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Published on: August 5, 2014
Amygdala Volumetry in Patients with Temporal Lobe Epilepsy and Normal Magnetic Resonance Imaging
Paramdeep Singh1, Rupinderjeet Kaur2, Kavita Saggar3
1Department of Radiology, Guru Gobind Singh Medical College and Hospital, Baba Farid University of Health Sciences, Faridkot, India.
Background:
It has been suggested that the pathophysiology of temporal lobe epilepsy may relate to abnormalities in various brain structures, including the amygdala. Patients with mesial temporal lobe epilepsy (MTLE) without MRI abnormalities (MTLE-NMRI) represent a challenge for diagnosis of the underlying abnormality and for presurgical evaluation. To date, however, only few studies have used quantitative structural Magnetic Resonance Imaging-based techniques to examine amygdalar pathology in these patients.
Material/Methods:
Based on clinical examination, 24-hour video EEG recordings and MRI findings, 50 patients with EEG lateralized TLE and normal structural Magnetic Resonance Imaging results were included in this study. Volumetric magnetic resonance imaging (MRI) studies of the amygdalas and hippocampi were conducted in 50 non-epileptic controls (age 7-79 years) and 50 patients with MTLE with normal MRI on a 1.5-Tesla scanner. Visual assessment and amygdalar volumetry were performed on oblique coronal T2W and T1W MP-RAGE images respectively. The T2 relaxation times were measured using the 16-echo Carr-Purcell-Meiboom-Gill sequence (TE, 22-352). Volumetric data were normalized for variation in head size between individuals. Results were assessed by SSPS statistic program.
Results:
Individual manual volumetric analysis confirmed statistically significant amygdala enlargement (AE) in eight (16%) patients. Overall, among all patients with AE and a defined epileptic focus, 7 had predominant increased volume ipsilateral to the epileptic focus. The T2 relaxometry demonstrated no hyperintense signal of the amygdala in any patient with significant AE.
Conclusions:
This paper presented AE in a few patients with TLE and normal MRI. These findings support the hypothesis that there might be a subgroup of patients with MTLE-NMRI in which the enlarged amygdala could be related to the epileptogenic process.
Insights
This study found amygdala enlargement in 16% of temporal lobe epilepsy patients with normal MRI scans. This suggests a potential link between enlarged amygdala and the epileptogenic process in a subset of these patients.
Area of Science:
- Neuroscience
- Epileptology
- Radiology
Background:
- Temporal lobe epilepsy (TLE) pathophysiology may involve brain structure abnormalities, particularly the amygdala.
- Mesial temporal lobe epilepsy (MTLE) patients without MRI abnormalities (MTLE-NMRI) pose diagnostic and presurgical evaluation challenges.
- Limited research has quantitatively assessed amygdalar pathology in MTLE-NMRI using structural MRI.
Purpose of the Study:
- To investigate amygdalar volume and T2 relaxation times in patients with MTLE-NMRI.
- To determine if amygdalar abnormalities correlate with the epileptogenic focus in TLE patients with normal MRI.
Main Methods:
- Volumetric MRI and T2 relaxometry of amygdalas and hippocampi were performed on 50 MTLE-NMRI patients and 50 controls.
- Standardized MRI sequences (T2W, T1W MP-RAGE) and a 16-echo Carr-Purcell-Meiboom-Gill sequence were used.
- Volumetric data were normalized for head size, and results analyzed using SPSS statistics.
Main Results:
- Statistically significant amygdala enlargement (AE) was confirmed in 8 (16%) patients with MTLE-NMRI.
- Seven of these patients showed increased amygdalar volume ipsilateral to the epileptic focus.
- No amygdalar hyperintense signal was detected via T2 relaxometry in patients with significant AE.
Conclusions:
- Amygdala enlargement (AE) was identified in a subset of TLE patients with normal MRI findings.
- These findings support the hypothesis of an enlarged amygdala contributing to the epileptogenic process in specific MTLE-NMRI cases.
