Clinical Neuroscience

[The role of neuronavigation in the preoperative invasive evaluation and surgical treatment of drug resistant epilepsies]

ERÕSS Loránd

SEPTEMBER 23, 2011

Clinical Neuroscience - 2011;64(09-10)

[For localizing the epileptogenic zone in cases of focal epilepsies detailed clinical investigations, imaging studies and electrophysiological methods are in use. In lesional epilepsies the intrapreoperatíve localization of the lesion and it’s location to the eloquent cortex is essential for the neurosurgeon. The development in image guided neurosurgery lead us to use neuronavigation systems to localize intracerebral lesions or functionally eloquent cortical areas or subcortical pathways during surgery. Neuronavigation brought changes in preoperatíve evaluation and in resective surgery in epilepsy as well. In this article we describe the basics of neuronavigation and enhance the advantages of the technique in epilepsy surgery during the presurgical evaluation with invasive electrodes, in resective surgery and DBS for epilepsy.]

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Clinical Neuroscience

[Functional magnetic resonance imaging for cortical mapping in epilepsy]

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[It is not only the total curative resection of pathological tissue or the minimization of symptoms to be considered in epilepsy surgery or other neurosurgical procedures, it is equally desirable to maintain the best possible quality of life. Cortical mapping methods can help achieve this goal by delineating eloquent areas, i.e. brain regions that are vital for providing an acceptable quality of life, albeit not prone to compensatory reorganization. These areas include among others the Broca and Wernicke regions for speech, the primary motor, sensory and visual cortices. Functional MRI gained importance in the last decade as a non-invasive clinical cortical mapping technique. This method is capable of localizing cortical areas selectively activated by a given task condition. Thus, selecting appropriate tasks can help mapping eloquent brain regions. Using functional MRI provides information that is complementary to other mapping methods. Moreover, it can replace invasive methods such as the Wada test. Here, we explain the background of functional MRI, compare it to other clinical mapping methods, explain the intricacies of paradigm selection, and show the limitations of the technique while also pointing out alternative uses.]

Clinical Neuroscience

[Magnetic resonance measuring and analitic methods in epilepsy]

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[Neuroradiology and magnetic resonance imaging (MRI) as its leading tool play a basic role in the diagnostics of epilepsy. The result of the MRI examination is of utmost importance in patients with therapy resistent focal epilepsy possibly requiring neurosurgical intervention. Based on the continuously developing MRI techniques, we can use an optimal imaging protocol. Cerebral structures can be evaluated on a microanatomical level on high-resolution images with thin slices. The three-dimensional (3D) sequence has high spatial resolution, properly distinguishes cerebral grey and white matter, provides the possibility of surface rendering and volumetry, as well as an anatomical basis for other methods like tractography, functional MRI and neuronavigation. Diffusion weighted and diffusion tensor imaging (DWI, DTI) and tractography has an important role in differential diagnostics and tractography visualizes the main white matter tracts and their relation with brain pathologies. MR perfusion (MRP) provides help in differential diagnostics and may have a future role in the determination of the epileptogenic focus in multifocal pathologies. MR spectroscopy (MRS) is important in differential diagnostics, lateralization of focal epilepsy and in the confirmation of hippocampal sclerosis. Several of these methods need special hardware, software and expertise, but the basic MRI protocol for epilepsy can be implemented in all modern MR scanners of middle or high field strength.]

Clinical Neuroscience

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[The author presents a brief overview of the EEG source localization method LORETA (Low Resolution Electromagnetic Tomography) with special reference to the not widely discussed data.]

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[The methodology and objectives of registrating high frequency oscillation in epilepsy]

CLEMENS Zsófia

[Technological advances in digital EEG allowed the recording the full frequency band of the EEG. Activity beyond the traditional 0.3-70 Hz band reflects both physiological and pathological processes. High frequency activity recorded from the epileptic brain has been related to both epileptogenicity and epileptogenesis. The article reviews research avenues, clinical applications, and the methodology of detecting and quantifying high frequency activity.]

Clinical Neuroscience

[Prolonged EEG-monitoring]

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[Prolonged EEG monitoring and video-EEG monitoring are basic methods on the level of epilepsy centers. These methods are able to make differences between epilepsy and non epileptic paroxysmal manifestations like psychogenic non epileptic seizures, parasomniac phenomena, narcolepsy. The application of the method, at least the video-EEG variant, needs team work, high level organisation, highly educated staff and high tech electrographic devices. Running the method even with these requirements is beneficial from the cost-benefit aspect as well.]

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