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Epilepsy is a heterogeneous neurological disease affecting approximately 50 million people worldwide. Genetic factors play an important role in both the onset and severity of the condition, with mutations in several ion‐channel genes being implicated, including those encoding the GABAA receptor. Here, we evaluated the frequency of additional mutations in the GABAA receptor by direct sequencing of the complete open reading frame of the GABRA1 and GABRG2 genes from a cohort of French Canadian families with idiopathic generalized epilepsy (IGE). Using this approach, we have identified three novel mutations that were absent in over 400 control chromosomes. In GABRA1, two mutations were found, with the first being a 25‐bp insertion that was associated with intron retention (i.e. K353delins18X) and the second corresponding to a single point mutation that replaced the aspartate 219 residue with an asparagine (i.e. D219N). Electrophysiological analysis revealed that K353delins18X and D219N altered GABAA receptor function by reducing the total surface expression of mature protein and/or by curtailing neurotransmitter effectiveness. Both defects would be expected to have a detrimental effect on inhibitory control of neuronal circuits. In contrast, the single point mutation identified in the GABRG2 gene, namely P83S, was indistinguishable from the wildtype subunit in terms of surface expression and functionality. This finding was all the more intriguing as the mutation exhibited a high degree of penetrance in three generations of one French Canadian family. Further experimentation will be required to understand how this mutation contributes to the occurrence of IGE in these individuals. [ABSTRACT FROM AUTHOR]

The phenotypic and etiologic spectrum in adults with nodular heterotopias (NHs) has been well characterized. However, there are no large pediatric case series. We, therefore, wanted to review the clinical features of NHs in our population. Hospital records of 31 patients with pathology or imaging-confirmed NHs were reviewed. Two-sided Fisher's exact t-test was used to assess associations between distribution of NHs and specific clinical features. NHs were distributed as follows: 8 (26%) unilateral focal subependymal, 3 (10%) unilateral diffuse subependymal, 5 (16%) bilateral focal subependymal, 12 (39%) bilateral diffuse subependymal, and 3 (10%) isolated subcortical. The phenotypic spectrum in our population differs from that described in adults. Significant morbidity and mortality are associated with presentation in childhood. Twenty-two of 31 patients (71%) died in the neonatal period or in childhood. Additional cerebral malformations were found in 80% and systemic malformations in 74%. The majority of patients had developmental delay, intellectual deficit, and intractable epilepsy. Patients with unilateral focal NHs were more likely to have ventriculomegaly (p = 0.027), and those with bilateral diffuse NHs more likely to have cerebellar abnormalities (p = 0.007). Isolated subcortical NHs were associated with multiple malformations (p = 0.049) and cardiac abnormalities (p = 0.027). Underlying etiology was heterogeneous and determined in only six cases (19%): del chr 1p36, del chr 15q11, pyruvate dehydrogenase deficiency, sialic acidosis type 1, Aicardi syndrome, and FLNA mutation. NHs are present in childhood as part of multiple cerebral and systemic malformations; developmental delay and refractory seizures are the rule rather than the exception. Milder forms go unrecognized until seizure onset in adulthood. [ABSTRACT FROM AUTHOR]

We present two methods of implantation for the investigation of suspected insular and perisylvian epilepsy that combine depth and subdural electrodes to capitalize on the advantages of each technique. Retrospective study of all intracranial EEG studies that included insular electrodes from 2004-2010. Patients were divided according to the implantation scheme. The first method (type 1) consisted of a craniotomy, insertion of insular electrodes after microdissection of the sylvian fissure, orthogonal implantation of mesiotemporal structures with neuronavigation, and coverage of the adjacent lobes with subdural electrodes. The second method (type 2) consisted of magnetic resonance imaging (MRI)-stereotactic frame-guided depth electrode implantation into insula and hippocampus using sagittal axes, and insertion of subdural electrodes through burr holes to cover the adjacent lobes. The combined implantations were developed and performed by one neurosurgeon (AB). Nineteen patients had an intracranial study that sampled the insula, among other regions. Sixteen patients were implanted using the first method, which allowed a mean of 4, 5, 20, 15, and 42 contacts per patient to be positioned into/over the insular, mesial temporal, neocortical temporal, parietal, and frontal areas, respectively. The second method (three patients) allowed a mean of 8, 7, 16, 6, and 9 contacts per patient to sample the same areas, respectively. The four patients in whom transient neurologic deficits occurred were investigated with use of type 1 implantation. Combined depth and subdural electrodes can be used safely to investigate complex insular/perisylvian refractory epilepsy. Choice of implantation scheme should be individualized according to presurgical data and the need for functional localization. [ABSTRACT FROM AUTHOR]

We sequenced genes coding for components of the SNARE complex ( STX1A, VAMP2, SNAP25) and their regulatory proteins (STXBP1/Munc18-1, SYT1), which are essential for neurotransmission, in 95 patients with idiopathic mental retardation. We identified de novo mutations in STXBP1 (nonsense, p.R388X; splicing, c.169+1G>A) in two patients with severe mental retardation and nonsyndromic epilepsy. Reverse transcriptase polymerase chain reaction and sequencing showed that the splicing mutation creates a stop codon downstream of exon-3. No de novo or deleterious mutations in STXBP1 were found in 190 control subjects, or in 142 autistic patients. These results suggest that STXBP1 disruption is associated with autosomal dominant mental retardation and nonsyndromic epilepsy. Ann Neurol 2009;65:748-753 [ABSTRACT FROM AUTHOR]

Gamma band electroencephalography (EEG) abnormalities have been reported in patients with epilepsy. We aimed to investigate whether patients with febrile seizures (FS) show abnormalities of the gamma frequency steady-state visual evoked potential (SSVEP) components evoked by intermittent photic stimulation (IPS). We analyzed the magnitude and phase alignment of the 50–100 Hz SSVEP components elicited by IPS from 12 FS patients, 5 siblings of FS patients, and 15 control children between 6 and 36 months of age. Patients with FS showed significantly higher SSVEP magnitude and phase alignment values when compared to both the siblings and control groups. Detected abnormalities could either represent the direct consequence of seizures or indicate a preexisting tendency to hypersynchrony in FS patients. Future prospective studies could assess whether SSVEP abnormalities are associated with complex rather than simple FS, or have a prognostic value for the development of epilepsy following FS. [ABSTRACT FROM AUTHOR]

Rationale: Few studies have looked at long-term epileptic and cognitive outcome of frontal lobe epilepsy (FLE) in children. Most are limited by inclusion of lesional and nonlesional patients. Goal: To define the epileptic and functional outcome of children with nonlesional FLE. Methods: We reviewed medical records and neuropsychological evaluations of patients with nonlesional FLE diagnosed between 1994 and 2004. We included children with either focal or regional frontal EEG and/or functional imaging abnormalities. We reviewed their charts for seizure and neuropsychological outcome. Results: We included 21 children. Twelve (57.1%) presented with daily seizures. Seizures were nocturnal in 8 of 21, secondarily generalized in 6 of 21, adversive in 5 of 21, and focal motor in 6 of 21. Although, initial seizure control was poor in 14 of 21, long-term control was achieved in 10 of 21 after 14.6 ± 22.3 months. Early development was normal in 12 of 21 but at later formal neuropsychological evaluation only 3 of 12 still had a normal profile. The majority of children had learning difficulties requiring special education prior to seizure onset (6 of 10). A clearly defined regression after seizure onset was observed in three children. The majority exhibited attention deficit and hyperactivity or impulsivity (14 of 21), behavioral problems (8 of 21), and cognitive impairments (10 of 21). Early seizure control was associated with a better cognitive outcome. Conclusion: Nonlesional FLE is associated with poor seizure and behavioral outcomes. Whether this is secondary to MRI-silent developmental lesions or to the progressive repercussion of seizures on frontal lobe functions remains uncertain. A prospective study with early neuropsychological assessment could help confirm the latter. [ABSTRACT FROM AUTHOR]

Background: West syndrome consists of infantile spasms with hypsarrhythmia and is perceived as a disorder of infants. Methods: We describe 10 patients with West syndrome with spasms that remitted, started again, and persisted (followed up for 8–25 years). Results: In all, West syndrome developed at younger than 17 months (five cryptogenic, six symptomatic). With initial treatment, spasms completely stopped for 4.5 months to 6 years, when epileptic spasms returned. Recurrent spasms were typical with brief arm extension, eye elevation, and head drop without falling. Spasms lasted 2–6 s in rhythmic strings over 20- to 60-min periods and occurred daily throughout follow-up. Persistent spasms were particularly troublesome, because of incontinence in one and postictal confusion in several. During the string of spasms, most refused to interact, and several would wander off. Up to 15 antiepileptic drugs did not render any patient spasm free. Only two had persistent spasms as the only seizure type; six also had intractable complex partial seizures, and three had occasional grand mal convulsions. Interictal EEGs showed multifocal spikes. Ictal recordings in six showed electrodecremental events. Conclusions: Recurrent spasms after remission of West syndrome represent an extremely resistant, distressing form of epilepsy. The onset of West syndrome is age related, but it does not reliably vanish. [ABSTRACT FROM AUTHOR]

Hemimegalencephaly is a rare congenital brain malformation, usually associated with mental retardation, refractory epilepsy, and progressive neurological deficits. We report the case of a 19-year-old female with de novo diagnosis of right hemimegalencephaly, normal intellectual function, and history of non-refractory epilepsy. She presented with weakness and paraesthesia of the left leg. Extensive evaluation was negative for other causes for the weakness, which was attributed to progressive neurological damage secondary to long-standing subclinical epileptic activity in the hemimegalencephalic hemisphere. This patient underwent a cerebral fluorodeoxyglucose positron emission tomography that demonstrated near-normal cortical metabolism. Formal neuropsychological evaluation revealed mild deficits in the affected hemisphere, but preserved general intellectual function. This case illustrates the wide phenotypic variations in this condition and raises questions about prenatal counselling for hemimegalencephaly. [ABSTRACT FROM AUTHOR]

Epilepsy is a heterogeneous neurological disease affecting approximately 50 million people worldwide. Genetic factors play an important role in both the onset and severity of the condition, with mutations in several ion-channel genes being implicated, including those encoding the GABA(A) receptor. Here, we evaluated the frequency of additional mutations in the GABA(A) receptor by direct sequencing of the complete open reading frame of the GABRA1 and GABRG2 genes from a cohort of French Canadian families with idiopathic generalized epilepsy (IGE). Using this approach, we have identified three novel mutations that were absent in over 400 control chromosomes. In GABRA1, two mutations were found, with the first being a 25-bp insertion that was associated with intron retention (i.e. K353delins18X) and the second corresponding to a single point mutation that replaced the aspartate 219 residue with an asparagine (i.e. D219N). Electrophysiological analysis revealed that K353delins18X and D219N altered GABA(A) receptor function by reducing the total surface expression of mature protein and/or by curtailing neurotransmitter effectiveness. Both defects would be expected to have a detrimental effect on inhibitory control of neuronal circuits. In contrast, the single point mutation identified in the GABRG2 gene, namely P83S, was indistinguishable from the wildtype subunit in terms of surface expression and functionality. This finding was all the more intriguing as the mutation exhibited a high degree of penetrance in three generations of one French Canadian family. Further experimentation will be required to understand how this mutation contributes to the occurrence of IGE in these individuals., (© 2011 The Authors. European Journal of Neuroscience © 2011 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.)

Idiopathic generalized epilepsy (IGE) has evidence of a strong genetic etiology. We conducted genomewide linkage analysis for genes responsible for familial IGE in French-Canadian pedigrees. Twenty families segregating autosomal dominant epilepsy were collected. Four larger IGE families sufficiently powerful for independent linkage analysis were genome-scanned and follow-up fine mapping was performed over regions with LOD scores >3.0. The genotyping of 16 smaller families was carried out at significantly linked loci for supportive linkage analysis and haplotype comparisons. One of the four families provided a significant linkage result at marker D10S1426 on chromosome 10 (two-point LOD score = 3.05, theta = 0, multipoint LOD score = 3.18). Fine mapping revealed a segregating haplotype and key recombination breakpoints, suggesting a candidate gene interval of 6.5 Mb. Multipoint linkage analyses using the additional 16 families yielded a maximum LOD score under heterogeneity of 4.23 (alpha = 0.34) at this locus. Evaluation of recombination breakpoints in these families narrowed the candidate region to 1.7 Mb. Sequencing of the two known genes in this region, NRP1 and PARD3, was negative for mutation. Replication of linkage to this locus in other cohorts of IGE families is essential to characterize the underlying genetic mechanism for the disease., ((c) 2008 Wiley-Liss, Inc.)

Mutations at mitochondrial DNA (mtDNA) nucleotide 8993 can cause neurogenic weakness, ataxia and retinitis pigmentosa (NARP syndrome), or maternally inherited Leigh syndrome (LS), with a correlation between the amount of mutant mtDNA and the severity of the neurological disease. The T8993C mutation is generally considered to be clinically milder than the T8993G mutation but when the level of heteroplasmy exceeds 90%, progressive neurodegeneration has been found. We report on a long-term follow-up of a patient who presented at 4 years of age with typical LS but showed an unexpected resolution of his symptoms and a favorable outcome. At 18 years of age, his neurological examination was near normal, with neither peripheral neuropathy nor retinopathy. mtDNA analysis identified the presence of T8993C mutation at high level (>95%) in the patient's blood leukocytes. This case report and literature review emphasizes the variability of the phenotypic expression of the T8993C mutation and the need for caution in predictive counseling in such patients. (c) 2007 Wiley-Liss, Inc., (Copyright 2007 Wiley-Liss, Inc.)

Diabetes mellitus and exocrine insufficiency are the commonest pancreatic manifestations of mitochondrial diseases. In contrast, pancreatitis has rarely been described in mitochondrial syndromes. We report on a patient with Kearns-Sayre syndrome and recurrent episodes of acute pancreatitis for which no explanation could be found other than the associated mitochondrial dysfunction. Interestingly, pharmacological disruption of mitochondrial metabolism in various models as well as in patients can cause pancreatitis, further supporting this association. A diagnosis of pancreatitis should be considered in any patients with mitochondrial disease and recurrent abdominal pain.