Morphometric Analysis of the Temporal Lobe in Temporal Lobe Epilepsy

Abstract

Summary:Purpose: Using high-resolution magnetic resonance imaging (MRI), we examined the temporal neocortex and the underlying white matter in patients with unilateral temporal lobe epilepsy (TLE) and in control subjects.Methods: The images of 27 patients and 42 control subjects were registered into stereotaxic space, corrected for image intensity inhomogeneity, and automatically segmented into gray matter, white matter, and cerebrospinal fluid (CSF) over a predetermined extent of the temporal lobe. The surface between the gray matter and CSF was extracted, indices of curvature (IOC) of the surface were calculated, and a frequency histogram of the IOC was obtained.Results: There was significant bilateral reduction in the totalIn temporal lobe epilepsy (TLE), the hippocampus is believed to be the critical structure for initiating and sustaining ictal discharges. Because a favorable response to unilateral temporal lobe resection is observed in >75% of patients (1,2), much attention has been paid to the correct lateralization of the epileptogenic hippocampus. Predominantly unilateral abnormalities of the hippocampus can now be identified by visual inspection of magnetic resonance imaging (MRI) scans (3-6) or by MR relaxometry or volumetry (7-1 1) in 70-90% of patients with TLE.Far less attention has been paid to the temporal neocortex in TLE. Hardiman et al. (12) volume of the temporal lobe and in the volume of gray matter. White matter volume was significantly reduced only in the temporal lobe ipsilateral to the seizure focus. There were significant changes in the position and amplitude of peaks in the frequency histogram of the IOC.Conclusions: The volume of gray matter was negatively correlated with duration of epilepsy, suggesting that neocortical changes may be a consequence of seizures. Changes in the frequency histogram of the IOC suggested an additional alteration in the surface morphology of the temporal lobe in TLE, possibly related to sulcal widening. Key Words: Magnetic resonance imaging-Epilepsy-Cerebral cortex-Image processing-Morphometrics. also be observed (3,5,6). Moreover, interictal glucose hypometabolism predominates in the lateral temporal cortex in subjects with unilateral mesial TLE (14,15). Using high-resolution MRI scans, we performed threedimensional volumetric and morphometric analysis of the temporal neocortex and the underlying white matter in patients with TLE and in control subjects. SUBJECTS AND METHODSFifteen subjects with intractable right TLE (RTLE, 7 males), 12 subjects with intractable left TLE (LTLE, 4 males), and 42 control subjects (22 males) were studied. The mkan age .was 32 years (range 9-51 years) for patients with RTLE, 39 years (range 23-63 years) for patients with LTLE, and 27 years (range 23-63 years) for control subjects. Data on age at seizure onset and duration of the current seizure disorder, calculated as the difference between the age at which the MRI scan was performed and age at seizure onset were obtained from hospital and outpatient medical charts. The mea...

A meta-analysis on progressive atrophy in intractable temporal lobe epilepsy

“…In 18 of the latter (47.4%), 14,16,[20][21][22]24,30,[33][34][35][36][37][38]40,42,[50][51][52] no statistical approaches were implemented to correct for the effects of age. Although the remaining studies addressed aging, no consistent method was chosen: 3 reported no significant effects of age on morphometric measures in controls, 15,32,48 3 found no effect of age or no effect of age at epilepsy onset in patients, 19,29,53 2 corrected for age at onset, 18,28 5 corrected for age in patients, 17,26,47,49,54 4 utilized MRI measures adjusted for age 13,31,39,46 (based on regression models derived from controls), 1 calculated epilepsy duration/age ratios, 23 2 statistically compared chronological age effects between patients and controls. 41,45 Among the longitudinal studies, 3 were singlecohort studies of patients without controls (interscan interval ranging from 2.3 to 3.4 years 27,41,44 ).…”

Increased temporolimbic cortical folding complexity in temporal lobe epilepsy

“…Using a region of interest-based index, we previously showed ipsilateral increased curvature of the superior temporal gyrus in TLE. 21 This initial observation has since been extended in a few automated wholebrain studies of cortical complexity, with inconsistent results. [7][8][9] While our present findings appear at odds with the decreased multilobar fractal dimension previously reported, 8 the nonspecific nature of the fractal dimension measurement limits a direct comparison with our method.…”

EEG Background Delta Activity in Temporal Lobe Epilepsy: Correlation with Volumetric and Spectroscopic Imaging

“…Volumetry of the gray and white matter of the temporal lobe was carried out in 29 patients and 28 control subjects (17 men and nine women; mean age, 27 years) according to a previously published protocol (7). In brief, images were acquired on a 1.5 T gyroscan (Philips Medical System, Eindhoven, The Netherlands), by using a T,-fast field echo (repetition time [TR] 18, echo time [TE] 10; 1 acquisition average pulse sequence; flip angle, 30"; matrix size, 256 x 256; voxel size, 1 mm x 1 mm x 1 mm).…”