Hyponatremia in acute polyneuropathy. Four cases with the syndrome of inappropriate secretion of antidiuretic hormone.

Abstract

HYPONATREMIA is a widely recognized complication of several central nervous system (CNS) disorders. Recent reports of hyponatremia in subarachnoid hemorrhage1and herpes simplex encephalitis2have added to a long list which includes meningitis,3head injuries,4brain tumors,5and a variety of other CNS illnesses.6-8The recognition of this complication is clinically important since hyponatremia per se may cause delirium, tremor, and convulsions, and thus create a problem in diagnosis or additionally insult an already damaged nervous system. It is less widely recognized that hyponatremia complicates acute para-infectious polyneuropathy, an illness usually considered to be restricted to the peripheral nervous system.9To our knowledge, only three such cases have been reported;10-12and in all, the lowered serum sodium produced no symptoms. This paper reports four cases of severe hyponatremia associated with, and complicating the course of, pareinfectious polyneuropathy. The evidence suggests that