Genetic Generalized Epilepsy Syndromes Research Articles

Electroencephalography in the Diagnosis of Genetic Generalized Epilepsy Syndromes.

Genetic generalized epilepsy (GGE) consists of several syndromes diagnosed and classified on the basis of clinical features and electroencephalographic (EEG) abnormalities. The main EEG feature of GGE is bilateral, synchronous, symmetric, and generalized spike-wave complex. Other classic EEG abnormalities are polyspikes, epileptiform K-complexes and sleep spindles, polyspike-wave discharges, occipital intermittent rhythmic delta activity, eye-closure sensitivity, fixation-off sensitivity, and photoparoxysmal response. However, admixed with typical changes, atypical epileptiform discharges are also commonly seen in GGE. There are circadian variations of generalized epileptiform discharges. Sleep, sleep deprivation, hyperventilation, intermittent photic stimulation, eye closure, and fixation-off are often used as activation techniques to increase the diagnostic yield of EEG recordings. Reflex seizure-related EEG abnormalities can be elicited by the use of triggers such as cognitive tasks and pattern stimulation during the EEG recording in selected patients. Distinct electrographic abnormalities to help classification can be identified among different electroclinical syndromes.

A comprehensive assessment of cognitive function in the common genetic generalized epilepsy syndromes

Considered to be benign conditions, the common genetic generalized epilepsy (GGE) syndromes are now known to be frequently accompanied by cognitive dysfunction. However, unresolved issues impede clinical management of this common comorbidity, including which cognitive abilities are most affected, whether there are differences between syndromes and how seizure type and mood symptoms affect cognitive dysfunction. We provide a detailed description of cognitive ability and evaluate factors contributing to cognitive dysfunction. A total of 76 adults with GGE were assessed with the Woodcock Johnson III Tests of Cognitive Abilities. Scores on tests of overall cognitive ability, acquired knowledge, long-term retrieval and speed of information processing were significantly below the normative mean. Long-term retrieval was a pronounced weakness with a large reduction in scores (d = 0.84). GGE syndrome, seizure type and the presence of recent psychopathology symptoms were not significantly associated with cognitive function. This study confirms previous meta-analytic findings with a prospective study, offers new insights into the cognitive comorbidity of these common epilepsy syndromes and reinforces the need for cognitive interventions in people with GGE.

Can EEG Differentiate Among Syndromes in Genetic Generalized Epilepsy?

To evaluate EEG differences among syndromes in genetic generalized epilepsy based on quantified data. Twenty-four-hour ambulatory EEGs were recorded in consecutive patients diagnosed with genetic generalized epilepsy. All epileptiform EEG abnormalities were quantified into density scores (total duration of epileptiform discharges per hour). One-way analysis of variance was conducted to find out differences in EEG density scores among the syndromes. Generalized linear mixed models were also fitted to explore the association between the proportion of "pure" generalized spike-wave paroxysms and fragments (without intervening polyspikes/polyspike-waves) and the syndromes. In total, 6,923 epileptiform discharges were analyzed from 105 abnormal EEGs. In the analysis of variance, six EEG variables were significantly different among syndromes: total spike density (P = 0.001), total polyspike and polyspike-wave density (P = 0.049), generalized spike-wave-only density (P < 0.001), generalized paroxysm density (P < 0.001), generalized paroxysm duration mean (P = 0.018), and generalized paroxysm duration maximum (P = 0.009). The density of epileptiform discharges and the paroxysm durations were the highest in juvenile absence epilepsy followed by juvenile myoclonic epilepsy, childhood absence epilepsy, and generalized epilepsy with tonic-clonic seizures only. Generalized linear mixed models revealed that "pure" generalized spike-wave discharges (without intervening polyspikes/polyspike waves) tended to be more frequent in absence epilepsies, although the difference was not statistically significant (P = 0.21). The findings of this study suggest that the density and duration of epileptiform discharges can help differentiate among genetic generalized epilepsy syndromes.

Generalized epilepsy syndromes and callosal thickness: Differential effects between patients with juvenile myoclonic epilepsy and those with generalized tonic-clonic seizures alone

PurposeThe definition of two well-studied genetic generalized epilepsy syndromes (GGE) − juvenile myoclonic epilepsy (JME) and epilepsy with generalized tonic-clonic seizures alone (GTCS) − suggests the absence of structural cerebral abnormalities. Nevertheless, there are various reports of such abnormalities (especially in JME), where effects mainly occur within thalamus and mesial prefrontal regions. This raises the question of whether JME is particularly linked to midline structure abnormalities, which may also involve the corpus callosum. MethodWe studied callosal morphology in a well-matched sample of 22 JME patients, 15 GTCS patients, and 42 controls (CTL) for all of whom we obtained T1-weighted data on a 3T MRI scanner. More specifically, we measured callosal thickness at 100 equidistant points across the callosal surface, and subsequently compared the three groups (JME, GTCS, and CTL) against each other. ResultsSignificant differences between JME patients and controls were observed within the callosal genu, anterior midbody, and isthmus, with thinner regions in JME patients. There were no significant differences between GTCS patients and controls, and also not between JME patients and GTCS patients. ConclusionThe present outcomes point to callosal abnormalities in JME patients suggesting an impairment of interhemisperic communication between prefrontal, motor, parietal and temporal cortices. These findings further support the notion that structural aberrations are present and differentiated across GGE syndromes, with significant callosal deviations from normality in JME.

Social cognition in Juvenile Myoclonic Epilepsy

ObjectiveJuvenile Myoclonic Epilepsy (JME) is a common genetic generalized epilepsy syndrome. Several studies have detailed cognitive and imaging abnormalities pointing to frontal lobe dysfunction, as well as disadvantageous behavioral traits and poor social outcome, challenging the commonly held view of JME being a benign disorder. Social cognition is the ability to elaborate mental representations of social interactions and to use them correctly in social contexts, and includes Theory of Mind (ToM), which pertains to the attribution of cognitive and affective mental states to self and others and seems to rely on complex fronto-temporal interactions. ToM has been recently assessed in focal epilepsy syndromes, but little is available for generalized epilepsies.We performed a cross-sectional study to assess social cognition, with an emphasis on ToM, as well as standard cognitive functions in patients with JME. MethodWe recruited twenty JME patients and twenty matched controls. Tests used to assess social cognition and ToM included the Emotion Attribution Task, Strange Stories Task (SST), Faux Pas Task (FPT), Reading the Mind in the Eyes Task and Social Situation Task. Subjects were also assessed via an extensive neuropsychological battery. ResultsPatients exhibited worse performance in the SST and in several scores of the FPT. They also showed widespread cognitive impairment, involving executive functions, psychomotor speed, verbal and visuo-spatial memory. ConclusionsIn addition to cognitive impairment for fronto-temporal tasks, some features of social cognition are also altered in JME. The latter deficit may underlie the poor social outcome previously described for these patients, and might also relate to imaging findings of frontal lobe dysfunction.

Epileptiform K-Complexes and Sleep Spindles: An Underreported Phenomenon in Genetic Generalized Epilepsy.

To study the frequency of epileptiform K-complexes and sleep spindles as well as clinical variables influencing those abnormalities. We prospectively performed 24-hour ambulatory EEGs in a cohort of patients with genetic generalized epilepsy diagnosed and classified according to the International League against Epilepsy criteria. Overlapping of epileptiform discharges with K-complexes and sleep spindles was defined as epileptiform K-complexes and epileptiform sleep spindles. The presence of epileptiform K-complexes and sleep spindles was tabulated for each patient, and frequencies were calculated. We performed multiple regression analysis to study the influence of clinical predictors on the occurrence of epileptiform K-complexes and sleep spindles. The predictor variables tested in the model were seizure-free duration, epilepsy duration, genetic generalized epilepsy syndrome, number of antiepileptic drugs, use of sodium valproate, and use of lamotrigine. A total of 107 patients (37 males and 70 females) were studied. The mean age was 28.5 ± 10.7 years (range, 13-58). Juvenile absence epilepsy was the most common epilepsy syndrome in the cohort (31.8%), followed by generalized epilepsy with tonic-clonic seizures only (26.2%), juvenile myoclonic epilepsy (26.2%), and childhood absence epilepsy (14%). Epileptiform K-complexes and sleep spindles were seen in 65.4% and 10.3% of patients, respectively. None of the clinical variables had any significant impact on the occurrence of epileptiform K-complexes and sleep spindles in our multivariable analysis. Epileptiform K-complexes are common in the sleep EEGs of patients diagnosed with genetic generalized epilepsy. This underreported phenomenon highlights the important association of arousals and epileptiform discharges in genetic generalized epilepsy.

Single-cell genetic expression of mutant GABAA receptors causing Human genetic epilepsy alters dendritic spine and GABAergic bouton formation in a mutation-specific manner.

Mutations in genes encoding for GABAA receptor subunits is a well-established cause of genetic generalized epilepsy. GABA neurotransmission is implicated in several developmental processes including neurite outgrowth and synapse formation. Alteration in excitatory/inhibitory synaptic activities plays a critical role in epilepsy, thus here we investigated whether mutations in α1 subunit of GABAA receptor may affect dendritic spine and GABAergic bouton formation. In particular, we examined the effects of three mutations of the GABRA1 gene (D219N, A322D and K353delins18X) that were found in a cohort of French Canadian families with genetic generalized epilepsy. We used a novel single-cell genetic approach, by preparing cortical organotypic cultures from GABRA1flox/flox mice and simultaneously inactivating endogenous GABRA1 and transfecting mutant α1 subunits in single glutamatergic pyramidal cells and basket GABAergic interneurons by biolistic transfection. We found that GABRA1−/− GABAergic cells showed reduced innervation field, which was rescued by co-expressing α1-A322D and α1-WT but not α1-D219N. We further found that the expression of the most severe GABRA1 missense mutation (α1-A322D) induced a striking increase of spine density in pyramidal cells along with an increase in the number of mushroom-like spines. In addition, α1-A322D expression in GABAergic cells slightly increased perisomatic bouton density, whereas other mutations did not alter bouton formation. All together, these results suggest that the effects of different GABAAR mutations on GABAergic bouton and dendritic spine formation are specific to the mutation and cannot be always explained by a simple loss-of-function gene model. The use of single cell genetic manipulation in organotypic cultures may provide a better understanding of the specific and distinct neural circuit alterations caused by different GABAA receptor subunit mutations and will help define the pathophysiology of genetic generalized epilepsy syndromes.

Seizure outcome in 175 patients with juvenile myoclonic epilepsy – A long-term observational study

Juvenile myoclonic epilepsy (JME) is a genetic generalized epilepsy syndrome. Under appropriate antiepileptic drugs (AED) up to 85% of patients become seizure-free, but many may have a relapse after AED withdrawal. We retrospectively studied 242 patients with JME at the Department of Neurology, Medical University Innsbruck, Austria (1975-2006). We analyzed age at seizure onset, age at last follow up, seizure types, photosensitivity, seizure outcome and neuroimaging findings; inclusion criterion was a medical treatment period of >2 years; exclusion criteria were traumatic or infectious brain injury before the onset of JME and/or gross structural pathology on neuroimaging. We identified 175 patients (111 women) with a median age at seizure onset of 15 years, (range 3-46) and a median age at follow-up (FU) of 38 years (range 14-87; median FU 8 years, range 2-38). Fourteen percent showed (24/175) photosensitivity on routine EEG. Seizure outcome: 62% (109/175) were seizure-free of myoclonic seizures (MS), generalized tonic clonic seizures (GTCS) and absence seizures (AS) for >1 year, and 53% (94/175) for >2 years, including 16 patients (9%) without AEDs. Thirty-one percent (54/175) were seizure-free between 2 and 5 years, 15% (26/175) between 6 and 10, and 8% (14/175) >10 years; 38% (66/175) were not seizure-free. Not seizure-free patients had more often MS, AS and GTCS within the first year of epilepsy than those who were seizure-free at last FU (11% vs. 3%, Chi(2)=4.679, df=1, p=0.043). Seizure-free patients had more often MS and GTCS as last seizure types in the year before becoming seizure-free (37% vs. 15%, p=0.003), whereas in not seizure-free group MS only and GTCS only persisted. JME does not always need lifelong treatment, as a substantial minority of patients remain seizure-free without AEDs. AS, MS and GTCS at onset of the disease are indicators of poor long-term seizure control.

O.308 Use of gold implants in paralytic lagophtalmos

Juvenile myoclonic epilepsy (JME) is a genetic generalized epilepsy syndrome. Under appropriate antiepileptic drugs (AED) up to 85% of patients become seizure-free, but many may have a relapse after AED withdrawal.We retrospectively studied 242 patients with JME at the Department of Neurology, Medical University Innsbruck, Austria (1975–2006). We analyzed age at seizure onset, age at last follow up, seizure types, photosensitivity, seizure outcome and neuroimaging findings; inclusion criterion was a medical treatment period of >2 years; exclusion criteria were traumatic or infectious brain injury before the onset of JME and/or gross structural pathology on neuroimaging.We identified 175 patients (111 women) with a median age at seizure onset of 15 years, (range 3–46) and a median age at follow-up (FU) of 38 years (range 14–87; median FU 8 years, range 2–38). Fourteen percent showed (24/175) photosensitivity on routine EEG. Seizure outcome: 62% (109/175) were seizure-free of myoclonic seizures (MS), generalized tonic clonic seizures (GTCS) and absence seizures (AS) for >1 year, and 53% (94/175) for >2 years, including 16 patients (9%) without AEDs. Thirty-one percent (54/175) were seizure-free between 2and 5 years, 15% (26/175) between 6 and 10, and 8% (14/175) >10 years; 38% (66/175) were not seizure-free. Not seizure-free patients had more often MS, AS and GTCS within the first year of epilepsy than those who were seizure-free at last FU (11% vs. 3%, Chi2 = 4.679, df = 1, p = 0.043). Seizure-free patients had more often MS and GTCS as last seizure types in the year before becoming seizure-free (37% vs. 15%, p = 0.003), whereas in not seizure-free group MS only and GTCS only persisted.JME does not always need lifelong treatment, as a substantial minority of patients remain seizure-free without AEDs. AS, MS and GTCS at onset of the disease are indicators of poor long-term seizure control.