Substrates of Localization‐Related Epilepsies: Biologic Implications of Localizing Findings in Humans

Spencer, Susan S.

doi:10.1111/j.1528-1157.1998.tb01349.x

Cited by 66 publications

(47 citation statements)

References 90 publications

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“…For example, although both absence and tonic-clonic seizures exhibit focal features Meeren et al, 2002;Nersesyan et al, 2003), both seizure types studied in this investigation are usually classified as "generalized" (ILAE, 1981). Because epilepsy surgery is usually reserved for localization related epilepsy (Lamoureux and Spencer, 1995;Spencer, 1998), it will be essential to extend these studies to models of localization related epilepsy as well. Another limitation already mentioned is the relatively limited spatial sampling of this method compared to functional neuroimaging.…”

Section: Figmentioning

confidence: 99%

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

Nersesyan

Hermán

Erdogan³

et al. 2004

J Cereb Blood Flow Metab

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Summary:There is broad agreement that generalized tonicclonic seizures (GTCS) and normal somatosensory stimulation are associated with increases in regional CBF. However, the data regarding CBF changes during absence seizures are controversial. Electrophysiologic studies in WAG/Rij rats, an established animal model of absence seizures, have shown spikewave discharges (SWD) that are largest in the perioral somatosensory cortex while sparing the visual cortex. Recent functional magnetic resonance imaging (fMRI) studies in the same model have also shown localized increases in fMRI signals in the perioral somatosensory cortex during SWD. Because fMRI signals are only indirectly related to neuronal activity, the authors directly measured CBF and neuronal activity from specific microdomains of the WAG/Rij cortex using a specially designed probe combining laser-Doppler flowmetry and extracellular microelectrode recordings under fentanyl/haloperidol anesthesia. Using this approach, parallel increases in neuronal activity and CBF were observed during SWD in the whisker somatosensory (barrel) cortex, whereas the visual cortex showed no significant changes. For comparison, these measurements were repeated during somatosensory (whisker) stimulation, and bicuculline-induced GTCS in the same animals. Interestingly, whisker stimulation increased neuronal activity and CBF in the barrel cortex more than during SWD. During GTCS, much larger increases that included both the somatosensory and visual cortex were observed. Thus, SWD in this model produce parallel localized increases in neuronal activity and CBF with similar distribution to somatosensory stimulation, whereas GTCS produce larger and more widespread changes. The normal response to somatosensory stimulation appears to be poised between two abnormal responses produced by two physiologically different types of seizures.

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Section: Figmentioning

confidence: 99%

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

Nersesyan

Hermán

Erdogan³

et al. 2004

J Cereb Blood Flow Metab

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“…Albumin is also the main www.intechopen.com component in maintaining osmotic plasma pressure. Thus far, albumin has been shown to activate various cell types, including rat astrocytes in culture 1995; and in brain slices 1998 (Figure 4). These effects, which were initially studied in astrocytes obtained from rat pups, were recently demonstrated in humans .…”

Section: Astrocytes Are Activated By Albuminmentioning

confidence: 99%

“…• Tight-junction-associated membrane proteins, including occludins, claudins and junctional adhesion molecules 1993;Martin-Pardura et al;1998;1999). These proteins form the extracellular component of TJs.…”

Section: The Structure and Function Of The Blood-brain Barriermentioning

confidence: 99%

“…Actin binds to ZO proteins, thereby providing structural support to the endothelial cells (Haskins et al;1998).…”

Section: The Structure and Function Of The Blood-brain Barriermentioning

confidence: 99%

“…For several decades, HS has been considered the source of the electrical events that cause spontaneous seizures (Falconer, 1974;Spencer 1998). However, HS is found in approximately 40-65% of patients who undergo surgery for TLE , and whether hippocampal sclerosis is the cause or the consequence of repeated seizures is still a matter of debate (Jefferys, 1999;Boison, 2008).…”

Section: Introductionmentioning

confidence: 99%

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The Role of Astrocytes in Epileptogenesis

Pastor¹,

Sola²

2011

Underlying Mechanisms of Epilepsy

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Cellular pathology of hilar neurons in Ammon's horn sclerosis

Zuschratter²,

et al. 1999

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In addition to functionally affected neuronal signaling pathways, altered axonal, dendritic, and synaptic morphology may contribute to hippocampal hyperexcitability in chronic mesial temporal lobe epilepsies (MTLE). The sclerotic hippocampus in Ammon's horn sclerosis (AHS)‐associated MTLE, which shows segmental neuronal cell loss, axonal reorganization, and astrogliosis, would appear particularly susceptible to such changes. To characterize the cellular hippocampal pathology in MTLE, we have analyzed hilar neurons in surgical hippocampus specimens from patients with MTLE. Anatomically well‐preserved hippocampal specimens from patients with AHS (n = 44) and from patients with focal temporal lesions (non‐AHS; n = 20) were studied using confocal laser scanning microscopy (CFLSM) and electron microscopy (EM). Hippocampal samples from three tumor patients without chronic epilepsies and autopsy samples were used as controls. Using intracellular Lucifer Yellow injection and CFLSM, spiny pyramidal, multipolar, and mossy cells as well as non‐spiny multipolar neurons have been identified as major hilar cell types in controls and lesion‐associated MTLE specimens. In contrast, none of the hilar neurons from AHS specimens displayed a morphology reminiscent of mossy cells. In AHS, a major portion of the pyramidal and multipolar neurons showed extensive dendritic ramification and periodic nodular swellings of dendritic shafts. EM analysis confirmed the altered cellular morphology, with an accumulation of cytoskeletal filaments and increased numbers of mitochondria as the most prominent findings. To characterize cytoskeletal alterations in hilar neurons further, immunohistochemical reactions for neurofilament proteins (NFP), microtubule‐associated proteins, and tau were performed. This analysis specifically identified large and atypical hilar neurons with an accumulation of low weight NFP. Our data demonstrate striking structural alterations in hilar neurons of patients with AHS compared with controls and non‐sclerotic MTLE specimens. Such changes may develop during cellular reorganization in the epileptogenic hippocampus and are likely to contribute to the pathogenesis or maintenance of temporal lobe epilepsy. J. Comp. Neurol. 414:437–453, 1999. © 1999 Wiley‐Liss, Inc.

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Substrates of Localization‐Related Epilepsies: Biologic Implications of Localizing Findings in Humans

Cited by 66 publications

References 90 publications

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

Relative Changes in Cerebral Blood Flow and Neuronal Activity in Local Microdomains during Generalized Seizures

The Role of Astrocytes in Epileptogenesis

Cellular pathology of hilar neurons in Ammon's horn sclerosis

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