Cerebral salt wasting: pathophysiology, diagnosis, and treatment

Suspected cerebral salt wasting syndrome secondary to traumatic brain injury in a dog

OBJECTIVE

To describe a dog with suspected cerebral salt wasting syndrome (CSWS) secondary to traumatic brain injury (TBI).

CASE SUMMARY

A 2-month-old intact male Chihuahua-American Pitbull Terrier mix weighing 1.94 kg presented to a veterinary teaching emergency room after suffering bite wound-penetrating trauma to the head. Treatment was initiated with hyperosmotic agents, fluid resuscitation, and analgesia. The dog's neurologic dysfunction warranted hospitalization and continuous monitoring. Within 24 hours, the dog developed hyponatremia (133 mmol/L compared to 143 mmol/L on presentation [reference interval 142-149 mmol/L]). As the dog had concurrent tachycardia, increase in urine sodium concentration, polyuria, and weight loss, a diagnosis of cerebral salt wasting was suspected. A 2% hypertonic saline constant rate infusion was administered for volume replacement, and the patient showed improvement in clinical signs and blood sodium concentration. The dog was discharged on Day 5. Recheck examination showed significant neurologic improvement with sodium just below the low end of the reference range (141 mmol/L [reference interval 142-149 mmol/L]).

NEW OR UNIQUE INFORMATION PROVIDED

This is the first description of suspected CSWS in veterinary medicine. Hyponatremia is a common finding in critically ill neurologic people, including those with TBI, and is typically associated with either syndrome of inappropriate antidiuretic hormone or CSWS. As treatment recommendations for syndrome of inappropriate antidiuretic hormone and CSWS are diametrically opposed, identifying the presence of hyponatremia and distinguishing between these 2 clinical entities is critical for improving patient care for those with TBI. This case highlights the characteristics and clinical progression regarding the diagnosis and management of suspected CSWS.

Initial dysnatremia and clinical outcomes in pediatric traumatic brain injury: a multicenter observational study

PURPOSE

We aimed to investigate the association between initial dysnatremia (hyponatremia and hypernatremia) and in-hospital mortality, as well as between initial dysnatremia and functional outcomes, among children with traumatic brain injury (TBI).

METHOD

We performed a multicenter observational study among 26 pediatric intensive care units from January 2014 to August 2022. We recruited children with TBI under 18 years of age who presented to participating sites within 24 h of injury. We compared demographics and clinical characteristics between children with initial hyponatremia and eu-natremia and between those with initial hypernatremia and eu-natremia. We defined poor functional outcome as a discharge Pediatric Cerebral Performance Category (PCPC) score of moderate, severe disability, coma, and death, or an increase of at least 2 categories from baseline. We performed multivariable logistic regression for mortality and poor PCPC outcome.

RESULTS

Among 648 children, 84 (13.0%) and 42 (6.5%) presented with hyponatremia and hypernatremia, respectively. We observed fewer 14-day ventilation-free days between those with initial hyponatremia [7.0 (interquartile range (IQR) = 0.0-11.0)] and initial hypernatremia [0.0 (IQR = 0.0-10.0)], compared to eu-natremia [9.0 (IQR = 4.0-12.0); p = 0.006 and p < 0.001]. We observed fewer 14-day ICU-free days between those with initial hyponatremia [3.0 (IQR = 0.0-9.0)] and initial hypernatremia [0.0 (IQR = 0.0-3.0)], compared to eu-natremia [7.0 (IQR = 0.0-11.0); p = 0.006 and p < 0.001]. After adjusting for age, severity, and sex, presenting hyponatremia was associated with in-hospital mortality [adjusted odds ratio (aOR) = 2.47, 95% confidence interval (CI) = 1.31-4.66, p = 0.005] and poor outcome (aOR = 1.67, 95% CI = 1.01-2.76, p = 0.045). After adjustment, initial hypernatremia was associated with mortality (aOR = 5.91, 95% CI = 2.85-12.25, p < 0.001) and poor outcome (aOR = 3.00, 95% CI = 1.50-5.98, p = 0.002).

CONCLUSION

Among children with TBI, presenting dysnatremia was associated with in-hospital mortality and poor functional outcome, particularly hypernatremia. Future research should investigate longitudinal sodium measurements in pediatric TBI and their association with clinical outcomes.

A Rare Pediatric Case of Neurobrucellosis With Cerebral Salt Wasting

The central nervous system involvement is a serious complication of brucellosis, which is known as neurobrucellosis, although rare. Here we report a 14-year-old case who developed neurobrucellosis and presented with cerebral salt wasting. As far as we know, our case is the first pediatric case of cerebral salt wasting caused by neurobrucellosis. Clinical manifestations of our patient have completely improved with treatment for Brucella.

Cerebral Salt Wasting Syndrome in the Setting of Hypovolemic Isotonic Hyponatremia: A Case Report

Cerebral salt wasting syndrome (CSWS) is a condition characterized as the loss of sodium secondarily due to an intracranial process, commonly following the neurosurgical resection of mass lesions. This condition leads to a hypovolemic hypotonic hyponatremia. The identification of this syndrome is often mistaken for syndrome of inappropriate anti-diuretic hormone (SIADH). The treatment for both conditions is vastly different. Given the risk of mortality when balancing sensitivities in hyponatremia and its commonality in clinical scenarios, a distinction is crucial. In this case report, we discuss a patient who presented with CSWS following the surgical resection of a pituitary adenoma. She subsequently developed hypernatremia, treated with DDAVP for the suspicion of diabetes insipidus. Once this was discontinued, she further presented with worsening hyponatremia. This hyponatremia persisted even after the discontinuation of DDAVP, with no significant intervention leading to hypovolemic isotonic hyponatremia, supporting a diagnosis of CSWS. Our findings stress the importance of the proper identification of hyponatremia with guided treatment following neurosurgical intervention and give physicians an insight into the anomalies of hyponatremia that should be further discussed.

Suspected medullary washout leading to severe polyuria following delayed cerebral ischemia: a case report

BACKGROUND

Delayed cerebral ischemia is a clinical entity commonly encountered in patients presenting with acute neurological injury and is often complicated by dysnatremias, such as the cerebral salt wasting syndrome. In this case report, we described an exceptional case of polyuria attributed to an initial cerebral salt wasting phenomenon and iatrogenic-induced medullary washout.

CASE PRESENTATION

A 53-year-old woman was admitted to our hospital for the management of a Modified Fisher scale grade 4 subarachnoid hemorrhage due to a ruptured posterior communicating aneurysm. She was initially managed with coil embolization and external ventricular drain due to secondary hydrocephalus. Throughout the course of her hospitalization, she developed severe polyuria reaching up to 40L per day. To keep up with the excessive urinary losses and maintain appropriate cerebral perfusion, fluid replacement therapy was adjusted every hour, reaching up to 1.3 L of crystalloid per hour in addition to aminergic support. An initial diagnosis of partial diabetes insipidus, followed by a cerebral salt wasting syndrome was suspected. While the urine output continued to increase, her serum urea concentration progressively decreased to a point of almost being undetectable on day 9. At that time, the presence of an interstitial medulla washout was hypothesized. Various pharmacological and non-pharmacological interventions were progressively introduced to regain normal renal homeostasis, including non-steroidal anti-inflammatory drugs, fludrocortisone, oral urea and high-protein intake. Medications were progressively weaned, and the patient was successfully discharged from the ICU.

CONCLUSIONS

Cerebral salt wasting should be considered in the initial differential diagnosis of a patient presenting with polyuria in the context of acute neurological injury. Early recognition of this entity is critical to quickly implement proper management. However, as shown in this case report, the concomitance of delayed cerebral ischemia may complexify that management.

A Probable Association of Aseptic Meningoencephalitis, Complicated With Cerebral Salt Wasting Syndrome Following COVID-19 Vaccination: A Case Report

Coronavirus disease-19 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurred worldwide, and it affected millions of people around the world and killed millions of lives without a definitive treatment. During this challenging time, vaccine production has been hugely carried out leading to the invention of many vaccines against COVID-19. As any vaccine can have some side effects, COVID-19 vaccines also need surveillance and reporting side effects worldwide. Currently, more than 10 vaccines are available against SARS-CoV-2 infection globally. There are many neurological complications reported by SARS-CoV-2 vaccines. There are some reported neurological complications, such as ischemic stroke, Guillain-Barré syndrome, transverse myelitis, Bell's palsy, cerebral venous sinus thrombosis, optic neuritis, meningoencephalitis, small fiber neuropathy, and Tolosa-Hunt syndrome. We present a case of an elderly man who presented with fever, fits, hyponatremia, and polyuria following COVID-19 vaccination and was found to have cerebral salt wasting (CSW) with the exclusion of other causes.

Sodium Homeostasis, a Balance Necessary for Life

Body sodium (Na) levels must be maintained within a narrow range for the correct functioning of the organism (Na homeostasis). Na disorders include not only elevated levels of this solute (hypernatremia), as in diabetes insipidus, but also reduced levels (hyponatremia), as in cerebral salt wasting syndrome. The balance in body Na levels therefore requires a delicate equilibrium to be maintained between the ingestion and excretion of Na. Salt (NaCl) intake is processed by receptors in the tongue and digestive system, which transmit the information to the nucleus of the solitary tract via a neural pathway (chorda tympani/vagus nerves) and to circumventricular organs, including the subfornical organ and area postrema, via a humoral pathway (blood/cerebrospinal fluid). Circuits are formed that stimulate or inhibit homeostatic Na intake involving participation of the parabrachial nucleus, pre-locus coeruleus, medial tuberomammillary nuclei, median eminence, paraventricular and supraoptic nuclei, and other structures with reward properties such as the bed nucleus of the stria terminalis, central amygdala, and ventral tegmental area. Finally, the kidney uses neural signals (e.g., renal sympathetic nerves) and vascular (e.g., renal perfusion pressure) and humoral (e.g., renin-angiotensin-aldosterone system, cardiac natriuretic peptides, antidiuretic hormone, and oxytocin) factors to promote Na excretion or retention and thereby maintain extracellular fluid volume. All these intake and excretion processes are modulated by chemical messengers, many of which (e.g., aldosterone, angiotensin II, and oxytocin) have effects that are coordinated at peripheral and central level to ensure Na homeostasis.

Hypernatremia in brain-dead patients

OBJECTIVES

Hypernatremia often occurs in patients with brain death. This study summarizes its characteristics.

METHODS

We recorded 57 patient's highest blood sodium value, as well as daily NT-proBNP, blood creatinine, and urine output. Further, we analyzed the time of the first rise in blood sodium, and the relationship between NT-proBNP, serum creatinine, urine output, and serum sodium.

RESULTS

There was no hyponatremia in these patients, and only seven of the 53 patients registered blood sodium between 137 and 150 mmol/L. We found that blood sodium started to rise at 36.0 (28.5-52.3) h, reaching the highest value in 79.0 (54.0-126.0) h. Urine volume and creatinine have no correlation with serum sodium level, while NT-proBNP has a significant correlation with serum sodium level.

CONCLUSION

It is necessary to conduct volume assessments and urine electrolyte testing on patients with brain death. BNP has a protective effect on water and electrolytes to prevent hypernatremia.

Continuous Renal Replacement Therapy in Acute Brain Injury

Acute brain injury is the sudden and reversible loss of brain self regulation capacity as a disruption of the blood-brain barrier that conditions metabolic and inflammatory disorders that can exacerbate acute kidney injury in a critical setting; specifically it has been described that the alterations of the internal environment that come from the severity of the acute kidney injury increases the risk of endocranial hypertension and cerebral edema; in this context, injuries should be identified and treated in a timely manner with a comprehensive approach. Continuous renal replacement therapy is an extracorporeal purification technique that has been gaining ground in the management of acute kidney injury in critically ill patients. Within its modalities, continuous venous venous hemofiltration is described as the therapy of choice in patients with acute brain injury due to its advantages in maintaining hemodynamic stability and reducing the risk of cerebral edema. Optimal control of variables such as timing to start renal replacement therapy, the prescribed dose, the composition of the replacement fluid and the anticoagulation of the extracorporeal circuit will have a significant impact on the evolution of the neurocritical patient with acute kidney injury. There are limited studies evaluating the role of hemofiltration in this context.

Cerebral salt wasting induced hyponatraemia presenting as catatonia

Cerebral salt wasting (CSW) is an important cause of hyponatraemia in the background of a central nervous system disease. It causes hypovolaemic hyponatraemia and is associated with polyuria and high urine sodium levels. It is important to distinguish it from the more common syndrome of inappropriate antidiuretic hormone and this is primarily based on the volume status. Although CSW has been known to present with confusion, stupor, abnormal behaviour and seizures, its association with catatonia is yet to be reported. We report a case in which the patient developed CSW and hyponatraemia as a sequela of tuberculous meningitis and presented with catatonia. Prompt correction of hyponatraemia resulted in complete reversal of catatonia. This highlights the importance of evaluating all patients with catatonia for electrolyte abnormalities, especially hyponatraemia as its correction leads to excellent outcomes.

Screening of potential spike glycoprotein / ACE2 dual antagonists against COVID-19 in silico molecular docking

The novel coronavirus disease has spread rapidly and caused sustained pressure on economic and medical resources to many countries. Vaccines and effective drugs are needed to fight against the epidemic. Traditional Chinese Medicine (TCM) plays an important and effective role in the treatment of COVID-19. Therefore, the active components of TCM are potential structural basis for the discovery of antiviral drugs. Through screening by molecular docking, Oleanolic acid, Tryptanthrin, Chrysophanol and Rhein were found to have better spike protein and ACE2 inhibitory activity, which could block the invasion and recognition of SARS-CoV-2 at the same time, should be investigated as antiviral candidates.

Cerebral Salt Wasting Syndrome Caused by Severe Traumatic Brain Injury in a Pediatric Patient and Review of the Literature

Background

Following acute traumatic brain injury, cerebral salt wasting (CSW) syndrome is considered as an important cause of hyponatremia apart from syndrome of inappropriate antidiuretic hormone. Differentiation between the two syndromes is crucial for the initiation of an adequate treatment. Case Presentation. We report a 15-year-old female adolescent, admitted to intensive care for acute severe traumatic brain injury. During his hospitalization, she developed a hyponatremia with an increase of urine output and hypovolemia. So, the most probable diagnosis was CSW. Initially, she was treated by hypertonic saline and volume expansion. However, his sodium level continued to fall despite infusion of hypertonic saline. That is why fludrocortisone was introduced initially at 50 μg/day then increased to 150 μg/day. Fludrocortisone was continued for the next months. Serum sodium level was 138 mmol/L after one month of treatment.

Conclusion

Hyponatremia may occur after severe traumatic brain injury that is why an adequate treatment initiated on time is necessary in order to reduce morbidity and mortality.

A multi-parameter study of the etiological diagnosis of hyponatremia after hypothalamic tumor surgery

OBJECTIVES

This study aimed to analyze the difference between cerebral salt-wasting syndrome (CSWS) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in patients with hyponatremia after hypothalamic tumor surgery, and to explore a convenient and effective way to identify CSWS and SIADH.

METHODS

Patients undergoing craniotomy of hypothalamic tumor admitted to the Department of The Affiliated Hospital of Qingdao University from December 2018 to May 2020 were enrolled in this study. Plasma brain natriuretic peptide (BNP), 24-h urine sodium, 24-h urine volume, and the diameter of the inferior vena cava (IVCD) were measured daily before operation and 1-7 days after operation, to analyze differences in plasma BNP, 24-h urinary sodium excretion, 24-h urine volume, and IVCD between the CSWS and SIADH.

RESULTS

The medical data of 31 patients with hypothalamic tumors were collected. Fifteen of these patients (48%) had postoperative hyponatremia, nine patients (29%) had CSWS, and six patients (19%) had SIADH. Plasma BNP, 24-h urinary sodium excretion, and 24-h urine volume in the CSWS group were significantly higher than those in the SIADH group. IVCD decreased in the CSWS group and increased in the SIADH group.

CONCLUSIONS

When hyponatremia occurs after hypothalamic tumor surgery, plasma BNP, 24-h urinary sodium excretion, 24-h urine volume, and IVCD are of great help in identifying CSWS and SIADH.

Late magnetic resonance imaging findings in trauma-induced central diabetes insipidus: Case report and review of literature

We presented the late magnetic resonance imaging characteristics in a 47-year-old male who diagnosed with a permanent trauma-induced diabetes insipidus. The patient developed polyuria following a deceleration injury which has been diagnosed as central diabetes insipidus based on the water deprivation test. Computed tomography or magnetic resonance evaluation of the pituitary gland is usually normal in such cases. Therefore, negative imaging studies do not exclude the diagnosis. However, MRI is more sensitive and can depict subtle injuries of the hypothalamus-pituitary axis in acute and late phases. The late MR imaging findings are not well established. To the best of our knowledge, this will be the first report to describe the late MR imaging features in a permanent case of trauma-induced diabetes insipidus.

Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is a neurologic emergency that requires immediate patient stabilization and prompt diagnosis and treatment. Early measures should focus on principles of advanced cardiovascular life support. The aneurysm should be evaluated and treated in a comprehensive stroke center by a multidisciplinary team capable of endovascular and, operative approaches. Once the aneurysm is secured, the patient is best managed by a dedicated neurocritical care service to prevent and manage complications, including a syndrome of delayed neurologic decline. The goal of such specialized care is to prevent secondary injury, reduce length of stay, and improve outcomes for survivors of the disease.

Acute hyponatremia after aneurysmal subarachnoid hemorrhage: Frequency, treatment, and outcome

We retrospectively examined the course of serum sodium levels in 180 patients with acute aneurysmal subarachnoid hemorrhage (SAH) who had been admitted to the anesthesiologic-neurosurgical intensive care unit of the University Medical Center Regensburg, Germany, between January 2014 and December 2018. Each patient file was analyzed regarding the frequency and intensity of hyponatremic episodes and the administered medication. At admission to the intensive care unit (ICU), 18patients had shown initial hyponatremia (<135 mmol/L) and 4 patients hypernatremia (greater than145 mmol/L). 88(48.9%) of the 158 patients with normal serum sodium levels developed at least one hyponatremic episode during ICU treatment. The number of hyponatremic episodes was similar between patients with higher-grade and lower-grade aneurysmal SAH (P = 0.848). At the end of ICU treatment, outcome did not differ between patients with and without hyponatremia (40/88, 45.5% vs. 38/70, 54.3%, P = 0.270). At 6 months after SAH, however, good outcome (Glasgow outcome scale, GOS 4-5) was more frequently observed in patients with hyponatremia (26/88, 29.5% vs. 32/70, 45.7%, P = 0.036). Medication with sodium chloride, fludrocortisone, or tolvaptan was initiated in 75.4% patients with mild hyponatremia (130-134 mmol/L) and in 92.9% with moderate hyponatremia (125-129 mmol/L). At 6 months after SAH, patients treated with tolvaptan had a lower rate of poor outcome than patients who had not received tolvaptan (1/14, 7.1% vs. 25/74, 33.8%, P = 0.045). In patients with acute aneurysmal SAH and hyponatremic episodes, consequent treatment of hyponatremia prevented impaired outcome. Because administration of tolvaptan rapidly normalized serum sodium levels, this therapy seems to be a promising treatment approach.

Distinguishing cerebral salt wasting syndrome and syndrome of inappropriate ADH in a patient with traumatic brain injury

A previously healthy 48-year-old woman was referred to our intensive care unit (ICU) from a neurosurgical ward due to deterioration of her conscious level. She had a road traffic accident 6 days earlier. On admission to the hospital, a brain CT demonstrated subarachnoid haemorrhage which was considered not amenable to surgical intervention. A second CT brain performed shortly after admission to ICU showed no change in comparison to the initial CT. Serum sodium level on ICU admission was 108 mEq/L; serum and urine osmolalities were 223 mOsm/kg and 438 mOsm/kg, respectively. Her hyponatraemia was initially attributed to syndrome of inappropriate antidiuretic hormone. However, a clinical impression of low volume status raised the suspicion of cerebral salt wasting syndrome. She was managed by infusion of hypertonic saline and fluids for 5 days and discharged from ICU after improvement of her conscious level and normalisation of serum sodium.

Severe symptomatic hyponatremia due to cerebral salt wasting syndrome in a patient with traumatic head injury and Dandy-Walker malformation of the brain

Cerebral salt wasting (CSW) is an uncommon cause of hyponatremia characterized by extracellular volume depletion, high urine sodium concentration and osmolality, and low serum uric acid concentration in association with central nervous system (CNS) disease. Distinguishing CSW from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), a much more common form of hyponatremia in this setting, can be challenging because both present with identical laboratory features. However, treatment of CSW and SIADH differs, making a correct diagnosis important. Here we present a case of CSW in a 75-year-old man in whom severe hyponatremia and volume depletion were discovered in the setting of traumatic head injury and Dandy-Walker malformation of the brain, a rare congenital brain malformation. Treatment with intravenous normal saline and later oral salt supplementation and fludrocortisone was successful.

Challenge of post-COVID era: management of cardiovascular complications in asymptomatic carriers of SARS-CoV-2

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), a highly pathogenic member of family coronaviridae, has caused an exponentially growing global pandemic termed as the coronavirus disease 2019 (COVID-19) with more than 12 million cases worldwide till date. This deadly disease has average fatality rate of 6.5% and even higher among elderly patients and patients with comorbidities. SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE-2) as the entry receptor into host cell. ACE-2, a type-I transmembrane metallocarboxypeptidase, is a critical regulator of the renin-angiotensin system. The entry of SARS-CoV-2 within host cells results in a reduced availability of ACE-2 on the host cell surface followed by significant downregulation of ACE-2 gene expression. As ACE-2 is a well-known cardio-protective molecule, its downregulation could result in severe cardiac disorders. This review deals with a challenging aspect of SARS-CoV-2 infected patients who are asymptomatic or have mild syndromes similar to influenza infections. These patients are proving to be the Achilles’ heel to combat COVID-19 mainly in developing countries of South Asia, where the average number of tests conducted per million individuals is considerably low. Consequently, there is high possibility that individuals with negligible respiratory trouble will not be tested for SARS-CoV-2. Hence, a huge percentage of the population have the risk of developing cardiovascular disorders as a bystander effect of viral infection apart from being potential reservoir of disease transmission. Based on available demographic as well as molecular data, this review predicts a huge spike in cardiovascular disorders among this undetected reservoir in post COVID-19 era.

Delayed Postoperative Hyponatremia Following Endoscopic Transsphenoidal Surgery for Non-Adenomatous Parasellar Tumors

Little is known about delayed postoperative hyponatremia (DPH) accompanied with transsphenoidal surgery for non-adenomatous skull base tumors (NASBTs). Consecutive data on 30 patients with parasellar NASBT was retrospectively reviewed with detailed analyses on perioperative serial sodium levels. Serological DPH (sodium ≤ 135 mmol/L) was observed in eight (27%), with four (13%) of them being symptomatic. DPH developed on postoperative day 7-12 where the mean sodium levels were 134 mmol/L (a mean of 7 mmol/L drop from the baseline) in asymptomatic and 125 mmol/L (a mean of 17.5 mmol/L drop from the baseline) in symptomatic DPH. Serological DPH was accompanied with "weight loss and hemoconcentration (cerebral salt wasting type)" in four (50%), "weight gain and hemodilution (syndrome of inappropriate antidiuretic hormone secretion type)" in three (38%), and no significant weight change in one. Intraoperative extradural retraction of the pituitary gland was the only significant factor for serological DPH (p = 0.035; odds ratio, 12.25 (95% confidence interval, 1.27-118.36)). DPH should be recognized as one of the significant postsurgical complications associated with TSS for NASBTs. Although the underlying mechanism is still controversial, intraoperative extradural compression of the pituitary gland and subsequent dysregulation of the hypothalamo-hypophyseal axis may be responsible.

An Integrative Review of Cerebral Salt Wasting Syndrome

BACKGROUND

Although cerebral salt wasting syndrome (CSWS) is widely recognized, its clinical characteristics, diagnostic criteria, and management have not been clearly defined. This study was undertaken to comprehensively review current literature and provide a more complete picture of CSWS. This review also aimed to provide information for nurses on how to differentiate cerebral salt wasting syndrome from syndrome of inappropriate antidiuretic hormone secretion.

METHODS

An integrative review was performed. Searches were conducted between May and July 2018. The primary information sources were CINAHL, Google Scholar, MEDLINE, PubMed, Scopus, and Web of Science. Included articles were published from 1954 to July 2018.

RESULTS

The essential features of CSWS are hyponatremia, hypovolemia, and increased urine output. Treatment regimens may be determined based on the acuity and severity of hyponatremia and hypovolemia as well as evident symptoms and signs.

CONCLUSION

This review may help neuroscience nurses become knowledgeable about CSWS for the drafting of appropriate nursing care plans and also be able to differentiate CSWS from syndrome of inappropriate antidiuretic hormone secretion as early as possible for timely and proper management.

Cardiovascular effects of glucagon-like peptide 1 receptor agonists: from mechanistic studies in humans to clinical outcomes

Type 2 diabetes mellitus (T2DM) is currently one of the most prevalent diseases, with as many as 415 million patients worldwide. T2DM is characterized by elevated blood glucose levels and is often accompanied by several comorbidities, such as cardiovascular disease. Treatment of T2DM is focused on reducing glucose levels by either lifestyle changes or medical treatment. One treatment option for T2DM is based on the gut-derived hormone glucagon-like peptide 1 (GLP-1). GLP-1 reduces blood glucose levels by stimulating insulin secretion, however, it is rapidly degraded, and thereby losing its glycaemic effect. GLP-1 receptor agonists (GLP-1RAs) are immune to degradation, prolonging the glycaemic effect. Lately, GLP-1RAs have spiked the interest of researchers and clinicians due to their beneficial effects on cardiovascular disease. Preclinical and clinical data have demonstrated that GLP-1 receptors are abundantly present in the heart and that stimulation of these receptors by GLP-1 has several effects. In this review, we will discuss the effects of GLP-1RA on heart rate, blood pressure, microvascular function, lipids, and inflammation, as measured in human mechanistic studies, and suggest how these effects may translate into the improved cardiovascular outcomes as demonstrated in several trials.

Anticancer Medications and Sodium Dysmetabolism

Therapeutic advances have revolutionised cancer treatment over the last two decades, but despite improved survival and outcomes, adverse effects to anticancer therapy such as dyselectrolytaemias do occur and need to be managed appropriately. This review explores essential aspects of sodium homeostasis in cancer with a focus on alterations arising from anticancer medications. Sodium and water balance are tightly regulated by close interplay of stimuli arising from hypothalamic osmoreceptors, arterial and atrial baroreceptors and the renal juxtaglomerular apparatus. This delicate balance can be disrupted by cancer itself, as well as the medications used to treat it. Some of the conventional chemotherapeutics, such as alkylating agents and platinum-based drugs, can cause hyponatraemia and, on rare occasions, hypernatraemia. Other conventional agents such as vinca alkaloids, as well as newer targeted cancer therapies including small molecule inhibitors and monoclonal antibodies, can cause hyponatraemia, usually as a result of inappropriate antidiuretic hormone secretion. Hyponatraemia can also sometimes occur secondarily to drug-induced hypocortisolism or salt-wasting syndromes. Another atypical but distinct mechanism for hyponatraemia is via pituitary dysfunction induced by immune checkpoint inhibitors. Hypernatraemia is uncommon and occasionally ensues as a result of drug-induced nephrogenic diabetes insipidus. Identification of the aetiology and appropriate management of these conditions, in addition to averting treatment-related problems, can be lifesaving in critical situations.

Hyponatremia in the Neurologically Ill Patient: A Review

Hyponatremia is a well-known disorder commonly faced by clinicians managing neurologically ill patients. Neurological disorders are often associated with hyponatremia during their acute presentation and can be associated with specific neurologic etiologies and symptoms. Patients may present with hyponatremia with traumatic brain injury, develop hyponatremia subacutely following aneurysmal subarachnoid hemorrhage, or may manifest with seizures due to hyponatremia itself. Clinicians caring for the neurologically ill patient should be well versed in identifying these early signs, symptoms, and etiologies of hyponatremia. Early diagnosis and treatment can potentially avoid neurologic and systemic complications in these patients and improve outcomes. This review focuses on the causes and findings of hyponatremia in the neurologically ill patient and discusses the pathophysiology, diagnoses, and treatment strategies for commonly encountered etiologies.

Activation of the renin-angiotensin system in high fructose-induced metabolic syndrome

High fructose intake induces hyperglycemia and hypertension. However, the mechanism by which fructose induces metabolic syndrome is largely unknown. We hypothesized that high fructose intake induces activation of the renin-angiotensin system (RAS), resulting in hypertension and metabolic syndrome. We provided 11-week-old Sprague–Dawley rats with drinking water, with or without 20% fructose, for two weeks. We measured serum renin, angiotensin II (Ang II), and aldosterone (Aldo) using ELISA kits. The expression of RAS genes was determined by quantitative reverse transcription polymerase chain reaction. High fructose intake increased body weight and water retention, regardless of food intake or urine volume. After two weeks, fructose intake induced glucose intolerance and hypertension. High fructose intake increased serum renin, Ang II, triglyceride, and cholesterol levels, but not Aldo levels. High fructose intake increased the expression of angiotensinogen in the liver; angiotensin-converting enzyme in the lungs; and renin, angiotensin II type 1a receptor (AT1aR), and angiotensin II type 1b receptor (AT1bR) in the kidneys. However, expression of AT1aR and AT1bR in the adrenal glands did not increase in rats given fructose. Taken together, these results indicate that high fructose intake induces activation of RAS, resulting in hypertension and metabolic syndrome.

Obesity-Related Glomerulopathy: A Latent Change in Obesity Requiring More Attention

BACKGROUND

Obesity has become a major public health problem, and the prevalence of kidney diseases has increased in parallel. Among kidney diseases caused by metabolic disorders, obesity-related glomerulopathy (ORG) is secondary to obesity.

SUMMARY

ORG is mainly caused by glomerular hyperfiltration, dysregulation of hormone and cytokine secretion in adipose tissues, and ectopic lipid accumulation in renal cells. ORG is pathologically characterized by glomerular hypertrophy, with or without focal and segmental glomerulosclerosis. Patients with ORG usually present with proteinuria concomitant with metabolic disorders such as dyslipidemia and hypertension. Weight loss, RAAS inhibitors, and improved insulin resistance can reduce the progression of ORG.

CONCLUSION

ORG is a growing renal pathological change in obese individuals, and a comprehensive understanding of the disease is pivotal to avoid its occurrence and improve quality of life for those with obesity. Key Messages:This review comprehensively describes the characteristics of ORG in pathological changes, clinical manifestations, pathogeneses and treatments.

Cerebral Salt-wasting Syndrome in a Critically Ill Patient: An Easily Neglected Syndrome in Intensive Care Unit (ICU)

BACKGROUND

Cerebral salt-wasting syndrome (CSWS), which usually secondary to cerebral diseases, is characterized by hyponatremia and hypovolemia. In clinical practice, it is quite difficult to distinguish CSWS from other hyponatremia syndrome, especially in Intensive Care Unit (ICU) where the conditions of patients are more complicated. Nonetheless, it is crucial because treatments might be fundamentally different.

CASE PRESENTATION

We discuss a case of patient who presented with refractory hyponatremia and hypovolemia after traumatic brain injury, finally was diagnosed with CSWS, and successfully treated with corticotropin.

CONCLUSIONS

This case report provides a unique opportunity to observe the trigger of subdural effusion-induced CSWS, and also it provides the classical therapy for CSWS in a critically ill patient. In view of the difficulty to tell CSWS from other similar diseases in ICU, ICU doctors should be aware of such condition.

Toxin to medicine and bioisosterism in drug development: a study of the discovery and development of ACE inhibitors from snake venom

The advent of the angiotensin-converting enzyme (ACE) inhibitors is a landmark in drug discovery and a breakthrough in the management of hypertension. Their clinical introduction has led to appreciable increase in the lifespan of hypertensive patients. And their development initiated a new era of structure-based or rational drug design that has subsequently been applied successfully for development of drugs for many other disorders. This paper presents an account of the discovery, design and development of ACE inhibitors from an academic perspective and possibly, as a guide to future research. The paper highlights the milestones and recounts the challenges encountered and the strategies applied in the search for ACE inhibitors. This exposition also expounds some of the concepts and intricacies of drug discovery, design and development. Keywords: drug development, ACE inhibitors, snake venom peptide, bioisosterism, antihypertensive agents

Inappropriate Antidiuretic Hormone Secretion and Cerebral Salt-Wasting Syndromes in Neurological Patients

The differential diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt-wasting syndrome (CSWS) in patients with neurological disorders has been a perplexing clinical controversy. The purpose of this review is to summarize the characteristics and risk factors of patients with different types of neurological disorders complicated by hyponatremia (HN) and review various methods to distinguish SIADH from CSWS. Common neurological disorders with high rates of HN include subarachnoid hemorrhage (SAH), traumatic brain injuries, stroke, cerebral tumors, central nervous system (CNS) infections, and Guillain-Barré syndrome (GBS), which have their own characteristics. Extracellular volume (ECV) status of patients is a key point to differentiate SIADH and CSWS, and a comprehensive assessment of relevant ECV indicators may be useful in differentiating these two syndromes. Besides, instead of monitoring the urinary sodium excretion, more attention should be paid to the total mass balance, including Na⁺, K⁺, Cl^-, and extracellular fluid. Furthermore, the dynamic detection of fractional excretions (FE) of urate before and after correction of HN and a short-term infusion of isotonic saline solution may be useful in identifying the etiology of HN. As for brain natriuretic peptide (BNP) or N-terminal prohormone of BNP (NT-proBNP), more prospective studies and strong evidence are needed to determine whether there is a pertinent and clear difference between SIADH and CSWS.

Angiotensin II: A New Vasopressor for the Treatment of Distributive Shock

PURPOSE

Angiotensin II (ATII) is a potent endogenous vasoconstrictor that has recently garnered regulatory approval for the treatment of distributive shock, including septic shock. Traditional vasoactive substances used in the management of distributive shock include norepinephrine, epinephrine, phenylephrine, and vasopressin. However, their use can be associated with deleterious adverse drug effects, such as splanchnic vasoconstriction and associated hypoperfusion. The purpose of this review is to describe ATII, including its pharmacologic mechanisms, pharmacokinetic profile, evidence of efficacy and tolerability, and potential role in contemporary critical care practice.

METHODS

Peer-reviewed clinical trials and relevant treatment guidelines published from 1966 to September 14, 2019, were identified from Medline/PubMed using the following search terms: angiotensin II OR angiotensin 2 AND shock OR septic shock OR vasodilatory shock. Pertinent review articles were reviewed for additional studies for inclusion and discussion. The final decision on the inclusion of studies in the current review was based on the expert opinion of the authors.

FINDINGS

On the basis of the available evidence, ATII is effective at elevating blood pressure in patients with distributive shock and appears to reduce the dose of concurrent vasopressors to maintain adequate blood pressure. ATII has been investigated for other causes of shock; however, robust evidence of off-label indications is lacking and is much needed. Clinical and cost benefits compared with traditional vasopressors have yet to be established.

IMPLICATIONS

ATII represents a welcome addition to the armamentarium of critical care clinicians. Enthusiasm for the use of ATII should be balanced with the current gaps in our understanding of ATII in patients with shock. Until further evidence provides more clinically meaningful benefits, as well as cost-effectiveness compared with currently available vasopressors, critical care clinicians should reserve ATII for salvage therapy in patients with septic shock.

Effects of oxytocin administration on the hydromineral balance of median eminence-lesioned rats

In the clinical setting, acute injuries in hypothalamic mediobasal regions, along with polydipsia and polyuria, have been observed in patients with cerebral salt wasting (CSW). CSW is also characterised by hypovolaemia and hyponatraemia as a result of an early increase in natriuretic peptide activity. Salt and additional amounts of fluid are the main treatment for this disorder. Similarly, experimental lesions to these brain regions, which include the median eminence (ME), produce a well-documented neurological model of polydipsia and polyuria in rats, which is preceded by an early sodium excretion of unknown cause. In the present study, oxytocin (OT) was used to increase the renal sodium loss and prolong the hydroelectrolyte abnormalities of ME-lesioned animals during the first few hours post-surgery. The objective was to determine whether OT-treated ME-lesioned animals increase their sodium appetite and water intake to restore the volume and composition of extracellular body fluid. Electrolytic lesion of the ME increased water intake, urinary volume and sodium excretion of food-deprived rats and also decreased urine osmolality and estimated plasma sodium concentration. OT administration at 8 hours post-surgery reduced water intake, urine output and plasma sodium concentration and also increased urine osmolality and urine sodium excretion between 8 and 24 hours post-lesion. From 24 to 30 hours, more water and hypertonic NaCl was consumed by OT-treated ME-lesioned rats than by physiological saline-treated-ME-lesioned animals. Food availability from 30 to 48 hours reduced the intake of hypertonic saline solution by ME/OT animals, which increased their water and food intake during this period. OT administration therefore appears to enhance the natriuretic effect of ME lesion, producing hydroelectrolyte changes that reduce the water intake of food-deprived animals. Conversely, the presence of hypertonic NaCl increases the fluid intake of these animals, possibly as a result of the plasma sodium depletion and hypovolaemic states previously generated. Finally, the subsequent increase in food intake by ME/OT animals reduces their need for hypertonic NaCl but not water, possibly in response to osmotic thirst. These results are discussed in relation to a possible transient activation of the ME with the consequent secretion of natriuretic peptides stored in terminal swellings, which would be augmented by OT administration. Electrolytic lesion of the ME may therefore represent a useful neurobiological model of CSW.

The Treatment of Arterial Hypertension

Arterial hypertension is the leading cause of death worldwide and is one of the most important public health problems. Arterial hypertension is a major cardiovascular risk factor with an increasing incidence. In this paper we set out to analyze a group of 3050 patients hospitalized between January 2013 and December 2017 in terms of drug therapy. We found that the majority of patients received drug treatment with a converting-enzyme inhibitor as a monotherapy, and the most common drug association was the association between conversion enzyme inhibitor and calcium channel blocker.

Sodium Perturbations After Pituitary Surgery

Sodium perturbations are a common complication after pituitary surgery, with hyponatremia being the most frequent. Postoperative assessments should be tailored to the early and late periods, and monitoring sodium perturbations is recommended. Cerebral salt wasting is rare after pituitary surgery, and diagnosis and management can be challenging. Providing patient counseling and close postoperative follow-up is important to effectively manage diabetes insipidus and reduce hospital readmissions due to sodium perturbations.

Posterior pituitary dysfunction following traumatic brain injury: review

Neurohypophysial dysfunction is common in the first days following traumatic brain injury (TBI), manifesting as dysnatremia in approximately 1 in 4 patients. Both hyponatremia and hypernatremia can impair recovery from TBI and in the case of hypernatremia, there is a significant association with excess mortality. Hyponatremia secondary to syndrome of inappropriate antidiuretic hormone secretion (SIAD) is the commonest electrolyte disturbance following TBI. Acute adrenocorticotropic hormone (ACTH)/cortisol deficiency occurs in 10-15% of TBI patients and can present with a biochemical picture identical to SIAD. For this reason, exclusion of glucocorticoid deficiency is of particular importance in post-TBI SIAD. Cerebral salt wasting is a rare cause of hyponatremia following TBI. Hyponatremia predisposes to seizures, reduced consciousness, and prolonged hospital stay. Diabetes insipidus (DI) occurs in 20% of cases following TBI; where diminished consciousness is present, appropriate fluid replacement of renal water losses is occasionally inadequate, leading to hypernatremia. Hypernatremia is strongly predictive of mortality following TBI. Most cases of DI are transient, but persistent DI is also predictive of mortality, irrespective of plasma sodium concentration. Persistent DI may herald rising intracranial pressure due to coning. True adipsic DI is rare following TBI, but patients are vulnerable to severe hypernatremic dehydration, exacerbation of neurologic deficits and hypothalamic complications, therefore clinicians should be aware of this possible variant of DI.

Responses of the renin-angiotensin-aldosterone system in pregnant chronic kidney disease patients with and without superimposed pre-eclampsia

Background

Women with chronic kidney disease (CKD) are at increased risk of superimposed pre-eclampsia (SPE). Accurate identification of SPE is challenging. We hypothesized that specific components of the renin-angiotensin-aldosterone system (RAAS) would discriminate between CKD and SPE. The aim of the study was to establish differences in circulating and intrarenal RAAS in women with CKD with and without SPE and compare these to normotensive controls (NCs) and women with pre-eclampsia (PE).

Methods

White European NC women (n = 20), women with PE (n = 9), normotensive CKD without SPE (n = 8) and with SPE (n = 11) were recruited in the third trimester. Plasma renin, plasma and urine total angiotensinogen (AGT) concentrations were quantified by enzyme-linked immunosorbent assay, urinary tetrahydroaldosterone (TH-aldo) concentration by gas chromatography-mass spectrometry and placental growth factor (PlGF) by immunoassay.

Results

Urinary TH-aldo:creatinine ratios were lower in women with PE or SPE compared with NC or women with CKD (P < 0.05 for all). The same group differences were observed for plasma active renin and PlGF concentrations (P < 0.05 for all). Urine total AGT was higher in women with PE compared with NC (P < 0.05) and urine TH-aldo:urine AGT was lower (P < 0.05). However, women with SPE had lower urinary AGT concentrations compared with women with PE (P < 0.05). No differences in plasma total AGT were observed between groups.

Conclusions

Women with SPE have a lower urinary TH-aldo:creatinine ratio, lower plasma active renin and lower PlGF concentrations than women with CKD, comparable to women with PE without pre-existing disease, suggestive of similar pathophysiology. These data suggest disruption of the RAAS pathway in SPE similar to PE. Exploration of the predictive value of RAAS components for adverse pregnancy events in women with CKD is required.

Think central nervous system tuberculosis, also in low-risk children: a Danish nationwide survey

BACKGROUND

Paediatric central nervous system (CNS) tuberculosis (TB) imposes a high risk of death and neurologic sequelae, particularly if the diagnosis is delayed. Children from non-TB endemic countries are particularly at risk of delayed or missed diagnosis. We aimed to investigate CNS TB in Denmark, a TB low-endemic country and where Bacillus Calmette-Guerin (BCG) vaccination is not a part of the vaccination schedule.

METHODS

A nationwide retrospective case survey of all children with CNS TB in 2000-2015 identified through the National Danish TB Notification Register. We assessed epidemiology, clinical and paraclinical features, diagnostic criteria, treatment and outcome.

RESULTS

Nine ethnic Danes and 12 children from TB-endemic countries with CNS TB were identified. Clinical features, C-reactive protein, chest X-ray and indirect TB screening assays all had low sensitivity (19-75%). All (18/18) patients had elevated cerebrospinal fluid (CSF) white blood cells and 15 of 17 (88%) had a combination of at least two characteristic CSF findings (lymphocyte predominance, elevated protein and/or hypoglycorrhachia). Cerebral computed tomography and magnetic resonance imaging were abnormal in 10 of 16 (63%) and 12 of 14 (86%), respectively. Treatment was initiated after a median of 3 days in children from TB-endemic countries, and after 10 days in ethnic Danish children. One patient died (5%): A native Danish girl who died before the diagnosis was established.

CONCLUSIONS

Children from non-TB endemic countries may be at risk of delayed diagnosis and poorer prognosis compared to high-risk children. Cerebral magnetic resonance imaging and characteristic CSF findings had high diagnostic sensitivity.

Propofol prevents human umbilical vein endothelial cell injury from Ang II-induced apoptosis by activating the ACE2-(1-7)-Mas axis and eNOS phosphorylation

Angiotensin II (AngII), a vasoactive peptide that elevates arterial blood pressure and results in hypertension, has been reported to directly induce vascular endothelial cell apoptosis. Recent work has demonstrated that propofol pre-treatment attenuates angiotensin II-induced apoptosis in human coronary artery endothelial cells. However, the underlying mechanism remains largely unknown. Here, we investigated human umbilical vein endothelial cells (HUVECs) subjected to angiotensin II-induced apoptosis in the presence or absence of propofol treatment and found that angiotensin II-induced apoptosis was attenuated by propofol in a dose-dependent manner. Furthermore, ELISA assays demonstrated that the ratio of angiotensin (1–7) (Ang (1–7)) to Ang II was increased after propofol treatment. We examined the expression of ACE2, Ang (1–7) and Mas and found that the ACE2-Ang (1–7)-Mas axis was up-regulated by propofol, while ACE2 overexpression increased phosphorylated endothelial nitric oxide synthase (phosphorylated eNOS) expression and siACE2 resulted in the repression of endothelial nitric oxide synthase (eNOS) phosphorylation. In conclusion, our study revealed that propofol can inhibit endothelial cell apoptosis induced by Ang II by activating the ACE2-Ang (1–7)-Mas axis and further up-regulating the expression and phosphorylation of eNOS.

N1-methylnicotinamide (MNAM) as a guardian of cardiovascular system

Atherosclerosis is identified as the formation of atherosclerotic plaques, which could initiate the formation of a blood clot in which its growth to coronary artery can lead to a heart attack. N-methyltransferase (NNMT) is an enzyme that converts the NAM (nicotinamide) to its methylated form, N1-methylnicotinamide (MNAM). Higher levels of MNAM have been reported in cases with coronary artery disease (CAD). Further, MNAM increases endothelial prostacyclin (PGI2) and nitric oxide (NO) and thereby causes vasorelaxation. The vasoprotective, anti-inflammatory and anti-thrombotic roles of MNAM have been well documented; however, the exact underlying mechanisms remain to be clarified. Due to potential role of MNAM in the formation of lipid droplets (LDs), it might exert its function in coordination with lipids, and their targets. In this study, we summarized the roles of MNAM in cardiovascular system and highlighted its possible mode of actions.

From renal salt wasting to SIADH

Hyponatraemia is common following major head injury and is associated with significant morbidity and mortality. A 20-year-old man presented with reduced consciousness after head trauma and was found to have a fractured skull base with bilateral frontal contusions. On day 3 of his admission, he developed hyponatraemia with raised urine sodium and osmolality, despite receiving dexamethasone and intravenous fluid therapy. His hyponatraemia worsened after the treatment with fluid restriction and oral salt. He was in negative fluid balance suggesting possible renal salt wasting. A trial of isotonic normal saline resulted in a further fall in serum sodium level. He was subsequently treated for suspected syndrome of inappropriate ADH with a hypertonic (3%) saline infusion. His sodium level and neurological status improved. This case report illustrates the confounding factors that commonly affect clinical decision-making when treating patients with hyponatraemia following head injury. The guidelines for diagnosis and management are discussed.

Systemic Complications Following Aneurysmal Subarachnoid Hemorrhage

Many systemic complications follow aneurysmal subarachnoid hemorrhage and are primarily due to sympathetic nervous system activation. These complications play an important role in the overall outcome of patients. The purpose of this review is to provide an update on the diagnosis, pathophysiology, and management of systemic complications specifically associated with aneurysmal subarachnoid hemorrhage. Special focus has been made on systemic complications that occur more frequently in patients with aneurysmal subarachnoid hemorrhage compared to other stroke subtypes and in the neurocritical care patient population. These complications include neurogenic pulmonary edema, electrocardiographic changes, troponin elevation, neurogenic stunned myocardium, hyponatremia, and anemia.

Prevention and Treatment of Hyponatremia in Patients with Subarachnoid Hemorrhage: A Systematic Review

BACKGROUND

Current guidelines for the management of hyponatremia in patients with subarachnoid hemorrhage (SAH) are not based on a systematic assessment of the literature. We evaluated published studies on the efficacy and safety of current preventative and treatment strategies for hyponatremia in patients with SAH.

METHODS

We searched the Cochrane Central Register of Controlled Trials, Embase, MEDLINE, and PubMed for relevant studies. Primary outcomes of interest included neurologic functional outcomes, symptomatic vasospasm, and others. Secondary outcomes included measures of sodium and volume status.

RESULTS

We included 5 out of 117 identified studies: 1 before-and-after observational trial (using fludrocortisone) and 4 randomized controlled trials (2 using fludrocortisone; 2 using hydrocortisone). All 5 trials had a high risk of bias in at least 1 domain. We could not perform a meta-analysis of functional outcomes; however, individual studies did not demonstrate statistically significant differences. Mineralocorticoid use did not statistically significantly reduce the incidence of symptomatic vasospasm (relative risk, 0.60; 95% confidence interval, 0.35-1.03; I² = 0%). The studies did not report other primary outcomes. In the 4 RCTs, mineralocorticoid use reduced natriuresis and volume contraction.

CONCLUSIONS

Current evidence does not demonstrate a benefit of preventative treatment with mineralocorticoids in clinically important outcomes, although a difference cannot be ruled out due to imprecision. Larger well-designed trials are needed to establish the impact of mineralocorticoids and fluid and sodium supplementation strategies on clinically relevant outcomes in the prevention and treatment of hyponatremia in patients with SAH.

Treatment of Hyponatremic Encephalopathy in the Critically Ill

OBJECTIVES

Hyponatremic encephalopathy, symptomatic cerebral edema due to a low osmolar state, is a medical emergency and often encountered in the ICU setting. This article provides a critical appraisal and review of the literature on identification of high-risk patients and the treatment of this life-threatening disorder.

DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION

Online search of the PubMed database and manual review of articles involving risk factors for hyponatremic encephalopathy and treatment of hyponatremic encephalopathy in critical illness.

DATA SYNTHESIS

Hyponatremic encephalopathy is a frequently encountered problem in the ICU. Prompt recognition of hyponatremic encephalopathy and early treatment with hypertonic saline are critical for successful outcomes. Manifestations are varied, depending on the extent of CNS's adaptation to the hypoosmolar state. The absolute change in serum sodium alone is a poor predictor of clinical symptoms. However, certain patient specific risks factors are predictive of a poor outcome and are important to identify. Gender (premenopausal and postmenopausal females), age (prepubertal children), and the presence of hypoxia are the three main clinical risk factors and are more predictive of poor outcomes than the rate of development of hyponatremia or the absolute decrease in the serum sodium.

CONCLUSIONS

In patients with hyponatremic encephalopathy exhibiting neurologic manifestations, a bolus of 100 mL of 3% saline, given over 10 minutes, should be promptly administered. The goal of this initial bolus is to quickly treat cerebral edema. If signs persist, the bolus should be repeated in order to achieve clinical remission. However, the total change in serum sodium should not exceed 5 mEq/L in the initial 1-2 hours and 15-20 mEq/L in the first 48 hours of treatment. It has recently been demonstrated in a prospective fashion that 500 mL of 3% saline at an infusion rate of 100 mL per hour can be given safely. It is critical to recognize the early signs of cerebral edema (nausea, vomiting, and headache) and intervene with IV 3% sodium chloride as this is the time to intervene rather than waiting until more severe symptoms develop. Cerebral demyelination is a rare complication of overly rapid correction of hyponatremia. The principal risk factors for cerebral demyelination are correction of the serum sodium more than 25 mEq/L in the first 48 hours of therapy, correction past the point of 140 mEq/L, chronic liver disease, and hypoxic/anoxic episode.

Cerebral salt wasting syndrome in patients with minor head trauma - two case reports

We describe two polytrauma patients without severe head trauma who developed Cerebral Salt Wasting Syndrome (CSWS) during their stay in our ICU with natriuresis, hyponatremia and hypovolemia. Hyponatremia encountered in CSWS and the syndrome of inadequate antidiuretic hormone secretion (SIADH) is a common electrolyte finding in patients with severe head trauma, subarachnoid hemorrhage, malignancy and infections of the central nervous system. CSWS was an unexpected electrolyte finding in our patients with minor head trauma without neurological or neurosurgical problems. To rule out other causes of hyponatremia (SIADH, secondary adrenal dysfunction and thyroid dysfunction) a correct diagnosis is very important, as proper treatment of CSWS with fluid and salt replacement will decrease mortality and morbidity. In conclusion, CSWS should be suspected in any polytrauma patient with minor head trauma and hyponatremia.