The study of nutritional disorders of the nervous system is complex for several reasons. First, multiple deficiencies may co-exist in the same patient in certain settings, such as malnutrition and malabsorption states. Second, nutritional disorders can occur with the ingestion of potentially toxic agents as in alcohol, making it difficult to separate the neurotoxic effects from a specific dietary deficiency. Third, in several disorders a single so-called biochemical lesion has not been identified, such as in Marchiafava-Bignami disease, central pontine myelinolysis, Strachan's syndrome, and deficiency amblyopia. Fourth, the rapidity of onset of some syndromes may not be interpreted as nutritional. Instead of evolving in a slowly progressive fashion, some deficiency states may become acutely symptomatic when triggered by an environmental stressor or sudden increase in metabolic demands for the deficient nutrient. The administration of intravenous glucose to a thiamine-depleted alcoholic patient may precipitate acute Wernicke-Korsakoff syndrome (WKS) owing to the sudden increase in thiamine-dependent carbohydrate catabolism. Intractable vomiting due to hyperemesis gravidarum may also cause WKS. Similarly, nitrous oxide administration to patients with asymptomatic cobalamin deficiency may cause an acute myeloneuropathy. Additionally, sudden changes in tissue osmolarity, such as the rapid correction of hyponatremia, may lead to central pontine myelinolysis (
Fifth, at times, the same deficient nutrient may not affect patients uniformly. Thiamine deficiency leads to capillary proliferation, petechiae, and microglial degeneration of midline central nervous system (CNS) nuclei in some patients, and in others, it leads to peripheral nerve axonal degeneration. Neurological symptoms and signs of individual deficiency states often overlap, making clinical distinction difficult. For example, encephalopathy may be seen in deficiencies of thiamine, cobalamin, and niacin; myeloneuropathy
40-1 -- ACUTE AND SUBACUTE PRESENTATION OF NUTRITIONAL DEFICIENCY SYNDROMES
Wernicke-Korsakoff syndrome Wernicke-Korsakoff syndrome Postgastroplasty neuropathy Vitamin Bl2 myeloneuropathy Central pontine myelinolysis
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