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.]



Further articles in this publication

Clinical Neuroscience

[Critical analysis of types and objectives of phamacological trials]


[Antiepileptic drug randomized controlled trial (RCT) design has been criticized in the near past. Designs emphasize conventions and regulations more than clinical aspects. In the new study that scrutinized RCT patient recruitment has also raised important ethical issues. The time has come when changes in RCT design seem imperative.]

Clinical Neuroscience

[Functional magnetic resonance imaging for cortical mapping in epilepsy]

KOZÁK Lajos Rudolf, TÓTH Vivien, BARSI Péter, RUDAS Gábor

[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

[Neuropsychological methods and trends in epilepsy management]


[Neuropsychological assessment makes its own valuable contribution to diagnosis in epilepsy, and the integration of those findings with the data from multiple sources provides the most comprehensive picture for a given epilepsy patient. The objective of this paper is to define and summarize the role and methods of neuropsychological assessment, and to present recommendations on themes for future clinical research in the neuropsychology of epilepsy.]

Clinical Neuroscience

[LORETA (Low Resolution Electromagnetic Tomography): A three-dimensional EEG source localization method]


[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.]

Clinical Neuroscience

[New generation antiepileptic drugs: what do they offer in terms of improved tolerability and safety?]

BIHARI Katalin

All articles in the issue

Related contents

Clinical Neuroscience

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


[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



[Aim of the study - Presentation of functional MRI performed at low magnetic field (1 Tesla) for planning microsurgical operation in a patient suffering from tumor close to an eloquent brain area. Methods - Microsurgical removal navigated by frameless stereotaxy of an intrinsic tumor located in eloquent area is indicated if speech function is not damaged, i.e. exact localisation and relationship of the tumor and speech area can be defined. Before operation an optimized EPI based 2D sequence was applied to yield functional MR images. At the planning of the operation the paradigm used for the localization of the sensory language cortex contained passive listening to a text. Control investigations were performed one month postoperatively. A specific psychological test, as an additional investigation to estimate the accurate level of the sensory language function, was also conducted. Results - Low resolution (matrix of 64×64) functional MR images visualized sensory speech center and auditory cortex satisfactorily. The scans showed clearly that the Wernicke's region was situated just above the tumor (WHO grade II glioma), and this finding increased the safety of intraoperative localization and reduced the risk of morbidity. Control examinations revealed minimal decrease in sensory language function, however, it was not noticeable for either the patient or her surroundings. Conclusion - Optimized functional MR imaging performed at low magnetic field can support planning of neurosurgical operations and reduce the morbidity of microsurgical interventions.]

Clinical Neuroscience

[Intracranial EEG monitoring methods]

TÓTH Márton, JANSZKY József

[Resective surgery is considered to be the best option towards achieving seizure-free state in drug-resistant epilepsy. Intracranial EEG (iEEG) is necessary if the seizure-onset zone is localized near to an eloquent cortical area, or if the results of presurgical examinations are discordant, or if an extratemporal epilepsy patient is MRI-negative. Nowadays, 3 kinds of electrodes are used: (1) foramen ovale (FO) electrodes; (2) subdural strip or grid electrodes (SDG); (3) deep electrodes (stereo-electroencephalographia, SEEG). The usage of FO electrode is limited to bitemporal cases. SDG and SEEG have a distinct philosophical approach, different advantages and disadvantages. SDG is appropriate for localizing seizure-onset zones on hemispherial or interhemispherial surfaces; it is preferable if the seizure-onset zone is near to an eloquent cortical area. SEEG is excellent in exploration of deeper cortical structures (depths of cortical sulci, amygdala, hippocampus), although a very precise planning is required because of the low spatial sampling. The chance for seizure-freedom is relatively high performing both methods (SDG: 55%, SEEG: 64%), beside a tolerable rate of complications.]

Clinical Neuroscience

[Endo-sonographic anatomy of the ventricular system]


[A preclinical cadaver study was performed to test a transendoscopic sonographic probe for neurosurgery. In 25 fresh post-mortem adult human cadaver with a total of 39 endo-sonographic dissections in the ventricular system were carried out. A sonograph with an outer diameter of 6 F was used and radial sonograms were made by a realtime image technique. First results showed precise imaging, comparable to a CT in a neighbouring area of 3 cm. In this publication, the authors describe the endo-neurosonographic anatomy of the ventricular system. The sonographic probe was advanced through the working canal of a ventriculoscope, then the endoscopic and sonographic imaging were compared. Results were documented by paralell sonographic and endoscopic photo and video recordings. Based on the authors experience, it is revealed that the additional sonographic view could also be used as a navigation tool.]

Clinical Neuroscience

[Interhemispheric propagation of seizures in mesial temporal lobe epilepsy]

ERÕSS Loránd, ENTZ László, FABÓ Dániel, JAKUS Rita, SZŰCS Anna, RÁSONYI György, KELEMEN Anna, BARCS Gábor, JUHOS Vera, BALOGH Attila, BARSI Péter, CLEMENS Zsófia, HALÁSZ Péter

[Objectives - To investigate interhemispheric propagation of mesial temporal lobe epilepsy seizures in patients undergoing long-term video-EEG monitoring with combined scalp and foramen ovale electrodes. Aim of the study - To reveal possible interhemispheric propagation patterns in mesial temporal lobe epilepsy, to improve presurgical evaluation of temporal epileptic patients. Methods - Sixty-five seizures from 20 patients were analyzed. We defined two contralateral seizure propagation patterns: Type I for those seizures that spread to the contralateral foramen ovale electrodes earlier than to the contralateral scalp electrodes, and type II for the opposite. Participants - Twenty drug resistant epileptic patients were investigated in frame of their presurgical evaluation. Results - The majority of seizures (80%) were classified as type I. Inter-foramen ovale electrode propagation time was significantly shorter for type I compared to type II seizures. Ninety percent of patients had either type I or type II seizures only. Patients with type I seizures significantly more often had mesiotemporal structural alterations evident on magnetic resonance imaging scans, and became more often seizure-free after surgery compared to patients with type II seizures whose surgical outcome was less favorable or surgery could not be indicated because of independent bilateral ictal seizure-onset. Conclusions - The two types of contralateral propagation patterns we are describing seem to represent two subtypes of mesial temporal lobe epilepsy with different morphological and prognostic features. The predominance of type I over type II seizures together with shorter propagation times for type I seizures indicate a role of a more direct and dominant interhemispheric pathway in mesial temporal lobe epilepsy.]