Management of neurosurgical patients with hyponatremia and natriuresis

Cerebral salt wasting syndrome in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

Hydroelectrolytic disturbances are part of the complications of subarachnoid hemorrhage. Cerebral salt wasting syndrome (CSWS) must be considered when hyponatremia is associated with a decrease in circulating volume. We performed this study to determine the clinical characteristics and management paradigm of patients with serum sodium concentration abnormalities and aneurysmatic subarachnoid hemorrhage.

METHODS

We analyzed retrospectively clinical and laboratory data from eight patients with subarachnoid hemorrhage due to rupture of an intracranial saccular aneurysm and cerebral salt wasting syndrome. Their course, as well as their clinical findings and treatment, are described.

RESULTS

In eight patients, hyponatremia that lasted for more than 24 hours was detected (serum sodium under 135 mEq/l). The sodium disturbance occurred between day 3 and day 10 in all cases, in six of them in day 7 or day 8. The specific treatment for CSWS was to increase volume delivery according to the characteristics of the patient. Except for one case, none of the remaining patients required more than 72 hours of treatment to correct hyponatremia. No treatment-related complications were found

CONCLUSION

Cerebral salt wasting syndrome, occurring in some patients with subarachnoid hemorrhage, is more commonly related to certain specific anatomic locations of the ruptured aneurysm, responds to sodium replacement therapy and fluids and can be diagnosed and treated based on the clinical, hydroelectrolytic and hemodynamic course of the patient. Further studies are needed to define the underlying mechanism of this condition.

Endocrine function and water metabolism in children and adolescents with surgically treated intra/parasellar tumors

Hydroelectrolytic disorders often complicate surgery of intra/parasellar tumors in children and adolescents. Eighteen patients undergoing microneurosurgical procedures for intra-supra-sellar craniopharyngioma (10 patients), hypothalamic germinomas (3 patients), hypothalamic-chiasmatic astrocytomas (3 patients), pituitary adenomas (2 patients) were studied. The hydroelectrolytic balance was assessed from 8 hours before surgery to 1 week after with a specific protocol in which water metabolism alterations were treated with standard procedure. Diabetes insipidus (DI) was observed in 10/18 patients before surgery and in 15/18 patients after surgery; during surgery it was effectively treated with synthetic desmopressin (DDAVP) and hydroelectrolytic solutions. Hyponatremia, isolated or associated (with diuresis contraction or polyuria), seen during surgery and in the following 24 hours, was treated with variation of the infusion rate. We show that close monitoring and treatment of hydroelectrolytic disorders in patients submitted to neurosurgery for intra/ parasellar tumors may significantly reduce their morbidity and mortality rate.

Two cases of cerebral salt wasting syndrome developing after cranial vault remodeling in craniosynostosis children

Hyponatremia has been recognized as an important postoperative metabolic complication after central nervous system (CNS) operations in children. If not appropriately treated, the postoperative hyponatremia can cause several types of CNS and circulatory disorders such as cerebral edema, increased intracranial pressure. The postoperative hyponatremia after CNS surgery has been considered as one of the underlying causes of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). In some cases, however, the cerebral salt wasting (CSW) syndrome has been detected. CSW syndrome is far less well-known than SIADH and also different from SIADH in diagnosis and treatment. It causes an increase in urine output and urine sodium after a trauma of CNS and dehydration symptoms. The appropriate treatment of CSW syndrome is opposite the usual treatment of hyponatremia caused by SIADH. The latter is treated with fluid restriction because of the increased level of free water and its dilutional effect causing hyponatremia, whereas the former is treated with fluid and sodium resuscitation because of the unusual loss of high urinary sodium. Early diagnosis and treatment of CSW syndrome after CNS surgery are, therefore, essential. We made a diagnosis of CSW syndrome in two craniosynostosis children manifesting postoperative hyponatremia and supplied them an appropriate amount of water and sodium via intravenous route. The hyponatremia or natricuresis of the children improved and neurologic and circulatory sequelae could be prevented.

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.

Hyponatremia in patients with central nervous system disease: SIADH versus CSW

The syndromes of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting (CSW) are two potential causes of hyponatremia is patients with disorders of the central nervous system. Distinguishing between these two causes can be challenging because there is considerable overlap in the clinical presentation. The primary distinction lies in the assessment of the effective arterial blood volume (EABV). SIADH is a volume-expanded state because of antidiuretic hormone-mediated renal water retention. CSW is characterized by a contracted EABV resulting from renal salt wasting. Making an accurate diagnosis is important because the treatment of each condition is quite different. Vigorous salt replacement is required in patients with CSW, whereas fluid restriction is the treatment of choice in patients with SIADH. Although most physicians are familiar with SIADH, they are much less familiar with CSW. This review emphasizes the need for CSW to be included in the differential diagnosis of hyponatremia in a patient with central nervous system disease. Distinguishing between these two disorders is of crucial importance because therapy indicated for one disorder but used in the other can result in negative clinical consequences.

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.

Very delayed hyponatremia after surgery and radiotherapy for a pituitary macroadenoma

Severe hyponatremia (118 mmol/l) with natriuresis, consistent with cerebral salt wasting syndrome (CSWS), occurred 38 days after transsphenoidal surgery in a 59-year-old woman affected by a pituitary non-functioning macroadenoma. From the 35th day after surgery, she showed progressive polyuria, hypotension and hyponatremia associated with natriuresis, decreased plasma and increased urinary osmolality. The clinical examination revealed signs of dehydration and gradual decline in the level of consciousness. The anterior pituitary function was normal due to appropriate replacement of thyroid and adrenal axis. The patient was treated with saline administration until normal natremia and water balance were restored and neurological symptoms had completely disappeared. This case focuses on the unusually prolonged time of development of post-surgery hyponatremia, despite delayed symptomatic hyponatremia being reported to commonly occur 7 days after transsphenoidal surgery. Therefore, we would advise not to limit the periodic follow-up of the hydroelectrolytic balance to the first two weeks after surgery, but to prolong it until after discharge from hospital. In fact, an early diagnosis is of great importance to prevent permanent neurological damage or death. Since CSWS and syndrome of inappropriate secretion of ADH, the two disorders alternatively imputed to generate post-surgical hyponatremia, are characterized by different pathogenic mechanisms and require opposing therapeutic approaches, the occurrence of extracellular volume dilution or of increased sodium renal loss should be carefully investigated. The evidences in favor of CSWS, the possible mechanisms behind the syndrome and diagnosis and management of patients with post-transsphenoidal surgery CSWS are discussed.

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.

Systemic complications of neurologic diseases

The systemic complications associated with neurologic disease constitute an extensive topic, because the central nervous system controls many of the functions of the other organ systems in the body and because the brain cannot live in isolation of these systems. The precise mechanisms of many of these systemic alterations are poorly understood, but they appear to depend on the location and the severity of the initial central nervous system pathologic lesion.

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.

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.

Improved efficiency of hypervolemic therapy with inhibition of natriuresis by fludrocortisone in patients with aneurysmal subarachnoid hemorrhage

OBJECT

To reduce the risk of ischemic complications in patients with subarachnoid hemorrhage (SAH), hypervolemic therapy is generally advocated. However, such conventional treatment cannot always ensure the maintenance of an effective intravascular volume expansion, because excessive natriuresis and osmotic diuresis occur after SAH. In this prospective study the authors examined the effects of inhibition of natriuresis with fludrocortisone acetate on intravascular volume expansion during hypervolemic therapy.

METHODS

Thirty patients with SAH were randomized and divided into two groups: controls (Group 1, 15 patients) and patients treated with 0.3 mg/day of fludrocortisone (Group 2, 15 patients). In all patients sodium and fluid intake levels were in excess of maintenance requirements in an attempt to maintain a positive water balance and a central venous pressure (CVP) of 8 to 12 cm H2O. The mean sodium and water intake levels for 14 days after SAH were significantly reduced by fludrocortisone in Group 2 (487+/-34.52 mEq/day and 5159.2+/-249.29 ml/day, respectively; p<0.01) compared with Group 1 (634.2+/-42.86 mEq/day and 6611.7+/-365.67 ml/day). Fludrocortisone significantly reduced the urinary sodium excretion (p<0.01) and urine volume (p<0.01) in parallel, and effectively prevented a negative shift in the sodium as well as water balance (p<0.01). The serum sodium level tended to decrease in Group 1, reaching 135 mEq/L on average, but not in Group 2 (p<0.01). Hyponatremia in Group 1 was always observed at the optimal range of CVP values. A decrease in serum potassium level within the range of 2.8 to 3.5 mEq/L was transiently noted in 11 patients (73.3%) of Group 2, but was easily corrected. Possible side effects of fludrocortisone, such as pulmonary edema, were not encountered.

CONCLUSIONS

Intravascular volume expansion in the presence of excessive natriuresis requires a large sodium and water intake and is often associated with hyponatremia. Inhibition of natriuresis with fludrocortisone can effectively reduce the sodium and water intake required for hypervolemia and prevent hyponatremia at the same time.

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.

Systematic approach for detection of endocrine disorders in children treated for brain tumors

Endocrine dysfunction can be challenging to diagnose in children treated for brain tumors. Treatments are available for hormonal replacement and when necessary, hormonal suppression. Without these endocrine treatment regimens, life can be unnecessarily difficult or unpleasant. An endocrine survey can be used to screen at-risk neuro-oncology patients once or twice a year to facilitate the recognition of endocrine dysfunction. It is hoped that through the use of a routine screening program, physicians will be able to diagnose and begin treatment of endocrine problems in a time-efficient manner.

Cerebral salt wasting syndrome in brain injury patients: a potential cause of hyponatremia

Hyponatremia is a common neuromedical problem seen in survivors of central nervous system injury. The etiology of this hyponatremia is often diagnosed as syndrome of inappropriate diuretic hormone (SIADH). Fluid restriction is usually the first line of treatment. However, this can exacerbate vasospasm and produce resultant ischemia. Cerebral salt wasting is a syndrome of renal sodium loss that may occur commonly after central nervous system injury, yet remains unrecognized. Treatment of cerebral salt wasting consists of hydration and salt replacement. This article uses a case report to discuss the importance of recognition of this syndrome, and treatment concerns are reviewed.

Risk factors for acute care transfer among traumatic brain injury patients

OBJECTIVE

Acute inpatient traumatic brain injury (TBI) rehabilitation has seen a jump in complexity of medical patient care over the past several years, often necessitating transfer back to an acute care facility. The purpose of this study was to determine the association between selected clinical variables and transfer from inpatient rehabilitation to an acute care facility.

DESIGN

A retrospective review of cases from 1992 to 1994.

SETTING

A TBI unit in a freestanding rehabilitation hospital.

PATIENTS

Twenty-two patients were identified as having received acute care transfer. This group was compared with 78 patients, admitted in the same interval, who did not require acute care transfer. The variables evaluated included recent surgery, pneumonia, fracture, intracranial blood, tracheostomy use, percutaneous feeding tube use, deep venous thrombosis, focal neurological examination, following simple commands, serum sodium level of < 135 mmol/L, serum white blood cell count of > 11,000 cells/microL, and serum hemoglobin level of < 10.0 g/dl.

ANALYSIS

Chi-square analysis was performed on the association between acute care transfer and the noted variables.

RESULTS

History of pneumonia (p < .03) and history of recent surgery (p < .02) were both associated with acute care transfer, and serum hemoglobin of < 10.0 g/dL had a trend towards association (p < .10).

CONCLUSION

Physiatrists caring for the TBI patient may warrant more acute observation of individuals with these parameters to prevent the problems necessitating acute care transfer.

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

OBJECTIVE

We had previously suggested a protocol for the management of neurosurgical patients with hyponatremia and natriuresis that was based on their volume status as determined by actual blood volume measurements. All patients in that study were found to be hypovolemic or normovolemic and responded, within 72 hours, to salt and fluid replacement. In the present study, the validity of that protocol was tested using central venous pressure as the sole measure of volume status of patients with hyponatremia and natriuresis.

METHOD

Twenty-five consecutive patients (26 cases) who fulfilled the inclusion criteria typically used to diagnose the syndrome of inappropriate secretion of antidiuretic hormone were included in the study. Central venous pressure was used to classify patients as hypovolemic (< 5 cm of water), normovolemic (6-10 cm of water), or hypervolemic (> 11 cm of water). Hypovolemic patients were given fluids (50 ml/kg/d) and salt (12 g/d). Normovolemic patients were given normal fluid with 12 g of salt per day. In addition, patients with anemia (hematocrit, < 27%) were administered whole blood. The end point was a serum sodium of more than or equal to 130 mEq/L measured in two consecutive samples 12 hours apart or 72 hours after entry into the study. If the serum sodium was less than 130 mEq/L at the end of 72 hours, the clinical condition of the patient determined further management.

RESULTS

Nineteen of 25 patients (26 cases) were hypovolemic, the rest were normovolemic. No patient was hypervolemic. Nineteen of 25 patients (26 cases) attained normal serum sodium values within 72 hours, and an additional 3 responded within the next 36 hours (108 h after entry into the study). One patient who was discharged on request had normalized her serum sodium a week later. Among the three nonresponders, who were severely hypovolemic, as revealed by blood volume measurement, and responded to increased fluid and salt administration. One was normovolemic and responded to increased salt administration. There were no complications related to the therapy.

CONCLUSION

Hyponatremia with natriuresis in the neurosurgical setting responds to salt and fluid replacement guided by the patients' volume status as determined by the central venous pressure. This study also offers further indirect evidence to suggest that the syndrome of hyponatremia with natriuresis is most often caused by "cerebral salt wasting" rather than by the syndrome of inappropriate secretion of antidiuretic hormone.

Pathogenesis of hyponatremia following subarachnoid hemorrhage due to ruptured cerebral aneurysm

BACKGROUND

Hyponatremia following subarachnoid hemorrhage (SAH) occurs due to the inappropriate secretion of antidiuretic hormone (SIADH). However, this condition is also sometimes associated with certain dehydration states.

METHODS

To clarify the pathogenesis, daily values of urine volume, water balance, and sodium balance (Na Bal) were correlated with plasma levels of atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), and plasma renin activity (PRA) in 31 cases of SAH.

RESULTS

Na Bal was markedly negative on days 2 and 3. Cumulative Na Bal showed continuous negative values until day 10 following SAH. ANP values showed a consistent elevation, while ADH showed only an initial surge. PRA, as the gross indicator of circulatory volume, showed a lack of suppression, indicating no increase in the circulatory volume.

CONCLUSION

Hyponatremia following SAH therefore appears to be the result of increased natriuresis, due to the inappropriate elevation of ANP rather than SIADH. In this situation, water restriction should not be recommended, since the circulatory volume is decreased.

Rapid natriuresis and preventive hypervolaemia for symptomatic vasospasm after subarachnoid haemorrhage

To prevent symptomatic cerebral vasospasm, we have used hypervolaemia (HV) or volume expansion in patients with aneurysmal subarachnoid haemorrhage (SAH) in recent years. In these patients we could not perform effective fluid and sodium (Na) replacement because of rapid and overwhelming water and Na loss. Although this phenomenon is characteristic under hypervolaemic states, we regard it important to elucidate the mechanism underlying initiation of vasospasm after aneurysmal SAH. Patients with aneurysmal SAH, operated on within 24 hours of onset, were analysed prospectively. We selected 17 patients in good pre-operative condition. Intravascular volume expansion was accomplished with plasma fractionate or albumin and crystalloid solutions in all patients. We divided the 17 patients into two groups; symptomatic spasm group (S-group) consisting of 4 cases developing transient ischaemic symptoms and non-symptomatic spasm group (NS-group) consisting of 13 cases. In S-group, rapid and marked natriuresis developed characteristically before the onset of ischaemic symptoms. The differences in daily Na balance between the two groups were significant on the 3rd and 5th days (p < 0.05). The mean cumulative Na balance in S-group during the 10 days of the study (-375 +/- 159 mEg) was higher than that of NS-group (-24.4 +/- 225 mEq) (p < 0.05). Rapid natriuresis preceded the development of ischaemic symptoms, and was important as a trigger for symptomatic vasospasm after SAH. We considered that hormonal disorders were implicated in this phenomenon, and atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), renin, and aldosterone were each measured three times during the period, with no significant differences, found between the two groups. It was speculated that another potent natriuretic factor, similar to ANP, induced a rapid selective natriuresis resulting in symptomatic vasospasm.

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.