“Hyponatremia in Stroke: Cerebral Salt Wasting Versus Syndrome of Inappropriate Anti-Diuresis”

Abstract

Hyponatremia is the most common electrolyte imbalance in neurologic patients. The causes of hyponatremia are varied, but in neurologically ill patients, is most commonly attributed to Syndrome of Inappropriate Anti-diuresis and Cerebral Salt Wasting. Both these entities are cerebral in origin but have distinct pathophysiology, prognosis and treatment options. The importance of distinguishing both lies in the fact that the therapy indicated for one if used for the other, can be deleterious. SIADH is a subclinically volume expanded state due to inappropriate anti-diuresis.. In stroke SIADH occurs due to AVP secretion inappropriate to the osmotic threshold. It thus requires fluid restriction as the treatment. CSW, on the other hand, is essentially a volume depleted state, which occurs due to the combined effects of decreased sympathetic outflow and increased natriuretic peptides and needs rigorous volume repletion. Hyponatremia, especially Cerebral Salt Wasting, occurring in the setting of stroke has been shown to worsen the prognosis of stroke, increase morbidity, short and long term mortality, and cause a poorer discharge disposition.. The purpose of this study is to observe the occurrence of SIADH vs CSW in the setting of stroke and to study the short term mortality, morbidity and discharge disposition among the two entities. This study is an observational descriptive study carried out to emphasise the importance of hyponatremia in the setting of a stroke and the impact it can have on the prognosis of the patient. The prevalence of hyponatremia in stroke patients in our study is 20%. It was found that hyponatremia per se, and Cerebral Salt Wasting in stroke resulted in poorer discharge disposition and longer duration of inhospital stay and significantly impacted on the short term in-hospital mortality. The pathophysiology of the two conditions (SIADH and CSW) being entirely different need a completely differing treatment regime and hence the distinction between the two is of utmost importance