A de novo loss-of-function GRIN2A mutation associated with childhood focal epilepsy and acquired epileptic aphasia.

OBJECTIVE: N-methyl-D-aspartate receptors (NMDAR) subunit GRIN2A/GluN2A mutations have been identified in patients with various neurological diseases, such as epilepsy and intellectual disability / developmental delay (ID/DD). In this study, we investigated the phenotype and underlying molecular mechanism of a GRIN2A missense mutation identified by next generation sequencing on idiopathic focal epilepsy using in vitro electrophysiology. METHODS: Genomic DNA of patients with epilepsy and ID/DD were sequenced by targeted next-generation sequencing within 300 genes related to epilepsy and ID/DD. The effects of one missense GRIN2A mutation on NMDAR function were evaluated by two-electrode voltage clamp current recordings and whole cell voltage clamp current recordings. RESULTS: We identified one de novo missense GRIN2A mutation (Asp731Asn, GluN2A(D731N)) in a child with unexplained epilepsy and DD. The D731N mutation is located in a portion of the agonist-binding domain (ABD) in the GluN2A subunit, which is the binding pocket for agonist glutamate. This residue in the ABD is conserved among vertebrate species and all other NMDAR subunits, suggesting an important role in receptor function. The proband shows developmental delay as well as EEG-confirmed seizure activity. Functional analyses reveal that the GluN2A(D731N) mutation decreases glutamate potency by over 3,000-fold, reduces amplitude of current response, shortens synaptic-like response time course, and decreases channel open probability, while enhancing sensitivity to negative allosteric modulators, including extracellular proton and zinc inhibition. The combined effects reduce NMDAR function. SIGNIFICANCE: We identified a de novo missense mutation in the GRIN2A gene in a patient with childhood focal epilepsy and acquired epileptic aphasia. The mutant decreases NMDAR activation suggesting NMDAR hypofunction may contribute to the epilepsy pathogenesis.

Pediatric Epileptic Encephalopathies: Pathophysiology and Animal Models.

Epileptic encephalopathies are syndromes in which seizures or interictal epileptiform activity contribute to or exacerbate brain function, beyond that caused by the underlying pathology. These severe epilepsies begin early in life, are associated with poor lifelong outcome, and are resistant to most treatments. Therefore, they represent an immense challenge for families and the medical care system. Furthermore, the pathogenic mechanisms underlying the epileptic encephalopathies are poorly understood, hampering attempts to devise novel treatments. This article reviews animal models of the three classic epileptic encephalopathies-West syndrome (infantile spasms), Lennox-Gastaut syndrome, and continuous spike waves during sleep or Landau-Kleffner syndrome-with discussion of how animal models are revealing underlying pathophysiological mechanisms that might be amenable to targeted therapy.

Hipermetabolismo temporal izquierdo en síndrome de Landau-Kleffner demostrado con PET F18-FDG: reporte de un caso con remisión metabólico-clínica postratamiento / Left temporal hypermetabolism detected in Landau-Kleffner syndrome with F18-FDG PET/CT: report of a case with metabolic and clinical remission after treatment

Brain F18-FDG Positron Emission Tomography (PET) has been used for studying focal epilepsy, with high sensitivity in detection of epileptogenic foci, even with normal magnetic resonance imaging (MRI). Some cases of Landau-Kleffner Syndrome (LKS) have shown PET abnormalities, mostly showing uni- or bilateral temporoparietal hypometabolism, although a heterogeneous group of alterations have been described. We report a case of LKS with a left hypermetabolic temporo-occipital area that responded to treatment, with clinical improvement and remission of PET hypermetabolic focus.

La positron emission tomography (PET) cerebral con F18-FDG ha sido utilizado para estudiar epilepsias focales con alta sensibilidad en la detección del área epileptógena, aun con resonancia magnética (RM) normal. La PET ha mostrado positividad en algunos casos de síndrome de Landau-Kleffner (SLK), la mayoría de las veces evidenciando hipometabolismo temporoparietal uni o bilateral, aunque un grupo heterogéneo de alteraciones asociadas ha sido descrito. Presentamos un caso de SLK con un área hipermetabólica temporooccipital izquierda, que respondió al tratamiento, con mejoría clínica y regresión del foco hipercaptante a la PET.

Possible involvement of the tip of temporal lobe in Landau-Kleffner syndrome.

Landau-Kleffner syndrome (LKS) is a childhood disorder of unknown etiology characterized by an acquired aphasia and epilepsy. We have performed comprehensive neurofunctional studies on an 8-year-old girl with typical LKS, with the aim of identifying lesions that may be responsible for her condition. 18F-fluoro-D-glucose (FDG) positron emission computed tomography (PET), 11C-Flumazenil (FMZ) PET, 99mTc-hexamethylpropyleneamine oxime single photon emission computed tomography (SPECT) and magnetoencephalography were performed before and after changes to the patient's medication led to a clinical improvement. Interictal SPECT showed hypoperfusion in the left frontal, left temporal, and left occipital lobes. 18F-FDG PET demonstrated a decrease in glucose metabolism medially in both temporal lobes and superiorly in the left temporal lobe. 11C-FMZ PET revealed a deficit in benzodiazepine receptor binding at the tip of the left temporal lobe. Magnetoencephalography demonstrated equivalent current dipoles located superiorly in the left temporal lobe. Our results suggest that the tip of the left temporal lobe plays an important role in the pathogenesis of LKS in our patient.

Safe and effective use of the ketogenic diet in children with epilepsy and mitochondrial respiratory chain complex defects.

PURPOSE: To evaluate the clinical efficacy and safety of the ketogenic diet (KD) for patients with intractable childhood epilepsy and mitochondrial respiratory chain (RC) complex defects. METHODS: A retrospective analysis evaluated outcomes in 14 children with intractable epilepsy and RC complex defects who were treated with the classic KD involving a 4:1 lipid to nonlipid ratio (% by weight), but without an initial fast and fluid restriction. Outcome measures included seizure frequency, electroencephalography (EEG) findings, the number of antiepileptic drugs, and adverse reactions. RESULTS: Of the 14 patients, 9 had Complex I defects, 1 had a Complex II defect, 3 had Complex IV defects, and 1 had combined Complex I and IV defects. Two patients with Complex IV defects showed clinical progress compatible with the Leigh disease. The epileptic diagnoses were as follows: 5 patients were diagnosed with infantile spasms, 4 with the Lennox-Gastaut syndrome, 1 with the Landau-Kleffner syndrome, 1 with nonspecific generalized seizure disorder, and 3 with partial seizure disorder. The study found that 7 patients became seizure-free after commencing the KD, three of whom successfully completed the diet without relapse. One patient with a greater than 90% seizure reduction, and 2 patients with seizure reductions between 50% and 90%, remained on the diet. Four patients, including two diagnosed with the Leigh disease, did not show any favorable responses to the diet or ceased the diet due to complications. CONCLUSIONS: The KD was a safe and effective therapy for seizures in children with intractable epilepsy and RC complex defects.

Episodic receptive aphasia in a child with Landau-Kleffner Syndrome: PET correlates.

We report a four-year-old boy with Landau-Kleffner Syndrome (LKS) characterized by episodic receptive aphasia lasting for few weeks followed by gradual recovery of baseline language functions. Neuropsychological evaluation during an episode showed severe impairment in verbal skills and comprehension, but relative preservation of non-verbal skills. Although he could carry on a conversation during remission, neuropsychological evaluation demonstrated findings reflective of receptive language deficits. Prolonged EEG disclosed frequent sharp-wave activity in the left and right temporal regions but no electrographic seizures. Glucose metabolism PET scan during the fourth episode of aphasia revealed intense hypermetabolism in the left temporal neocortex. Awake EEG during the PET tracer uptake period showed 6.0 spikes/min in the left temporal region and 4.0 spikes/min in the right. A repeat PET scan during remission showed hypometabolism in the left temporal cortex. Awake EEG during the FDG uptake period showed 16.0 spikes/min in the right temporal region and 0.3 spikes/min in the left. During his fifth aphasic episode, EEG (without PET) showed 0.16 spikes/min in the right temporal region and none in the left. Intermittent short episodes of predominantly receptive aphasia with near-total recovery between episodes can be one of the clinical presentations of LKS. This case illustrates the dynamic changes of glucose metabolism in the temporal lobe during episodes of aphasia and remission in a case with LKS. The clinical course of our patient with transient EEG and PET findings suggest that glucose metabolism in LKS cannot be attributed solely to interictal epileptiform activities on scalp EEG.

Brain-derived neurotrophic factor and autoantibodies to neural antigens in sera of children with autistic spectrum disorders, Landau-Kleffner syndrome, and epilepsy.

BACKGROUND: Brain derived neurotrophic factor (BDNF) elevation in newborn sera predicts intellectual/social developmental abnormalities. Other autoantibodies (AAs) to endothelial cells (ECs) and myelin basic protein (MBP) are also elevated in some children. We tested relationships between BDNF, BDNF AAs, and other AAs in children with these disorders. METHODS: BDNF levels and IgG/IgM autoantibodies to BDNF, ECs, MBP, and histones were measured in children with autism, childhood disintegrative disorder (CDD), pervasive developmental delay-not otherwise specified (PDD-nos), acquired epilepsy, Landau-Kleffner syndrome (LKS); healthy children (HC), and children with non-neurological illnesses (NNI). RESULTS: Mean BDNF levels were elevated in children with autism and CDD, (p < or = 0.0002) compared to HC or NNI. Mean IgG and IgM BDNF AAs were elevated in children with autism, CDD and epilepsy (p < or = 0.0005) compared to HC but not to NNI. Mean IgM AA EC titers detected by immunocytochemistry were higher in autism, PDD-NOS, epilepsy, and LKS (p < or = 0.005) compared to HC and NNI. While mean ELISA IgG EC AAs were higher in autism and PPD-NOS (p < 0.005) compared to HC but not NNI, ELISA IgM EC AAs were higher in children with autism, CDD, PDD-NOS, and epilepsy compared to both HC and NNI (p < 0.0005). Mean anti-MBP IgG and IgM titers were higher in all study groups (p < 0.005) except for LKS compared to both HC and NNI. CONCLUSION: Children with developmental disorders and epilepsy have higher AAs to several neural antigens compared to controls. The presence of both BDNF AAs and elevated BDNF levels in some children with autism and CDD suggests a previously unrecognized interaction between the immune system and BDNF.

Chronic auditory agnosia following Landau-Kleffner syndrome: a 23 year outcome study.

We report a 27-year-old woman with chronic auditory agnosia following Landau-Kleffner Syndrome (LKS) diagnosed at age 4 1/2. She grew up in the hearing/speaking community with some exposure to manually coded English and American Sign Language (ASL). Manually coded (signed) English is her preferred mode of communication. Comprehension and production of spoken language remain severely compromised. Disruptions in auditory processing can be observed in tests of pitch and duration, suggesting that her disorder is not specific to language. Linguistic analysis of signed, spoken, and written English indicates her language system is intact but compromised because of impoverished input during the critical period for acquisition of spoken phonology. Specifically, although her sign language phonology is intact, spoken language phonology is markedly impaired. We argue that deprivation of auditory input during a period critical for the development of a phonological grammar and auditory-verbal short-term memory has limited her lexical and syntactic development in specific ways.

Landau-Kleffner syndrome: metabolic abnormalities in temporal lobe are a common feature.

Landau-Kleffner syndrome (acquired epileptic aphasia) is characterized by language regression following normal acquisition of language skills, accompanied by epileptiform abnormalities on the electroencephalogram (EEG) with or without clinical seizures. Continuous spikes and waves during slow wave sleep may be seen on the EEG, but are not required to make the diagnosis. Structural neuroimaging with computed tomography (CT) and magnetic resonance imaging (MRI) is typically normal. We have evaluated 17 children (aged 2.4 to 10.6 yr) with Landau-Kleffner syndrome using positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) in order to determine whether there are metabolic abnormalities common to this syndrome. Patients were awake for the uptake period of FDG, and the EEG was monitored. On a visual analysis of the PET images, patients showed metabolic abnormalities in the temporal lobes. Two children had focal hypermetabolism in the left temporal cortex, one of whom also showed right temporal cortex hypometabolism. The remaining patients (n = 15) showed bilateral temporal hypometabolism, and comparison of these patients with a neurologically normal age-matched control group (n = 8) demonstrated significantly reduced glucose metabolism bilaterally in middle temporal gyrus (P < .02). In addition, other cortical regions displayed hypometabolism, although these regions were not consistently abnormal in all patients. The finding of temporal lobe abnormalities in all Landau-Kleffner syndrome patients suggests that temporal lobe structures are important in the pathophysiology of this syndrome, whereas the presence of additional cortical abnormalities in many patients indicates that extensive brain functional disturbances are common.