title: Age at onset and seizure frequency affect white matter diffusion coefficient in patients with mesial temporal lobe epilepsy.
abstract: In mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), structural abnormalities are present not only in the hippocampus but also in the white matter with ipsilateral predominance. Although the timing of epilepsy onset is commonly associated with clinical and semiological dissimilarities, limited data exist regarding white matter diffusion changes with respect to age at epilepsy onset. The aim of this study was to investigate diffusion changes in the white matter of patients with unilateral MTLE-HS with respect to clinical parameters and to compare them with an age- and sex-matched healthy control group. Apparent diffusion coefficients (ADCs) were derived using monoexponential approaches from 22 (11 early and 11 late age at onset) patients with unilateral MTLE-HS and 22 age- and sex-matched control subjects after acquiring diffusion-weighted images on a 3T MRI system. Data were analyzed using two-tailed t-tests and multiple linear regression models. In the group with early onset MTLE-HS, ADC was significantly elevated in the ipsilateral hemispheric (p=0.04) and temporal lobe white matter (p=0.01) compared with that in controls. These differences were not detectable in late onset MTLE-HS patients. Apparent diffusion coefficient of the group with early onset MTLE-HS was negatively related to age at epilepsy onset in the ipsilateral hemispheric white matter (p=0.03) and the uncinate fasciculus (p=0.03), while in patients with late onset MTLE-HS, ADC was no longer dependent on age at epilepsy onset itself but rather on the seizure frequency in the ipsilateral uncinate fasciculus (p=0.03). Such diffusivity pattern has been associated with chronic white matter degeneration, reflecting myelin loss and higher extracellular volume which are more pronounced in the frontotemporal regions and also depend on clinical features. In the group with early onset MTLE-HS, the timing of epilepsy seems to be the major cause of white matter abnormalities while in late onset disease, it has a secondary role in provoking diffusion changes.
authors.affiliation: Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Neurobiology of Stress Research Group, H-7624 Pécs, Ifjúság Street 20., Hungary. Electronic address: szilvia.anett.nagy@gmail.com.
authors.forename: Szilvia A
authors.initials: SA
authors.lastname: Nagy
authors.affiliation: Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: horvath.reka@pte.hu.
authors.forename: Réka
authors.initials: R
authors.lastname: Horváth
authors.affiliation: Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: petzinger.gabor@gmail.com.
authors.forename: Gábor
authors.initials: G
authors.lastname: Perlaki
authors.affiliation: Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: gergo.orsi@gmail.com.
authors.forename: Gergely
authors.initials: G
authors.lastname: Orsi
authors.affiliation: MR Research Centre, Semmelweis University, H-1083 Budapest, Balassa Street 6., Hungary. Electronic address: pbarsi@mrkk.sote.hu.
authors.forename: Péter
authors.initials: P
authors.lastname: Barsi
authors.affiliation: Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: john.flora04@gmail.com.
authors.forename: Flóra
authors.initials: F
authors.lastname: John
authors.affiliation: Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; Department of Neurosurgery, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: andrhorvath@gmail.com.
authors.forename: Andrea
authors.initials: A
authors.lastname: Horváth
authors.affiliation: Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: kovacs.norbert@pte.hu.
authors.forename: Norbert
authors.initials: N
authors.lastname: Kovács
authors.affiliation: Department of Radiology, University of Pécs, H-7624 Pécs, Ifjúság Street 13., Hungary. Electronic address: bogner.peter@pte.hu.
authors.forename: Péter
authors.initials: P
authors.lastname: Bogner
authors.affiliation: Department of Medical Biology, University of Pécs, H-7624 Pécs, Szigeti Street 12., Hungary; Central Electron Microscopic Laboratory, University of Pécs, H-7624 Pécs, Honvéd Street 1., Hungary. Electronic address: hajnalka.abraham@aok.pte.hu.
authors.forename: Hajnalka
authors.initials: H
authors.lastname: Ábrahám
authors.affiliation: Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: bone.beata@pte.hu.
authors.forename: Beáta
authors.initials: B
authors.lastname: Bóné
authors.affiliation: Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: gyimesi.csilla@pte.hu.
authors.forename: Csilla
authors.initials: C
authors.lastname: Gyimesi
authors.affiliation: Pécs Diagnostics Center, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary; Department of Neurosurgery, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: doczi.tamas@pte.hu.
authors.forename: Tamás
authors.initials: T
authors.lastname: Dóczi
authors.affiliation: Department of Neurology, University of Pécs, H-7623 Pécs, Rét Street 2., Hungary; MTA-PTE, Clinical Neuroscience MR Research Group, H-7623 Pécs, Rét Street 2., Hungary. Electronic address: janszky.jozsef@pte.hu.
authors.forename: József
authors.initials: J
authors.lastname: Janszky
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009186:Myelin Sheath / Q000473:pathology; D012598:Sclerosis / Q000473:pathology; D012640:Seizures / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Age at epilepsy onset; Apparent diffusion coefficient; Diffusion-weighted imaging; Mesial temporal lobe epilepsy with hippocampal sclerosis