Neuroimaging and Epilepsy: State of the Art
Neuroimaging and Epilepsy: State of the Art
The sophisticated spectrum of neuroimaging modalities for epilepsy has expanded in the modern era. Although all seizure disorders are generally treated initially with antiepileptic drugs, "it is only the study of their origin and history" that ultimately leads to therapeutic success, as stated by WR Gowers in 1881. Neuroimaging modalities that allow a glimpse into the living brain now include CT, MRI, fMRI, magnetic resonance spectroscopy (MRS), magnetoencephalography (MEG), PET, and SPECT.
Improvements in neuroimaging have led to a dramatic reduction in cases of "cryptogenic" refractory partial epilepsy, where no lesion can be found despite clinical evidence of a localized seizure focus. In one study, 58% of brain lesions responsible for epilepsy were detected by CT, but the more sensitive MRI detected 83%. One lesion, a thrombosed arteriovenous malformation, was detected by CT and not MRI, demonstrating the complementary diagnostic nature of CT and MRI. Because this is an older study, it is likely that the sensitivity of both CT and MRI for intracranial lesions would be even greater now.
Many institutions have 1.5-Tesla MRI scanners, although more powerful magnets have led to 3.0-Tesla and even 7.0-Tesla MRI scanners. The added field strength produces images with greater detail and offers the opportunity to better define both normal and abnormal neuroanatomy. Cavernous angiomas, dysembryoplastic neuroepithelial tumors, gangliogliomas, low-grade intra-axial tumors, meningiomas, mixed gliomas, neurocutaneous disorders, oligodendrogliomas, and areas of traumatic brain injury may be implicated by MRI as likely seizure foci in the appropriate clinical setting.
Modern Neuroimaging
The sophisticated spectrum of neuroimaging modalities for epilepsy has expanded in the modern era. Although all seizure disorders are generally treated initially with antiepileptic drugs, "it is only the study of their origin and history" that ultimately leads to therapeutic success, as stated by WR Gowers in 1881. Neuroimaging modalities that allow a glimpse into the living brain now include CT, MRI, fMRI, magnetic resonance spectroscopy (MRS), magnetoencephalography (MEG), PET, and SPECT.
Improvements in neuroimaging have led to a dramatic reduction in cases of "cryptogenic" refractory partial epilepsy, where no lesion can be found despite clinical evidence of a localized seizure focus. In one study, 58% of brain lesions responsible for epilepsy were detected by CT, but the more sensitive MRI detected 83%. One lesion, a thrombosed arteriovenous malformation, was detected by CT and not MRI, demonstrating the complementary diagnostic nature of CT and MRI. Because this is an older study, it is likely that the sensitivity of both CT and MRI for intracranial lesions would be even greater now.
Bigger Magnet, Better View
Many institutions have 1.5-Tesla MRI scanners, although more powerful magnets have led to 3.0-Tesla and even 7.0-Tesla MRI scanners. The added field strength produces images with greater detail and offers the opportunity to better define both normal and abnormal neuroanatomy. Cavernous angiomas, dysembryoplastic neuroepithelial tumors, gangliogliomas, low-grade intra-axial tumors, meningiomas, mixed gliomas, neurocutaneous disorders, oligodendrogliomas, and areas of traumatic brain injury may be implicated by MRI as likely seizure foci in the appropriate clinical setting.
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