MRI segmentation analysis in temporal lobe and idiopathic generalized epilepsy

BMC Neurology MRI segmentation analysis in temporal lobe and idiopathic generalized epilepsy Hila Goldberg 1 2 Arie Weinstock 0 1 3 Niels Bergsland 6 Michael G Dwyer 6 Osman Farooq 0 1 Mona Sazgar 5 Guy Poloni 6 Cierra Treu 0 Bianca Weinstock-Guttman 0 Murali Ramanathan 4 Robert Zivadinov 0 6 0 Department of Neurology, State University of New York , Buffalo, NY , USA 1 Comprehensive Epilepsy Program, State University of New York , Buffalo, NY , USA 2 Bar-Ilan's Faculty of Medicine in the Galilee , Safed , Israel 3 Department of Neurology, Comprehensive Epilepsy Program, Women and Children's Hospital of Buffalo , 219 Bryant Street, Buffalo, NY 14222 , USA 4 Department of Pharmaceutical Sciences, State University of New York , Buffalo, NY , USA 5 Department of Neurology, University of California , Orange, Irvine, CA , USA 6 Buffalo Neuroimaging Analysis Center, The Jacobs Neurological Institute, State University of New York , Buffalo, NY , USA Background: Temporal lobe epilepsy (TLE) and idiopathic generalized epilepsy (IGE) patients have each been associated with extensive brain atrophy findings, yet to date there are no reports of head to head comparison of both patient groups. Our aim was to assess and compare between tissue-specific and structural brain atrophy findings in TLE to IGE patients and to healthy controls (HC). Methods: TLE patients were classified in TLE lesional (L-TLE) or non-lesional (NL-TLE) based on presence or absence of MRI temporal structural abnormalities. High resolution 3 T MRI with automated segmentation by SIENAX and FIRST tools were performed in a group of patients with temporal lobe epilepsy (11 L-TLE and 15 NL-TLE) and in15 IGE as well as in 26 HC. Normal brain volume (NBV), normal grey matter volume (NGMV), normal white matter volume (NWMV), and volumes of subcortical deep grey matter structures were quantified. Using regression analyses, differences between the groups in both volume and left/right asymmetry were evaluated. Additionally, laterality of results was also evaluated to separately quantify ipsilateral and contralateral effects in the TLE group. Results: All epilepsy groups had significantly lower NBV and NWMV compared to HC (p < 0.001). L-TLE had lower hippocampal volume than HC and IGE (p = 0.001), and all epilepsy groups had significantly lower amygdala volume than HC (p < = 0.004). In L-TLE, there was evidence of atrophy in both ipsilateral and contralateral structures. Conclusions: Our study revealed that TLE and IGE patients demonstrated similar overall tissue-specific brain atrophy, although specific structures differences were appreciated. L-TLE also appeared to behave differently than NL-TLE, with atrophy not limited to the ipsilateral side. Temporal lobe epilepsy; Idiopathic generalized epilepsy; MRI segmentation; Brain atrophy - Background Temporal lobe epilepsy (TLE) is the most common cause of partial epilepsy, and mesial temporal sclerosis (MTS) is the major pathological finding, occurring in roughly 50% of TLE patients. An estimated 30% of patients exhibit other identifiable magnetic resonance imaging (MRI) findings such as cortical dysplasia, low grade tumors or cavernous hemangiomas. The remaining 20% have no definite abnormalities observed visually on qualitative MRI assessment, and are often referred as non-lesional TLE [1] (NL TLE). Identifying the specific structures and neuronal pathways affected in TLE can help further understand the underlying mechanisms and disease chronicity. Different tissue-specific atrophy studies have been reported separately in epileptic syndromes including TLE, extra-temporal epilepsy, and idiopathic generalized epilepsy (IGE). In TLE, hippocampal involvement has been considerably investigated by various methods of MRI volumetric analyses, both manual and automatic [2-7]. Most studies have found significant reductions in hippocampal volumes, predominantly ipsilateral to the seizure focus [4-6], although relation to disease duration and seizure severity remains controversial [8-12]. Additional studies in TLE have reported more extensive structural involvement outside the temporal structures [9,10,13], in particular bilateral atrophy of the thalami has been consistently reported [9,11,14-16]. IGE are a group of age-related epilepsies with complex genetic backgrounds, subdivided according to the predominant seizure types (absence, myoclonic, or generalized tonic-clonic) and age of onset. The IGE are typically divided in the following sub-syndromes: childhood absence epilepsy (CAE), juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME), and IGE with generalized tonic-clonic seizures [17]. In IGE, various volumetric studies have reported findings of structural abnormalities [18-23], though reports implicating the thalamus are still somewhat contradictory [15,19-22,24]. While thalamic volumes in patients with IGE were not significantly different from those of normal control subjects in some reports [15], (...truncated)