RESUMO
MAIN AIM: To electrophysiologically determine the impact of moderate to severe chronic hypoxia (H) resulting from a wide array of CHD (HCHD) conditions on the integrity of brainstem function. MATERIALS AND METHODS: Applying brainstem auditory-evoked response methodology, 30 chronically afflicted HCHD patients, who already had undergone heart surgery, were compared to 28 healthy control children (1-15 yo) matched by age, gender and socioeconomic condition. Blood oxygen saturation was clinically determined and again immediately before brainstem auditory-evoked response testing. RESULTS: Among HCHD children, auditory wave latencies (I, III and V) were significantly longer (medians: I, 2.02 ms; III, 4.12 ms, and; V, 6.30 ms) compared to control (medians: I, 1.67ms; III, 3.72 ms, and; V, 5.65 ms), as well as interpeak intervals (HCHD medians: I-V, 4.25 ms, and; III-V, 2.25ms; control medians: I-V, 3.90 ms and, III-V, 1.80 ms) without significant differences in wave amplitudes between groups. A statistically significant and inverse correlation between average blood oxygen saturation of each group (control, 94%; HCHD, 78%) and their respective wave latencies and interpeak intervals was found. CONCLUSIONS: As determined by brainstem auditory-evoked responses, young HCHD patients manifestly show severely altered neuronal conductivity in the auditory pathway strongly correlated with their hypoxic condition. These observations are strongly supported by different brainstem neurological and image studies showing that alterations, either in microstructure or function, result from the condition of chronic hypoxia in CHD. The non-altered wave amplitudes are indicative of relatively well-preserved neuronal relay nuclei.
Assuntos
Potenciais Evocados Auditivos do Tronco Encefálico , Hipóxia , Humanos , Criança , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Tronco EncefálicoRESUMO
OBJECTIVE: Iron is an important oligoelement participating in multiple metabolic processes, including the synthesis of catecholamines, and its deficiency (ID) throughout development is particularly insidious on brain maturation and the emergence of cognitive functions during school age. A working memory (WM) study in 8-10-year-old ID children is presented. It is hypothesized that an impairment in WM exists in ID school-age children and a substantial restoration of this mental ability should occur after iron supplementation. METHODS: Event-related potentials (ERPs) were recorded during the completion of a Sternberg-type task in control, ID and ID-iron supplemented children. RESULTS: ID children showed less correct answers and diminished ERP amplitude in frontal, central, parietal and temporal regions compared to control children. After iron supplementation and normalizing bodily iron stores, behavioral and ERP differences disappeared between ID and control children. CONCLUSIONS: Considering that WM is fundamentally related to attention ability, the results presented here confirm and reinforce previous observations: ID severely diminishes attention [Otero GA, Pliego-Rivero FB, Contreras G, Ricardo J, Fernandez T. Iron supplementation brings up a lacking P300 in iron deficient children. Clin Neurophysiol 2004;115:2259-66] and WM while iron supplementation substantially restores the cognitive capabilities tested. SIGNIFICANCE: This is one of very few reports using ERP showing a diminished WM capability in ID school-age children.
Assuntos
Distúrbios do Metabolismo do Ferro/complicações , Transtornos da Memória/dietoterapia , Transtornos da Memória/etiologia , Memória de Curto Prazo/fisiologia , Recuperação de Função Fisiológica/fisiologia , Análise de Variância , Atenção/efeitos dos fármacos , Atenção/fisiologia , Células Sanguíneas/fisiologia , Criança , Eletroencefalografia/métodos , Potenciais Evocados/efeitos dos fármacos , Potenciais Evocados/fisiologia , Feminino , Hematócrito/métodos , Hemoglobinas/metabolismo , Humanos , Ferro/administração & dosagem , Ferro/sangue , Distúrbios do Metabolismo do Ferro/dietoterapia , Distúrbios do Metabolismo do Ferro/patologia , Masculino , Testes Neuropsicológicos , Recuperação de Função Fisiológica/efeitos dos fármacos , Estatísticas não Paramétricas , Fatores de TempoRESUMO
OBJECTIVE: A decrease in iron concentration is accompanied by alterations in catecholaminergic and GABAergic neurotransmission systems, important in learning, memory and attention. It was hypothesized that iron deficient children would present attention deficits. A visual-event related potentials (ERPs) study is presented using an oddball paradigm in order to determine the P300 in ID children. METHODS: After medical examination, blood was obtained from 201 children for a complete hematological study. Two groups were selected, iron deficient (ID) (serum iron <60 microg/dl) and control (C) (serum iron >60 microg/dl). In both groups ERPs were recorded while executing a continuous performance task (oddball paradigm). Afterwards iron levels were restored in ID children by iron supplementation (ID-IS group) and all tests reapplied. RESULTS: ID children almost lacked a P300 in central and parietal regions. After iron supplementation, P300 clearly became evident although its Pz amplitude remained smaller compared to C children. CONCLUSIONS: A clear and strong correlation was found between ID and attention alterations in children. Iron supplementation nearly brings the P300 to normal levels although it is not known if the P300 difference in Pz is due to other nutritional/environmental deficits or to developmental psychomotor impairments in ID children. SIGNIFICANCE: It has been long known that iron deficient children have cognitive impairments but there is an insufficient number of electrophysiological works allowing to identify the source of this problem. In this work an attention deficit is demonstrated in ID children through a severely reduced P300, which recovers substantially after iron supplementation.