A cross-sectional MRI study of brain regional atrophy and clinical characteristics of temporal lobe epilepsy with hippocampal sclerosis

Alhusaini, Saud; Doherty, Colin P.; Scanlon, Cathy; Ronan, Lisa; Maguire, Sinead; Borgulya, Gabor; Brennan, Paul; Delanty, Norman; Fitzsimons, Mary; Cavalleri, Gianpiero L.

doi:10.1016/j.eplepsyres.2011.11.005

« Previous Next »Epilepsy Research
Volume 99, Issue 1 , Pages 156-166, March 2012

A cross-sectional MRI study of brain regional atrophy and clinical characteristics of temporal lobe epilepsy with hippocampal sclerosis

Saud Alhusaini
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin 2, Ireland
- Department of Neurophysics, Beaumont Hospital, Dublin 9, Ireland
Colin P. Doherty
- Department of Neurology, St. James's Hospital, Dublin 8, Ireland
Cathy Scanlon
- Department of Neurophysics, Beaumont Hospital, Dublin 9, Ireland
Lisa Ronan
- Department of Neurophysics, Beaumont Hospital, Dublin 9, Ireland
Sinead Maguire
- Department of Radiology, Beaumont Hospital, Dublin 9, Ireland
Gabor Borgulya
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin 2, Ireland
Paul Brennan
- Department of Radiology, Beaumont Hospital, Dublin 9, Ireland
Norman Delanty
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin 2, Ireland
- Department of Neurology, Beaumont Hospital, Dublin 9, Ireland
Mary Fitzsimons
- Department of Neurophysics, Beaumont Hospital, Dublin 9, Ireland
Gianpiero L. Cavalleri
- Department of Molecular and Cellular Therapeutics, The Royal College of Surgeons in Ireland, Dublin 2, Ireland
- Corresponding author. Tel.: +353 01 4022146; fax: +353 01 4022453.

Received 18 August 2011; received in revised form 9 November 2011; accepted 13 November 2011. published online 26 December 2011.

Summary

Purpose

Applying a cross-sectional design, we set out to further characterize the significance of extrahippocampal brain atrophy in a large sample of ‘sporadic’ mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE+HS). By evaluating the influence of epilepsy chronicity on structural atrophy, this work represents an important step towards the characterization of MRI-based volumetric measurements as genetic endophenotypes for this condition.

Methods

Using an automated brain segmentation technique, MRI-based volume measurements of several brain regions were compared between 75 patients with ‘sporadic’ MTLE+HS and 50 healthy controls. Applying linear regression models, we examined the relationship between structural atrophy and important clinical features of MTLE+HS, including disease duration, lifetime number of partial and generalized seizures, and history of initial precipitating insults (IPIs).

Results

Significant volume loss was detected in ipsilateral hippocampus, amygdala, thalamus, and cerebral white matter (WM). In addition, contralateral hippocampal and bilateral cerebellar grey matter (GM) volume loss was observed in left MTLE+HS patients. Hippocampal, amygdalar, and cerebral WM volume loss correlated with duration of epilepsy. This correlation was stronger in patients with prior IPIs history. Further, cerebral WM, cerebellar GM, and contralateral hippocampal volume loss correlated with lifetime number of generalized seizures.

Conclusion

Our findings confirm that multiple brain regions beyond the hippocampus are involved in the pathogenesis of MTLE+HS. IPIs are an important factor influencing the rate of regional atrophy but our results also support a role for processes related to epilepsy chronicity. The consequence of epilepsy chronicity on candidate brain regions has important implications on their application as genetic endophenotypes.

Keywords: Mesial temporal lobe epilepsy, Quantitative MRI, Endophenotype