Hyponatremia in neurosurgical patients: clinical guidelines development

Diagnosis and treatment of hyponatremia: a systematic review of clinical practice guidelines and consensus statements

BACKGROUND

Hyponatremia is a common electrolyte disorder. Multiple organizations have published guidance documents to assist clinicians in managing hyponatremia. We aimed to explore the scope, content, and consistency of these documents.

METHODS

We searched MEDLINE, EMBASE, and websites of guideline organizations and professional societies to September 2014 without language restriction for Clinical Practice Guidelines (defined as any document providing guidance informed by systematic literature review) and Consensus Statements (any other guidance document) developed specifically to guide differential diagnosis or treatment of hyponatremia. Four reviewers appraised guideline quality using the 23-item AGREE II instrument, which rates reporting of the guidance development process across six domains: scope and purpose, stakeholder involvement, rigor of development, clarity of presentation, applicability, and editorial independence. Total scores were calculated as standardized averages by domain.

RESULTS

We found ten guidance documents; five clinical practice guidelines and five consensus statements. Overall, quality was mixed: two clinical practice guidelines attained an average score of >50% for all of the domains, three rated the evidence in a systematic way and two graded strength of the recommendations. All five consensus statements received AGREE scores below 60% for each of the specific domains.The guidance documents varied widely in scope. All dealt with therapy and seven included recommendations on diagnosis, using serum osmolality to confirm hypotonic hyponatremia, and volume status, urinary sodium concentration, and urinary osmolality for further classification of the hyponatremia. They differed, however, in classification thresholds, what additional tests to consider, and when to initiate diagnostic work-up. Eight guidance documents advocated hypertonic NaCl in severely symptomatic, acute onset (<48 h) hyponatremia. In chronic (>48 h) or asymptomatic cases, recommended treatments were NaCl 0.9%, fluid restriction, and cause-specific therapy for hypovolemic, euvolemic, and hypervolemic hyponatremia, respectively. Eight guidance documents recommended limits for speed of increase of sodium concentration, but these varied between 8 and 12 mmol/L per 24 h. Inconsistencies also existed in the recommended dose of NaCl, its initial infusion speed, and which second line interventions to consider.

CONCLUSIONS

Current guidance documents on the assessment and treatment of hyponatremia vary in methodological rigor and recommendations are not always consistent.

Hyponatremia in Patients with Spontaneous Intracerebral Hemorrhage

Hyponatremia is the most frequently encountered electrolyte abnormality in critically ill patients. Hyponatremia on admission has been identified as an independent predictor of in-hospital mortality in patients with spontaneous intracerebral hemorrhage (sICH). However, the incidence and etiology of hyponatremia (HN) during hospitalization in a neurointensive care unit following spontaneous intracerebral hemorrhage (sICH) remains unknown. This was a retrospective analysis of consecutive patients admitted to Detroit Receiving Hospital for sICH between January 2006 and July 2009. All serum Na levels were recorded for patients during the ICU stay. HN was defined as Na <135 mmol/L. A total of 99 patients were analyzed with HN developing in 24% of sICH patients. Patients with HN had an average sodium nadir of 130 ± 3 mmol/L and an average time from admission to sodium <135 mmol/L of 3.9 ± 5.7 days. The most common cause of hyponatremia was syndrome of inappropriate antidiuretic hormone (90% of HN patients). Patients with HN were more likely to have fever (50% vs. 23%; p = 0.01), infection (58% vs. 28%; p = 0.007) as well as a longer hospital length of stay (14 (8–25) vs. 6 (3–9) days; p < 0.001). Of the patients who developed HN, fifteen (62.5%) patients developed HN in the first week following sICH. This shows HN has a fairly high incidence following sICH. The presence of HN is associated with longer hospital length of stays and higher rates of patient complications, which may result in worse patient outcomes. Further study is necessary to characterize the clinical relevance and treatment of HN in this population.

Incidence, Etiology and Outcomes of Hyponatremia after Transsphenoidal Surgery: Experience with 344 Consecutive Patients at a Single Tertiary Center

Hyponatremia is often seen after transsphenoidal surgery and is a source of considerable economic burden and patient-related morbidity and mortality. We performed a retrospective review of 344 patients who underwent transsphenoidal surgery at our institution between 2006 and 2012. Postoperative hyponatremia was seen in 18.0% of patients at a mean of 3.9 days postoperatively. Hyponatremia was most commonly mild (51.6%) and clinically asymptomatic (93.8%). SIADH was the primary cause of hyponatremia in the majority of cases (n = 44, 71.0%), followed by cerebral salt wasting (n = 15, 24.2%) and desmopressin over-administration (n = 3, 4.8%). The incidence of postoperative hyponatremia was significantly higher in patients with cardiac, renal and/or thyroid disease (p = 0.0034, Objective Risk (OR) = 2.60) and in female patients (p = 0.011, OR = 2.18) or patients undergoing post-operative cerebrospinal fluid drainage (p = 0.0006). Treatment with hypertonic saline (OR = −2.4, p = 0.10) and sodium chloride tablets (OR = −1.57, p = 0.45) was associated with a non-significant trend toward faster resolution of hyponatremia. The use of fluid restriction and diuretics should be de-emphasized in the treatment of post-transsphenoidal hyponatremia, as they have not been shown to significantly alter the time-course to the restoration of sodium balance.

Co-occurring malformations of cortical development and SCN1A gene mutations

OBJECTIVE

To report on six patients with SCN1A mutations and malformations of cortical development (MCDs) and describe their clinical course, genetic findings, and electrographic, imaging, and neuropathologic features.

METHODS

Through our database of epileptic encephalopathies, we identified 120 patients with SCN1A mutations, of which 4 had magnetic resonance imaging (MRI) evidence of MCDs. We collected two further similar observations through the European Task-force for Epilepsy Surgery in Children.

RESULTS

The study group consisted of five males and one female (mean age 7.4 ± 5.3 years). All patients exhibited electroclinical features consistent with the Dravet syndrome spectrum, cognitive impairment, and autistic features. Sequencing analysis of the SCN1A gene detected two missense, two truncating, and two splice-site mutations. Brain MRI revealed bilateral periventricular nodular heterotopia (PNH) in two patients and focal cortical dysplasia (FCD) in three, and disclosed no macroscopic abnormality in one. In the MRI-negative patient, neuropathologic study of the whole brain performed after sudden unexpected death in epilepsy (SUDEP), revealed multifocal micronodular dysplasia in the left temporal lobe. Two patients with FCD underwent epilepsy surgery. Neuropathology revealed FCD type IA and type IIA. Their seizure outcome was unfavorable. All four patients with FCD exhibited multiple seizure types, which always included complex partial seizures, the area of onset of which co-localized with the region of structural abnormality.

SIGNIFICANCE

MCDs and SCN1A gene mutations can co-occur. Although epidemiology does not support a causative role for SCN1A mutations, loss or impaired protein function combined with the effect of susceptibility factors and genetic modifiers of the phenotypic expression of SCN1A mutations might play a role. MCDs, particularly FCD, can influence the electroclinical phenotype in patients with SCN1A-related epilepsy. In patients with MCDs and a history of polymorphic seizures precipitated by fever, SCN1A gene testing should be performed before discussing any epilepsy surgery option, due to the possible implications for outcome.

Hyponatremia is an independent predictor of in-hospital mortality in spontaneous intracerebral hemorrhage

BACKGROUND AND PURPOSE

Hyponatremia is the most frequent electrolyte disturbance in critical care. Across various disciplines, hyponatremia is associated with increased mortality and longer hospital stay, yet in intracerebral hemorrhage (ICH) no data are available. This the first study that investigated the prevalence and clinical associations of hyponatremia in patients with ICH.

METHODS

This observational study included all consecutive spontaneous ICH patients (n=464) admitted during a 5-year period to the Department of Neurology. Patient characteristics, in-hospital measures, mortality, and functional outcome (90 days and 1 year) were analyzed to determine the effects of hyponatremia (Na<135 mEq/L). Multivariable regression analyses were calculated for factors associated with hyponatremia and predictors of in-hospital mortality.

RESULTS

The prevalence of hyponatremia on hospital admission was 15.6% (n=66). Normonatremia was achieved and maintained in almost all hyponatremia patients<48 hours. In-hospital mortality was roughly doubled in hyponatremia compared with nonhyponatremia patients (40.9%; n=27 versus 21.1%; n=75), translating into a 2.5-fold increased odds ratio (P<0.001). Multivariable analyses identified hyponatremia as an independent predictor of in-hospital mortality (odds ratio, 2.2; 95% confidence interval, 1.05-4.62; P=0.037). Within 90 days after ICH, hyponatremia patients surviving hospital stay were also at greater risk of death (odds ratio, 4.8; 95% confidence interval, 2.1-10.6; P<0.001); thereafter, mortality rates were similar.

CONCLUSIONS

Hyponatremia was identified as an independent predictor of in-hospital mortality with a fairly high prevalence in spontaneous ICH patients. The presence of hyponatremia at hospital admission is related to an increased short-term mortality in patients surviving acute care, possibly reflecting a preexisting condition that is linked to worse outcome due to greater comorbidity. Correction of hyponatremia does not seem to compensate its influence on mortality, which strongly warrants future research.

Delayed postoperative hyponatremia after transsphenoidal surgery: prevalence and associated factors

Object

Transient delayed postoperative hyponatremia (DPH) after transsphenoidal surgery (TSS) is common and can have potentially devastating consequences. However, the true prevalence of transient symptomatic and asymptomatic DPH has not been studied in a large patient cohort with close and accurate follow-up.

Methods

A retrospective analysis of a single-institution prospective database was conducted; all patients undergoing TSS for lesions involving the pituitary gland were followed up in a multidisciplinary neuroendocrine clinic, and demographic, imaging, and clinical data were prospectively collected. Patients were examined preoperatively and followed up postoperatively in a standardized fashion, and their postoperative sodium levels were measured at Weeks 1 and 2 postoperatively. Levels of hyponatremia were rated as mild (serum sodium concentration 130–134 mEq/L), moderate (125–129 mEq/L), or severe (< 125 mEq/L). Routine clinical questionnaires were administered at all postoperative office visits. Postoperative hyponatremia was analyzed for correlations with demographic and clinical features and with immediate postoperative physiological characteristics.

Results

Over a 4-year interval, 373 procedures were performed in 339 patients who underwent TSS for sellar and parasellar lesions involving the pituitary gland. The mean (± SD) age of patients was 48 ± 18 years; 61.3% of the patients were female and 46.1% were obese (defined as a body mass index [BMI] ≥ 30). The overall prevalence of DPH within the first 30 days postoperatively was 15.0%; 7.2% of the patients had mild, 3.8% moderate, and 3.8% severe hyponatremia. The incidence of symptomatic hyponatremia requiring hospitalization was 6.4%. The Fisher exact test detected a statistically significant association of DPH with female sex (p = 0.027) and a low BMI (p = 0.001). Spearman rank correlation detected a statistically significant association between BMI and nadir serum sodium concentration (r = 0.158, p = 0.002) and an inverse association for age (r = −0.113, p = 0.031). Multivariate analyses revealed a positive correlation between postoperative hyponatremia and a low BMI and a trend toward association with age; there were no associations between other preoperative demographic or perioperative risk factors, including immediate postoperative alterations in serum sodium concentration. Patients were treated with standardized protocols for hyponatremia, and DPH was not associated with permanent morbidity or mortality.

Conclusions

Delayed postoperative hyponatremia was a common result of TSS; a low BMI was the only clear predictor of which patients will develop DPH. Alterations in immediate postoperative sodium levels did not predict DPH. Therefore, an appropriate index of suspicion and close postoperative monitoring of serum sodium concentration should be maintained for these patients, and an appropriate treatment should be undertaken when hyponatremia is identified.

A review of the neurological and neurosurgical implications of tuberculosis in children

Tuberculous involvement of the central nervous system (CNS) and vertebral column is the most lethal and disabling form of tuberculosis (TB). Several factors contribute to poor outcome, including cerebrovascular involvement with ischemia, hydrocephalus, direct parenchymal injury and formation of abscess and inflammation in the brain and spinal cord, hyponatremia, seizures, and delayed diagnosis. Spinal spondylitis from TB and associated spinal deformity is the leading cause of paraplegia in developing countries. The evidence for supportive treatment of TB infection of the CNS is limited, leading to substantial differences in management protocols. Many of the treatment approaches used in TB infection of the CNS have been extrapolated from treatment of other acute neurological disorders such as bacterial meningitis and traumatic brain injury. We review data from the available literature and highlight questions relating to the neurological and neurosurgical care of children with TB infection of the CNS and vertebral column.

Therapeutic effect of conivaptan bolus dosing in hyponatremic neurosurgical patients

STUDY OBJECTIVE

To determine the natremic response of a single 20-mg bolus dose of conivaptan, an arginine vasopressin antagonist, in hyponatremic neurosurgical patients with the syndrome of inappropriate antidiuretic hormone secretion (SIADH).

DESIGN

Retrospective medical record review.

SETTING

Neurosurgical intensive care unit of a tertiary care referral hospital.

PATIENTS

Thirty-two hyponatremic patients with SIADH who were admitted to the neurosurgical intensive care unit and received a single 20-mg bolus dose of conivaptan between January and December 2011.

MEASUREMENTS AND MAIN RESULTS

Each patient's natremic response over 48 hours was determined. The primary end point was an increase in serum sodium level of 4 mEq/L or greater over the first 24 hours. The mean ± SD baseline serum sodium level was 129.8 ± 3.4 mEq/L, which increased to 133.1 ± 3.2 mEq/L at 6 hours after administration of the bolus dose of conivaptan. The serum sodium level at 24 hours was 134.2 ± 3.2 mEq/L, indicating a 24-hour natremic response of 4.3 ± 2.6 mEq/L (range 1-13 mEq/L) from baseline (p<0.001). Eighteen patients (56%) met the primary end point. The mean ± SD fluid balance over the first 24 hours was -783 ± 440 ml. The mean ± SD change in serum sodium level from 24 to 48 hours was 0.5 ± 1.3 mEq/L. No adverse effects or injection-site reactions were noted. The patients who failed to reach the primary end point were treated with repeated doses of conivaptan plus other agents.

CONCLUSION

We recommend a single 20-mg dose of conivaptan as the preferred initial approach to treating patients with SIADH who are in the neurosurgical intensive care unit. The 24-hour natremic response should then dictate whether additional doses of conivaptan or other therapeutic interventions are required. We believe that such an approach is safe and will result in a controlled and predictable increase in the serum sodium concentration.

Pituitary dysfunction after aneurysmal subarachnoid hemorrhage is associated with impaired early outcome

OBJECTIVE

Poor outcome and neuropsychological sequelae after aneurysmal subarachnoid hemorrhage (SAH) is a persistent problem. Pituitary dysfunction has been proposed as a contributing factor. Clinical studies have given variable and conflicting results on its importance and incidence after SAH. The aim of this study was to prospectively examine SAH patients with assessment of endocrine function in the acute stage and at early follow-up and to compare clinical SAH features to endocrine abnormalities indicating pituitary dysfunction.

METHODS

Endocrine function was assessed by basal hormonal concentrations at 5 to 10 days and 3 to 6 months after SAH. Growth hormone deficiency also was evaluated by the growth hormone releasing hormone-arginine stimulation test at follow-up. Clinical outcome was assessed and scored according to the Glasgow Outcome Scale.

RESULTS

Fifty-one SAH patients were included and assessed in the acute stage after the bleed. Six were lost to follow-up. The overall prevalence of pituitary dysfunction was 37% and 27% in the acute stage and at follow-up, respectively. Patients with evidence of pituitary dysfunction had significantly worse outcome according to Glasgow Outcome Scale at both occasions. The ruptured aneurysm was more commonly located in the circle of Willis among patients with pituitary dysfunction in the acute stage.

CONCLUSIONS

The present results support earlier findings that hormonal abnormalities are not infrequent after SAH. Furthermore, our data suggest that pituitary dysfunction is associated with worse clinical outcome and is more common among patients with bleeding sites close to the hypothalamus.

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.

Patterns in neurosurgical adverse events: open cerebrovascular neurosurgery

OBJECT

As part of a project to devise evidence-based safety interventions for specialty surgery, we sought to review current evidence concerning the frequency of adverse events in open cerebrovascular neurosurgery and the state of knowledge regarding methods for their reduction. This review represents part of a series of papers written to consolidate information about these events and preventive measures as part of an ongoing effort to ascertain the utility of devising system-wide policies and safety tools to improve neurosurgical practice.

METHODS

The authors performed a PubMed search using search terms "cerebral aneurysm", "cerebral arteriovenous malformation", "intracerebral hemorrhage", "intracranial hemorrhage", "subarachnoid hemorrhage", and "complications" or "adverse events." Only papers that specifically discussed the relevant complication rates were included. Papers were chosen to be included to maximize the range of rates of occurrence for the reported adverse events.

RESULTS

The review revealed hemorrhage-related hyperglycemia (incidence rates ranging from 27% to 71%) and cerebral salt-wasting syndromes (34%-57%) to be the most common perioperative adverse events related to subarachnoid hemorrhage (SAH). Next in terms of frequency was new cerebral infarction associated with SAH, with a rate estimated at 40%. Many techniques are advocated for use during surgery to minimize risk of this development, including intraoperative neurophysiological monitoring, but are not universally used due to surgeon preference and variable availability of appropriate staffing and equipment. The comparative effectiveness of using or omitting monitoring technologies has not been evaluated. The incidence of perioperative seizure related to vascular neurosurgery is unknown, but reported seizure rates from observational studies range from 4% to 42%. There are no standard guidelines for the use of seizure prophylaxis in these patients, and there remains a need for prospective studies to support such guidelines. Intraoperative rupture occurs at a rate of 7% to 35% and depends on aneurysm location and morphology, history of rupture, surgical technique, and surgeon experience. Preventive strategies include temporary vascular clipping. Technical adverse events directly involving application of the aneurysm clip include incomplete aneurysm obliteration and parent vessel occlusion. The rates of these events range from 5% to 18% for incomplete obliteration and 3% to 12% for major vessel occlusion. Intraoperative angiography is widely used to confirm clip placement; adjuncts include indocyanine green video angiography and microvascular Doppler ultrasonography. Use of these technologies varies by institution.

DISCUSSION

A significant proportion of these complications may be avoidable through development and testing of standardized protocols to incorporate monitoring technologies and specific technical practices, teamwork and communication, and concentrated volume and specialization. Collaborative monitoring and evaluation of such protocols are likely necessary for the advancement of open cerebrovascular neurosurgical quality.

Pituitary hormone level changes and hypxonatremia in aneurysmal subarachnoid hemorrhage

The aim of this study was to investigate the changes in serum pituitary hormone levels and the mechanism of hyponatremia in aneurysmal subarachnoid hemorrhage (SAH). Nuclear medical tests and serum electrolyte monitoring were performed in 49 aneurysmal SAH cases and 10 healthy volunteers. The levels of serum pituitary hormones were significantly higher in the SAH patients compared with the control group on days 1–3 and 7–9 after SAH onset (P<0.05). The peak value occurred on days 7–9. The rate of hyponatremia was 49.0% in the 49 SAH patients. The incidence of severe hyponatremia was significantly higher in Fisher grades III–IV and Hunt-Hess grades III–IV compared with Fisher grades I–II and Hunt-Hess grades I–II, respectively (P<0.05). There was no correlation between the site of aneurysm and the rate of hyponatremia. The incidence of symptomatic cerebral vasospasm was significantly higher in the hyponatremia group and Fisher grades III–IV compared with the normal serum sodium group and Fisher grades I–II, respectively. Serum pituitary hormone levels were positively correlated with blood loss and disease severity in patients with aneurysmal SAH. Hyponatremia may be considered an important indicator of SAH. SAH patients are likely to benefit from intense monitoring and regulation of serum sodium.

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.

Serum sodium based modification of the MELD does not improve prediction of outcome in acute liver failure

Background

Acute liver failure (ALF) is a devastating clinical syndrome with a high mortality rate. The MELD score has been implied as a prognostic tool in ALF. Hyponatremia is associated with lethal outcome in ALF. Inclusion of serum sodium (Na) into the MELD score was found to improve its predictive value in cirrhotic patients. Therefore the aim of this study was to determine whether inclusion of serum Na improves the predictive value of MELD in ALF compared to established criteria.

Methods

In a prospective single center study (11/2006–12/2010), we recruited 108 consecutive ALF patients (64% females / 36% males), who met the criteria defined by the “Acute Liver Failure Study Group Germany”. Upon admission, clinical and laboratory data were collected, King’s College Criteria (KCC), Model of End Stage Liver Disease score (MELD), and serum sodium based modifications like the MELD-Na score and the United Kingdom Model of End Stage Liver Disease score (UKELD) were calculated and area under the receiver operating characteristic curve analyses were performed regarding the prediction of spontaneous recovery (SR) or non-spontaneous recovery (NSR; death or transplantation).

Results

Serum bilirubin was of no prognostic value in ALF, and Na also failed to predict NSR in ALF. The classical MELD score was superior to sodium-based modifications and KCC.

Conclusions

We validated the prognostic value of MELD-Na and UKELD in ALF. Classic MELD score calculations performed superior to KCC in the prediction of NSR. Serum Na and Na-based modifications of MELD did not further improve its prognostic value.

[Aneurysmal subarachnoid hemorrhage]

Acute subarachnoid hemorrhage (SAH) is a severe and acute life-threatening cerebrovascular disease. Approximately 80% of all acute non-traumatic SAHs are the result of a ruptured cerebrovascular aneurysm. Despite advances in diagnosis and treatment a high morbidity and mortality still exists. Apart from the primary cerebral damage there are also secondary complications, such as vasospasm, rebleeding, hydrocephalus, cerebral edema or hydrocephalus. For an appropriate therapy an understanding of the extensive pathophysiology, the options in diagnostics and therapy and the complications of the disease are essential. Anesthesiologists are decisively involved in the therapy of the primary and secondary damages and subsequently in the outcome as well. This article provides an overview of the perioperative and intensive care management of patients with SAH.

Cerebral salt wasting treated with fludrocortisone in a 17-year-old boy

Cerebral salt wasting is characterized by inappropriate natriuresis and volume contraction with associated cerebral pathology. It is distinct from the syndrome of inappropriate antidiuretic hormone secretion, which is characterized by inappropriate retention of free water. We report a patient with a porencephalic cyst who developed cerebral salt wasting. His initial treatment was supplementation of water and salt, which did not improve natriuresis or volume contraction. Fludrocortisone administration effectively managed the cerebral salt wasting.

Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/american Stroke Association

PURPOSE

The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

A formal literature search of MEDLINE (November 1, 2006, through May 1, 2010) was performed. Data were synthesized with the use of evidence tables. Writing group members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council's Levels of Evidence grading algorithm was used to grade each recommendation. The guideline draft was reviewed by 7 expert peer reviewers and by the members of the Stroke Council Leadership and Manuscript Oversight Committees. It is intended that this guideline be fully updated every 3 years.

RESULTS

Evidence-based guidelines are presented for the care of patients presenting with aSAH. The focus of the guideline was subdivided into incidence, risk factors, prevention, natural history and outcome, diagnosis, prevention of rebleeding, surgical and endovascular repair of ruptured aneurysms, systems of care, anesthetic management during repair, management of vasospasm and delayed cerebral ischemia, management of hydrocephalus, management of seizures, and management of medical complications.

CONCLUSIONS

aSAH is a serious medical condition in which outcome can be dramatically impacted by early, aggressive, expert care. The guidelines offer a framework for goal-directed treatment of the patient with aSAH.

Dysnatremia in the ICU

PURPOSE OF REVIEW

Dysnatremias, disorders of sodium concentration, are exceedingly common in critically ill patients and confer increased risk for adverse outcomes including mortality. The physiology that underpins the diagnosis and management of these disorders is complex. This review seeks to discuss current literature regarding the pathophysiology, diagnosis, epidemiology, and management of these disorders.

RECENT FINDINGS

The role of arginine vasopressin in the maintenance of normal and pathologic plasma osmolality increasingly is refined, improving our ability to diagnose and understand dysnatremia. Identified recent epidemiologic studies highlight the frequent hospital acquisition or exacerbation of dysnatremia, confirm the recognized adverse consequences and explore the potential causality. Despite the complex nature of these disorders, simple consensus treatment strategies have emerged.

SUMMARY

Dysnatremia remains a common disorder across the spectrum of critically ill patients. It is frequently hospital acquired. Simplified treatment regimens are proposed and the potential for prevention or earlier recognition and intervention is emphasized. Future directions of interest include further exploration of how dysnatremia contributes to adverse outcomes and new treatment strategies.

Emergency management of increased intracranial pressure

Primary neurological injury in children can be induced by diverse intrinsic and extrinsic factors including brain trauma, tumors, and intracranial infections. Regardless of etiology, increased intracranial pressure (ICP) as a result of the primary injury or delays in treatment may lead to secondary (preventable) brain injury. Therefore, early diagnosis and aggressive treatment of increased ICP is vital in preventing or limiting secondary brain injury in children with a neurological insult. Present management strategies to improve survival and neurological outcome focus on reducing ICP while optimizing cerebral perfusion and meeting cerebral metabolic demands. Targeted therapies for increased ICP must be considered and implemented as early as possible during and after the initial stabilization of the child. Thus, the emergency physician has a critical role to play in early identification and treatment of increased ICP. This article intends to identify those patients at risk of intracranial hypertension and present a framework for the emergency department investigation and treatment, in keeping with contemporary guidelines. Intensive care management and the treatment of refractory increases in ICP are also outlined.

Novel treatment targets for cerebral edema

Cerebral edema is a common finding in a variety of neurological conditions, including ischemic stroke, traumatic brain injury, ruptured cerebral aneurysm, and neoplasia. With the possible exception of neoplasia, most pathological processes leading to edema seem to share similar molecular mechanisms of edema formation. Challenges to brain-cell volume homeostasis can have dramatic consequences, given the fixed volume of the rigid skull and the effect of swelling on secondary neuronal injury. With even small changes in cellular and extracellular volume, cerebral edema can compromise regional or global cerebral blood flow and metabolism or result in compression of vital brain structures. Osmotherapy has been the mainstay of pharmacologic therapy and is typically administered as part of an escalating medical treatment algorithm that can include corticosteroids, diuretics, and pharmacological cerebral metabolic suppression. Novel treatment targets for cerebral edema include the Na(+)-K(+)-2Cl(-) co-transporter (NKCC1) and the SUR1-regulated NC(Ca-ATP) (SUR1/TRPM4) channel. These two ion channels have been demonstrated to be critical mediators of edema formation in brain-injured states. Their specific inhibitors, bumetanide and glibenclamide, respectively, are well-characterized Food and Drug Administration-approved drugs with excellent safety profiles. Directed inhibition of these ion transporters has the potential to reduce the development of cerebral edema and is currently being investigated in human clinical trials. Another class of treatment agents for cerebral edema is vasopressin receptor antagonists. Euvolemic hyponatremia is present in a myriad of neurological conditions resulting in cerebral edema. A specific antagonist of the vasopressin V1A- and V2-receptor, conivaptan, promotes water excretion while sparing electrolytes through a process known as aquaresis.

Etiology and management of hyponatremia in neurosurgical patients

Hyponatremia is the most common electrolyte disorder encountered in neurosurgical patients. The aggressive treatment of hyponatremia in this group is critical, as hyponatremia can lead to mental status changes, seizures, vasospasm, cerebral edema, and even death. When it occurs, it represents a failure of one of several homeostatic mechanisms that tightly regulate serum sodium. In these patients, hyponatremia is most commonly due to the syndrome of inappropriate antidiuretic hormone (SIADH) or cerebral salt wasting (CSW). It can be problematic to differentiate between these 2 as they share key features, including low serum sodium, low serum osmolality, a higher urine osmolality than serum osmolality, and an elevated urinary sodium concentration. Furthermore, distinctions between CSW and SIADH, namely extracellular fluid (ECF) volume and total sodium balance, are often difficult to establish. Syndrome of inappropriate antidiuretic hormone is characterized by a volume-expanded state, whereas CSW is characterized by a volume-contracted state. Determining the exact cause remains a clinical imperative as the treatment for each is different. The rate at which serum sodium is corrected must be attended to, as rapid shifts in serum sodium pose potential risk of cerebral pontine myelinolysis.

In vivo sodium concentration continuously monitored with fluorescent sensors

Sodium balance is vital to maintaining normal physiological function. Imbalances can occur in a variety of diseases, during certain surgical operations or during rigorous exercise. There is currently no method to continuously monitor sodium concentration in patients who may be susceptible to hyponatremia. Our approach was to design sodium specific fluorescent sensors capable of measuring physiological fluctuations in sodium concentration. The sensors are submicron plasticized polymer particles containing sodium recognition components that are coated with biocompatible poly(ethylene) glycol. Here, the sensors were brought up in saline and placed in the subcutaneous area of the skin of mice by simple injection. The fluorescence was monitored in real time using a whole animal imager to track changes in sodium concentrations. This technology could be used to monitor certain disease states or warn against dangerously low levels of sodium during exercise.

Suprasellar arachnoid cyst resulting in the syndrome of inappropriate antidiuretic hormone secretion

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is occasionally seen after hypothalamic injury or dysfunction, although it typically occurs in association with other endocrine disturbances. It is has never been described as a presenting feature of a suprasellar arachnoid cyst (SAC) in the pediatric population. The authors describe the case of an enlarging SAC resulting in SIADH as the only presenting feature, with an otherwise normal hypothalamic-pituitary axis. An SAC was diagnosed in utero in this 5-month-old girl who had a normal functioning hypothalamic-pituitary axis on presentation. Because of cyst enlargement and hydrocephalus, the patient was scheduled for surgery; however, preoperative labs revealed SIADH. After stabilizing the serum sodium concentration with fluid restriction and the administration of 3% sodium chloride, the patient underwent endoscopic cyst fenestration. Postoperatively, she had complete resolution of the SIADH. Syndrome of inappropriate antidiuretic hormone secretion as the presenting symptom of an SAC has not been previously described. In the aforementioned patient, the proposed mechanism for SIADH was enlargement of the suprasellar arachnoid cyst causing compression of the supraoptic and paraventricular nuclei and thus overstimulating the secretion of arginine vasopressin, which resulted in SIADH. The association of SIADH with an SAC is reportable, as is the resolution of the SIADH via cyst fenestration. The authors suggest that SIADH is an uncommon presenting feature of SACs and that syndrome resolution is possible with cyst decompression.