Cerebral salt wasting in subarachnoid hemorrhage rats: model, mechanism, and tool

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.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

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.

Tolvaptan treatment in hyponatremia due to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH): effects on survival in patients with cancer

PURPOSE

To investigate the clinical outcomes of patients with hyponatremia who received supportive treatment or tolvaptan plus supportive treatment and the effects of treatment and other variables on overall survival METHODS: This study included oncology patients who were hospitalized at two oncology centers between January 1, 2016 and December 31, 2019 for hyponatremia (sodium levels < 135 mEq/L) and who received tolvaptan plus supportive treatment (n = 22) or supportive treatment only (n = 42).

RESULTS

The median age of all the patients was 59 years (range 26-85) and 64.1% of the patients were male. There was no statistically significant difference between patients in the tolvaptan plus supportive treatment (TpST) group and the supportive treatment only (ST) group in terms of gender and age (p > 0.05). In the TpST group, recovery days of the hyponatremia after treatment and the length of hospital stay was shorter and hyponatremia symptoms and hospital complications were less frequent compared to the ST group (p < 0.05). There was no significant difference between the TpST group and the ST group in terms of overall survival (OS). OS was shorter in men who were non-responders to hyponatremia treatment and had recurrent hyponatremia. Multivariable analysis showed that normal sodium levels after treatment decreased the risk of death.

CONCLUSION

In the treatment of hyponatremia in cancer patients, TpST was found to have more positive effects on blood sodium levels, length of hospital stay, hospital complications, and hyponatremia symptoms compared to ST. A decreased risk of death was observed in patients with normal sodium levels after treatment.

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.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

A Comparison of Pathophysiology in Humans and Rodent Models of Subarachnoid Hemorrhage

Non-traumatic subarachnoid hemorrhage (SAH) affects an estimated 30,000 people each year in the United States, with an overall mortality of ~30%. Most cases of SAH result from a ruptured intracranial aneurysm, require long hospital stays, and result in significant disability and high fatality. Early brain injury (EBI) and delayed cerebral vasospasm (CV) have been implicated as leading causes of morbidity and mortality in these patients, necessitating intense focus on developing preclinical animal models that replicate clinical SAH complete with delayed CV. Despite the variety of animal models currently available, translation of findings from rodent models to clinical trials has proven especially difficult. While the explanation for this lack of translation is unclear, possibilities include the lack of standardized practices and poor replication of human pathophysiology, such as delayed cerebral vasospasm and ischemia, in rodent models of SAH. In this review, we summarize the different approaches to simulating SAH in rodents, in particular elucidating the key pathophysiology of the various methods and models. Ultimately, we suggest the development of standardized model of rodent SAH that better replicates human pathophysiology for moving forward with translational research.

Post-cytokine-release Salt Wasting as Inverse Tumor Lysis Syndrome in a Non-cerebral Natural Killer-cell Neoplasm

The pathogenesis of cerebral/renal salt-wasting syndrome remains unknown. We herein present a case of salt-wasting syndrome with a natural killer-cell neoplasm without cerebral invasion. A 78-year-old man with hemophagocytic syndrome received two cycles of chemotherapy that did not induce tumor lysis syndrome, but repeatedly caused polyuria and natriuresis. The expression of tumor necrosis factor-α in the neoplasm led us to hypothesize that an oncolysis-induced cytokine storm may have caused renal tubular damage and salt wasting. Our theory may explain the pathogenic mechanism of cerebral/renal salt-wasting syndrome associated with other entities, including cerebral disorders, owing to the elevation of cytokine levels after subarachnoid hemorrhage.

Cerebral salt wasting after traumatic brain injury: a review of the literature

Electrolyte imbalances are common among patients with traumatic brain injury (TBI). Cerebral salt wasting (CSW) is an electrolyte imbalance characterized by hyponatremia and hypovolemia. Differentiating the syndrome of inappropriate antidiuretic hormone and CSW remains difficult and the pathophysiological mechanisms underlying CSW are unclear. Our intent was to review the literature on CSW within the TBI population, in order to report the incidence and timing of CSW after TBI, examine outcomes, and summarize the biochemical changes in patients who developed CSW. We searched MEDLINE through 2014, hand-reviewed citations, and searched abstracts from the American Association for the Surgery of Trauma (2003-2014). Publications were included if they were conducted within a TBI population, presented original data, and diagnosed CSW. Publications were excluded if they were review articles, discussed hyponatremia but did not differentiate the etiology causing hyponatremia, or presented cases with chronic disease. Fifteen of the 47 publications reviewed met the selection criteria; nine (60%) were case reports, five (33%) were prospective and 1 (7%) was a retrospective study. Incidence of CSW varied between 0.8 - 34.6%. The populations studied were heterogeneous and the criteria used to define hyponatremia and CSW varied. Though believed to play a role in the development of CSW, increased levels of natriuretic peptides in patients diagnosed with CSW were not consistently reported. These findings reinforce the elusiveness of the CSW diagnosis and the need for strict and consistent diagnostic criteria.

The harmful effects of subarachnoid hemorrhage on extracerebral organs

Subarachnoid hemorrhage (SAH) is a devastating neurological disorder. Patients with aneurysmal SAH develop secondary complications that are important causes of morbidity and mortality. Aside from secondary neurological injuries, SAH has been associated with nonneurologic medical complications, such as neurocardiogenic injury, neurogenic pulmonary edema, hyperglycemia, and electrolyte imbalance, of which cardiac and pulmonary complications are most common. The related mechanisms include activation of the sympathetic nervous system, release of catecholamines and other hormones, and inflammatory responses. Extracerebral complications are directly related to the severity of SAH-induced brain injury and indicate the clinical outcome in patients. This review provides an overview of the extracerebral complications after SAH. We also aim to describe the manifestations, underlying mechanisms, and the effects of those extracerebral complications on outcome following SAH.

Hyponatremia following mild/moderate subarachnoid hemorrhage is due to SIAD and glucocorticoid deficiency and not cerebral salt wasting

CONTEXT

Hyponatremia is common after acute subarachnoid hemorrhage (SAH) but the etiology is unclear and there is a paucity of prospective data in the field. The cause of hyponatremia is variously attributed to the syndrome of inappropriate antidiuresis (SIAD), acute glucocorticoid insufficiency, and the cerebral salt wasting syndrome (CSWS).

OBJECTIVE

The objective was to prospectively determine the etiology of hyponatremia after SAH using sequential clinical examination and biochemical measurement of plasma cortisol, arginine vasopressin (AVP), and brain natriuretic peptide (BNP).

DESIGN

This was a prospective cohort study.

SETTING

The setting was the National Neurosurgery Centre in a tertiary referral centre in Dublin, Ireland.

PATIENTS

One hundred patients with acute nontraumatic aneurysmal SAH were recruited on presentation.

INTERVENTIONS

Clinical examination and basic biochemical evaluation were performed daily. Plasma cortisol at 0900 hours, AVP, and BNP concentrations were measured on days 1, 2, 3, 4, 6, 8, 10, and 12 following SAH. Those with 0900 hours plasma cortisol<300 nmol/L were empirically treated with iv hydrocortisone.

MAIN OUTCOME MEASURES

Plasma sodium concentration was recorded daily along with a variety of clinical and biochemical criteria. The cause of hyponatremia was determined clinically. Later measurement of plasma AVP and BNP concentrations enabled a firm biochemical diagnosis of the cause of hyponatremia to be made.

RESULTS

Forty-nine of 100 developed hyponatremia<135 mmol/L, including 14/100<130 mmol/L. The cause of hyponatremia, and determined by both clinical examination and biochemical hormone measurement, was SIAD in 36/49 (71.4%), acute glucocorticoid insufficiency in 4/49 (8.2%), incorrect iv fluids in 5/49 (10.2%), and hypovolemia in 5/49 (10.2%). There were no cases of CSWS.

CONCLUSIONS

The most common cause of hyponatremia after acute nontraumatic aneurysmal SAH is SIAD. Acute glucocorticoid insufficiency accounts for a small but significant number of cases. We found no cases of CSWS.

Development of an experimental model to study the pathophysiology of cerebral salt wasting following subarachnoid hemorrhage

Hyponatremia is frequent following cranial -neurosurgery or acute brain injury like subarachnoid hemorrhage (SAH), and increases mortality by 30%. The patho-physiology is not understood nor does a causal therapy exist. Since clinical trials are potentially dangerous in this very ill population, we examined whether an established rat model allows studying cerebral salt wasting (CSW) following SAH. The daily urine sodium excretion as well as plasma sodium, osmolality and antidiuretic hormone (ADH) levels were measured for 10 days. Following the injection of 300 μl of blood into the great cistern (SAH(severe)), natriuresis peaked twice (days 1 and 3-5, p < 0.05) resulting in a plasma sodium nadir (day 1 - 133.9 mmol/L, day 5 - 132.6 mmol/L), while following the injection of 300 μL saline (ICP(control)), natriuresis occurred delayed on days 4-5 (p < 0.05). Following double SAH (200 μL twice, 24 h apart), a natriuresis on day 4 resulted in a hyponatremia (131.7 mmol/L, p = 0.025). Neither SAH(mild) (100 μL), the injection of hemolyzed blood (100 μL) or hypertonic saline (200 μL) replicated the effect. The immediate release of ADH (32.23 ± 34.87 pg/mL) following SAH(severe) normalized over the next few days. We conclude that first, the rat model of SAH is suitable for studying CSW, second the increase in intracranial pressure generates the delayed hyponatremia, and third, the ADH release does not mediate natriuresis.

Cisplatin-induced renal salt wasting syndrome

Cisplatin was the first platinum compound to be introduced as a chemotherapeutic agent with antineoplastic activity against a wide variety of solid tumors. Renal impairment with a decline in glomerular filtration has been the classical nephrotoxicity of cisplatin. Renal salt wasting syndrome is yet another, though it is not common. Previous studies were identified by searching the Pubmed database using the following keywords: cisplatin, cisplatin nephrotoxicity, renal salt wasting, and salt loosing nephropathy. Renal salt wasting syndrome has been described in 17 case reports since 1984. It is a rare side effect of cisplatin that manifests with polyuria, hypovolemia, and hyponatremia, and, because of similarities in clinical settings and laboratory values, it is frequently misdiagnosed as a syndrome of inappropriate antidiuretic hormone. Other causes of polyuria and hyponatremia should be excluded. Treatment aims at restoring the lost water and salt. Substituting cisplatin with carboplatin depends on individual clinical settings. Prognosis is excellent, as recovery was the rule in all the reported cases.

Cerebral salt wasting: pathophysiology, diagnosis, and treatment

Cerebral salt wasting (CSW) is a syndrome of hypovolemic hyponatremia caused by natriuresis and diuresis. The mechanisms underlying CSW have not been precisely delineated, although existing evidence strongly implicates abnormal elevations in circulating natriuretic peptides. The key in diagnosis of CSW lies in distinguishing it from the more common syndrome of inappropriate secretion of antidiuretic hormone. Volume status, but not serum and urine electrolytes and osmolality, is crucial for making this distinction. Volume and sodium repletion are the goals of treatment of patients with CSW, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids.

Cervicothoracolumbar spinal epidural abscess and cerebral salt wasting

BACKGROUND CONTEXT

Spinal epidural abscess (SEA) is a rare infectious disease. However, if left unrecognized and untreated, the clinical outcome of SEA can be devastating.

PURPOSE

To report a rare clinical presentation of a cervicothoracolumbar SEA with cerebral salt wasting (CSW).

STUDY DESIGN

Case report.

METHODS

Clinical history, physical and laboratory findings, and magnetic resonance imaging studies of a patient with cervicothoracolumbar SEA and CSW.

RESULTS

We report the case of a 15-year-old boy with cervicothoracolumbar SEA complicated with CSW and treated with conservative methods.

CONCLUSIONS

In conclusion, CSW can be seen at the follow-up period of the SEA and the clinicians must be aware of this entity.

Cerebral salt wasting syndrome: review

Hyponatremia is the most frequent electrolyte disorder in critically neurological patients. Cerebral salt wasting syndrome (CSW) is defined as a renal loss of sodium during intracranial disease leading to hyponatremia and a decrease in extracellular fluid volume. The pathogenesis of this disorder is still not completely understood. Sympathetic responses as well as some natriuretic factors play a role in this syndrome. Distinction between SIADH and CSW might be difficult. The essential point is the volemic state. It is necessary to rule out other intermediate causes. Treatment requires volume replacement and maintenance of a positive salt balance. Mineral corticoids may be useful in complicated cases.

Prediction of symptomatic cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage: relationship to cerebral salt wasting syndrome

OBJECTIVES

Symptomatic cerebral vasospasm is a major complication in patients with subarachnoid hemorrhage (SAH). Symptomatic cerebral vasospasm has been reported to be related to the patient's blood volume which is influenced by cerebral salt wasting syndrome (CSWS). We undertook a prospective study to assess whether the onset of symptomatic cerebral vasospasm was predictable or not, by observing the phenomena of CSWS (natriuresis and osmotic diuresis).

METHODS

Sixty-seven consecutive aneurysmal SAH patients were analysed. After surgery, all patients underwent hypervolemic therapy in order to keep central venous pressure (CVP) within 8-12 cmH(2)O, serum sodium level above 140 mEq/l and a positive water balance. Patients were classified into two groups: those without symptomatic cerebral vasospasm (n=55) and those with symptomatic cerebral vasospasm (n=12). To estimate natriuresis and osmotic diuresis, sodium in/out, water in/out, CVP and other parameters were measured and compared between the two groups.

RESULTS

One day before symptomatic cerebral vasospasm, three factors reached statistical difference in the group that experienced symptomatic cerebral vasospasm: sodium balance, urine volume and water balance. On the day of symptomatic cerebral vasospasm, two factors reached statistical difference: sodium excretion and urine volume. No factor was significantly different 2 days before symptomatic cerebral vasospasm.

DISCUSSION

Symptomatic cerebral vasospasm has a strong relationship with CSWS. Negative sodium and water balance and increased urine volume indicate a predictor of symptomatic cerebral vasospasm. To predict symptomatic cerebral vasospasm, strict observations are required, because CSWS and symptomatic cerebral vasospasm which follows, develop rapidly.

Hyponatremia in patients with traumatic brain injury: incidence, mechanism, and response to sodium supplementation or retention therapy with hydrocortisone

BACKGROUND

Hyponatremia is a frequently observed electrolyte abnormality in patients with central nervous system disease. Several mechanisms, such as SIADH, hypopituitarism, and CSWS, have been proposed with varied incidences among several studies. We attempted to clarify the incidence and mechanism of hyponatremia for each type of TBI. We also assessed the efficacy of sodium supplementation and retention therapy. For sodium retention therapy, hydrocortisone was administered, expecting its mineralocorticoid effect, when the hyponatremia was associated with excess natriuresis.

METHODS

Retrospective analysis of 298 patients with TBI between January 2003 and December 2004 was performed. The incidence, background, clinical data, and outcome were evaluated.

RESULTS

Of the 298 patients, 50 (16.8%) presented hyponatremia during the time course. Hyponatremia was associated with longer hospital stay (P < .001) and bad outcome (P = .02). Among these 50 patients, 37 recovered from the hyponatremia with simple sodium supplementation. The remaining 13 patients presented massive natriuresis and required additional sodium retention therapy. Hydrocortisone statistically reduced the amount of sodium excretion (P = .002) and returned the serum sodium level to a normal value.

CONCLUSIONS

A high rate of hyponatremia after TBI was observed. Further studies are required to establish the precise mechanism of hyponatremia after TBI. Clear definition of CSWS is required to avoid confusion of the pathophysiology that causes hyponatremia. Hydrocortisone was useful to prevent excess natriuresis.

[Cerebral salt wasting syndrome: experimental study in rats]

INTRODUCTION

The cerebral salt wasting syndrome (CSWS) is characterized by hyponatraemia secondary to excessive natriuesis with osmotic duiresis. This syndrome, frequently, occurs after subarachnoid haemorrhage (SAH), but may occur after any acute cerebral aggression.

OBJECTIVES

The aim of the study was to assess the frequency of the CSWS in animal models with, SAH, cerebral ischemia (CI), and cranial trauma (CT), and its correlation with the secretion of brain natriuretic peptide (BNP).

METHOD

Four groups of rats were selected: group SAH (n=7) consisted of SAH induced by perforation of the carotid artery in its intracerebral part; group CI (n=7) consisted of CI induced by ligature of the carotid artery; group CT (n=7) consisted of induced CT; and a control group Sham (n=7). Weight, serum sodium, BNP, and urinary sodium, were measured at baseline and 24 hours after.

RESULTS

Rats with SAH had significant natriuresis and diuresis with negative sodium balance (-95.9+/-447.4 mumol) with a significant difference (P<0.05) compared to the rats of the CI and the Sham groups. There was no difference in the 24 hours level of BNP between the four different groups.

CONCLUSION

We conclude that SAH, in animal models, induced high diuresis with negative sodium balance in the first 24 hours. These findings were absents in the others groups. This was independent of the BNP secretion and may correspond to the early occurrence of a CSWS.

Hyponatremia in the neurosurgical patient: epidemiology, pathophysiology, diagnosis, and management

OBJECTIVE

Hyponatremia is an important and common electrolyte disorder in critically ill neurosurgical patients that has been reported in association with a number of different primary diagnoses. The correct diagnosis of the pathophysiological cause is vital because it dramatically alters the treatment approach.

METHODS

We review the epidemiology and presentation of patients with hyponatremia, the pathophysiology of the disorder with respect to sodium and fluid balance, and the diagnostic procedures for determining the correct cause.

RESULTS

We then present the various treatment options, including discussion of one of the newest groups of agents, the arginine vasopressin receptor antagonists, currently under study for the treatment of hyponatremia in neurosurgical patients.

CONCLUSION

Hyponatremia is a serious comorbidity in neurosurgical patients that requires particular attention as its treatment varies by cause and its consequences can affect neurological outcome.