Medicine (Austin & Northern Health) - Research Publications

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    Hippocampal malrotation is an anatomic variant and has no clinical significance in MRI-negative temporal lobe epilepsy
    Tsai, M-H ; Vaughan, DN ; Perchyonok, Y ; Fitt, GJ ; Scheffer, IE ; Berkovic, SF ; Jackson, GD (WILEY-BLACKWELL, 2016-10-01)
    OBJECTIVE: There is considerable difficulty in diagnosing hippocampal malrotation (HIMAL), with different criteria of variable reliability. Here we assess qualitative and quantitative criteria in HIMAL diagnosis and explore the role of HIMAL in magnetic resonance imaging (MRI)-negative temporal lobe epilepsy (TLE). METHODS: We studied the MRI of 155 adult patients with MRI-negative TLE and 103 healthy volunteers, and we asked (1) what are the qualitative and quantitative features that allow a reliable diagnosis of HIMAL, (2) how common is HIMAL in a normal control population, and (3) is HIMAL congruent with the epileptogenic side in MRI-negative TLE. RESULTS: We found that the features that are most correlated with the expert diagnosis of HIMAL are hippocampal shape change with hippocampal diameter ratio > 0.8, lack of normal lateral convex margin, and a deep dominant inferior temporal sulcus (DITS) with DITS height ratio > 0.6. In a blinded analysis, a consensus diagnosis of unilateral or bilateral HIMAL was made in 25 of 103 controls (24.3% of people, 14.6% of hippocampi-14 left, six right, 10 bilateral) that did not differ from 155 lesion-negative TLE patients where 25 had HIMAL (16.1% of patients, 11.6% of hippocampi-12 left, two right, 11 bilateral). Of the 12 with left HIMAL only, 9 had seizures arising from the left temporal lobe, whereas 3 had right-sided seizures. Of the two with right HIMAL only, both had seizures arising from the left temporal lobe. SIGNIFICANCE: HIMAL is an anatomic variant commonly found in controls. HIMAL is also an incidental nonpathologic finding in adult MRI-negative TLE and should not influence surgical decision making.
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    GRIN2A mutations cause epilepsy-aphasia spectrum disorders
    Carvill, GL ; Regan, BM ; Yendle, SC ; O'Roak, BJ ; Lozovaya, N ; Bruneau, N ; Burnashev, N ; Khan, A ; Cook, J ; Geraghty, E ; Sadleir, LG ; Turner, SJ ; Tsai, M-H ; Webster, R ; Ouvrier, R ; Damiano, JA ; Berkovic, SF ; Shendure, J ; Hildebrand, MS ; Szepetowski, P ; Scheffer, IE ; Mefford, HC (NATURE PUBLISHING GROUP, 2013-09-01)
    Epilepsy-aphasia syndromes (EAS) are a group of rare, severe epileptic encephalopathies of unknown etiology with a characteristic electroencephalogram (EEG) pattern and developmental regression particularly affecting language. Rare pathogenic deletions that include GRIN2A have been implicated in neurodevelopmental disorders. We sought to delineate the pathogenic role of GRIN2A in 519 probands with epileptic encephalopathies with diverse epilepsy syndromes. We identified four probands with GRIN2A variants that segregated with the disorder in their families. Notably, all four families presented with EAS, accounting for 9% of epilepsy-aphasia cases. We did not detect pathogenic variants in GRIN2A in other epileptic encephalopathies (n = 475) nor in probands with benign childhood epilepsy with centrotemporal spikes (n = 81). We report the first monogenic cause, to our knowledge, for EAS. GRIN2A mutations are restricted to this group of cases, which has important ramifications for diagnostic testing and treatment and provides new insights into the pathogenesis of this debilitating group of conditions.
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    Clinical genetic study of the epilepsy-aphasia spectrum
    Tsai, M-H ; Vears, DF ; Turner, SJ ; Smith, RL ; Berkovic, SF ; Sadleir, LG ; Scheffer, IE (WILEY-BLACKWELL, 2013-02-01)
    PURPOSE: To characterize the frequency and nature of the family history of seizures in probands with epilepsy falling within the epilepsy-aphasia spectrum (EAS) in order to understand the genetic architecture of this group of disorders. METHODS: Patients with epileptic encephalopathy with continuous spike-and-wave during sleep (ECSWS), Landau-Kleffner syndrome (LKS), atypical benign partial epilepsy (ABPE), and intermediate epilepsy-aphasia disorders (IEAD) were recruited. All affected and available unaffected relatives up to three degrees of relatedness underwent phenotyping using a validated seizure questionnaire. Pedigrees were constructed for all families. The proportion of affected relatives according to each degree of relatedness was calculated. The epilepsy phenotypes in close relatives were analyzed. The data were compared to the families of probands with benign childhood epilepsy with centrotemporal spikes (BECTS) using the same methodology. KEY FINDINGS: Thirty-one probands, including five ECSWS, three LKS, one ABPE, and 22 IEAD were recruited. The mean age of seizure onset was 3.9 (range 0.5-7) years. A male predominance was seen (68%, 21/31) . Sixteen (51.6%) of 31 had a positive family history of seizures. Among 1,254 relatives, 30 (2.4%) had a history of seizures: 13 (10.2%) of 128 first-degree relatives, 5 (1.7%) of 291 second-degree relatives, and 12 (1.4%) of 835 third-degree relatives. Thirteen had febrile seizures, including two who had both febrile seizures and epilepsy. Of the 19 relatives with epilepsy, 4 had BECTS, 4 epilepsies with focal seizures of unknown cause, 3 IEAD, and 7 unclassified. One had genetic generalized epilepsy. In the families of the BECTS probands, 9.8% of first-degree, 3% of second-degree, and 1.5% of third-degree relatives had seizures, which was not significantly different from the EAS cohort families. SIGNIFICANCE: The frequencies of seizures in relatives of probands with EAS suggest that the underlying genetic influence of EAS is consistent with complex inheritance and similar to BECTS. The phenotypic pattern observed in the affected relatives comprised predominantly febrile seizures and focal seizures. These findings suggest that a shared genetic predisposition to focal epilepsies underpins the epilepsy-aphasia spectrum.