[Nutritional and metabolic aspects of neurological diseases]

The central nervous system regulates food intake, homoeostasis of glucose and electrolytes, and starts the sensations of hunger and satiety. Different nutritional factors are involved in the pathogenesis of several neurological diseases. Patients with acute neurological diseases (traumatic brain injury, cerebral vascular accident hemorrhagic or ischemic, spinal cord injuries, and cancer) and chronic neurological diseases (Alzheimer's Disease and other dementias, amyotrophic lateral sclerosis, Parkinson's Disease) increase the risk of malnutrition by multiple factors related to nutrient ingestion, abnormalities in the energy expenditure, changes in eating behavior, gastrointestinal changes, and by side effects of drugs administered. Patients with acute neurological diseases have in common the presence of hyper metabolism and hyper catabolism both associated to a period of prolonged fasting mainly for the frequent gastrointestinal complications, many times as a side effect of drugs administered. During the acute phase, spinal cord injuries presented a reduction in the energy expenditure but an increase in the nitrogen elimination. In order to correct the negative nitrogen balance increase intakes is performed with the result of a hyper alimentation that should be avoided due to the complications resulting. In patients with chronic neurological diseases and in the acute phase of cerebrovascular accident, dysphagia could be present which also affects intakes. Several chronic neurological diseases have also dementia, which lead to alterations in the eating behavior. The presence of malnutrition complicates the clinical evolution, increases muscular atrophy with higher incidence of respiratory failure and less capacity to disphagia recuperation, alters the immune response with higher rate of infections, increases the likelihood of fractures and of pressure ulcers, increases the incapacity degree and is an independent factor to increase mortality. The periodic nutritional evaluation due to the evolutionary changes should be part of the treatment. At the same time to know the metabolic and nutritional characteristics is important to be able to prevent and treat early the possible side effects. If nutritional support is indicated, the enteral route is the route of choice although some times, mainly in critical patients, parentral nutrition is necessary to ensure the administration of the required nutrients.