Cerebral correlates of declarative memory dysfunctions in early traumatic brain injury.

We investigated residual brain damage in subjects who suffered severe traumatic brain injury (TBI) in childhood, and its relationship with declarative memory impairment. Magnetic resonance imaging (MRI) volumetric data and memory performance were compared between 16 adolescents with antecedents of severe TBI and 16 matched normal controls. Volumes of grey matter, white matter, cerebrospinal fluid (CSF), hippocampus, and caudate nuclei were measured. Verbal memory was assessed by the Rey's Auditory Verbal Learning test and visual memory by the Rey's Complex Figure. TBI patients performed significantly worse than controls in both verbal and visual memory. Patients presented decreased white matter volume and increased CSF. The hippocampus was reduced, but not the caudate nuclei. Memory performance correlated with CSF. Plasticity is incomplete for structural and functional deficits in children with TBI. Hippocampal atrophy, white matter loss, and memory impairment remain until adolescence. Memory sequelae are related more to diffuse brain injury, as reflected by MRI findings of increased CSF, than to hippocampal injury.

[Cognitive deficit in perinatal asphyxia]. / Déficit cognitivos en la asfixia perinatal.

INTRODUCTION: During the period 1950 1970 the relation between perinatal asphyxia and cognitive alterations was studied. More recently the neuropsychological approach has been introduced to detect more subtle defects. DEVELOPMENT: With regard to intelligence, alterations in the intelligence quotient resulting from anoxia are more commonly seen in young children than in adolescents, probably because of compensation mechanisms. It is widely accepted that severe asphyxia causes motor and cognitive alterations and leads to cerebral palsy, epilepsy and intellectual retardation. The effects of mild or moderate asphyxia are still controversial. CONCLUSION: Thorough neuropsychological examination, particularly assessment of memory and frontal function, helps to identify subtle deficits which may explain some learning problems observed in children who have a history of moderate asphyxia but previously no clear neurological diagnosis.

Déficit cognitivos en la asfixia perinatal / Cognitive deficit in perinatal asphyxia

Introducción. En las décadas de los años 50-70 se llevaron a cabo diversos estudios sobre la asociación entre asfixia perinatal y las alteraciones cognitivas. Más recientemente se ha introducido la óptica neuropsicológica para identificar déficit más sutiles. Desarrollo. Respecto a la inteligencia, las alteraciones de cociente intelectual resultantes de la anoxia se observan más frecuentemente en niños de corta edad respecto a los adolescentes, probablemente debido a mecanismos compensatorios. Se acepta ampliamente que la asfixia grave causa alteraciones motoras y cognitivas y que produce parálisis cerebral, epilepsia y retraso intelectual. Respecto a la asfixia leve o moderada existen aun controversias. Conclusión. La exploración neuropsicológica exhaustiva, que incluye en especial la valoración de la memoria y las funciones frontales, ayuda a identificar déficit sutiles que podrían explicar algunas disfunciones escolares observadas en niños con antecedentes de asfixia moderada, que no presentaron anteriormente un claro diagnóstico neurológico (AU)

Neuropsychological long-term sequelae of perinatal asphyxia.

OBJECTIVE: To investigate the long-term neuropsychological consequences of perinatal asphyxia (PA). METHODS: A group of adolescents were assessed with antecedents of mild (n = 8) and moderate (n = 20) PA, and a matched group of 28 healthy adolescents as a control group. Neuropsychological assessment included tests of memory, perceptual-motor skills, and frontal lobe functions, because these are areas of cognitive functioning susceptible to hypoxic conditions. RESULTS: Subjects with moderate PA showed significant differences from the control group on tests related to delayed recall for both verbal and visual information, perceptual-motor speed, and tests assessing attention and executive functions. Conversely, subjects in the mild PA group exhibited scores which were similar to those of the control group in all the assessed variables. CONCLUSION: The present findings demonstrate that subtle but persistent neuropsychological deficits were observed in adolescents with antecedents of moderate PA, but not in those classified with mild asphyxia.

(1)H-MR spectroscopy is sensitive to subtle effects of perinatal asphyxia.

The authors performed neuropsychological and (1)H-MRS studies in 18 subclinical patients with antecedents of perinatal asphyxia (PA) and in 18 matched control subjects. Patients with PA showed reduced values of N-acetylaspartate (NAA) in both the basal ganglia and the midtemporal region (MTR) and reduced NAA/choline values in the MTR. Neuropsychological testing showed group differences in tasks related to attention and memory. These results indicate persistent dysfunctions in cerebral structures vulnerable to hypoxia and demonstrate the utility of MRS for the long-term evaluation of cerebral sequelae of neonatal asphyxia.

[Attention deficit hyperactivity disorder. Cerebral asymmetry observed on magnetic resonance]. / Trastorno por déficit de atención con hiperactividad. Asimetrías cerebrales observadas en resonancia magnética.

INTRODUCTION: Anatomical and functional neuroimaging data from subjects with Attention Deficit Hyperactivity Disorder (ADHD) have consistently implicated a reversal of cerebral asymmetry and suggested a fronto-striatal dysfunction in this disorder. OBJECTIVE: The aim of this study is to investigate the brain asymmetries in a homogeneous and non-medicated sample of adolescents with ADHD who had been previously studied in our laboratory. PATIENTS AND METHODS: T1-weighted magnetic resonance images were obtained for 11 adolescents with ADHD and 19 control subjects. Frontal and posterior brain regions, caudate nucleus, and ventricular system were quantitatively measured. RESULTS: A reversed pattern of asymmetry for the caudate nucleus (right > left) was found in ADHD when compared to the control group. We also found a reversed pattern of asymmetry for the frontal lobe (right < left) and a smaller right frontal volume (prefrontal specifically) in the ADHD subjects most severely impaired. Right caudate and frontal measures were inversely correlated. CONCLUSIONS: ADHD is associated with fronto-striatal abnormalities, which may be explicable via extant neurodevelopmental theories. Enlargement of the right caudate nucleus may suggest the failure of a process of synaptic 'pruning' by which attentional functions could be improperly transferred from the basal ganglia to frontal regions during development.

Trastorno por déficit de atención con hiperactividad. Asimetrías cerebrales observadas en resonancia magnética / Attention deficit hyperactivity disorder. Cerebral asymmetry observed on magnetic resonance

Introducción. Los estudios de neuroimagen estructural y funcional en sujetos con trastorno por déficit de atención con hiperactividad (TDAH) han sugerido una inversión de los patrones de asimetría cerebral y una disfunción del sistema fronto-estriatal. Objetivo. El propósito de esta investigación es estudiar las asimetrías cerebrales de una muestra homogénea y no medicada de adolescentes con TDAH. Pacientes y métodos. Se realizaron las resonancias magnéticas potenciadas en T1 de 11 adolescentes con TDAH y 19 sujetos normales que formaban el grupo control. Se realizó la medición cuantitativa semiautomatizada de diversas regiones y estructuras cerebrales: regiones frontal y posterior, núcleo caudado y sistemaventricular.Resultados.Seobservaunpatróninversodeasimetría del núcleo caudado (derecho > izquierdo) en el grupo TDAH en comparación con el grupo control. También en el grupo TDAH se aprecia la asimetría inversa de los lóbulos frontales (derecho < izquierdo) y un menor volumen frontal derecho (región prefrontal concretamente) en los sujetos con TDAH más gravemente afectados.El núcleo caudado y las medidas frontales presentaron una correlación negativa. Conclusiones. ElTDAH está asociado con alteraciones del sistema fronto-estriatal cerebral, alteración que es coherente conlas teorías del neurodesarrollo. El fracaso en el fenómeno regresivo que conlleva el proceso de apoptosiso `muerte neuronal programada' podría ser el mecanismo subyacente al mayor tamaño del núcleo caudado derecho. Como consecuencia, la transferencia de las funciones atencionales de los ganglios basales al lóbulo frontal se produciría de forma inapropiada a lo largo del desarrollo (AU)