Hyponatremia and Brain Injury: Historical and Contemporary Perspectives

Abstract

Hyponatremia is common in neurocritical care patients and is associated with significant morbidity and mortality. Despite decades of research into the syndrome of inappropriate antidiuretic hormone (SIADH) and cerebral salt wasting (CSW), their underlying pathophysiological mechanisms are still not fully understood. This paper reviews the history behind our understanding of hyponatremia in patients with neurologic injury, including the first reports of CSW and SIADH, and current and future challenges to diagnosis and management in this setting. Such challenges include distinguishing CSW, SIADH, and hypovolemic hyponatremia due to a normal pressure natriuresis from the administration of large volumes of fluids, and hyponatremia due to certain medications used in the neurocritical care population. Potential treatments for hyponatremia include mineralocorticoids and vasopressin 2 receptor antagonists, but further work is required to validate their usage. Ultimately, a greater understanding of the pathophysiological mechanisms underlining hyponatremia in neurocritical care patients remains our biggest obstacle to optimizing patient outcomes in this challenging population.

Fluctuation in Serum Sodium Levels Related to Ipragliflozin Administration in a Patient with Diabetic Nephropathy and Sequela of Traumatic Brain Injury

“…Furthermore, we observed an elevation of the plasma BNP levels, which is one of characteristics of CSWS (6). Therefore, we considered the possibility of CSWS as the cause of hyponatremia after brain injury in the present case (5,6).…”

“…CSWS and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are considered to be the two principal causes of hyponatremia in patients with acute brain injury (5). In this case, the sNa levels began to decrease two weeks after brain injury.…”

From renal salt wasting to SIADH

“…Patients with neurosurgical conditions provide a particular challenge to the clinician as they are often treated with considerable volumes of saline-containing fluid with consequent dynamic changes in blood and extracellular volumes 4. A large volume of saline can lead to an expansion of extracellular fluid volume,12 but may also result in a pressure natriuresis due to a reduction in renal sodium absorption and release of natriuretic agents 13.…”

“…Differentiating syndrome of inappropriate antidiuretic hormone (SIADH) secretion from renal (cerebral) salt wasting (RSW)3 and other causes is challenging in the presence of concurrent medications and following the administration of saline-containing intravenous fluids 4. However, careful consideration of the differential diagnoses may avoid inappropriate treatment that could compromise the optimal clinical outcome.…”

Hiponatremias en el paciente neurocrítico: enfoque terapéutico basado en la evidencia actual

“…Las principales características que permiten establecer el diagnóstico diferencial entre CPS y SIADH se muestran en la tabla 1 2,8,12,16 .…”