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  • Key words Epilepsy  (3)
  • Key words Ammon’s horn sclerosis  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Perilesional neurochemical changes in focal epilepsies (1996)
    Springer
    Acta neuropathologica 91 (1996), S. 376-384 
    Details
    ISSN: 1432-0533
    Keywords: Key words Epilepsy ; Immunohistochemistry ; Neurotransmitter ; Pathology ; Tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Circumscribed cortical lesions are frequently encountered in patients with chronic focal epilepsies. However, the pathogenesis of seizures is poorly understood. To determine whether the perilesional cortex shows evidence for abnormal excitatory or inhibitory neurochemical activity, we immunohistochemically examined the distribution of the α1 subunit of the GABAA receptor (GABAR), the N-methyl-d-aspartate receptor subunit 1 (NR1), and glutamate decarboxylase (GAD) in 30 surgical specimens of neocortical epilepsy-associated lesions. These comprised 7 low-grade gliomas, 2 gangliogliomas, 2 dysembryoplastic neuroepithelial tumors, 4 glioneuronal malformations, 5 vascular malformations, and 10 glial or gliomesodermal scars. All specimens originated from patients with chronic pharmacoresistant epilepsy. In 73% of the cases there was a distinct difference in immunoreactivity for GABAR, GAD or NR1 between the perilesional zone and the normal cortex. With each of the markers there was reduced perilesional immunoreactivity in 30% of the specimens. Increased staining for GAD was seen in 17%, for GABAR in 7%, and for NR1 in 13% of the cases. The age at surgery, onset of seizures, epilepsy duration, and maximal seizure frequency did not differ significantly between patients with normal and those with altered perilesional immunoreactivity patterns. Although the perilesional changes for GAD, GABAR or NR1 were heterogeneous, they suggest a disturbed balance between excitatory and inhibitory synaptic transmission which may contribute to the pathogenesis of focal seizures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050439
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  • 2
    Electronic Resource
    Electronic Resource
    Neuronal loss and gliosis of the amygdaloid nucleus in temporal lobe epilepsy (1997)
    Springer
    Acta neuropathologica 93 (1997), S. 606-610 
    Details
    ISSN: 1432-0533
    Keywords: Key words Ammon’s horn sclerosis ; Amygdala ; Hippocampus ; Pathology ; Seizures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although clinical and electrophysiological evidence indicates that the amygdaloid body plays an important role in the pathogenesis of temporal lobe epilepsy, there are very few detailed data on histopathological changes in this nucleus in epilepsy patients. In the present study we have examined the lateral nucleus of the amygdaloid body in 70 surgical specimens from patients with temporal lobe epilepsy and in 10 control specimens with respect to neuronal density and gliosis. The results were compared to the neuronal loss in the hippocampal formation. Our goal was to examine the pathological alterations of the amygdaloid body and their correlation with other morphological changes in temporal lobe epilepsy. In epilepsy patients with Ammon’s horn sclerosis or focal lesions of the temporal lobe, the neuronal density of the lateral amygdaloid nucleus was significantly decreased as compared to normal controls (P 〈 0.001). Overall, the mean volumetric density in epilepsy patients was reduced to 59% of that in normal individuals. There was no correlation between the neuronal density in the lateral amygdaloid nucleus and that in the different segments of the hippocampal formation or to the age at onset or the duration of epilepsy. The neuronal loss of the amygdaloid nucleus correlated well with the presence of fibrillary gliosis. Our findings demonstrate that the amygdaloid body is severely altered in most patients with temporal lobe epilepsy and that these changes are independent of those in the hippocampus. The presence of neuronal loss and gliosis in the amygdaloid nucleus of patients with focal lesions but no Ammon’s horn sclerosis is compatible with an involvement of the amygdala in secondary epileptogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050658
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  • 3
    Electronic Resource
    Electronic Resource
    An increase of hippocampal calretinin-immunoreactive neurons correlates with early febrile seizures in temporal lobe epilepsy (1999)
    Springer
    Acta neuropathologica 97 (1999), S. 31-39 
    Details
    ISSN: 1432-0533
    Keywords: Key words Ammon’s horn sclerosis ; Calcium-binding proteins ; Cajal-Retzius cells ; Development ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Numerous studies indicate that initial precipitating injuries (IPI) such as febrile seizures during early childhood may play a pivotal role in the pathogenesis of temporal lobe epilepsy (TLE) and Ammon’s horn sclerosis (AHS). Previous data demonstrate an increase of horizontally oriented neurons in molecular layers of hippocampal subfields, which are immunoreactive for calretinin (CR-ir) and resemble Cajal-Retzius-like cells. Cajal-Retzius cells are transiently expressed in the murine developing hippocampus and are critically involved in neuronal pattern formation. Here we investigated a potential relationship between the distribution of horizontally oriented calretinin-immunoreactive neurons and the clinical history of TLE patients with AHS. Horizontally oriented neurons in the molecular layer of the hippocampal formation have been visualized by antibodies against the calcium-binding proteins calretinin and calbindin D-28k. Cell counts derived from 27 epilepsy patients with AHS were compared with autopsy specimens from developing and adult normal human hippocampus (n = 26). During ontogeny, CR-ir cells showed a marked perinatal peak in the CA1 and dentate gyrus molecular layer (CA1-ML, DG-ML) followed by a gradual postnatal decline. In hippocampal specimens from TLE patients with AHS and seizure onset before the age of 4 years, significantly higher levels of CR-ir neurons in CA1-ML (P = 0.05) and DG-ML (P 〈 0.05) were encountered than in AHS patients without precipitating seizures or with an uneventful early medical history. However, all three groups had higher levels of CR-ir neurons compared to adult controls obtained at autopsy (P 〈 0.01). In addition, AHS specimens showed increased CR-ir neuropil staining throughout the DG-ML compared with the restricted distribution of CR-ir fibers within the superficial granule cell layer visible in controls. These findings suggest that a condsiderable number of TLE patients with AHS display signs of impaired hippocampal maturation and circuitry formation as indicated by increased numbers of Cajal-Retzius like cells. It remains to be elucidated, how these changes contribute to the pathogenesis of TLE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050952
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  • 4
    Electronic Resource
    Electronic Resource
    Hippocampal loss of the GABAA receptor a1 subunit in patients with chronic pharmacoresistant epilepsies (1994)
    Springer
    Acta neuropathologica 88 (1994), S. 313-319 
    Details
    ISSN: 1432-0533
    Keywords: Key words Epilepsy ; Gamma aminobutyric acid ; Receptor ; Ammon's horn sclerosis ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Alterations of gamma aminobutyric acid (GABA)-mediated neurotransmission have been implicated in the pathogenesis of epilepsies. Here we examine the distribution of the GABAA receptor in the hippocampus of 78 surgical specimens from patients with chronic pharmacoresistant focal epilepsies. The receptor was localized immunohistochemically with the monoclonal antibody bd-24 which selectively recognizes the α1 subunit of the GABAA receptor. The results were compared with the receptor distribution of 28 normal hippocampal specimens obtained at autopsy. In the great majority of the surgical specimens a loss of GABAA receptor immunoreactivity was present in CA1 (92.3  %), CA4 (78.2  %), the dentate granular cell layer (70.5  %) and the molecular layer of the dentate gyrus (65.4  %). The subiculum revealed a normal staining pattern in all but 4 cases. In no instance did we observe an increase of immunoreactivity in any region or cell population. The decrease of GABAA receptor immunoreactivity was closely related to neuronal loss in the respective specimen and to Ammon's horn sclerosis. There was no correlation between GABAA receptor loss and the patient's age at surgery, duration of seizures, age at onset of seizures and to the presence or absence of secondary generalized tonic clonic seizures. The data suggest that the observed loss of GABAA receptor immunoreactivity is a secondary phenomenon rather than an event that is relevant for the pathogenesis of epileptic seizures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310375
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  • 5
    Electronic Resource
    Electronic Resource
    Neural antigens in oligodendrogliomas and dysembryoplastic neuroepithelial tumors (1997)
    Springer
    Acta neuropathologica 94 (1997), S. 436-443 
    Details
    ISSN: 1432-0533
    Keywords: Key words Epilepsy ; Immunohistochmistry ; Receptor ; Neurotransmitter ; Tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Oligodendrogliomas and dysembryoplastic neuroepithelial tumors (DNT) are frequently associated with epilepsies and share the presence of oligodendroglia-like cells with small round nuclei and optically empty perinuclear halos. The two entities may be difficult to discriminate in small surgical specimens and the origin and differentiation of the oligodendroglia-like cells has been controversial. To better characterize and distinguish the two entities we examined 25 oligodendrogliomas and 16 DNT immunohistochemically for the presence of the proliferation–associated Ki-67 antigen and the following neural antigens: the α1 subunit of the GABAA receptor (GABAR), N-methyl-d-aspartate receptor subunit 1 (NR1), glutamate decarboxylase, neuronal nuclei antigen (NeuN), the embryonal form of the neural cell adhesion molecule (E-NCAM), synaptophysin, neurofilament protein (NFP), and glial fibrillary acidic protein (GFAP). Labeling indices for the Ki-67 antigens were generally less than 1% in both entities. In oligodendrogliomas, more than 50% of the tumors contained NR1- or E-NCAM-positive oligodendroglia-like cells, whereas NeuN-positive tumor cells were never observed. In DNT, NeuN- and NR1-positive tumor cells were present in 44% of the cases each; E-NCAM positivity was less frequent (19%). In both entities, immunoreactivity of oligodendroglia-like cells for GABAR and glutamate decarboxylase was rare and positivity for synaptophysin and neurofilament protein was absent. Some GFAP-positive tumor cells were present in approximately 70% of the cases in both entities. Except for the striking difference in NeuN positivity, the immunohistochemical profiles of oligodendroglia-like cells in DNT and oligodendrogliomas largely overlap and the differential diagnosis continues to rest mainly on conventional histopathological features. The NR1 positivity and the recently reported generation of action potentials in oligodendroglioma cells are consistent with neuronal differentiation and may contribute to the high epileptogenic potential of oligodendrogliomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050730
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