Temporal lobe epilepsy (TLE) is among the most common chronic seizure disorders, accounting for approximately one-fourth of all cases of epilepsy. Although hippocampal sclerosis is the most common pattern of damage in TLE, there is electrophysiological and neuropathological evidence in both humans and animal models of this condition for the involvement of the parahippocampal region. / In clinical practice, the investigation and treatment of patients with epilepsy has been revolutionized by the advent of MRI, which has been demonstrated to be a reliable and accurate indicator of pathologic findings underlying epilepsy. Advances in image acquisition and processing techniques combined with detailed descriptions of anatomy and cytoarchitectonic borders of parahippocampal structures on histologic sections have created the basis for precise determination of the boundaries of these cortical areas on MRI. This dissertation presents a series of MRI studies aimed at assessing volume changes in vivo of the parahippocampal region, and further elucidating its role in the pathogenesis of TLE. / To accomplish this we developed a standardized MRI protocol to measure the volume of the parahippocampal region structures in vivo. In agreement with previous neuropathological studies (Meencke and Veith, 1991), our results showed that damage to the mesial temporal lobe involves not only the hippocampus and the amygdala, but also the parahippocampal region structures in patients with intractable TLE. Within the parahippocampal region, the entorhinal cortex was the most affected structure. We observed that the atrophy was more severe in the anterior portion of the mesial temporal lobe involving mostly the hippocampal head and body as well as the EC. This pattern of atrophy, characterized by an antero-posterior gradient of pathology, may be explained by a disruption of entorhinal-hippocampal connections. / To evaluate the clinical role of entorhinal cortex volumetry we studied groups of TLE patients with hippocampal atrophy and those with normal hippocampal volumes as well as patients with extra-temporal lobe epilepsy. / Entorhinal cortex volumetry could provide correct lateralization of the seizure focus in 73% of TLE patients with hippocampal atrophy. Entorhinal cortex atrophy seems to be specific to TLE, since we found no atrophy in other forms of epilepsy, including frontal lobe and primary generalized epilepsy. We subsequently demonstrated that entorhinal cortex atrophy ipsilateral to the seizure focus can be the only MRI sign of mesial temporal damage in 64% of patients with normal hippocampal volumes.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85081 |
| Date | January 2004 |
| Creators | Bernasconi-Ladbon, Neda |
| 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: 002166649, proquestno: AAINR06316, Theses scanned by UMI/ProQuest. |
Page generated in 0.0019 seconds