Rhinal Cortex Asymmetries in Patients with Mesial Temporal Sclerosis
Abstract number :
1.207
Submission category :
Year :
2001
Submission ID :
912
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
C.E. O[ssquote]Brien, MA(Clin Neuropsy), Psychology, The University of Melbourne, Parkville, Victoria, Australia; S.C. Bowden, PhD, Psychology, The University of Melbourne, Parkville, Victoria, Australia; S.J. Vogrin, BAppliSc (Hons), Victorian Epilepsy C
RATIONALE: The rhinal cortex, comprising the entorhinal (ErC) and perirhinal (PrC) cortices, is one component of the limbic system which may be affected in patients with epilepsy and other temporal lobe pathologies. The current study extends quantitative examination of the limbic system through development and validation of volumetric protocols to measure the ErC and PrC.
METHODS: Volumetric protocols for both ErC and PrC are described. Volumes were calculated from MRI studies using ANALYZE 7.5 and based on detailed anatomical definitions developed for the study. Data from 61 patients with unilateral mesial temporal sclerosis (MTS: 33 left, 28 right) and 20 neurologically normal controls were initially analysed using three, 2-way ANOVAs to compare volumes of hippocampus, ErC and PrC. Subsequently, a 4-way ANOVA was used to examine effects of side of MTS, hemisphere, structure and handedness on volume in patients only.
RESULTS: Inter-rater reliabilities for the ErC and PrC volume protocols were found to be high (range .86-.92). Ipsilateral hippocampal volume was reduced in patients with MTS, while contralateral volume did not differ significantly from controls. In the patients, rhinal cortex volumes were reduced as a function of laterality of disease. In left MTS patients, PrC volume was reduced, but only in the left hemisphere, while ErC volume was bilaterally reduced. In right MTS patients, right hemisphere ErC volume was reduced, while PrC volumes did not differ from controls in either hemisphere. In the patients, a significant 4-way interaction was found between side of MTS, hemisphere, structure and handedness. Post-hoc contrasts showed that in left MTS patients, handedness affected hippocampal and PrC volumes, left hemisphere volumes being larger in left handers than right handers. For right MTS patients, handedness affected ErC volume, right hemisphere volume being larger in right handers.
CONCLUSIONS: This quantitative study is the first to demonstrate reliable in vivo evidence of morphometric changes in both ErC and PrC in a substantial number of patients with unilateral MTS. The novel finding of a relationship between handedness, structure and disease status in these patients may suggest a role for cerebral dominance in modulating the expression of MTS. Further, the data provide preliminary support for a functional distinction within the limbic system, whereby the role of the PrC may differ from that of the ErC.
Support: Australian Research Council Grant to Stephen Bowden and Mark Cook.