Validation study of a central venous pressure-based protocol for the management of neurosurgical patients with hyponatremia and natriuresis

Surgery for Central Nervous System Tuberculosis in Children

Tuberculosis (TB) is the second most common cause of death due to a single infectious agent worldwide after COVID-19. Central nervous system tuberculosis is widely prevalent in the world, especially in the developing countries and continues to be a socioeconomic problem. It is highly devastating form of tuberculosis leading to unacceptable levels of morbidity and mortality despite appropriate antitubercular therapy. The clinical symptoms are varied and nonspecific. They can be easily overlooked. Tuberculous meningitis is the most common presentation and its sequelae viz. vasculitis, infarction and hydrocephalus can be devastating. The ensuing cognitive, intellectual, and endocrinological outcome can be a significant source of morbidity and mortality, especially in resource constrained countries. Early diagnosis and treatment of tuberculous meningitis and institution of treatment is helpful in limiting the course of disease process. The diagnosis of CNS tuberculosis remains a formidable diagnostic challenge. The microbiological methods alone cannot be relied upon. CSF diversion procedures need to be performed at the appropriate time in order to achieve good outcomes. Tuberculous pachymeningitis and arachnoiditis are morbid sequelae of tuberculous meningitis. Tuberculomas present as mass lesions in the craniospinal axis. Tuberculous abscess can mimic pyogenic abscess and requires high index of suspicion. Calvarial tuberculosis is seen in children and responds well to antituberculous chemotherapy. Tuberculosis of the spinal cord is seen similar to intracranial tuberculosis in pathogenesis but with its own unique clinical manifestations and management. Multidrug-resistant tuberculosis is a formidable problem, and alternate chemotherapy should be promptly instituted. The pathogenesis, clinical features, diagnosis, and management of central nervous system tuberculosis in children are summarized. Heightened clinical suspicion is paramount to ensure prompt investigation. Early diagnosis and treatment are essential to a gratifying outcome and prevent complications.

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.

Tuberculosis of the central nervous system in children

BACKGROUND

Central nervous system tuberculosis (CNS TB) in children is still a socioeconomic problem in developing countries. It has varied manifestations, symptoms are nonspecific, diagnosis can be challenging, and treatment may be difficult. It is often missed or overlooked. Among the various pathological entities, tuberculous meningitis is the most common and devastating manifestation. The resultant vasculitis, infarction, and hydrocephalus can be life-threatening. It can have grave cognitive, intellectual, and endocrine sequelae if not treated in time resulting in handicap, especially in resource constraint countries. Early diagnosis and treatment of tuberculous meningitis is the single most important factor determining outcome. Tuberculous hydrocephalus needs to be recognized early, and cerebrospinal fluid diversion procedure needs to be performed in adequate time to prevent morbidity or mortality in some cases. Tuberculous pachymeningitis and arachnoiditis are rare in children. Tuberculous abscess can mimic pyogenic abscess and requires high index of suspicion. Calvarial tuberculosis is seen in children and responds well to antituberculous chemotherapy. Drug-resistant tuberculosis is a formidable problem, and alternate chemotherapy should be promptly instituted.

AIM

The pathogenesis, clinical features, diagnosis, and management of central nervous system tuberculosis in children are summarized.

CONCLUSION

Heightened clinical suspicion, early diagnosis, appropriate antituberculous treatment, and surgery in relevant situation are essential for a gratifying outcome and preventing complications.

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.

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.

A Study of Hyponatremia in Acute Encephalitis Syndrome: A Prospective Study From a Tertiary Care Center in India

PURPOSE:

To evaluate the frequency and causes of hyponatremia in acute encephalitis syndrome (AES) and its effect on outcome.

PATIENTS AND METHODS:

Consecutive patients with AES were subjected to neurological evaluation including Glasgow Coma Scale, focal weakness, movement disorder, and reflex changes. The etiology of AES was based on blood and cerebrospinal fluid enzyme-linked immunosorbent assay and polymerase chain reaction. We have categorized patients into neurological or systemic AES. Hyponatremia was diagnosed if 2 consecutive serum sodium levels were below 135 mEq/L, 24 hours apart. Serum and urinary osmolality and electrolytes were measured on alternate days. Fluid intake, output, and body weight were measured daily. The hyponatremia was categorized into syndrome of inappropriate secretion of antidiuretic hormone (SIADH), cerebral salt wasting (CSW), or miscellaneous group. Outcome at 1 month was assessed by modified Rankin scale.

RESULTS:

Of 79 patients, 34 had neurologic AES and 45 had systemic AES; 22 (27.8%) patients had hyponatremia. The neurologic AES as compared to systemic AES was more commonly associated with hyponatremia (38.2% vs 20%, P = .07), need longer hospitalization (25.0 vs 12.5 days, P = .003), and longer time for sodium correction (13.3 vs 8.2 days, P = .05). The hyponatremia was due to CSW in 12 patients, SIADH in 2 patients, and indeterminate in 8 patients. Thirty-six patients had poor outcome (15 died) and 43 had good outcome which was not related to hyponatremia.

CONCLUSION:

Hyponatremia occurs in one-third of patients with AES, being commoner in neurologic AES, and CSW is the commonest cause.

Diagnosis and Treatment of Cerebral Salt Wasting Syndrome With Cryptococcal Meningitis in HIV Patient

Hyponatremia is one of the most common electrolyte imbalances in HIV patients. The differential diagnosis may include hypovolemic hyponatremia, syndrome of inappropriate antidiuretic hormone secretion (SIADH), and adrenal insufficiency. Here, we describe a case of hyponatremia secondary to cerebral salt wasting syndrome (CSWS) in an HIV patient with cryptococcal meningitis. A 52-year-old man with a history of diabetes and HIV was admitted for headache and found to have cryptococcal meningitis. He was also found to have asymptomatic hyponatremia. He had signs of hypovolemia, such as orthostatic hypotension, dry mucosa, decreased skin turgor, hemoconcentration, contraction alkalosis, and high BUN/Cr ratio. The laboratory findings revealed sodium of 125 mmol/L, potassium of 5.5 mmol/L, urine osmolality of 522 mOsm/kg, urine sodium of 162 mmol/L, and urine chloride of 162 mmol/L. We started normal saline for hypovolemia, each 1 L prior and after amphotericin therapy. However, hypovolemia did not improve significantly despite IV fluid. Cosyntropin stimulation test was negative, and renin level was 0.25 ng·mL·h, with the aldosterone level of <1 ng/dL, the serum brain natriuretic peptide of 15 pg/mL, and serum uric acid of 2.8 mg/dL. The diagnosis of CSWS was suspected, fludrocortisone was tried, and hypovolemia and hyponatremia improved. Cryptococcal meningitis in HIV patients can present with CSWS, and the distinction between CSWS and SIADH is important because the treatment for CSWS is different than that of SIADH. Both share a similar clinical picture except that CSWS presents with constant hypovolemia despite volume replacement. Salt tablets, normal saline, or fludrocortisone can be used for treatment.

Transient Oliguria during Anesthesia in Cerebral Salt Wasting Syndrome

Cerebral salt wasting syndrome is a hyponatremic and hypovolemic condition caused by intracranial disorders, such as head injury, subarachnoid hemorrhage, brain tumor, and brain operations. We report a case of a 5-year-old girl that had cerebral salt wasting syndrome with marked polyuria who showed transient oliguria during general anesthesia. The patient had undergone an operation for traumatic intracranial hemorrhage three months prior and has had marked polyuria and hyponatremia since then. After induction of anesthesia for cranioplasty, the patient had oliguria during surgery and then resumed polyuria in the post-operative period.

Atrial natriuretic factor: is it responsible for hyponatremia and natriuresis in neurosurgery?

Objective

To evaluate the presence of hyponatremia and natriuresis and their association with atrial natriuretic factor in neurosurgery patients.

Methods

The study included 30 patients who had been submitted to intracranial tumor resection and cerebral aneurism clipping. Both plasma and urinary sodium and plasma atrial natriuretic factor were measured during the preoperative and postoperative time periods.

Results

Hyponatremia was present in 63.33% of the patients, particularly on the first postoperative day. Natriuresis was present in 93.33% of the patients, particularly on the second postoperative day. Plasma atrial natriuretic factor was increased in 92.60% of the patients in at least one of the postoperative days; however, there was no statistically significant association between the atrial natriuretic factor and plasma sodium and between the atrial natriuretic factor and urinary sodium.

Conclusion

Hyponatremia and natriuresis were present in most patients after neurosurgery; however, the atrial natriuretic factor cannot be considered to be directly responsible for these alterations in neurosurgery patients. Other natriuretic factors are likely to be involved.

Hyponatremia in Critically Ill Patients

Disorders of sodium and water metabolism are frequently encountered in hospitalized patients. Hyponatremia in critically ill patients can cause significant morbidity and mortality. Inappropriate treatment of hyponatremia can add to the problem. The diagnosis and management of salt and water abnormalities in critically ill patients is often challenging. The increasing knowledge about aquaporins and the role of vasopressin in water metabolism has enhanced our understanding of these disorders. The authors have outlined the general approach to the diagnosis and management of hyponatremia. A systematic approach by clinicians, using a detailed history, physical examination, and relevant diagnostic tests, will assist in efficient management of salt and water problems.

A study of hyponatremia in tuberculous meningitis

SETTING

In view of paucity of studies on predictors of hyponatremia in tuberculous meningitis (TBM) and its influence on outcome, this study was undertaken.

OBJECTIVE

To study the frequency, predictors and prognosis of hyponatremia in TBM.

DESIGN

In this prospective hospital based study, 76 patients with TBM (definite 18 and probable 58) were enrolled. The severity of meningitis was graded as I-III and hyponatremia as severe (<120mEq/L), moderate (120-129mEq/L) or mild (130-134mEq/L). Hospital death was noted and functional outcome was assessed by modified Rankin Scale (mRS) on discharge.

RESULTS

34 (44.7%) TBM patients had hyponatremia (mild 3, moderate 23 and severe 8). Hyponatremia was due to cerebral salt wasting in 17, syndrome of inappropriate secretion of antidiuretic hormone in 3 and miscellaneous causes in 14 patients. Hyponatremia was related to GCS score and basal exudates. Outcome of TBM was related to duration of hospitalization, GCS score, focal deficit, mechanical ventilation, severity of TBM, age and comorbidities. Cerebral salt wasting was related to severity of TBM.

CONCLUSION

Hyponatremia occurred in 44.7% of TBM patients. Cerebral salt wasting was the commonest cause of hyponatremia and was related to the severity of TBM.

Etiology of postoperative hyponatremia following pediatric intracranial tumor surgery

OBJECT Cerebral salt wasting (CSW) and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) cause postoperative hyponatremia in neurosurgery patients, can be difficult to distinguish clinically, and are associated with increased morbidity. The authors aimed to determine risk factors associated with CSW and SIADH among children undergoing surgery for intracranial tumors. METHODS This retrospective cohort study included children 0-19 years of age who underwent a first intracranial tumor surgery with postoperative hyponatremia (sodium ≤ 130 mEq/L). CSW was differentiated from SIADH by urine output and fluid balance, exclusive of other causes of hyponatremia. The CSW and SIADH groups were compared with basic bivariate analysis and recursive partitioning. RESULTS Of 39 hyponatremic patients, 17 (44%) had CSW and 10 (26%) had SIADH. Patients with CSW had significantly greater natriuresis compared with those with SIADH (median urine sodium 211 vs 28 mEq/L, p = 0.01). Age ≤ 7 years and female sex were significant risk factors for CSW (p = 0.03 and 0.04, respectively). Both patient groups had hyponatremia onset within the first postoperative week. Children with CSW had trends toward increased sodium variability and symptomatic hyponatremia compared with those with SIADH. Most received treatment, but inappropriate treatment was noted to worsen hyponatremia. CONCLUSIONS The authors found that CSW was more common following intracranial tumor surgery and was associated with younger age and female sex. Careful assessment of fluid balance and urine output can separate patients with CSW from those who have SIADH, and high urine sodium concentrations (> 100 mEq/L) support a CSW diagnosis. Patients with CSW and SIADH had similar clinical courses, but responded to different interventions, making appropriate diagnosis and treatment imperative to prevent morbidity.

Syndrome of inappropriate antidiuretic hormone secretion and cerebral/renal salt wasting syndrome: similarities and differences

Hyponatremia (sodium levels of <135 mEq/L) is one of the most common electrolyte imbalances in clinical practice, especially in patients with neurologic diseases. Hyponatremia can cause cerebral edema and brain herniation; therefore, prompt diagnosis and proper treatment is important in preventing morbidity and mortality. Among various causes of hyponatremia, diagnosing syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral/renal salt wasting syndrome (C/RSW) is difficult due to many similarities. SIADH is caused by excess of renal water reabsorption through inappropriate antidiuretic hormone secretion, and fluid restriction is the treatment of choice. On the other hand, C/RSW is caused by natriuresis, which is followed by volume depletion and negative sodium balance and replacement of water and sodium is the mainstay of treatment. Determinating volume status in hyponatremic patients is the key point in differential between SIADH and C/RSW. However, in most situations, differential diagnosis of these two diseases is difficult because they overlap in many clinical and laboratory aspects, especially to assess differences in volume status of these patients. Although distinction between the SIADH and C/RSW is difficult, improvement of hypouricemia and an increased fractional excretion of uric acid after the correction of hyponatremia in SIADH, not in C/RSW, may be one of the helpful points in discriminating the two diseases. In this review, we compare these two diseases regarding the pathophysiologic mechanisms, diagnosis, and therapeutic point of view.

Clinical analysis of brain trauma-associated SIADH

The objective of this study was to analyze the clinical features of brain trauma associated syndrome of inappropriate antidiuretic hormone secretion. A retrospective analysis was performed for the electrolytes and osmolality of blood and urine samples of brain injury patients, which have been collected in our department since last 20 years. Four cases of brain injury patients met the criteria of SIADH, and three of them were cured but one patient died. In conclusion, the pathogenesis and treatment of SIADH associated with brain injury are different from hyponatremia. Early diagnosis and treatment can reduce the morbidity and mortality of patients with traumatic brain injury.

Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations

Hyponatremia is a serious, but often overlooked, electrolyte imbalance that has been independently associated with a wide range of deleterious changes involving many different body systems. Untreated acute hyponatremia can cause substantial morbidity and mortality as a result of osmotically induced cerebral edema, and excessively rapid correction of chronic hyponatremia can cause severe neurologic impairment and death as a result of osmotic demyelination. The diverse etiologies and comorbidities associated with hyponatremia pose substantial challenges in managing this disorder. In 2007, a panel of experts in hyponatremia convened to develop the Hyponatremia Treatment Guidelines 2007: Expert Panel Recommendations that defined strategies for clinicians caring for patients with hyponatremia. In the 6 years since the publication of that document, the field has seen several notable developments, including new evidence on morbidities and complications associated with hyponatremia, the importance of treating mild to moderate hyponatremia, and the efficacy and safety of vasopressin receptor antagonist therapy for hyponatremic patients. Therefore, additional guidance was deemed necessary and a panel of hyponatremia experts (which included all of the original panel members) was convened to update the previous recommendations for optimal current management of this disorder. The updated expert panel recommendations in this document represent recommended approaches for multiple etiologies of hyponatremia that are based on both consensus opinions of experts in hyponatremia and the most recent published data in this field.

Hyponatremia after aneurysmal subarachnoid hemorrhage: Implications and outcomes

BACKGROUND

Hyponatremia is the most common electrolyte abnormality seen in patients with aneurysmal SAH. Clinically significant hyponatremia (Serum Sodium <131 mEq/L) which needs treatment, has been redefined recently and there is a paucity of outcome studies based on this. This study aims to identify the mean Serum Sodium (S.Na+) level and its duration among inpatients with SAH and to identify the relationship between hyponatremia and the outcome status of patients undergoing surgery for SAH.

MATERIALS AND METHODS

This outcome study is undertaken in the department of neurosurgery, The Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala. Medical records of all patients with SAH from 1(st) January to 31(st) July 2010 were reviewed. Preoperative status was assessed using World Federation of Neurosurgical Societies (WFNS) grading system. Discharge status was calculated using the Glasgow outcome score scale.

RESULTS

Fifty nine patients were included in the study and 53 (89.8%) of them have undergone surgical treatment. Hyponatremia was observed in 22 of 59 patients (37%). The mean Sodium level of hyponatremic patients was 126.97 mEq/L for a median duration of two days. Glasgow outcome score was good in 89.8% of patients. We lost two patients, one of whom had hyponatremia and vasospasm.

CONCLUSION

Hyponatremia is significantly associated with poor outcome in patients with SAH. Anticipate hyponatremia in patients with aneurysmal subarachnoid hemorrhage, timely detect and appropriately treat it to improve outcome. It is more common in patients who are more than 50 years old and whose aneurysm is in the anterior communicating artery. Our comprehensive monitoring ensured early detection and efficient surgical and nursing management reduced morbidity and mortality.

Renal salt-wasting syndrome in children with intracranial disorders

Hypotonic hyponatremia, a serious and recognized complication of any intracranial disorder, results from extra-cellular fluid volume depletion, inappropriate anti-diuresis or renal salt-wasting. The putative mechanisms by which intracranial disorders might lead to renal salt-wasting are either a disrupted neural input to the kidney or the elaboration of a circulating natriuretic factor. The key to diagnosis of renal salt-wasting lies in the assessment of extra-cellular volume status: the central venous pressure is currently considered the yardstick for measuring fluid volume status in subjects with intracranial disorders and hyponatremia. Approximately 110 cases have been reported so far in subjects ≤18 years of age (male: 63%; female: 37%): intracranial surgery, meningo-encephalitis (most frequently tuberculous) or head injury were the most common underlying disorders. Volume and sodium repletion are the goals of treatment, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids (fludrocortisone). It is worthy of a mention, however, that some authorities contend that cerebral salt wasting syndrome does not exist, since this diagnosis requires evidence of a reduced arterial blood volume, a concept but not a measurable variable.

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.

Hyponatremia in neurosurgical patients: clinical guidelines development

OBJECTIVE

Neurosurgical patients have a high risk of hyponatremia and associated complications. We critically evaluated the existing literature to identify the determinants for the development of hyponatremia and which management strategies provided the best outcomes.

METHODS

A multidisciplinary panel in the areas of neurosurgery, nephrology, critical care medicine, endocrinology, pharmacy, and nursing summarized and classified hyponatremia literature scientific studies published in English from 1950 through 2008. The panel's recommendations were used to create an evaluation and treatment protocol for hyponatremia in neurosurgical patients at the University of Florida.

RESULTS

Hyponatremia should be further investigated and treated when the serum sodium level is less than 131 mmol/L (class II). Evaluation of hyponatremia should include a combination of physical examination findings, basic laboratory studies, and invasive monitoring when available (class III). Obtaining levels of hormones such as antidiuretic hormone and natriuretic peptides is not supported by the literature (class III). Treatment of hyponatremia should be based on severity of symptoms (class III). The serum sodium level should not be corrected by more than 10 mmol/L/d (class III). Cerebral salt wasting should be treated with replacement of serum sodium and intravenous fluids (class III). Fludrocortisone may be considered in the treatment of hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm (class I). Hydrocortisone may be used to prevent natriuresis in subarachnoid hemorrhage patients (class I). Hyponatremia in subarachnoid hemorrhage patients at risk of vasospasm should not be treated with fluid restriction (class II). Syndrome of inappropriate antidiuretic hormone may be treated with urea, diuretics, lithium, demeclocycline, and/or fluid restriction (class III).

CONCLUSION

The summarized literature on the evaluation and treatment of hyponatremia was used to develop practice management recommendations for hyponatremia in the neurosurgical population. However, the practice management recommendations relied heavily on expert opinion because of a paucity of class I evidence literature on hyponatremia.

Cerebral salt wasting versus SIADH: what difference?

The term cerebral salt wasting (CSW) was introduced before the syndrome of inappropriate antidiuretic hormone secretion was described in 1957. Subsequently, CSW virtually vanished, only to reappear a quarter century later in the neurosurgical literature. A valid diagnosis of CSW requires evidence of inappropriate urinary salt losses and reduced "effective arterial blood volume." With no gold standard, the reported measures of volume depletion do not stand scrutiny. We cannot tell the difference between CSW and the syndrome of inappropriate antidiuretic hormone secretion. Furthermore, the distinction does not make a difference; regardless of volume status, hyponatremia complicating intracranial disease should be treated with hypertonic saline.

Hyponatremia treatment guidelines 2007: expert panel recommendations

Although hyponatremia is a common, usually mild, and relatively asymptomatic disorder of electrolytes, acute severe hyponatremia can cause substantial morbidity and mortality, particularly in patients with concomitant disease. In addition, overly rapid correction of chronic hyponatremia can cause severe neurologic deficits and death, and optimal treatment strategies for such cases are not established. An expert panel assessed the potential contributions of aquaretic nonpeptide small-molecule arginine vasopressin receptor (AVPR) antagonists to hyponatremia therapies. This review presents their conclusions, including identification of appropriate treatment populations and possible future indications for aquaretic AVPR antagonists.

Syndromes related to sodium and arginine vasopressin alterations in post-operative neurosurgery

BACKGROUND: Cerebral salt wasting syndrome (CSWS), syndrome of inappropriate antidiuretic hormone secretion (SIADH) and diabetes insipidus (DI) are frequently found in postoperative neurosurgery. PURPOSE: To identify these syndromes following neurosurgery. METHOD: The study included 30 patients who had been submitted to tumor resection and cerebral aneurysm clipping. Sodium levels in serum and urine and urine volume were measured daily up to the 5th day following surgery. Plasma arginine vasopressin (AVP) was measured on the first, third and fifth days post-surgery. RESULTS: CSWS was found in 27/30 patients (90%), in 14 (46.7%) of whom it was associated with a reduction in the levels of plasma AVP (mix syndrome). SIADH was found in 3/30 patients (10%). There was no difference between the two groups of patients. CONCLUSION: CSWS was the most common syndrome found, and in half the cases it was associated with DI. SIADH was the least frequent syndrome found.

Disorders of body water homeostasis in critical illness

Disorders of sodium and water homeostasis are among the most commonly encountered disturbances in the critical care setting, because many disease states cause defects in the complex mechanisms that control the intake and output of water and solute. Because body water is the primary determinant of extracellular fluid osmolality, disorders of body water balance can be categorized into hypoosmolar and hyperosmolar disorders depending on the presence of an excess or a deficiency of body water relative to body solute. Because the main constituent of plasma osmolality is sodium, hypoosmolar and hyperosmolar disease states are generally characterized hy hyponatremia and hypernatremia, respectively. After a brief review of normal water metabolism, this article focuses on the diagnosis and treatment of hyponatremia and hypernatremia in the critical care setting.

Disturbances of sodium in critically ill adult neurologic patients: a clinical review

Disorders of sodium and water balance are common in critically ill adult neurologic patients. Normal aspects of sodium and water regulation are reviewed. The etiology of possible causes of sodium disturbance is discussed in both the general inpatient and the neurologic populations. Areas of importance are highlighted with regard to the differential diagnosis of sodium disturbance in neurologic patients, and management strategies are discussed. Specific discussions of the etiology, diagnosis, and management of cerebral salt wasting syndrome, the syndrome of inappropriate antidiuretic hormone secretion, and central diabetes insipidus are presented, as well as the problems of overtreatment. The importance of diagnosis at an early stage of these diseases is stressed, with a recommendation for conservative management of milder cases.

Tuberculous meningitis complicated with hydrocephalus and cerebral salt wasting syndrome in a three-year-old boy

Cerebral salt wasting syndrome (CSWS) is a syndrome of hyponatremia and natriuresis described in patients with intracranial diseases. We describe a 3-year-old boy with tuberculous meningitis complicated by hydrocephalus and CSWS and emphasize the different clinical presentation and management of patients with CSWS and the syndrome of inappropriate secretion of antidiuretic hormone.

Hyponatremia in critically ill neurological patients

BACKGROUND

Hyponatremia is the most common and important electrolyte disorder encountered in the neurologic intensive care unit (NICU). Advances in our knowledge of the pathophysiological mechanisms at play in patients with acute neurologic disease have improved our understanding of this derangement.

REVIEW SUMMARY

Evaluation of hyponatremia requires a structured approach beginning with the measurement of serum and urine osmolalities. Most cases of hyponatremia in the NICU are associated with serum hypotonicity. Iatrogenic causes, most conspicuously inadequate tonicity of intravenous fluids, should be promptly identified and removed when possible. Two main mechanisms are responsible for most non-iatrogenic cases of hyponatremia in patients with neurologic or neurosurgical disease: inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting syndrome (CSW). Distinction between these two syndromes may be difficult and must be based on an accurate assessment of the patient's volume status. SIADH is associated with normal or slightly expanded volume status and should be treated with fluid restriction. Patients with CSW are hypovolemic and require adequate fluid and sodium replacement. Correction of hyponatremia should not exceed 8 to 10 mmol/L over any 24-hour period to avoid the risk of osmotic demyelination.

CONCLUSIONS

Hyponatremia may complicate the clinical course of many acute neurologic and neurosurgical disorders. It is most often iatrogenic causes, CSW, or SIADH. Physicians working with critically ill neurologic patients should be familiar with management strategies addressing these underlying pathophysiological mechanisms.

Hyponatraemia and hypovolemic shock with tuberculous meningitis

A 12-year-old boy with tuberculous meningitis and hydrocephalous, after undergoing revision of ventriculo-peritoneal shunt had persistent impairment of sensorium and episodes of hyponatremia (serum sodium 104 to 125 mmol/l), accompanied by polyuria, signs of poor peripheral, perfusion hypotension and low CVP, and high urinary sodium excretion (114-60 mmol/l). A diagnosis of cerebral salt wasting syndrome (CSWS) was made and was treated with saline replacement and fludrocortisone (10 microg/kg/day). Within next 3 days the sensorium, signs of shock, urine output and serum and urinary sodium returned to normal. The case illustrates that life-threatening hyponatremia in a child with neurological illness could be caused by CSWS, which must be differentiated from Syndrome of inappropriate antidiuretic hormone secretion (SIADH), as CSWS requires rigorous salt and volume replacement in contrast to fluid restriction in SIADH.

Severe hyponatraemia: investigation and management in a district general hospital

AIMS

To study the incidence, investigation, and management of severe hyponatraemia (serum sodium < 120 mmol/litre) over a period of six months in a district general hospital.

METHODS

The laboratory computer was used to identify all inpatients who had a serum sodium concentration of less than 120 mmol/litre over a six month period. The records of these patients were reviewed for the relevant demographic, clinical, and laboratory data, in addition to diagnosis, treatment, and outcome of hospitalisation.

RESULTS

Forty two patients were studied, with a female to male ratio of 2 : 1. Nine patients had central nervous system symptoms, and four of these patients died in hospital. Only 14 patients had their urinary electrolytes and/or osmolality checked. A diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) was mentioned in eight patients, sometimes without checking their urinary electrolytes or osmolality. Twenty one patients died in hospital. The patients who died did not have lower serum sodium values or a higher rate of correction of hyponatraemia, but they all suffered from advanced medical conditions.

CONCLUSIONS

The possible cause of hyponatraemia should always be sought and that will require an accurate drug history, clinical examination, and assessment of fluid volume, plus the measurement of urinary electrolytes and osmolality in a spot urine sample. The diagnosis of SIADH should not be confirmed without the essential criteria being satisfied. The current or recent use of diuretics is a possible pitfall in the diagnosis of SIADH. The rate of serum sodium correction of less than 10 mmol/day is probably the safest option in most cases.

Cerebral salt wasting syndrome as a postoperative complication after surgical resection of acoustic neuroma

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary care, university hospital.

PATIENTS

The authors describe two patients operated on for acoustic neuroma in whom hyponatremia occurred after intervention.

INTERVENTIONS

Acoustic neuroma surgery.

RESULTS

Wrong diagnosis in case of central nervous system disorder associated with hyponatremia can have fatal consequences.

CONCLUSIONS

To the authors' knowledge, this is the first case report associating cerebral salt wasting syndrome with previous surgical resection of acoustic neuroma.

Hyponatremia in acute brain disease: the cerebral salt wasting syndrome

Hyponatremia in acute brain disease is a common occurrence, especially after an aneurysmal subarachnoid hemorrhage. Originally, excessive natriuresis, called cerebral salt wasting, and later the syndrome of inappropriate antidiuretic hormone secretion (SIADH), were considered to be the causes of hyponatremia. In recent years, it has become clear that most of these patients are volume-depleted and have a negative sodium balance, consistent with the original description of cerebral salt wasting. Elevated plasma concentrations of atrial or brain natriuretic peptide have been identified as the putative natriuretic factor. Hyponatremia and volume depletion may aggravate neurological symptoms, and timely treatment with adequate replacement of water and NaCl is essential. The use of fludrocortisone to increase sodium reabsorption by the renal tubules may be an alternative approach.

Management of hyponatraemia in patients with acute cerebral insults

Hyponatraemia is a common finding in patients with acute cerebral insults. The main differential diagnosis is between syndrome of inappropriate ADH secretion and cerebral salt wasting. Our aim is to review the topic of hyponatraemia in patients with acute cerebral insults and suggest a clinical approach to diagnosis and management.

[Hyponatremia in neurologic intensive care: cerebral salt wasting syndrome and inappropriate antidiuretic hormone secretion]

Hyponatraemia is a frequent complication in neurologically injured patients; it is a secondary cerebral injury. Hyponatraemia leads to consciousness problems, convulsions, worsening of the neurological status and thus the neurological evaluation. Hyponatraemia is secondary to free water retention (inappropriate ADH secretion) or to renal salt loss. The cerebral salt wasting syndrome (CSWS) has been described with head injury, subarachnoid haemorrhage and after several sorts of brain insults. It is characterised by an increased natriuresis and diuresis. Diagnosis is based on hyponatraemia, hypernatriuresis, increased diuresis and hypovolaemia. However, inappropriate ADH secretion and CSWS share several diagnostic criteria. The atrial natriuretic factor and the C-type natriuretic factors play a role in the development of the CSWS. The diagnostic approach and monitoring are based on the assessment of sodium and water losses. Therapy is based on correction of the circulating volume and natraemia. Speed of correction is a matter of debate: slow correction presents the risk of further neurological injury whereas rapid correction presents the risk of central pontine myelinosis.