Cerebral MRI as an important diagnostic tool in temporal lobe epilepsy Poster No.: C-2190 Congress: ECR 2014 Type: Educational Exhibit Authors: A. Puiu, D. Negru; Iasi/RO Keywords: Neuroradiology brain, MR, Diagnostic procedure, Seizure disorders DOI: 10.1594/ecr2014/C-2190 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 20
Learning objectives To emphasize the main morphological changes in temporal lobe epilepsy based on a series of cases, focusing on the analysis of hippocampus. To emphasize the importance of cerebral MRI study for the diagnosis of partial temporal epilepsy, associated or not with generalized seizures. To establish the sequences and sections that must be used for a complete morphologic analysis of the cerebrum when this pathology is suspected. Page 2 of 20
Background One of 200 patients in Europe is affected by epileptic disease, with an annual incidence of 1:2000. Epilepsy is characterized by abnormal neural activity of one or more subsets of cortical neurons. This activity can lead to partial or generalized seizures, the statistics being in the favor of partial or focal ones (60% vs. 30%). Generalized seizures are more frequent in the pediatric population while the partial ones are frequently diagnosed in the adult and old population. Temporal lobe epilepsy (TLE) is the most frequent type of partial treatment resistant epilepsy. The clinical presentation of a TL seizure consists of an association of different intensity phenomena as: memory impairment, aura (somatosensory, special sensory, psychic of autonomic phenomena) preceding the complex partial seizure of temporal lobe origin. Patients with TLE often have impaired language function or deficits in memory function, especially if the dominant temporal lobe is involved. Aura can consist of olfactory and more rarely gustatory hallucinations. Patients can also have auditory hallucinations or they may report distortion of size (micropsia or macropsia) or shape of objects. Some patients may also describe vertigo. As psychic phenomena, during a TL seizure patients may report a 'déjà vu' o 'jamais vu' feeling. They may associate fear or anxiety, sometimes very strong; sometimes, a sense of autoscopy (seeing their own body from outside) is described. Autonomic phenomena consist of some sympathetic reactions: increasing of the heart rate, piloerection, sweating. Aura is followed by a temporal lobe complex partial seizure which begins with a motionless stare, midriasis, behavioral arrest. Sometimes, patients may continue their motor activity or have reactive automatisms. This complex partial seizure can evolve to secondarily generalized tonic-clonic seizure, this one being often the cause of patient's presentation to neurology department. TLE can have a morphological background which is important to be known in order to establish the therapy plan. Page 3 of 20
The imaging technique that offers the most information regarding the structure of the cerebrum, including the temporal regions presumed to be responsible for this subtype of seizures, is magnetic resonance imaging (MRI). The modifications in temporal lobe epilepsy detectable by MRI are: - mesial/hippocampal sclerosis - tumors - cortical malformations - vascular disorders By far, the most frequent one is hippocampal sclerosis. It consists of an atrophy of the hippocampus with unknown causes, which occurs usually unilaterally, the side of the incriminated temporal lobe as being the origin of the seizure (often revealed by EEG examination). Hippocampus is that part of the temporal lobe supposed to play a role in the memory and recognition processes. Its normal structure and MRI appearance are shown in figure 1 and 2. High-resolution MRI assesses detailed internal structural changes in the hippocampus that reflect neuronal cell loss or gliosis and more sensitively show laterality of changes, correlated with laterality of EEG modifications. Medical literature defines mesial sclerosis by loss of neural normal structure of the hippocampus and its transformation in an area of gliosis more or less extensive. These physiopathological processes are reflected in MRI images by signal changes as hyper-intensity of cortex in T2 and FLAIR sequences (gliosis phenomenon). These signal changes are often associated with a loss of volume of the hippocampus (atrophy). Therefore, the mesial sclerosis has been defined by the association between hyper T2 signal and atrophy of the hippocampus. It is possible that sometimes these changes would not be that obvious and then we can search for and identify indirect signs of mesial sclerosis, such as loss or effacement of digits of the hippocampal head or dilatation of temporal horn of lateral ventricle. We tried to establish the frequency of these structural changes within a number of 32 cases referred to our clinic as known or suspected patients with epilepsy during 8 months (January-August 2013) and to correlate it with literature facts. Page 4 of 20
Images for this section: Fig. 1: Temporal lobe anatomy scheme - coronal plane de.wikipedia under GFDL/GNU license Page 5 of 20
Fig. 2: Temporal lobe anatomy scheme - coronal plane - detail http://www.radiologyassistant.nl/en/p48f4c4ccd9682/brain-anatomy.html Page 6 of 20
Fig. 3: Normal T2 MRI appearance of hippocampal head Page 7 of 20
Fig. 4: Normal T2 MRI appearance of hippocampal body Page 8 of 20
Findings and procedure details In order to analyze the structural changes of the hippocampus we performed a cerebral MRI using a 1.5 T machine. We tried to standardize the acquisition using the following sequences: T2, FLAIR, T1 for all our patients and T1+Gd only to the patients with no contraindications or who didn't refuse the contrast medium administration by personal reasons. In order to analyze the changes in shape or volume of the hippocampus, we focused mostly on the perpendicular coronal planes but axial planes turned out to be also useful in some particular cases. The analysis of cerebral structures in our study group of 32 cases revealed a number of 23 patients (71.8 %) with no cerebral lesion and a number of 9 patients (28.1%) within we identified pathological changes: - 6 patients with mesial sclerosis - 2 patients with cystic lesions of the temporal lobe (one with a right hippocampal cyst and one with an anterior left temporal cyst) - 1 patient with no temporal structure changes but with cystic changes within his left parietal lobe. The 6 patients we diagnosed with mesial sclerosis were carriers of the following changes: st - 1 patient - 11 years old female with loss of volume of the right hippocampus (fig. 5) nd - 2 patient - 3 yo male with dilatation of temporal horn of the right lateral ventricle (fig. 6, 7) rd - 3 patient - 34 yo female with hyper T2 signal of the right hippocampus (fig. 8, 9) th - 4 patient -37 yo female with dilatation of temporal horn of the right lateral ventricle, right hippocampal atrophy and hyper-intensity of signal in FLAIR sequence (fig. 10-13) th - 5 patient - 28 yo male with left hippocampal atrophy and dilatation of ipsilateral temporal horn of the lateral ventricle th - 6 patient - 41 yo male with right hippocampal atrophy and dilatation of ipsilateral temporal horn of the lateral ventricle. Page 9 of 20
Images for this section: Fig. 5: T2w coronal section of 11 yo female with atrophy of the right hippocampus Page 10 of 20
Fig. 6: T2w coronal section of 3 yo male with dilatation of temporal horn of the right lateral ventricle Page 11 of 20
Fig. 7: FLAIR coronal section of 3 yo male with dilatation of temporal horn of the right lateral ventricle Page 12 of 20
Fig. 8: Coronal T2w section of 34 yo female showing hyper-intensity in hippocampal gyrus Page 13 of 20
Fig. 9: Axial FLAIR section of 34 yo female showing hyper-intensity in hippocampal gyrus Page 14 of 20
Fig. 10: 37 yo female with mesial sclerosis - T2w coronal section showing atrophy of the right hippocampal head Page 15 of 20
Fig. 11: 37 yo female with mesial sclerosis - T2w coronal section showing atrophy of the right hippocampal body Page 16 of 20
Fig. 12: 37 yo female with mesial sclerosis - T2w axial section showing atrophy of the right hippocampal head and dilatation of ipsilateral temporal horn of lateral ventricle Page 17 of 20
Fig. 13: FLAIR axial section showing slight hypersignal of the right hippocampal head and dilatation of ipsilateral temporal horn of lateral ventricle Page 18 of 20
Conclusion Cerebral MRI is the neuroimaging modality of choice for patients with temporal lobe epilepsy. Adequate sequences and plans can help an experienced eye to identify the morphological changes included in the entity of mesial sclerosis. Most brain MRI scans do not include coronal images, but for temporal lobe epilepsy this sequence, performed in a plane perpendicular to the hippocampal body is more informative than are the axial and sagittal cuts. The most important sequences and therefore imperative for the analysis of the hippocampus are T2 and FLAIR. These were the sequences that helped us to identify the changes we mentioned above in the 6 cases of mesial sclerosis. Page 19 of 20
References 1. 2. 3. 4. 5. Hogan RE, Wang L, Bertrand ME, et al. MRI-based high-dimensional hippocampal mapping in mesial temporal epilepsy. Brain 2004;127:1731-40 Bandt SK, Werner N, Dines J, Rashid S, Eisenman LN, Hogan RE, et al. Trans-middle temporal gyrus selective amygdalohippocampectomy for medically intractable mesial temporal lobe epilepsy in adults: Seizure response rates, complications, and neuropsychological outcomes. Epilepsy Behav. Jul 2013;28(1):17-21. M. Garcia-Finana, C.E. Denby, S.S. Keller, U.C. Wieshmann, N. Roberts Degree of Hippocampal Atrophy Is Related to Side of Seizure Onset in Temporal Lobe Epilepsy - AJNR May 2006 27: 1046-1052 Luby M, Spencer DD, Kim JH, et al. Hippocampal MRI volumetrics and temporal lobe substrates in medial temporal lobe epilepsy. Magn Reson Imaging 1995;13:1065-71 Engel J Jr, McDermott MP, Wiebe S, Langfitt JT, Stern JM, Dewar S, et al. Early surgical therapy for drug-resistant temporal lobe epilepsy: a randomized trial. JAMA Mar 7 2012;307(9):922-30. Page 20 of 20