There are several clinically significant specific cognitive disorders related to heavy use of alcohol. We present the issue of alcohol-related osmotic demyelinating syndromes (ODS), which are defined by myelin damage in several brain areas. Based on the typical location of the lesions, we distinguish central pontine myelinolysis (CPM) and extrapontine myelinolysis (EPM or Marchiafava-Bignami disease), respectively. The immediate cause of myelinolysis is a sudden change in plasma sodium concentration with related osmolality dysbalance, including hyponatremia as well as hypernatremia. There are several factors that trigger the onset of CPM and EPM in alcohol-addicted patients: the effect of alcohol on diuresis, malnutrition and liver damage. ODS have typically acute onset, they include various clinical symptoms, and have poor prognosis. The basis of their treatment is slow and careful correction of hypo- or hyper-natremia under the supervision of an internist, while managing the underlying causes.

Key words: alcohol – sodium – osmotic demyelination – central pontine myelinolysis – extrapontine myelinolysis