Epileptic Disorders


Imaging characteristics of temporopolar blurring in the context of hippocampal sclerosis Volume 24, numéro 1, February 2022


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1 Department of Neurology, University of Campinas – UNICAMP, Campinas, SP, Brazil
2 Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada
3 Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre and Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
4 Multimodal Imaging and Connectome Analysis lab, McConnell Brain Imaging Centre and Montreal Neurological Institute, McGill University, Montreal, Canada
5 Department of Bioengineering, University of Pennsylvania, Philadelphia, USA and Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London, UK
6 Institute of Neurobiology, Universidad Nacional Autonoma de Mexico, Queretaro 76230, Mexico
7 Phramongkutklao Hospital, Bangkok, Thailand
8 The Florey Institute of Neuroscience and Mental Health and The University of Melbourne, Australia
9 Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, USA
10 Department of Neurosurgery, University Hospital Erlangen, Germany and Department of Neurosurgery, University Hospital Halle (Saale), Germany
11 Neurology Unit, University of Modena and Reggio Emilia, Modena, Italy
12 Epilepsy Center, Cleveland Clinic, Cleveland, USA
13 Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, China
14 Department of Pathology, University of Campinas – UNICAMP, Campinas, SP, Brazil
* Correspondence: Fernando Cendes Department of Neurology, Universidade Estadual de Campinas - UNICAMP, Rua Vital Brasil, 251, Cidade Universitária Zeferino Vaz, Campinas, SP. CEP-13083-888, Brazil

We present an illustrative case to address anterior temporal lobe atrophy with poor delineation of the temporopolar gray-white matter interface based on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images in patients with temporal lobe epilepsy associated with hippocampal sclerosis (TLE-HS). A 52-year-old woman with pharmacoresistant seizures since the age of six months underwent a previous MRI scan using a suboptimal protocol which was reported as unremarkable. MRI performed according to an epilepsy protocol showed classic signs of left HS and ipsilateral temporal polar atrophy with blurring of the gray-white matter boundary on FLAIR images. She underwent a left amygdalohippocampectomy and anterior temporal resection and remains seizure-free after 24 months. Histopathological analyses showed HS and no signs of focal cortical dysplasia (FCD). Blurring and atrophy of the ipsilateral temporal pole are common in TLE-HS and often misinterpreted as FCD. This relates to delayed myelination in patients with seizures before the age of two, is more pronounced on FLAIR sequences, and gives a false impression of cortical thickening. However, the T1-weighted images show a relatively well-demarcated cortical-subcortical transition and normal cortical thickness. By contrast, the cortical thickening in FCD is observed on both T1-weighted and FLAIR images. Since FCD also occurs in temporal lobe regions, it is important to differentiate the extra-hippocampal MRI abnormalities in TLE-HS from those likely to be FCD. This case highlights the importance of evaluation based on detailed imaging, which should always be conducted considering the EEG, seizure semiology, and other clinical information.

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