Browsing by Author "Monteiro, JP"
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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.
- Cerebral Sinovenous Thrombosis in Children: Clinical Presentation and Extension, Localization and Recanalization of ThrombosisPublication . Vieira, JP; Luis, C; Monteiro, JP; Temudo, T; Campos, MM; Quintas, S; Nunes, SMany important questions regarding pathophysiology and treatment of cerebral sinovenous thrombosis need clarification and may depend on further knowledge on the etiology, site, extension and recanalization of the thrombosis. We studied these variables in a cohort of children and adolescents from seven Portuguese Centers. We conclude from our results that the deep venous system and the superior longitudinal sinus are less frequently affected with thrombosis but have a greater potential for serious neurologic disease and for major sequelae. Non-recanalization, at least in the long term, is not an adverse prognostic factor. Extensive propagation of the thrombus from the initial site of origin seems to be common. The early identification of risk factors and their treatment coupled with an aggressive attitude towards diagnosis and treatment for thrombosis involving the deep venous system would be warranted.
- 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