[Default mode network and Alzheimer's disease]. / Red neural por defecto y enfermedad de Alzheimer.

Brain functioning is mainly intrinsic, not primarily reflexive. This is supported by the high energy requirements of the resting brain (20% of all the energy consumed) which only marginally increases with changes in brain activity. Modern neuroimaging and neurophysiological techniques have led to the discovery of the so called brain default mode network (DMN), a constellation of brain regions which support brain activity at rest and whose discharges decrease during task-induced activities. Another characteristic of the DMN are the elevated levels of aerobic glycolysis (Warburg effect), that is, metabolism of glucose to lactic acid in the presence of sufficient levéis of oxygen. In Alzheimer's disease there is amyloid deposition and metabolic disruption at the DMN regions. Changes in connectivity among the different nodes of the DMN and its connections with the hippocampus have been reported. The characteristics of the DMN and its relation to Alzheimer's disease are discussed. This issue is of interest in the pathogenesis and possibly for its usefulness as a biomarker of the disease.

Red neural por defecto y enfermedad de Alzheimer / Default mode network and Alzheimer's disease

Brainfunctioning is mainly intrinsic, notprimarily reflexive. This is supported by the high energy requirements ofthe resting brain (20% ofall the energy consumed) which only marginally increases with changes in brain activity. Modern neuroimaging and neurophysiological techniques have led to the discovery of the so called brain default mode network (DMN), a constellation of brain regions which support brain activity at rest and whose discharges decrease during task-induced activities. Another characteristic ofthe DMN are the elevated levéis of aerobic glycolysis (Warburg effect), that is, metabolism ofglucose to lactic acid in thepresence ofsufficient levéis ofoxygen. In Alzheimer's disease there is amyloid deposition and metabolic disruption at the DMN regions. Changes in connectivity among the different nodes ofthe DMN and its connections with the hippocampus have been reported. The characteristics ofthe DMN and its relation to Alzheimer's disease are discussed. This issue is ofinterest in the pathogenesis and possibly for its usefulness as a biomarker ofthe disease.

[One hundred years of Alzheimer's disease: immunotherapy a hope?]. / Cien años de la enfermedad de Alzheimer: La inmunoterapia ¿una esperanza?

In 1906 Alois Alzheimer, described the cerebral lesions characteristic of the disorder that received his name: senile plaques and neurofibrillary tangles. Alzheimer's disease (AD) is now, 100 years after, the most prevalent form of dementia in the world. The longer life expectancy and aging of the population renders it as a serious public health problem of the future. Urgent methods of diagnosis and treatment are required, since the definitive diagnosis of AD continues to be neuropathologic. In the last 30 years several drugs have been approved to retard the progression of the disease; however, there are still no curative or preventive treatments. Although still in experimentation, the visualization of amyloid deposition by positron emission tomography or magnetic resonance imaging will allow in vivo diagnosis of AD. In addition, experiments with the amyloid vaccine are still ongoing, and very recent data suggest that intravenous gammaglobulins may be beneficial and safe for the treatment of AD.

Cien años de la enfermedad de Alzheimer: La inmunoterapia ¿una esperanza? / One hundred years of Alzheimer's disease: Immunotherapy a hope?

In 1906 Alois Alzheimer, described the cerebral lesions characteristic of the disorder that received his name: senile plaques and neurofibrillary tangles. Alzheimer's disease (AD) is now, 100 years after, the most prevalent form of dementia in the world. The longer life expectancy and aging of the population renders it as a serious public health problem of the future. Urgent methods of diagnosis and treatment are required, since the definitive diagnosis of AD continues to be neuropathologic. In the last 30 years several drugs have been approved to retard the progression of the disease; however, there are still no curative or preventive treatments. Although still in experimentation, the visualization of amyloid deposition by positron emission tomography or magnetic resonance imaging will allow in vivo diagnosis of AD. In addition, experiments with the amyloid vaccine are still ongoing, and very recent data suggest that intravenous gammaglobulins may be beneficial and safe for the treatment of AD.

Inhalación crónica de solventes orgánicos y neuropatía: caso clínico / Chronic inhalation of organic solvents and neuropathy. Clinical case

A young man had indulged in chronic solvent vapor abuse for 14 years. After an abstinence period of 4 months, neurological evaluation showed distal limb weakness, predominantly of the lower extremities, and moderate loss of reflexes. Sensory signs were absent. Electromyographyc evidence of chronic partial denervation was shown. Maximal motor conduction velocities were reduced and distal motor sensory latencies were increased, presumably because of secondary demyelinating changes. CT revealed diffuse atrophy of cerebral hemispheres, however the mental status of the patients was judged normal. Thus, chronic exposure to slvente vapor may cause peripheral nervous system impairment without evidence of clinical effects on the central nervous system

Siringomielia: aspectos clínicos y diagnósticos / Syringomyelia: clinical and diagnostic considerations

Se estudió a 10 pacientes hospitalizados, portadores de una siringomielia. El diagnóstico clínico se corroboró con TAC de médula y/o cirugía. De los 10 pacientes estudiados dos casos presentaron un síndrome sensitivo disociado clásico. En tres hubo compromiso de todas las modalidades sensitivas y en los cinco restantes de la sensibilidad tactil y termoalgésica. Se concluye en base a estas observaciones que el síndrome siringomiélico clásico no está siempre presente en los pacientes portadores de siringomielia. Se describen los hallazgos clínicos en este grupo de pacientes y se propone utilizar el término de síndrome medular central para denominar el cuadro clínico encontrado en estos casos