Multiple brain lesions in a young man with hypernatraemia.

1 of 2 DESCRIPTION A 47-year-old patient with a history of chronic alcoholism was admitted to our hospital with sudden loss of consciousness, respiratory failure and severe hypernatraemia (173 mEq/l); he had no other alterations in routine laboratory analyses. During admittance he experienced mental status fl uctuations and developed a spastic tetraparesis, a bilateral Babinski sign and a bilateral facial paresis (locked in status). Brain MRI ( fi gure 1 ) showed symmetric lesions in the pons and thalami with areas of restricted diffusion and no signifi cant mass effect. The pons lesion spared the external pontine fi bres and had a trident shape. Clinical history together with MR images suggested an osmotic demyelination syndrome (ODS), specifi cally a case of central pontine and extrapontine myelinolysis. ODS is a rare condition caused by severe electrolyte imbalance. 1 It usually occurs during a rapid iatrogenic correction of hyponatraemia but has sometimes been described in a hypernatraemia context without sudden deviations of sodium concentration. 2 It puts the nerve cells, particularly oligodendrocytes, at risk of cellular dehydration and demyelination. Alcohol addicts and malnourished individuals are at higher risk of developing it because they usually have a defi ciency in organic osmolytes. 3 In this patient’s case alcoholism probably acted as a predisposing factor. 2 3 Myelinolysis predominantly affects the pons due to the intercrossing arrangement of oligodendrocytes, which limits the ability of these cells to increase their volume. 3 Extrapontine myelinolysis occurs in 10% of the cases. The patient’s hypernatraemia was slowly corrected but his condition has not improved; he is currently in a long-term care unit. Images in...