A series of studies were undertaken with the aim of assessing the static and dynamic profiles of the most common types of epileptogenic lesions: hippocampal sclerosis and cortical developmental malformations. Neuronal metabolic dysfunction measured by proton magnetic resonance spectroscopic imaging (1H-MRSI) overlaps the structural lesion displayed by magnetic resonance imaging (MRI), The extent of neuronal metabolic dysfunction, however, tends to be wider than the MRI-visible lesion and may reflect the intrinsic nature and extent of the original epileptogenic damage. In addition, neuronal metabolic dysfunction and synchronized neuronal firing often coincide spatially and vary together in intensity possibly reflecting the severity of the epileptogenic process. / Non-foreign tissue lesional, temporal lobe epilepsy (TLE) syndrome is a heterogeneous condition, which displays a spectrum of neuronal damage. The different patterns of neuronal damage measured by MRI volumetry (MRIVol) and 1H-MRSI enable accurate probabilistic prediction of TLE lateralization and discrimination of TLE from extra-TLE. Furthermore, both MRIVol and 1H-MRSI have a prognostic value in surgical TLE patients, which can be used to streamline surgical candidates. / The neuronal damage is present in the early stages of the epileptogenic process in patients with localization related epilepsy. This process is dynamic and shows a slow progressive neuronal loss and dysfunction in TLE patients, which is not related to seizure burden. Neuronal metabolic dysfunction, lesions, spikes, cognitive decline, and psychiatric disorders are part of the epileptogenic process. These different domains parallel each other in a given time, although their pathophysiological processes are distinct. Thus seizures and neuronal damage co-exist but are not causally related. / Normalization of neuronal metabolic function is seen in post-operative seizure-free patients, with a recovery half time of six months. However, the process of neuronal recovery does not occur in patients who are seizure-free due to antiepileptic medication. The epileptogenic process causes disruption of normal neuronal network and in order to reverse this disruption the epileptogenic area must be isolated or resected surgically. The epileptic state is a translation in time of the activity of the epileptogenic process. Seizures, stereotyped behavioral manifestations, are the hallmark of the epileptogenic process, Absence of seizures, however, does not reflect inactivity of the epileptogenic process, Neuronal damage as measured by NAA/Cr can serve as a surrogate marker of the epileptogenic state.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36638 |
| Date | January 2000 |
| Creators | Li, Li Min, 1964- |
| Contributors | Arnold, D. L. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Neuroscience.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001976377, proquestno: NQ64604, Theses scanned by UMI/ProQuest. |
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