in patients with HYP onsets, the most affected areas were on the medial surface of each hemisphere, including parahippocampal regions and cingulate gyrus, whereas in patients with LVF onsets, the lateral surface of the anterior temporal lobe and orbitofrontal cortex showed the greatest effect. Most patients with HYP onset seizures were seizure-free after resective surgery, while a higher proportion of patients with LVF onset seizures had only worthwhile improvement. Our findings confirm the view that recurrent seizures cause progressive changes in cortical thickness, and provide information concerning the structural basis of two different epileptogenic networks responsible for MTLE. One, identified by HYP ictal onsets, chiefly involves hippocampus and is associated with excellent outcome after standardized anteromedial temporal resection, while the other also involves lateral temporal and orbitofrontal cortex and a seizure-free surgical outcome occurs less after this procedure. These results suggest that a more extensive tailored resection may be required for patients with the second type of MTLE.

No MeSH data available.


Related in: MedlinePlus

Beta maps illustrating the magnitude of the interaction between ictal EEG onset pattern and epilepsy duration on cortical gray matter thickness after controlling for age and gender.Lateral (left column) and medial surfaces (right column) of cerebral hemisphere ipsilateral (top row) and contralateral to the SOZ (bottom row). Cortical areas colored yellow, orange, and red indicate thinner GM (in mm) per year of epilepsy in patients with HYP onset seizures, whereas areas colored blue, indigo, and violet correspond to reduced GM per year of epilepsy in patients with LVF onset seizures. Shades of green depict areas of minimal or no thinning per year of disease (color-coded scale upper right corner). Permutation tests correcting for multiple comparisons were significant (ipsilateral: p = 0.037, contralateral: p = 0.037). Areas masked in white are brain areas not applicable for this analysis.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4388829&req=5

pone.0123588.g005: Beta maps illustrating the magnitude of the interaction between ictal EEG onset pattern and epilepsy duration on cortical gray matter thickness after controlling for age and gender.Lateral (left column) and medial surfaces (right column) of cerebral hemisphere ipsilateral (top row) and contralateral to the SOZ (bottom row). Cortical areas colored yellow, orange, and red indicate thinner GM (in mm) per year of epilepsy in patients with HYP onset seizures, whereas areas colored blue, indigo, and violet correspond to reduced GM per year of epilepsy in patients with LVF onset seizures. Shades of green depict areas of minimal or no thinning per year of disease (color-coded scale upper right corner). Permutation tests correcting for multiple comparisons were significant (ipsilateral: p = 0.037, contralateral: p = 0.037). Areas masked in white are brain areas not applicable for this analysis.

Mentions: The interaction between cortical thickness and epilepsy duration, expressed as reduced GM in millimeters per year of epilepsy, is depicted on the beta maps in Fig 5. In the ipsilateral hemisphere of the HYP onset group, areas with the largest reduction in thickness per year of disease were found on the medial surface that included parahippocampal gyrus, anterior cingulate gyrus, dorsomedial prefrontal cortex, and superior frontal gyrus (Fig 5B). In the LVF onset group, reduced thickness was prominent in orbitofrontal region of inferior frontal gyrus (Fig 5A), as well as anterior temporal lobe extending towards temporopolar regions (Fig 5B).


Ictal depth EEG and MRI structural evidence for two different epileptogenic networks in mesial temporal lobe epilepsy.

Memarian N, Madsen SK, Macey PM, Fried I, Engel J, Thompson PM, Staba RJ - PLoS ONE (2015)

Beta maps illustrating the magnitude of the interaction between ictal EEG onset pattern and epilepsy duration on cortical gray matter thickness after controlling for age and gender.Lateral (left column) and medial surfaces (right column) of cerebral hemisphere ipsilateral (top row) and contralateral to the SOZ (bottom row). Cortical areas colored yellow, orange, and red indicate thinner GM (in mm) per year of epilepsy in patients with HYP onset seizures, whereas areas colored blue, indigo, and violet correspond to reduced GM per year of epilepsy in patients with LVF onset seizures. Shades of green depict areas of minimal or no thinning per year of disease (color-coded scale upper right corner). Permutation tests correcting for multiple comparisons were significant (ipsilateral: p = 0.037, contralateral: p = 0.037). Areas masked in white are brain areas not applicable for this analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388829&req=5

pone.0123588.g005: Beta maps illustrating the magnitude of the interaction between ictal EEG onset pattern and epilepsy duration on cortical gray matter thickness after controlling for age and gender.Lateral (left column) and medial surfaces (right column) of cerebral hemisphere ipsilateral (top row) and contralateral to the SOZ (bottom row). Cortical areas colored yellow, orange, and red indicate thinner GM (in mm) per year of epilepsy in patients with HYP onset seizures, whereas areas colored blue, indigo, and violet correspond to reduced GM per year of epilepsy in patients with LVF onset seizures. Shades of green depict areas of minimal or no thinning per year of disease (color-coded scale upper right corner). Permutation tests correcting for multiple comparisons were significant (ipsilateral: p = 0.037, contralateral: p = 0.037). Areas masked in white are brain areas not applicable for this analysis.
Mentions: The interaction between cortical thickness and epilepsy duration, expressed as reduced GM in millimeters per year of epilepsy, is depicted on the beta maps in Fig 5. In the ipsilateral hemisphere of the HYP onset group, areas with the largest reduction in thickness per year of disease were found on the medial surface that included parahippocampal gyrus, anterior cingulate gyrus, dorsomedial prefrontal cortex, and superior frontal gyrus (Fig 5B). In the LVF onset group, reduced thickness was prominent in orbitofrontal region of inferior frontal gyrus (Fig 5A), as well as anterior temporal lobe extending towards temporopolar regions (Fig 5B).

Bottom Line: MRI analysis found reduced cortical thickness correlated with longer duration of epilepsy.One, identified by HYP ictal onsets, chiefly involves hippocampus and is associated with excellent outcome after standardized anteromedial temporal resection, while the other also involves lateral temporal and orbitofrontal cortex and a seizure-free surgical outcome occurs less after this procedure.These results suggest that a more extensive tailored resection may be required for patients with the second type of MTLE.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States of America.

ABSTRACT
Hypersynchronous (HYP) and low voltage fast (LVF) activity are two separate ictal depth EEG onsets patterns often recorded in presurgical patients with MTLE. Evidence suggests the mechanisms generating HYP and LVF onset seizures are distinct, including differential involvement of hippocampal and extra-hippocampal sites. Yet the extent of extra-hippocampal structural alterations, which could support these two common seizures, is not known. In the current study, preoperative MRI from 24 patients with HYP or LVF onset seizures were analyzed to determine changes in cortical thickness and relate structural changes to spatiotemporal properties of the ictal EEG. Overall, onset and initial ipsilateral spread of HYP onset seizures involved mesial temporal structures, whereas LVF onset seizures involved mesial and lateral temporal as well as orbitofrontal cortex. MRI analysis found reduced cortical thickness correlated with longer duration of epilepsy. However, in patients with HYP onsets, the most affected areas were on the medial surface of each hemisphere, including parahippocampal regions and cingulate gyrus, whereas in patients with LVF onsets, the lateral surface of the anterior temporal lobe and orbitofrontal cortex showed the greatest effect. Most patients with HYP onset seizures were seizure-free after resective surgery, while a higher proportion of patients with LVF onset seizures had only worthwhile improvement. Our findings confirm the view that recurrent seizures cause progressive changes in cortical thickness, and provide information concerning the structural basis of two different epileptogenic networks responsible for MTLE. One, identified by HYP ictal onsets, chiefly involves hippocampus and is associated with excellent outcome after standardized anteromedial temporal resection, while the other also involves lateral temporal and orbitofrontal cortex and a seizure-free surgical outcome occurs less after this procedure. These results suggest that a more extensive tailored resection may be required for patients with the second type of MTLE.

No MeSH data available.


Related in: MedlinePlus