Voxel-Based Analysis of Structural MRI Images Predicts Outcome Following Temporal Lobectomy
Abstract number :
1.199
Submission category :
Year :
2001
Submission ID :
418
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
M.J. Koepp, MD PhD, National Society for Epilepsy, Institute of Neurology, London, United Kingdom; F.G. Woermann, MD, Klinik Mara, Bethel Clinic, Bielefeld, Germany; A. Hammers, MD, National Society for Epilepsy, Institute of Neurology, London, United Kin
RATIONALE: To correlate post-operative seizure outcome in patients with temporal lobe epilepsy (TLE) and unilateral hippocampal sclerosis with abnormalities on pre-operative structural MRI images using an automated voxel-based, automated analysis.
METHODS: We studied 55 patients with TLE and unilateral hippocampal sclerosis (30 left-sided) and 35 healthy controls. 29 patients (mean age 30,8 years, range: 22-48 years) were seizure-free following surgery with a mean follow-up of 42 months (range: 24-60 months), 26 patients had seizures at some time following surgery (mean age: 28 years, range: 20-56 years; mean follow-up: 36 months, range: 24-60 months). T1- weighted high resolution MRI scans of the patient and control groups were spatially normalized, segmented into gray and white matter images and smoothed using a 12mm gaussian kernel. We used Statistical Parametric Mapping (SPM) to detect gray and white matter changes in the patient group when compared to control subjects, and correlated the distribution of abnormalities with the post-operative outcome.
RESULTS: We detected gray matter decreases (and corresponding white matter increases) in the ipsilateral hippocampus, ipsilateral temporal neocortex, ipsilateral thalamus and frontal lobes bilaterally. Group-comparison of seizure-free patients with patients suffering from seizures postoperatively showed a significant reduction of gray matter (and increase of white matter) in the ipsilateral hippocampus, more pronounced in those with left-sided hippocampus sclerosis (p corrected =0.046). There were no differences in quantitative hippocampal volume measurements between these two groups. When compared to controls, patients with post-operative seizures had wide-spread, mainly bifrontal increases in gray matter, whereas gray matter increases in seizure-free patients were confined predominantly to the ipsilateral anterior temporal lobe.
CONCLUSIONS: Our findings provide further evidence of widespread pathology in mesial TLE beyond the sclerotic hippocampus. In the group of patients who became seizure-free post-operatively, pre-operative structural MRI abnormalities were confined to the resected temporal lobe.[figure]
Support: This study was supported by the National Society for Epilepsy.