Hyponatraemia in neurosurgical patients: diagnosis using derived parameters of sodium and water homeostasis

Is cerebral salt wasting related to sympathetic dysregulation in tuberculous meningitis?

BACKGROUND

Cerebral Salt wasting (CSW) is common in Tuberculous Meningitis (TBM) and is suggested to be due to sympathetic dysregulation of renal blood supply but has not been proven.

OBJECTIVE

To evaluate plasma Catecholamines in TBM patients with CSW and correlate with the markers of stress.

MATERIALS AND METHODS

The diagnosis of TBM was based on clinical, CSF and MRI criteria. Catecholamines level was measured by LC-MS on admission, at the time of hyponatremia and on correction of hyponatremia. Catecholamine levels were correlated with clinical and laboratory markers of stress, hyponatremia and severity of CSW using pre-defined criteria.

RESULTS

There were 24 patients with TBM (12 with CSW) and 12 controls. The median age of patients was 31 (18-75) years and 12 (50 %) were females. TBM patients with CSW had significantly higher levels of catecholamines compared to controls (p < 0.001). TBM patients with CSW had higher levels of norepinephrine than those without CSW (p = 0.034). Sequential studies revealed that dopamine and epinephrine increased at the time of hyponatremia and declined on its correction. Severity of TBM was related to dopamine (p = 0.04) and severity of CSW was related to epinephrine (p = 0.016).

CONCLUSION

CSW in TBM seems to be related to catecholamine dysregulation.

Polyuria in relation to dysnatraemias in neurocritical care

INTRODUCTION

Polyuria has the potential to cause severe water and sodium imbalance. We studied the epidemiology of polyuria in association with dysnatraemias and whether polyuria is an independent risk factor for higher mortality and poorer outcome in neurocritical care.

METHODS

We performed an analysis of a 3-year prospective database containing 902 neurocritical care patients. Polyuria was defined as diuresis above 4000 ml/day, hyponatraemia as a serum sodium (SeNa) < 135 mmol/l and hypernatraemia as SeNa > 150 mmol/l.

RESULTS

We identified polyuria in 236 (26.2%) patients (639 days). Polyuric patients stayed in the neurointensive care unit (NICU) longer than those without polyuria (mean: 10.7 vs. 3.5 days, p < 0.001). These patients also had more frequent cerebral complications (p < 0.001) and a poorer outcome upon discharge from the NICU (p = 0.032). NICU mortality had borderline significance in relation to whether the patients were polyuric (p = 0.055). There were only 49 (20.8%) patients with dysnatraemia who were shown to have a significantly higher NICU mortality (p = 0.006). There were no differences in frequency between hyponatraemic and hypernatraemic polyuric patients (p = 0.127). Polyuric patients with hypernatraemia suffered poorer outcomes (p = 0.009) and higher NICU mortality (p < 0.001), but they had a lower Glasgow Coma Scale or GCS recorded at the onset of polyuria (p < 0.001). Cerebral salt wasting (CSW) was thought to be the cause of polyuria in 7 (3.0%) patients and central diabetes insipidus (CDI) in another 5 (2.1%) patients. Univariate models showed polyuria to be a risk factor for poor outcome (odds ratio [OR] = 1.39, p = 0.032) and had a borderline significance for mortality during their NICU stay (OR = 1.83, p = 0.055). These factors did not appear as significant following multivariate logistic regression analysis.

CONCLUSION

Polyuria often occurred in neurocritical care patients, but was not usually associated with sodium imbalance, CSW or CDI. We did not find that polyuria was a significant predictor of increased mortality or poorer outcome in NICU patients.

Outcome and frequency of sodium disturbances in neurocritically ill patients

Sodium disturbances are frequent and serious complications in neurocritically ill patients. Hyponatremia is more common than hypernatremia, which is, however, prognostically worse. The aim of this study was to analyse outcome and frequency of sodium disturbances in relation to measured serum osmolality in neurologic-neurosurgical critically ill patients. A 5-year retrospective collection of patients (pts) and laboratory data were made from the Laboratory Information System database in the Clinical Biochemistry Department. The criteria for patients' inclusion was acute brain disease and serum sodium (SNa(+)) <135 mmol/l (hyponatremia) or SNa(+) >150 mmol/l (hypernatremia). Hypoosmolality was defined as measured serum osmolality (SOsm) <275 mmol/kg, hyperosmolality as SOsm >295 mmol/kg. We performed analysis of differences between hyponatremia and hypernatremia and subanalysis of differences between hypoosmolal hyponatremia and hypernatremia. From 1,440 pts with acute brain diseases there were 251 (17 %) pts with hyponatremia (mean SNa(+) 131.78 ± 2.89 mmol/l, SOsm 279.46 ± 11.84 mmol/kg) and 75 (5 %) pts with hypernatremia (mean SNa(+) 154.38 ± 3.76 mmol/l, SOsm 326.07 ± 15.93 mmol/kg). Hypoosmolal hyponatremia occurred in 50 (20 % of hyponatremic patients) pts (mean SNa(+) 129.62 ± 4.15 mmol/l; mean SOsm 267.35 ± 6.28 mmol/kg). Multiple logistic regression analysis showed that hypernatremia is a significant predictor of mortality during neurologic-neurosurgical intensive care unit (NNICU) stay (OR 5.3, p = 0.002) but not a predictor of bad outcome upon discharge from NNICU, defined as Glasgow Coma Scale 1-3. These results showed that hypernatremia occurred less frequently than all hyponatremias, but more often than hypoosmolal hyponatremia. Hypernatremia was shown to be a significant predictor of NNICU mortality compared to hyponatremia.

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.

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.

Hyponatremia in the neurosurgical patient: diagnosis and management

Hyponatremia is frequently encountered in patients who have undergone neurosurgery for intracranial processes. Making an accurate diagnosis between the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) in patients in whom hyponatremia develops is important because treatment differs greatly between the conditions. The SIADH is a volume-expanded condition, whereas CSW is a volume-contracted state that involves renal loss of sodium. Treatment for patients with SIADH is fluid restriction and treatment for patients with CSW is generally salt and water replacement. In this review, the authors discuss the differential diagnosis of hyponatremia, distinguish SIADH from CSW, and highlight the diagnosis and management of hyponatremia, which is commonly encountered in patients who have undergone neurosurgery, specifically those with traumatic brain injury, aneurysmal subarachnoid hemorrhage, recent transsphenoidal surgery for pituitary tumors, and postoperative cranial vault reconstruction for craniosynostosis.

Timing of surgery for supratentorial aneurysmal subarachnoid haemorrhage: report of a prospective study

OBJECTIVES

The debate on the timing of aneurysm surgery after subarachnoid haemorrhage (SAH) pivots on the balance of the temporal risk for fatal rebleeding versus the risk of surgical morbidity when operating early on an acutely injured brain. By following a strict management protocol for SAH, the hypothesis has been tested that in the modern arena of treatment for aneurysmal SAH the timing of surgery to secure supratentorial aneurysms does not affect surgical outcome.

METHODS

Over a 6 year period, patients admitted with a diagnosis of SAH to a regional neurosurgical unit have been prospectively studied. All have been on a management protocol in which early transfer and resuscitation has been followed regardless of age and clinical condition. Angiographic investigation and surgery have been pursued in those who have been able to at least flex to pain. A total of 1168 patients (60.7% female, mean age 54.3) with proved SAH were received on median day 1 (86.4% arrived within 3 days) of the ictus. Of these, 784 (67.1%) showed aneurysms on angiography and were prepared for surgery. Those who received surgery for a supratentorial aneurysm within 21 days of the ictus were included in the final analysis (n=550). Patients with an initial negative angiogram, with posterior circulation aneurysms, or aneurysms treated by endovascular means, with aneurysms requiring emergency surgery for space occupying haematomas, with aneurysms which re-bled before surgery, and those who received very late surgery (after 21 days from ictus) were excluded. Surgical outcomes at hospital discharge and after 6 months were assessed using the Glasgow outcome score (GOS). Discharge destination and duration of stay in a neurosurgical ward were also documented. The influence of the timing of surgery (early group day 1-3 postictus, intermediate group day 4-10, or late group day 11-21) was analysed prospectively.

RESULTS

60.2% of cases fell into the early surgery group, 32.4% into the intermediate group, and 7.5% into the late operated group. Late surgery was due to delays in diagnosis, transfer, and logistic factors, but not clinical decision. The demographic characteristics, site of aneurysm, and clinical condition of the patients at the time of initial medical assessment were balanced in the three surgical timing groups. There was no significant difference in GOS between the surgical timing groups at 6 months (favourable GOS score 4 and 5: 83.2%, 80.5%, and 83.8% respectively; p=0.47, Kruskal-Wallis test). Outcome was favourable in 84% of patients under 65 years, and 70% in those over 65. The discharge destinations (home, referring hospital, nursing home, rehabilitation centre) showed no significant difference between surgical timing groups. There was no significant difference in mean time to discharge after admission to this hospital from the referring hospital (16.2, 16.2, and 14.6 days for early, intermediate, and late groups respectively; p=0.789, Analysis of variance (ANOVA)). As a result, there was reduction in the mean duration of total hospital inpatient stay in favour of the earliest operated patients (mean time 18.1, 22.0, and 28.3 days respectively; p=0.001. ANOVA showed that besides age, the only determinant of surgical outcome and duration of stay was presenting clinical grade (p<0.0005).

CONCLUSION

The current management of patients presenting with SAH from anterior circulation aneurysms allows early surgery to be followed safely regardless of age. The only independent variables affecting outcome are age and clinical grade at presentation. The timing of surgery did not significantly affect surgical outcome, promoting a policy for early surgery that avoids the known risks of rebleeding and reduces inpatient stay.

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.

Hyponatremia in the postoperative craniofacial pediatric patient population: a connection to cerebral salt wasting syndrome and management of the disorder

Hyponatremia after cranial vault remodeling has been noted in a pediatric patient population. If left untreated, the patients may develop a clinical hypoosmotic condition that can lead to cerebral edema, increased intracranial pressure, and eventually, to central nervous system and circulatory compromise. The hyponatremia has traditionally been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH); however, in our patients the treatment has been resuscitation with normal saline as opposed to fluid restriction (the accepted treatment of SIADH), thus placing the diagnosis of SIADH in question. Patients who developed hyponatremia after intracranial injury or surgery were, until recently, grouped together as having SIADH. However, there are diagnosis and treatment differences between SIADH and another distinct but poorly understood disorder that is designated cerebral salt wasting syndrome (CSW). CSW is associated with increased urine output and increased urine sodium concentration and volume contraction, and it is frequently seen after a central nervous system trauma. We therefore developed a prospective study to evaluate the cause of the sodium imbalance.Ten consecutive pediatric patients who underwent intracranial surgery for various craniosynostotic disorders were postoperatively monitored in the pediatric intensive care unit for hemodynamic, respiratory, and fluid management. The first four patients were evaluated for electrolyte changes and overall fluid balance to determine the consistency with which these changes occurred. The remaining six patients had daily (including preoperative) measurement of serum electrolytes, urine electrolytes, urine osmolarity, serum antidiuretic hormone (ADH), aldosterone, and atrial natriuretic hormone (ANH). All patients received normal saline intravenous replacement fluid in the postoperative period. All of the patients developed a transient hyponatremia postoperatively, despite normal saline resuscitation. Serum sodium levels as low as 128 to 133 mEq per liter (normal, 137 to 145 mEq per liter) were documented in the patients. All patients had increased urine outputs through the fourth postoperative day (>1 cc/kg/h). The six patients who were measured had an increased ANH level, with a peak value as high as 277 pg/ml (normal, 25 to 77 pg/ml). ADH levels were low or normal in all but one patient, who had a marked increase in ADH and ANH. Aldosterone levels were variable. On the basis of these results, all but one patient showed evidence of CSW characterized by increased urine output, normal or increased urine sodium, low serum sodium, and increased ANH levels. The other patient had similar clinical findings consistent with CSW but also had an increase in ADH, thus giving a mixed laboratory picture of SIADH and CSW. The association of CSW to cranial vault remodeling has previously been ignored. This study should prompt reevaluation of the broad grouping of SIADH as the cause of all hyponatremic episodes in our postoperative patient population. An etiologic role has been given to ANH and to other, as yet undiscovered, central nervous system natriuretic factors. All of the patients studied required normal saline resuscitation, a treatment approach that is contrary to the usual management of SIADH. These findings should dictate a change in the postoperative care for these patients. After cranial vault remodeling, patients should prophylactically receive normal saline, rather than a more hypotonic solution, to avoid sodium balance problems.

[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.

Cerebral salt wasting syndrome

There is significant evidence to show that many patients with hyponatremia and intracranial disease who were previously diagnosed with SIADH actually have CSW. The critical difference between SIADH and CSW is that CSW involves renal salt loss leading to hyponatremia and volume loss, whereas SIADH is a euvolemic or hypervolemic condition. Attention to volume status in patients with hyponatremia is essential. The primary treatment for CSW is water and salt replacement. The mechanisms underlying CSW are not understood but may involve ANP or other natriuretic factors and direct neural influence on renal function. Future investigation is needed to better define the incidence of CSW in patients with intracranial disease, identify other disorders that can lead to CSW, and elucidate the mechanisms underlying this syndrome.

Hyponatraemia: biochemical and clinical perspectives

Hyponatraemia is a common bio-chemical abnormality, occurring in about 15% of hospital inpatients. It is often associated with severe illness and relatively poor outcome. Pathophysiologically, hyponatraemia may be spurious, dilutional, depletional or redistributional. Particularly difficult causes and concepts of hyponatraemia are the syndrome of inappropriate antidiuresis and the sick cell syndrome, which are discussed here in detail. Therapy should always be targeted at the underlying disease process. 'Hyponatraemic symptoms' are of doubtful importance, and may be more related to water overload and/or the causative disease, than to hyponatraemia per se. Artificial elevation of plasma sodium by saline infusion carries the risk of induction of osmotic demyelination (central pontine myelinolysis).

Acute hyponatraemia secondary to cerebral salt wasting syndrome in a patient with tuberculous meningitis

A 30-year-old HIV-positive man presented with acute hydrocephalus secondary to tuberculous meningitis, for which an external ventricular drain was inserted. He developed marked natriuresis in the postoperative period, which resulted in acute hyponatraemia (131 to 122 mmol/l) and a contraction of his intravascular volume. A diagnosis of cerebral salt wasting syndrome was made, and he responded to sodium and fluid loading. This case highlights the differentiation of cerebral salt wasting syndrome from the more commonly occurring syndrome of inappropriate anti-diuretic hormone secretion as the aetiology of the hyponatraemia.

Are the increasing clinical demands for osmolality measurements and their associated electrolytes appropriate?

An audit of urine and plasma osmolalities and their associated urea and electrolytes over a 4 week period found that there were 124 plasma and 96 urine osmolality requests from 67 patients. In 21 patients (31.3 per cent), the osmolality results were useful in reaching a more precise diagnosis. In a further 11 cases, urine osmolality rather than plasma would have been appropriate. Seventy-one per cent originated from the Intensive Therapy Unit and were largely requested reflexly by the hospital computer order communication system. Plasma osmolal gaps could be calculated on 80 occasions (65 per cent). The formula 1.89 Na + 1.38 K + 1.03 urea + 1.08 glucose + 7.45 proved to be more accurate than the formula [Na+K] x 2 + urea+glucose (in mmol/L) with the latter showing a positive bias when compared to measured values. The osmolal gap was > 10 mOsm/Kg using the more complex formula on 23 occasions in 16 patients but only twice using the simpler calculation. These 16 patients usually had organ failure and were very ill. Urine sodium and potassium were measured on 72 occasions in 27 of these patients but urine chloride was never requested. Urine sodium < 20 mmol/L was found in 7 patients all of whom had relative or absolute hypovolaemia. Urine sodium was measured in 73 per cent of patients investigated for SIADH in general wards. Data was available to calculate the urine osmolal gap on 52 occasions. The value was > 100 mmol/L in 10 cases and this may be used as an index of the renal ammonium response to acidosis. Much potential derived information from simple indices is unused. As a result of this study, there was an approximate halving of the subsequent request volume.

Water and sodium disorders following surgical excision of pituitary region tumours

A prospective observational study of the pathophysiology of sodium and water disorders in patients with pituitary region tumours after surgical excision was carried out in 20 patients. Serial pre-operative and post-operative fluid and sodium balance, plasma and urine elctrolyte biochemistry and their derived parameters, and circulating hormones associated with fluid balance, atrial natriureic peptide (ANP) and antidiuretic hormone (ADH) were documented to correlate with the patients' clinical conditions. Ten out of these twenty cases developed diabetes insipidus (DI) requiring ADH replacement therapy, although in the majority (6 cases), this way only a transient event. Of the nine patients who developed hyponatraemia, six had symptoms such as impaired consciousness and convulsions. Four patients developed alternating hypoatraemia and hypernatraemia, which constituted a difficult group, where appropriate sodium and fluid management, and ADH replacement therapy were based upon twice daily plasma and urine biochemistry and their derived parameters. Whilst DI in this group of patients was the result of a low circulating ADH level, hyponatraemia was not associated with an exaggerated ADH activity (6.0 +/- 2.3 vs 7.4 +/- 2.3 pmol/ml, mean +/- SEM). Rather, hyponatraemia was strongly associated with an elevated circulating ANP concentration (82.4 +/- 10.5 vs 30.0 +/- 3.1 pmol/ml, mean +/- SEM, p < 0.001), resulting in salt wasting and hypovolaemia.

An audit of aneurysmal subarachnoid haemorrhage: earlier resuscitation and surgery reduces inpatient stay and deaths from rebleeding

OBJECTIVE

To audit the outcome in patients with subarachnoid haemorrhage (SAH) after a change in management strategy.

METHODS

A retrospective analysis of patients with aneurysmal subarachnoid haemorrhage over a 20 month period (phase 1) was followed by a prospective analysis of patients presenting during the next 20 months (phase 2) in which a protocol driven management regime of immediate intravenous fluid resuscitation and earlier surgery was pursued. Patients in this phase were grouped into those receiving early (within four days of subarachnoid haemorrhage) and late (after four days of subarachnoid haemorrhage) surgery. In phase 1, 75 out of a total of 92 patients underwent surgery on (median) day 12. From phase 2, 109 patients out of a total of 129 underwent surgery on (median) day 4, 58 of which had their surgery within 4 days of the subarachnoid haemorrhage. Patients in each phase/group were well matched for demographic features, site of aneurysm, and severity of subarachnoid haemorrhage.

RESULTS

The surgical morbidity and mortality were no different in the two phases (P < 0.92; chi2 test). The management outcomes in the two phases of the study were also no different (P < 0.52). However, there was a significant reduction in the rebleed rate in patients undergoing surgery within four days of the subarachnoid haemorrhage in phase 2 (P < 0.0001) with an associated trend towards reduced incidence of postoperative ischaemia (P = 0.06) and mortality (P = 0.11). Operating earlier in phase 2 of the trial resulted in a lower total hospital inpatient stay of 15.8 (95% CI 13.1-18.5) days for survivors compared with 25.7 (95% CI 21.6-29.8) days in the late group (P < 0.00001; t test).

CONCLUSIONS

surgical morbidity and mortality seemed independent of the timing of aneurysm surgery. Early surgery within four days was associated with a highly significant reduction in rebleed rate, and in the duration of total hospital inpatient stay.

Cerebral salt wasting syndrome: a review

Hyponatremia is frequently seen in neurosurgical patients and is often attributed to inappropriate secretion of antidiuretic hormone. A number of studies in recent years have shown that hyponatremia in many patients with intracranial disease may actually be caused by cerebral salt wasting, in which a renal loss of sodium leads to hyponatremia and a decrease in extracellular fluid volume. The appropriate treatment of cerebral salt wasting fluid and salt replacement, is opposite from the usual treatment of hyponatremia caused by inappropriate secretion of antidiuretic hormone. This review summarizes the evidence in favor of cerebral salt wasting in patients with intracranial disease, examines the possible mechanisms responsible for this phenomenon, and discusses methods for diagnosis and treatment.

Cerebral salt wasting syndrome

Hyponatremia following acute or chronic central nervous system injury which is due to excessive Na+ loss in the urine without an increase in the body fluid, has been described as Cerebral Salt Wasting Syndrome (CSWS). This syndrome is often confused with dilutional hyponatremia secondary to inappropriate ADH secretion. Accurate diagnosis and management are mandatory for to improve the course of the disease. In this study a patient with CSW Syndrome is presented and the treatment and diagnosis of this syndrome are discussed in view of the literature.

Delayed hyponatremia after transsphenoidal surgery for pituitary adenoma. Report of nine cases

Hyponatremia, usually attributed to the syndrome of inappropriate secretion of antidiuretic hormone, typically occurs in a delayed fashion following transsphenoidal removal of a pituitary adenoma. In a series of 99 consecutive patients who underwent transsphenoidal surgery for pituitary adenoma, nine patients developed delayed hyponatremia, seven of whom were symptomatic. Of these seven patients, four had been discharged from the hospital and required readmission on postoperative Day 7 to 9. In the nine patients who developed hyponatremia, on the average, serum sodium levels began to fall on Day 4 and reached a nadir on Day 7 (mean serum sodium nadir 123 mmol/L). The development of delayed hyponatremia was associated with the presence of a macroadenoma in eight of the nine patients. Seven of the nine patients had serum sodium levels less than 130 mmol/L and required treatment. One patient was treated with fluid restriction alone and six were treated with both fluid restriction and intravenous urea therapy. Twenty-four and 48 hours after urea administration, serum sodium levels rose by an average of 6 and 10 mmol/L, respectively, and at discharge, levels averaged 136 mmol/L. Intravenous administration of urea provides a rapid yet safe means of correcting symptomatic hyponatremia when fluid restriction alone is inadequate. In this article, the authors discuss the pathogenesis of delayed hyponatremia.

Hyponatremic natriuretic syndrome in tuberculous meningitis: the probable role of atrial natriuretic peptide

Hyponatremia has been reported in up to one third of patients with intracranial disease and has frequently been associated with tuberculous meningitis, often complicated by hydrocephalus. The lowered plasma sodium levels were previously attributed to the syndrome of inappropriate secretion of antidiuretic hormone. A controlled prospective study of 24 patients with tuberculous meningitis and hydrocephalus was carried out. Analyses of serum electrolytes and cerebrospinal fluid were performed. Plasma and cerebrospinal fluid levels of atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) were measured by radioimmunoassay. Fifteen patients were found to be hyponatremic (plasma sodium < 130 mmol/L) and ANP levels of 12 to 1,488 pg/ml were present (median, 26 pg/ml). The remaining 9 patients had normal plasma sodium values between 130 and 145 mmol/L, and in these, plasma ANP values varied between 12 and 21.7 pg/ml (median, 12 pg/ml). The difference between these two groups was not statistically significant. (Control values from patients undergoing myelography were established to range between 12 and 40 pg/ml; median, 14.4 pg/ml.) ANP levels were undetectable in the cerebrospinal fluid in all. Plasma ADH levels in the hyponatremic group were between 7 and 159 pg/ml (median, 40 pg/ml). In the normonatremic group, plasma ADH levels of 25 to 250 pg/ml (median, 29 pg/ml) were obtained. (The controls ranged between 3.6 and 35 pg/ml; median, 10.4 pg/ml). In the hyponatremic group, there was a moderate negative correlation (r = -0.683) between plasma ANP and plasma sodium (P = 0.02). No correlation between plasma ADH and plasma sodium was found (r = -0.168; P = 0.62).(ABSTRACT TRUNCATED AT 250 WORDS)