Primary and Secondary Spike Foci Following Depth Lesions

Proctor, Florry; Prince, David A.; Morrell, Frank

doi:10.1001/archneur.1966.00470140041006

Cited by 13 publications

(2 citation statements)

References 7 publications

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“…On the other hand, we did find that spontaneous seizures showed a propagation to the homologous regions of the opposite hemisphere and most frequently to the rhinencephalon in 45%. This seems to be in accordance with the experimental findings in animals (Guerrero-Figueroa et al, 1964; Proctor et al, 1966) that mirror foci are not limited to the cortex but have been established in limbic and other structures synaptically related to a primary subcortical focus. We know also that the commissural connections of the two cerebral hemispheres are extensive.…”

Section: Discussionsupporting

confidence: 92%

Comparative Value of Spontaneous and Chemically and Electrically Induced Seizures in Establishing the Lateralization of Temporal Lobe Seizures

et al. 1979

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Summary: A retrospective clinical study is presented which is based on 133 patients with uncontrolled temporal lobe seizures who underwent bilateral stereoelectroencephalographic exploration. The aim of the study was to evaluate quantitatively the degree of agreement among spontaneous and chemically and electrically induced seizures, as well as between each of these seizures and the spontaneous interictal activity (“spiking”). To simplify the problem, only the side of origin and not the exact site of onset of the ictal discharge within the temporal lobe was dealt with. Special attention was paid to whether or not a seizure propagated to the homotopic regions of the opposite hemisphere, thus dealing with the still controversial question of the independent secondary epileptogenic lesion or “mirror” focus in man. The clinical outcome of surgery in 64 cases of temporal lobe epilepsy in which the operation was based on the conclusions of the SEEG exploration with or without recording of spontaneous seizures confirmed the outstanding importance of the spontaneous seizures in identifying the side of the primary epileptogenic zone. The degree of positive correlation between the spontaneous and the induced seizures varied from 77% for the electrically and 60% for the chemically induced seizures. On the other hand, the spontaneous interictal activity agreed only in approximately two‐thirds of cases: best with the electrically induced and less with the spontaneous seizure. Chemically induced seizures agreed the least. The authors conclude: (1) Because of relatively frequent discrepancies between the side of onset of the seizures and the lateralization of interictal epileptic activity, the recording of seizures is of primary importance for assessing the results of the SEEG examination. (2) The recording of spontaneous seizures is preferable to that of electrically or chemically induced seizures. (3) The reliability of the lateralization suggested by electrically induced seizures is somewhat higher than that of chemically provoked seizures. (4) Special caution should be exercised in determining the lateralization of seizures with contralateral propagation. RÉSUMÉ Une étude clinique rétrospective est faite sur 133 malades présentant une épilepsie du lobe temporal résistant à la thérapeutique et ayant subi une exploration stéréo‐EEG bilatérale. Le but de ce travail est Ďévaluer quantitativement les rapports entre les différents types de crises (spontanées, induites par des moyens chimiques et par la stimulation électrique). Une corrélation a également été faite entre les différents types de crises et Ľactivité intercritique spontanea (pointes). Pour simplifier le probleme, seul le côté de la décharge critique onginelle dans le lobe temporal a été envisage. Un interet particulier a porte sur le probleme de la propagation dventuelle aux regimes homologues de l'hemisphere oppose dans le but de discuter la question controversy des lesions epileptogènes secondares indépendantes ou des “foyers en miroir” chez l'homme. Les interventi...

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Section: Discussionsupporting

confidence: 92%

Comparative Value of Spontaneous and Chemically and Electrically Induced Seizures in Establishing the Lateralization of Temporal Lobe Seizures

et al. 1979

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“…There is similar midline thalamic hypometabolism in the rat model used in this study (63). Proctor et al (65) demonstrated a well‐synchronized interaction of spike activity between the medial dorsal thalamus and the amygdala after focal application of penicillin to the amygdala, supporting the concept of a physiologic interaction of epileptiform activity between the limbic system and its thalamic contacts. One difference between the human and rat findings is the strongly lateralized abnormalities in the human, with more variable but bilateral involvement of changes in physiology and pathology in the rat models.…”

Section: Discussionsupporting

confidence: 76%

The Midline Thalamus: Alterations and a Potential Role in Limbic Epilepsy

et al. 2001

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Summary: Purpose:In limbic or mesial temporal lobe epilepsy, much attention has been given to specific regions or cell populations (e.g., the hippocampus or dentate granule cells). Epileptic seizures may involve broader changes in neural circuits, and evidence suggests that subcortical regions may play a role. In this study we examined the midline thalamic regions for involvement in limbic seizures, changes in anatomy and physiology, and the potential role for this region in limbic seizures and epilepsy Methods: Using two rat models for limbic epilepsy (hippocampal kindled and chronic spontaneous limbic epilepsy) we examined the midline thalamus for evidence of involvement in seizure activity, alterations in structure, changes in the basic in vitro physiology of the thalamic neurons. We also explored how this region may influence limbic seizures. Results:The midline thalamus was consistently involved with seizure activity from the onset, and there was significant neuronal loss in the medial dorsal and reuniens/rhomboid nuclei. In addition, thalamic neurons had changes in synaptically mediated and voltage-gated responses. Infusion of lidocaine into the midline thalamus significantly shortened afterdischarge duration.Conclusions: These observations suggest that this thalamic region is part of the neural circuitry of limbic epilepsy and may play a significant role in seizure modulation. Local neuronal changes can enhance the excitability of the thalamolimbic circuits.

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