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Clinical applications of functional MRI in epilepsy.

Kesavadas C, Thomas B - Indian J Radiol Imaging (2008)

Bottom Line: It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively.Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized.Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy.

View Article: PubMed Central - PubMed

Affiliation: Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum - 695 011, India.

ABSTRACT
The role of functional MRI (fMRI) in the presurgical evaluation of patients with intractable epilepsy is being increasingly recognized. Real-time fMRI is an easily performable diagnostic technique in the clinical setting. It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively. Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized. This review article describes the biophysical basis of blood-oxygen-level-dependent (BOLD) fMRI and the methodology adopted, including the design, paradigms, the fMRI setup, and data analysis. Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy. Finally, the special issues involved in fMRI of epilepsy patients and the various challenges of clinical fMRI are detailed.

No MeSH data available.


Related in: MedlinePlus

Three patients with seizures due to a gliotic area. In the first patient, the gliosis was due to an old healed granuloma. Axial FLAIR and inline BOLD coregistered on 3D-FLASH (A, B) images, obtained after left hand movement vs rest, show that the right motor hand area is well away from the gliotic area (white arrow). In the second patient, the gliosis was postsurgical. Inline BOLD fMRI coregistered on 3D-FLASH images, obtained after bilateral hand movement vs rest and tongue movement vs rest (C, D) show that the left hand area is placed closer to the gliotic area, while the face area on the left side is not seen. The left hand activation area is pulled towards the gliotic area. The third patient showed gliosis in the occipital cortex probably secondary to perinatal hypoglycemia. Sagittal FLAIR and inline BOLD fMRI coregistered on axial FLAIR images obtained after visual stimulation show minimal activation in the gliotic left occipital cortex. Most of the visual activation is from the right side. All the three patients, in whom fMRI helped in surgical planning, underwent resection of the gliotic area without developing neurological deficits
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Figure 0008: Three patients with seizures due to a gliotic area. In the first patient, the gliosis was due to an old healed granuloma. Axial FLAIR and inline BOLD coregistered on 3D-FLASH (A, B) images, obtained after left hand movement vs rest, show that the right motor hand area is well away from the gliotic area (white arrow). In the second patient, the gliosis was postsurgical. Inline BOLD fMRI coregistered on 3D-FLASH images, obtained after bilateral hand movement vs rest and tongue movement vs rest (C, D) show that the left hand area is placed closer to the gliotic area, while the face area on the left side is not seen. The left hand activation area is pulled towards the gliotic area. The third patient showed gliosis in the occipital cortex probably secondary to perinatal hypoglycemia. Sagittal FLAIR and inline BOLD fMRI coregistered on axial FLAIR images obtained after visual stimulation show minimal activation in the gliotic left occipital cortex. Most of the visual activation is from the right side. All the three patients, in whom fMRI helped in surgical planning, underwent resection of the gliotic area without developing neurological deficits

Mentions: In our series of patients, fMRI results matched those from intraoperative cortical stimulation, for lesions in, or close to the eloquent cortex. They also matched Wada test results for language hemispheric dominance.[18] Eloquent cortex mapping was performed in epilepsy patients with tumor, gliosis, or malformation of cortical development in, or close to the eloquent cortex. Our neurosurgeons have found fMRI for eloquent cortex mapping most useful in patients with gliosis, in whom the distortion in anatomy makes prediction of the eloquent cortex extremely difficult. Usually gliotic lesions pull the functionally active areas towards them. Space-occupying lesions such as tumors of the brain primarily displace the functional cortex. For this reason, resection within the boundaries of a lesion should not directly damage the eloquent cortex and result in a significant deficit. In contrast, functional reorganization may or may not happen within the dysplastic cortex in malformations of cortical development. Our study using fMRI on cortical malformations showed that functional reorganization is unpredictable in these lesions.[26] The dysplastic cortex can retain useful brain function. The following three cases illustrate the usefulness of fMRI in selecting patients for surgery, tailoring surgical resection, and in predicting the postsurgical outcome [Figures 6–8].


Clinical applications of functional MRI in epilepsy.

Kesavadas C, Thomas B - Indian J Radiol Imaging (2008)

Three patients with seizures due to a gliotic area. In the first patient, the gliosis was due to an old healed granuloma. Axial FLAIR and inline BOLD coregistered on 3D-FLASH (A, B) images, obtained after left hand movement vs rest, show that the right motor hand area is well away from the gliotic area (white arrow). In the second patient, the gliosis was postsurgical. Inline BOLD fMRI coregistered on 3D-FLASH images, obtained after bilateral hand movement vs rest and tongue movement vs rest (C, D) show that the left hand area is placed closer to the gliotic area, while the face area on the left side is not seen. The left hand activation area is pulled towards the gliotic area. The third patient showed gliosis in the occipital cortex probably secondary to perinatal hypoglycemia. Sagittal FLAIR and inline BOLD fMRI coregistered on axial FLAIR images obtained after visual stimulation show minimal activation in the gliotic left occipital cortex. Most of the visual activation is from the right side. All the three patients, in whom fMRI helped in surgical planning, underwent resection of the gliotic area without developing neurological deficits
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2747426&req=5

Figure 0008: Three patients with seizures due to a gliotic area. In the first patient, the gliosis was due to an old healed granuloma. Axial FLAIR and inline BOLD coregistered on 3D-FLASH (A, B) images, obtained after left hand movement vs rest, show that the right motor hand area is well away from the gliotic area (white arrow). In the second patient, the gliosis was postsurgical. Inline BOLD fMRI coregistered on 3D-FLASH images, obtained after bilateral hand movement vs rest and tongue movement vs rest (C, D) show that the left hand area is placed closer to the gliotic area, while the face area on the left side is not seen. The left hand activation area is pulled towards the gliotic area. The third patient showed gliosis in the occipital cortex probably secondary to perinatal hypoglycemia. Sagittal FLAIR and inline BOLD fMRI coregistered on axial FLAIR images obtained after visual stimulation show minimal activation in the gliotic left occipital cortex. Most of the visual activation is from the right side. All the three patients, in whom fMRI helped in surgical planning, underwent resection of the gliotic area without developing neurological deficits
Mentions: In our series of patients, fMRI results matched those from intraoperative cortical stimulation, for lesions in, or close to the eloquent cortex. They also matched Wada test results for language hemispheric dominance.[18] Eloquent cortex mapping was performed in epilepsy patients with tumor, gliosis, or malformation of cortical development in, or close to the eloquent cortex. Our neurosurgeons have found fMRI for eloquent cortex mapping most useful in patients with gliosis, in whom the distortion in anatomy makes prediction of the eloquent cortex extremely difficult. Usually gliotic lesions pull the functionally active areas towards them. Space-occupying lesions such as tumors of the brain primarily displace the functional cortex. For this reason, resection within the boundaries of a lesion should not directly damage the eloquent cortex and result in a significant deficit. In contrast, functional reorganization may or may not happen within the dysplastic cortex in malformations of cortical development. Our study using fMRI on cortical malformations showed that functional reorganization is unpredictable in these lesions.[26] The dysplastic cortex can retain useful brain function. The following three cases illustrate the usefulness of fMRI in selecting patients for surgery, tailoring surgical resection, and in predicting the postsurgical outcome [Figures 6–8].

Bottom Line: It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively.Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized.Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy.

View Article: PubMed Central - PubMed

Affiliation: Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum - 695 011, India.

ABSTRACT
The role of functional MRI (fMRI) in the presurgical evaluation of patients with intractable epilepsy is being increasingly recognized. Real-time fMRI is an easily performable diagnostic technique in the clinical setting. It has become a noninvasive alternative to intraoperative cortical stimulation and the Wada test for eloquent cortex mapping and language lateralization, respectively. Its role in predicting postsurgical memory outcome and in localizing the ictal activity is being recognized. This review article describes the biophysical basis of blood-oxygen-level-dependent (BOLD) fMRI and the methodology adopted, including the design, paradigms, the fMRI setup, and data analysis. Illustrative cases have been discussed, wherein the fMRI results influenced the seizure team's decisions with regard to diagnosis and therapy. Finally, the special issues involved in fMRI of epilepsy patients and the various challenges of clinical fMRI are detailed.

No MeSH data available.


Related in: MedlinePlus