Hyponatraemia (serum sodium <135 mmol/L) is the commonest electrolyte derangement postneurosurgery. It is associated with higher morbidity, prolonged hospital stay, and highermortality. There is also a significant associated economic burden.Syndrome of Inappropriate Anti-diuretic hormone secretion (SIADH) and Cerebral Salt Wasting (CSW) are the main causes of hyponatraemia in the neurosurgical setting. However, adrenal insufficiency, hypothyroidism, medication side effects, and excessive hypotonic intravenous fluid infusion are also all recognised causes of hyponatraemia. Identifying causes of hyponatraemia and clinical differentiation between SIADH and CSW are vital, as they require different management strategies; fluid restriction for the former versus fluids and salts replacement for the latter. This is an observational prospective study that aims to identify the prevalence and the causes of hyponatraemia in post-neurosurgical patients at Macquarie University Hospital, and in particular to differentiate between SIADH and CSW, and document management used. This study was conducted at Macquarie University Hospital from June 2016 to April 2017. Patients were recruited from ICU and the neurosurgical Ward. Inclusion criteria include any patient with serum sodium <135 mmol/L following pituitary, cerebral or spinal surgery. Patients with prior hyponatraemia, fluid overloadstatessuch as heart failure, liver cirrhosis, and patients on medications that can cause hyponatraemia, for example, thiazides, carbamazepine, haloperidol, and furosemidewere excluded from this study.Statistical analysis was performed using SPSS Version 24; student t-test was used with a P value <0.05 considered as significant. Total 38 patients in total were recruited. The prevalence of hyponatraemia in post-neurosurgical intervention was 6.1%. Most of the patients were asymptomatic. We classified the hyponatraemic patients according to aetiology into five groups: 16 patients with SIADH (42.1%), 15 unclassified patients (39.5%), 3 patients with CSW (7.9%), 3 patients with adrenal insufficiency (7.9%), and one patient with hypothyroidism (2.6%). Despite the fact that both clinical and biochemical parameters of SIADH and CSW were quite similar, we could differentiate between the two conditions depending on the state of dehydration (P-value<0.01). Hyponataremia is common following neurosurgery. It is often multifactorial, and it is essential to identify the aetiology of hyponatraemia in each individual patient in order to address the appropriate treatment. SIADH is the commonest cause of hyponatraemia, followed by unclassified cases, CSW, adrenal insufficiency, and hypothyroidism. Fluid restriction is the most common treatment modality for treating hyponatraemia, yet it can not be used in all cases. It can cause deleterious consequences in patients with CSW, and adrenal insufficiency as patients in these categories are volume depleted.
- And neurosurgery