Browsing by Author "Ferreira, JC"
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- Anatomical and Physiological Basis of Continuous Spike-Wave of Sleep Syndrome after Early Thalamic LesionsPublication . Leal, A; Calado, E; Vieira, JP; Mendonça, C; Ferreira, JC; Ferreira, H; Carvalho, D; Furtado, F; Gomes, R; Monteiro, JPOBJECTIVE: Early neonatal thalamic lesions account for about 14% of continuous spike-wave of sleep (CSWS) syndrome, representing the most common etiology in this epileptic encephalopathy in children, and promise useful insights into the pathophysiology of the disease. METHODS: We describe nine patients with unilateral neonatal thalamic lesions which progressed to CSWS. Longitudinal whole-night and high-density electroencephalograms (EEGs) were performed, as well as detailed imaging and clinical evaluation. Visual evoked potentials were used to probe cortical excitability. RESULTS: Thalamic volume loss ranged from 19% to 94%, predominantly on medial and dorsal nuclei and sparing the ventral thalamus. Lesions produced white matter loss and ventricle enlargement on the same hemisphere, which in four patients was associated with selective loss of thalamic-cortical fibers. Cortical thickness quantification failed to reveal hemispheric asymmetries. Impact on EEG rhythms was mild, with a volume-loss-related decrease in alpha power and preservation of sleep spindles. The sleep continuous spiking was lateralized to the hemisphere with the lesion. Visual cortex stimulation in five patients with posterior cortex spiking revealed an abnormal frequency-dependent excitability at 10-20Hz on the side of the lesion. SIGNIFICANCE: Unilateral selective thalamic-cortical disconnection is a common feature in our patients and is associated with both a focal pattern of CSWS and a pathological type of frequency-dependent excitability (peak: 10-20Hz). We propose that this excitability represents an abnormal synaptic plasticity previously described as the augmenting response. This synaptic plasticity has been described as absent in the corticocortical interactions in healthy experimental animals, emerging after ablation of the thalamus and producing a frequency-dependent potentiation with a peak at 10-20Hz. Because this response is potentiated by sleep states of reduced brainstem activation and by appropriate stimulating rhythms, such as sleep spindles, the simultaneous occurrence of these two factors in nonrapid-eye-movement sleep is proposed as an explanation for CSWS in our patients.
- Doenças Neuromusculares na Idade Pediátrica em Portugal - Estudo PreliminarPublication . Santos, MA; Fineza, I; Moreno, T; Cabral, P; Ferreira, JC; Lopes Silva, R; Vieira, JP; Moreira, A; Dias, AI; Calado, E; Monteiro, JP; Fonseca, MJ; Moço, C; Furtado, F; Campos, MM; Gonçallves, O; Gomes, R; Barbosa, C; Figueiroa, S; Temudo, T; Fagundes, F
- LAMA2 Gene Analysis in a Cohort of 26 Congenital Muscular Dystrophy PatientsPublication . Oliveira, J; Santos, R; Soares-Silva, I; Jorge, P; Vieira, E; Oliveira, ME; Moreira, A; Coelho, T; Ferreira, JC; Fonseca, MJ; Barbosa, C; Prats, J; Aríztegui, ML; Martins, ML; Moreno, T; Heinimann, K; Barbot, C; Pascual-Pascual, SI; Cabral, A; Fineza, I; Santos, M; Bronze-da-Rocha, ECongenital muscular dystrophy type 1A (MDC1A) is caused by mutations in the LAMA2 gene encoding laminin-alpha2. We describe the molecular study of 26 patients with clinical presentation, magnetic resonance imaging and/or laminin-alpha2 expression in muscle, compatible with MDC1A. The combination of full genomic sequencing and complementary DNA analysis led to the particularly high mutation detection rate of 96% (50/52 disease alleles). Besides 22 undocumented polymorphisms, 18 different mutations were identified in the course of this work, 14 of which were novel. In particular, we describe the first fully characterized gross deletion in the LAMA2 gene, encompassing exon 56 (c.7750-1713_7899-2153del), detected in 31% of the patients. The only two missense mutations detected were found in heterozygosity with nonsense or truncating mutations in the two patients with the milder clinical presentation and a partial reduction in muscle laminin-alpha2. Our results corroborate the previous few genotype/phenotype correlations in MDC1A and illustrate the importance of screening for gross rearrangements in the LAMA2 gene, which may be underestimated in the literature.
- Origin of Frontal Lobe Spikes in the Early Onset Benign Occipital Lobe Epilepsy (Panayiotopoulos Syndrome)Publication . Leal, A; Ferreira, JC; Dias, AI; Calado, EObjective: Early onset benign occipital lobe epilepsy (Panayiotopoulos syndrome [PS]) is a common and easily recognizable epilepsy. Interictal EEG spike activity is often multifocal but most frequently localized in the occipital lobes. The origin and clinical significance of the extra-occipital spikes remain poorly understood. Methods: Three patients with the PS and interictal EEG spikes with frontal lobe topography were studied using high-resolution EEG. Independent component analysis (ICA) was used to decompose the spikes in components with distinct temporal dynamics. The components were mapped in the scalp with a spline-laplacian algorithm. Results: The change in scalp potential topography from spike onset to peak, suggests the contribution of several intracranial generators, with different kinetics of activation and significant overlap. ICA was able to separate the major contributors to frontal spikes and consistently revealed an early activating group of components over the occipital areas in all the patients. The local origin of these early potentials was established by the spline-laplacian montage. Conclusions: Frontal spikes in PS are consistently associated with early and unilateral occipital lobe activation, suggesting a posteroanterior spike propagation. Significance: Frontal spikes in the PS represent a secondary activation triggered by occipital interictal discharges and do not represent an independent focus.