Interictal spike localization using a standard realistic head model: simulations and analysis of clinical data

Silva, C; Almeida, Rita; Oostendorp, Thom F.; Ducla-Soares, E.; Foreid, John Peter; Pimentel, Teresa

doi:10.1016/s1388-2457(99)00025-5

Cited by 20 publications

(12 citation statements)

References 16 publications

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“…The accurate localization of epileptogenic foci for the children is especially critical to distinguish the functional brain areas on the large extratemporal lobes from the pathological structures. The RG head model is reported to be able to increase the accuracy of the dipole localization for the interictal spikes (Silva et al, 1999). In another work (Herrendorf et al, 2000), by using the RG head model, the origin of interictal epileptiform discharges was localized to the primary epileptogenic zone in cases of extratemporal epileptogenesis.…”

Section: Discussionmentioning

confidence: 99%

“…Studies have shown that, assuming a single dipole source model, the average error reflected by the difference between the locations of the calculated dipole and the intracranial source was 10mm for a four-shell spherical head model (Cohen et al, 1990), and 8.5 mm for a three-shell realistic model (Homma et al, 1994). Previous work has shown that the use of realistic geometry (RG) head models is able to increase the dipole localization accuracy for epileptiform spikes compared with the spherical head model (Silva et al, 1999). And another study reported that use of the RG head model increased source localization accuracy as compared with that using the 3-sphere head model (Roth et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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Noninvasive cortical imaging of epileptiform activities from interictal spikes in pediatric patients

et al. 2011

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Improved non-invasive localization of the epileptogenic foci prior to epilepsy surgery would improve surgical outcome in patients with partial seizure disorders. A critical component for the identification of the epileptogenic brain is the analysis of electrophysiological data obtained during ictal activity from prolonged intracranial recordings. The development of a noninvasive means to identify the seizure onset zone (SOZ) would thus play an important role in treating patients with intractable epilepsy. In the present study, we have investigated non-invasive imaging of epileptiform activity in patients with medically intractable epilepsy by means of a cortical potential imaging (CPI) technique. Eight pediatric patients (1M/7F, ages 4-14 year) with intractable partial epilepsy were studied. Each patient had multiple (6 to 14) interictal spikes (IIS) subjected to the CPI analysis. Realistic geometry boundary element head models were built using each individual's MRI in order to maximize the imaging precision. CPI analysis was performed on the IISs, and extrema in the estimated CPI images were compared with SOZs as determined from the ictal electrocorticogram (ECoG) recordings, as well as the resected areas in the patients and surgical outcomes. The distances between the maximum cortical activities of the IISs reflected by the estimated cortical potential distributions and the SOZs were determined to quantitatively evaluate the performance of the CPI in localizing the epileptogenic zone. Ictal ECoG recordings revealed that six patients exhibited a single epileptogenic focus while two patients had multiple foci. In each patient, the CPI results revealed an area of activity overlapping with the SOZs as identified by ictal ECoG. The distance from the extreme of the CPI images at the peak of IIS to the nearest intracranial electrode associated with the onset of the ictal activity was evaluated for each patient and the averaged distance was 4.6 mm. In the group of patients studied, the CPI imaged epileptogenic foci were within the resected areas. According to the follow-up of the eight patients included, two were seizure free and six had substantial reduction in seizure frequency. These promising results demonstrate the potential for noninvasive localization of the epileptogenic focus from interictal scalp EEG recordings. Confirmation of our results may have a significant impact on the process of presurgical planning in pediatric patients with intractable epilepsy by dramatically reducing or potentially eliminating the use of intracranial recording.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Noninvasive cortical imaging of epileptiform activities from interictal spikes in pediatric patients

et al. 2011

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“…In this work, two different models for the head were used: a four concentric spherical model, approximating the brain, the CSF, the skull, and the scalp; and a standard realistic head model based on the geometrical structure of a plastic skull model [29], consisting of a set of three layers which model the brain, the skull, and the scalp.…”

Section: Head Modelsmentioning

confidence: 99%

“…For the radii of the spheres, we used the following values: 7.0, 7.2, 7.8, and 8.2 cm [29,31]. For the electric conductivities, we used the following values: 0.20, 1.3, 0.016, and 0.20 Sm -1 for the brain, the CSF, the skull, and the scalp, respectively [22,30].…”

Section: Head Modelsmentioning

confidence: 99%

A simple method for calculating the depth of EEG sources using minimum norm estimates (MNE)

Pinto

Quintão

2007

Med Bio Eng Comput

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Neural source localization using electroencephalographic data is usually performed using either dipolar models or minimum norm based techniques. While the former demands a priori information about the number of active sources and is particularly suitable for generators, which occupy small pieces of cortical tissue, the major drawbacks of the second approach are its dependence on the uncorrelated noise, and its tendency to localize the sources at the surface. In this paper, a simple mathematical procedure, based on the behavior of the dispersion of the minimum norm solutions, is introduced, in order to estimate the depth of the sources. The correct position of the active generators is obtained using successively deeper surfaces instead of the application of a regularization matrix, as is commonly described in the bibliography. The evaluation of this technique is performed using single and double dipolar simulated generators and two different models for the head: spherical and realistic. The results yield a mean accuracy of about 10 mm for the most disadvantageous situations studied and thus, this method seems to be very promising to handle the depth of the neural generators.

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“…Despotovic model results in a dipole location error [2], [3]. This is particularly important when studied sources are located in the occipital or temporal lobes [4].…”

Section: Introductionmentioning

confidence: 99%

A realistic volume conductor model of the neonatal head: Methods, challenges and applications

Despotović

Vansteenkiste

Philips

2013

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

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Developing a realistic volume conductor head model is an important step towards a non-invasive investigation of neuro-electrical activity in the brain. For adults, different volume conductor head models have been designed and successfully used for electroencephalography (EEG) source analysis. However, creating appropriate neonatal volume conductor head model for EEG source analysis is a challenging task mainly due to insufficient knowledge of head tissue conductivities and complex anatomy of the developing newborn brain. In this work, we present a pipeline for modeling a realistic volume conductor model of the neonatal head, where we address the modeling challenges and propose our solutions. We also discuss the use of our realistic volume conductor head model for neonatal EEG source analysis.

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Interictal spike localization using a standard realistic head model: simulations and analysis of clinical data

Cited by 20 publications

References 16 publications

Noninvasive cortical imaging of epileptiform activities from interictal spikes in pediatric patients

Noninvasive cortical imaging of epileptiform activities from interictal spikes in pediatric patients

A simple method for calculating the depth of EEG sources using minimum norm estimates (MNE)

A realistic volume conductor model of the neonatal head: Methods, challenges and applications

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