Hyponatremia in the neurosurgical patient: diagnosis and management

High Urinary Sodium Concentrations in Severe SIADH: Case Reports of 2 Patients and Literature Review

We present two cases of severe hyponatremia secondary to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with very high urine sodium concentrations (>130 mmol/L). The first patient had hyponatremia from traumatic brain injury (TBI) while the second case had a history of recurrent SIADH triggered by various causes including gastritis. In both cases, fluid administration and/or consumption worsened the hyponatremia. Although a low urine sodium of <30 mmol/L is highly suggestive of hypovolemic hyponatremia and good response to saline infusion, there is lack of clarity of the threshold of which high urine sodium concentration can differentiate various causes of natriuresis such as SIADH, renal or cerebral salt wasting. Apart from high urine osmolality (>500 mOsm/kg), persistence of high urine sodium concentrations may be useful to predict poor response to fluid restriction in SIADH. More studies are needed to delineate treatment pathways of patients with very high urine osmolality and urine sodium concentrations in SIADH.

Multipotential and systemic effects of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality of people at all ages. Biochemical, cellular and physiological events that occur during primary injury lead to a delayed and long-term secondary damage that can last from hours to years. Secondary brain injury causes tissue damage in the central nervous system and a subsequent strong and rapid inflammatory response that may lead to persistent inflammation. However, this inflammatory response is not limited to the brain. Inflammatory mediators are transferred from damaged brain tissue to the bloodstream and produce a systemic inflammatory response in peripheral organs, including the cardiovascular, pulmonary, gastrointestinal, renal and endocrine systems. Complications of TBI are associated with its multiple and systemic effects that should be considered in the treatment of TBI patients. Therefore, in this review, an attempt was made to examine the systemic effects of TBI in detail. It is hoped that this review will identify the mechanisms of injury and complications of TBI, and open a window for promising treatment in TBI complications.

Incidence and Possible Predictors of Sodium Disturbance After Craniopharyngioma Resection Based on QST Classification

OBJECTIVE

Serum sodium abnormalities are one of the most common manifestations after radical craniopharyngioma (CP) excision. The aim of this study was to report the incidence and possible predictors of serum sodium disturbance and explore features of sodium destabilization manifestation among QST classification results after CP resection.

METHODS

A retrospective analysis was performed of clinical, biochemical, radiologic, and operative data for 134 successive patients who underwent primary CP removal between September 2016 and March 2018. Univariate and multivariate analyses were conducted to determine predictors.

RESULTS

Sixty patients (44.8%) experienced hyponatremia and 67 patients (50%) hypernatremia; the median time of onset was 6 days and the first day after surgery, respectively. The incidence, onset, severity, and type of sodium disturbance among different types of CP differed significantly based on statistical tests (P < 0.05). Sodium disturbance was more common and severe in patients with type T tumors (P < 0.05). Age, tumor type, and preoperative diabetes insipidus were independent prognostic factors for obvious disorders of serum sodium.

CONCLUSIONS

Hyponatremia/hypernatremia is common after primary CP resection. The site of tumor origin has a direct effect on the growth pattern of CP, which may serve as a useful index for anticipating sodium perturbation after surgery. The level of sodium in children and patients with type T tumors, preoperative diabetes insipidus should be monitored closely throughout hospitalization.

Malignant middle cerebral artery infarction following subacute subdural hematoma: A case report and literature review

Background:

Subacute subdural hematomas (ASDH) are only treated surgically when they cause mass effect significant enough to give symptoms. Rarely, sub-ASDH may cause enough pressure to result in a malignant middle cerebral artery (MCA) territory infarction. Decompressive craniectomy (DC) is the last resort to reduce intracranial pressure following malignant MCA infarction. Herein, we review the literature and describe a case of MCA/posterior cerebral artery (PCA) territories infarction following drainage of a sub-ASDH that was treated with DC with good outcome.

Case Description:

We report a case of malignant right-sided MCA/PCA infarction in a 62-year-old man who presented with progressive headache following a cycling incident leading to a head injury. Initial CT head demonstrated a small right ASDH. He had no neurological deficit, headache settled on analgesia, and there was no expansion of the SDH on the repeat CT; therefore, he was managed conservatively. He was admitted 6-days later with worsening headaches and hyponatremia. Repeat CT revealed an increase in size of the hematoma and mass effect leading to a mini-craniotomy and evacuation of hematoma. He developed left-sided hemiplegia, slurred speech and hyponatremia, and CT head demonstrated a right-sided MCA/PCA infarction with significant mass effect. He underwent emergent DC and subsequent cranioplasty and ultimately recovered to mRS of 2.

Conclusion:

SDH are frequent neurosurgical entities. Malignant MCA/PCA strokes following mini-craniotomies are rare but need to be considered especially during the consent process.

Higher plasma NT-proBNP levels correlate with syndrome of inappropriate antidiuretic hormone and poor prognosis in neurological patients

Background

Hyponatremia induced by syndrome of inappropriate antidiuretic hormone secretion (SIADH) was common electrolyte disturbance encountered in critically ill neurological diseases, which has normal or increased fluid volume. Brain natriuretic peptide (BNP), which is released in equal proportion to N-terminal pro-brain natriuretic peptide (NT-proBNP), plays vital roles in regulation of volume status. The relationship between SIADH and NT-proBNP levels in neurological diseases has rarely been reported.

Methods

A retrospective cross-sectional study was conducted to analyze plasma NT-proBNP levels in 33 patients with SIADH and 23 controlled eunatremic patients with neurological diseases.

Results

Baseline NT-proBNP levels were compared between two groups [SIADH group: median 311 pg/mL, interquartile range (IQR) 110–768 pg/mL] vs. eunatremic group: median 46 pg/mL, IQR, 12–96 pg/mL) (P<0.05). Plasma NT-proBNP levels were markedly increased in hyponatremic patients who had two or more complications than those who had less complication (P<0.05). In SIADH patients, NT-proBNP levels in remission phase were lower to levels at baseline. Furthermore, no death was seen in eunatremic patients, while five SIADH patients died from complications.

Conclusions

SIADH had higher plasma NT-proBNP levels and poorer prognosis compared to eunatremic neurological patients. NT-proBNP serves as a biomarker of disease severity while not extracellular volume (ECV) status in critically ill neurological patients.

Delayed Postoperative Hyponatremia Following Endoscopic Transsphenoidal Surgery for Non-Adenomatous Parasellar Tumors

Little is known about delayed postoperative hyponatremia (DPH) accompanied with transsphenoidal surgery for non-adenomatous skull base tumors (NASBTs). Consecutive data on 30 patients with parasellar NASBT was retrospectively reviewed with detailed analyses on perioperative serial sodium levels. Serological DPH (sodium ≤ 135 mmol/L) was observed in eight (27%), with four (13%) of them being symptomatic. DPH developed on postoperative day 7-12 where the mean sodium levels were 134 mmol/L (a mean of 7 mmol/L drop from the baseline) in asymptomatic and 125 mmol/L (a mean of 17.5 mmol/L drop from the baseline) in symptomatic DPH. Serological DPH was accompanied with "weight loss and hemoconcentration (cerebral salt wasting type)" in four (50%), "weight gain and hemodilution (syndrome of inappropriate antidiuretic hormone secretion type)" in three (38%), and no significant weight change in one. Intraoperative extradural retraction of the pituitary gland was the only significant factor for serological DPH (p = 0.035; odds ratio, 12.25 (95% confidence interval, 1.27-118.36)). DPH should be recognized as one of the significant postsurgical complications associated with TSS for NASBTs. Although the underlying mechanism is still controversial, intraoperative extradural compression of the pituitary gland and subsequent dysregulation of the hypothalamo-hypophyseal axis may be responsible.

Assessment of Acute Kidney Injury in Neurologically Injured Patients Receiving Hypertonic Sodium Chloride: Does Chloride Load Matter?

Background: Increasing evidence suggests that large-volume infusions of 0.9% sodium chloride (NaCl) for resuscitation are associated with hyperchloremic metabolic acidosis, renal vasoconstriction, and increased risk of acute kidney injury (AKI). Patients with neurological injury may require hypertonic NaCl for therapeutic hypernatremia, treatment of cerebral salt wasting, hyponatremia, or elevated intracranial pressure. Consequently, this increased exposure to chloride may result in an increased risk for development of AKI. Objective: The primary aim of this study was to describe the risk for development of AKI in neurologically injured patients receiving large volumes of intravenous hypertonic NaCl. Methods: This single-center, retrospective study looked at neurologically injured patients who received hypertonic NaCl and sodium acetate. Data were collected to assess renal function, hyperchloremia, and acidemia. Receiver operating characteristic (ROC) curve analysis was used to determine the predictive association between the amount of daily and overall chloride exposure and development of AKI. Results: A total of 301 patients were screened, and of those, 142 were included. Of the 142 patients included, 13% developed AKI, and 38% developed hyperchloremia. Additionally, 32% of patients were switched from NaCl to sodium acetate after an average of 3.4 ± 1.5 days of NaCl therapy. The ROC curve demonstrated that if patients received greater than 2055 mEq of chloride over 7 days, they were more likely to develop AKI (sensitivity 72%, specificity 70%; P = 0.002; area under the curve = 0.7). Conclusion and Relevance: Neurologically injured patients receiving hypertonic sodium therapy with a high chloride load are at risk of developing hyperchloremia and AKI.

Sodium Perturbations After Pituitary Surgery

Sodium perturbations are a common complication after pituitary surgery, with hyponatremia being the most frequent. Postoperative assessments should be tailored to the early and late periods, and monitoring sodium perturbations is recommended. Cerebral salt wasting is rare after pituitary surgery, and diagnosis and management can be challenging. Providing patient counseling and close postoperative follow-up is important to effectively manage diabetes insipidus and reduce hospital readmissions due to sodium perturbations.

Treatment of Hyponatremia in Patients with Acute Neurological Injury

BACKGROUND

Little data exist regarding the practice of sodium management in acute neurologically injured patients. This study describes the practice variations, thresholds for treatment, and effectiveness of treatment in this population.

METHODS

This retrospective, multicenter, observational study identified 400 ICU patients, from 17 centers, admitted for ≥48 h with subarachnoid hemorrhage (SAH), traumatic brain injury (TBI), intraparenchymal hemorrhage, or intracranial tumors between January 1, 2011 and July 31, 2012. Data collection included demographics, APACHE II, Glascow Coma Score (GCS), serum sodium (Na+), fluid rate and tonicity, use of sodium-altering therapies, intensive care unit (ICU) and hospital length of stay, and modified Rankin score upon discharge. Data were collected for the first 21 days of ICU admission or ICU discharge, whichever came first. Sodium trigger for treatment defined as the Na+ value prior to treatment with response defined as an increase of ≥4 mEq/L at 24 h.

RESULTS

Sodium-altering therapy was initiated in 34 % (137/400) of patients with 23 % (32/137) having Na⁺ >135 mEq/L at time of treatment initiation. The most common indications for treatment were declining serum Na⁺ (68/116, 59 %) and cerebral edema with mental status changes (21/116, 18 %). Median Na⁺ treatment trigger was 133 mEq/L (IQR 129-139) with no difference between diagnoses. Incidence and treatment of hyponatremia was more common in SAH and TBI [SAH (49/106, 46 %), TBI (39/97, 40 %), ICH (27/102, 26 %), tumor (22/95, 23 %); p = 0.001]. The most common initial treatment was hypertonic saline (85/137, 62 %), followed by oral sodium chloride tablets (42/137, 31 %) and fluid restriction (15/137, 11 %). Among treated patients, 60 % had a response at 24 h. Treated patients had lower admission GCS (12 vs. 14, p = 0.02) and higher APACHE II scores (12 vs. 10, p = 0.001). There was no statistically significant difference in outcome when comparing treated and untreated patients.

CONCLUSION

Sodium-altering therapy is commonly employed among neurologically injured patients. Hypertonic saline infusions were used first line in more than half of treated patients with the majority having a positive response at 24 h. Further studies are needed to evaluate the impact of various treatments on patient outcomes.

Acute symptomatic hyponatremia following elective rhinoplasty: A case report

We present the first reported case of symptomatic hyponatremia after elective rhinoplasty. A 42-year old female underwent cosmetic rhinoplasty without complication and was discharged home after an uneventful recovery from general anesthesia. Just prior to midnight on the day of surgery, she reported nausea, which was treated with supportive care. Four hours later, she developed emesis, altered mental status, and seizure-like activity prompting medical transport to the emergency department. Upon arrival, she was hypotensive (BP 78/54), tachycardic (HR 112 bpm), hyponatremic (116 mmol/L), hypoosmotic (239 mOsm/kg), and had decreased consciousness (GCS = 10). She was admitted to the intensive care unit and had a central line placed for hypertonic saline infusion. Urinalysis was suggestive of SIADH (UrNa 111 mmol/L, UrOsm 546 mOsm/kg) and Nephrology was consulted. Her serum sodium was corrected over three days and her mental status improved. Surgeons should maintain a low threshold for further evaluation in patients who deviate from the expected postoperative recovery pathway. This report demonstrates that normal postoperative symptoms may mask underlying physiological abnormalities that can progress to acute life-threatening illness and underscores the importance of direct patient observation in the immediate postoperative period.

Scientific Basis of Hyponatremia and Its Clinical Presentations

Purpose

To describe causes, pathophysiologic mechanisms, and classifications of hyponatremia, and to describe clinical symptoms and underlying disease states associated with different levels of hyponatremia.

Summary

The key to comprehending hyponatremia is to understand body water content and plasma osmolality and accurately assess arterial volume. Hyponatremia results from sodium dilution because of retained water or sodium depletion because of electrolyte loss in excess of water loss. Body sodium, water, and extracellular fluid (ECF) volume are tightly regulated by mechanisms that act to maintain a closely controlled concentration of solutes in the ECF. These forces act to regulate water content and sodium excretion to maintain normal intravascular volume. The body closely defends normal plasma osmolality within a narrow range primarily by controlling the release of arginine vasopressin (AVP) and via the thirst mechanism. A number of factors can stimulate inappropriate AVP release and cause or worsen hyponatremia. Dysregulation of AVP plays an important role in heart failure and cirrhosis, common causes of hypervolemic hyponatremia.

Conclusion

Body water content and plasma osmolality are tightly regulated by the action of AVP. A variety of disease states are associated with hyponatremia related to inappropriate AVP release. The cause of the electrolyte disturbance must be determined, because it can have profound implications for treatment. Differential diagnosis can be guided by observation of the rapidity of onset as well as volume status changes. If untreated or treated inappropriately, hyponatremia can impact morbidity and mortality.

Considerations in Fluids and Electrolytes After Traumatic Brain Injury

Appropriate fluid management of patients with traumatic brain injury (TBI) presents a challenge for many clinicians. Many of these patients may receive osmotic diuretics for the treatment of increased intracranial pressure or develop sodium disturbances, which act to alter fluid balance. However, establishment of fluid balance is extremely important for improving patient outcomes after neurologic injury. The use of hyperosmolar fluids, such as hypertonic saline, has gained significant interest because they are devoid of dehydrating properties and may have other beneficial properties for patients with TBI. Electrolyte derangements are also common after neurologic injury, with many having neurologic manifestations. In addition, the role of electrolyte abnormalities in the secondary neurologic injury cascade is being delineated and may offer a potential future therapeutic intervention.

Diffuse traumatic brain injury affects chronic corticosterone function in the rat

As many as 20-55% of patients with a history of traumatic brain injury (TBI) experience chronic endocrine dysfunction, leading to impaired quality of life, impaired rehabilitation efforts and lowered life expectancy. Endocrine dysfunction after TBI is thought to result from acceleration-deceleration forces to the brain within the skull, creating enduring hypothalamic and pituitary neuropathology, and subsequent hypothalamic-pituitary endocrine (HPE) dysfunction. These experiments were designed to test the hypothesis that a single diffuse TBI results in chronic dysfunction of corticosterone (CORT), a glucocorticoid released in response to stress and testosterone. We used a rodent model of diffuse TBI induced by midline fluid percussion injury (mFPI). At 2months postinjury compared with uninjured control animals, circulating levels of CORT were evaluated at rest, under restraint stress and in response to dexamethasone, a synthetic glucocorticoid commonly used to test HPE axis regulation. Testosterone was evaluated at rest. Further, we assessed changes in injury-induced neuron morphology (Golgi stain), neuropathology (silver stain) and activated astrocytes (GFAP) in the paraventricular nucleus (PVN) of the hypothalamus. Resting plasma CORT levels were decreased at 2months postinjury and there was a blunted CORT increase in response to restraint induced stress. No changes in testosterone were measured. These changes in CORT were observed concomitantly with altered complexity of neuron processes in the PVN over time, devoid of neuropathology or astrocytosis. Results provide evidence that a single moderate diffuse TBI leads to changes in CORT function, which can contribute to the persistence of symptoms related to endocrine dysfunction. Future experiments aim to evaluate additional HP-related hormones and endocrine circuit pathology following diffuse TBI.

[The rate of hyponatremia in neurosurgical patients (comparison between the data from the Burdenko Neurosurgical Instutite and the literature) and recommendations for the diagnosis and treatment]

Hyponatremia is a relatively frequent and serious complication in patients with various neurosurgical pathologies.

OBJECTIVE

This study is aimed at assessing the incidence of hyponatremia in neurosurgical patients depending on the pathology.

MATERIAL AND METHODS

This paper presents a retrospective analysis 39 479 cases of patients operated on at the Burdenko Neurosurgical Institute from 2008 to 2014.

RESULTS

A total of 785 hyponatremic patients with Na level lower than 130 mmol/l (2% of all operated patients) were identified. Mortality in patients with hyponatremia was 14.3%, which is tenfold higher compared to the rest of population of patients without hyponatremia who were operated on during the same period. In adults, hyponatremia most frequently occurred after resection of craniopharyngiomas (11%) and as a result of acute cerebrovascular accident (22%). In children, it occurred after resection of craniopharyngiomas (10%), astrocytomas (7%), ependymomas (24%), and germ cell tumors (10.5%).

CONCLUSION

This study, which was mainly statistical one, was not aimed at detailed investigation of hyponatremia in different groups of neurosurgical patients. We only tried to draw the attention of various experts to those categories of patients, where focused and in-depth developments are more than important. Obviously, already gained international experience should be taken into account for this

PURPOSE

Therefore, this article presents the literature data on the etiology and pathogenesis of hyponatremia. We describe the details of the various classifications of hyponatremia, its clinical symptoms, diagnosis, and treatments, primarily based on the recommendations of the last European consensus of various specialists (2014).

Etiology of postoperative hyponatremia following pediatric intracranial tumor surgery

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

Systemic manifestations of traumatic brain injury

Traumatic brain injury (TBI) affects functioning of various organ systems in the absence of concomitant non-neurologic organ injury or systemic infection. The systemic manifestations of TBI can be mild or severe and can present in the acute phase or during the recovery phase. Non-neurologic organ dysfunction can manifest following mild TBI or severe TBI. The pathophysiology of systemic manifestations following TBI is multifactorial and involves an effect on the autonomic nervous system, involvement of the hypothalamic-pituitary axis, release of inflammatory mediators, and treatment modalities used for TBI. Endocrine dysfunction, electrolyte imbalance, and respiratory manifestations are common following TBI. The influence of TBI on systemic immune response, coagulation cascade, cardiovascular system, gastrointestinal system, and other systems is becoming more evident through animal studies and clinical trials. Systemic manifestations can independently act as risk factors for mortality and morbidity following TBI. Some conditions like neurogenic pulmonary edema and disseminated intravascular coagulation can adversely affect the outcome. Early recognition and treatment of systemic manifestations may improve the clinical outcome following TBI. Further studies are required especially in the field of neuroimmunology to establish the role of various biochemical cascades, not only in the pathophysiology of TBI but also in its systemic manifestations and outcome.

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.

Evaluation of influence of chronic kidney disease and sodium disturbances on clinical course of acute and sub-acute stage first-ever ischemic stroke

BACKGROUND

Chronic kidney disease (CKD) is an independent risk factor for cardiovascular morbidity and mortality. Hyponatremia is the most common electrolyte disturbance encountered in the neurological and neurosurgical intensive care units, and can exacerbate existing neurological deficits. The objective of this study was to observe the influences of chronic kidney disease and sodium disturbances on the clinical course of acute and sub-acute stages of first-ever ischemic stroke.

MATERIAL AND METHODS

464 patients with previously diagnosed chronic kidney disease (aged 70.42±11.49 years; 250 women) who had experienced their first-ever ischemic stroke were qualified. The following examinations were performed: serum levels of sodium, creatinine, lipids, estimated glomerular filtration rate (eGFR), neurological state on 1st day of stroke (according to National Institutes of Health Stroke Scale), functional state measured with the Rankin scale, (RS) and mortality rate at 1 month after stroke.

RESULTS

The neurological state on 1st day of stroke was worse and the median RS (30 days after stroke) was higher in patients with eGFR ≤60 ml/ (min×1.73). Men with eGFR ≤60 ml had greater neurological deficits and increased mortality within 1 month. In patients with eGFR >60 ml/, male sex was more often associated with worse outcomes at 1 month after ischemic stroke. Hyponatremia was associated with a more severe state in both the acute and sub-acute stages of stroke, with higher incidence of death within 1 month after stroke. Men with hyponatremia had greater neurological deficits on the 1st day and increased mortality within 1 month.

CONCLUSIONS

Renal impairment and hyponatremia are associated with worse neurological outcomes in patients in the acute stage of their first-ever stroke and within 1 month after the event. Males with impaired kidney function and hyponatremia have a more severe course in their first-ever ischemic stroke, as well as having increased mortality.

Clinical guidelines for management of diabetes insipidus and syndrome of inappropriate antidiuretic hormone secretion after pituitary surgery

Changes in water metabolism and regulation of vasopressin (AVP) or antidiuretic hormone (ADH) are common complications of pituitary surgery. The scarcity of studies comparing different treatment and monitoring strategies for these disorders and the lack of prior clinical guidelines makes it difficult to provide recommendations following a methodology based on grades of evidence. This study reviews the pathophysiology of diabetes insipidus and inappropriate ADH secretion after pituitary surgery, and is intended to serve as a guide for their diagnosis, differential diagnosis, treatment, and monitoring.

Cerebral salt wasting syndrome in post-operative pediatric brain tumor patients

BACKGROUND

Cerebral salt wasting syndrome (CSWS) and the syndrome of inappropriate antidiuretic hormone (SIADH) are both causes of hyponatremia in pediatric neurosurgical patients often with similar presenting symptoms; however, despite similar clinical characteristics the treatment for CSWS and SIADH can be drastically different, which makes the distinction critical for post-operative treatment. Further complicating matters, are the exact mechanism for CSWS which remains unclear, and the incidence and severity of CSWS is not well studied in pediatric neurosurgical patients. We hypothesized that CSWS occurs frequently in post-operative brain tumor patients and is an important cause of post-operative hyponatremia in these patients.

METHODS

We designed a single institution retrospective cohort study of all pediatric brain tumor patients undergoing craniotomy for tumor resection at our institution between January 2005 and December 2009.

RESULTS

Of the 282 patients undergoing 291 operations, post-operative CSWS was identified in 15 cases (5%), and was more frequently observed than SIADH (nine cases, 3%). Median onset of CSWS was on post-operative day 3, lasting a median of 2.5 days. Patients with CSWS were more likely to have suffered post-operative stroke (40 vs. 4.6%, P < 0.001), have chiasmatic/hypothalamic tumors (40 vs. 3.8%, P = 0.002), and be younger (mean age 5.9 vs. 9.7 years, P = 0.01) than eunatremic patients. In addition, nearly half of the patients with CSWS (47%) had post-operative hyponatremic seizures.

CONCLUSION

The diagnosis of CSWS should be strongly considered in hyponatremic pediatric patients with significant natriuresis following brain tumor resection, and a treatment initiated promptly to prevent neurologic sequeleae.

Is hyponatremia mistreated? Challenging the current paradigm

BACKGROUND

Hyponatremia is a common but often mistreated clinical situation in the ICU. This often requires the physician to identify the underlying problem, adrenal insufficiency. However, by the textbook, the current treatment always involves sodium chloride supplementation to hyponatremic patients, either intravenous or oral intake. We hypothesize that the mechanism behind most hyponatremia is most likely to be the sodium and water redistribution from the serum to the cells or the interstitial spaces due to the insufficient cortical steroid, not the sodium deficiency. As we have no reason to believe the patients have lost that much sodium which caused hyponatremia. Therefore, giving this type of hyponatremic patients (adrenal insufficient) sodium chloride is always ineffective and sometimes catastrophic.

METHODS

We discuss the possible mechanism for hyponatremia in critically ill/post surgery patients who are mostly likely to be adrenal insufficient rather than absolute sodium deficiency. In combination with many other common but unexplainable symptoms such as nausea, vomiting, obstinate diarrhea, hypotension and coma in the ICU, it is highly likely that hyponatremia is a condition which reflects the patients' adrenal function. The evidence supporting our hypothesis is that, (1) the serum sodium level does not always respond well to sodium supplementation therapy; (2) those aforementioned symptoms alleviated simultaneously with the serum sodium level returned to normal after the hydrocortisone or prednisone was administered without any oral/intravenous sodium supplementation; (3) patient with an elevated serum/urine cortisol level suffers from aforementioned unexplainable symptoms does not warrant him being adrenal sufficient. If the patient also has hyponatremia, the diagnosis can be considered as "relative adrenal insufficiency" and the patient would respond well to hydrocortisone or prednisone therapy.

CONCLUSIONS

We hypothesize that hyponatremia without significant loss of sodium can be used as an indicator to monitor the patients' adrenal function regardless of the serum/urine cortisol level. Furthermore, we propose a novel approach toward hyponatremia treatment in critically ill patients would be hydrocortisone or prednisone therapy depending on the circumstances.

[Nutritional therapy in traumatic brain injury : Update 2012]

Severe traumatic brain injury ranks among the most common causes of death in young adults in western countries. Severe traumatic brain injury is typically followed by a pronounced pathophysiological cascade that accounts for many deaths. The aim of intensive care medicine after traumatic brain injury is to minimize and to control the consequences of this potentially fatal cascade. The avoidance of hypoxemia, arterial hypotension, intracranial hypertension, hyperthermia, hyperglycemia, hypoglycemia and thromboembolic complications is essential in preventing this cascade. The effect of nutrition has been rather underestimated as a means of improving the outcome after traumatic brain injury. Nutrition should be started within the first 24 h after trauma. Enteral, wherever applicable, should be the route of administration of nutrition. Enteral administration of the whole calculated calorie requirement on day 1 after trauma, if possible, lowers the infection and overall complication rates. The present review gives an update of a practical approach to nutrition in traumatic brain injury.

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.

Extreme correction of hyponatremia in a patient treated with intravenous conivaptan

Intravenous administration of conivaptan, an arginine vasopressin (AVP) receptor antagonist, has been demonstrated to be a safe and effective therapy for euvolemic and hypervolemic hyponatremia. In this case report, we report an extremely rapid correction of serum sodium with a typical dosing regimen of conivaptan. The patient was a 24 year woman who presented with nausea and vomiting, and was found on imaging to have two intracranial tumors, one of which was a large pituitary macroadenoma. Her serum sodium declined to 121mmol/L and intravenous conivaptan therapy was started. After approximately 25mg of conivaptan, her sodium increased 16mmol/L over 8.5hours. Fortunately, in this case, this correction was well tolerated, and the patient experienced no adverse effects of such a dramatic correction of serum sodium. Despite the good clinical result in this case, it should serve as a warning regarding the use of conivaptan, that although a gradual steady improvement in serum sodium can be expected in the majority of patients, more extreme corrections can be inadvertently achieved with even moderate doses. Thus, the exact clinical situation should be taken into consideration, especially in cases of subacute to chronic hyponatremia, where such an extreme correction could lead to neurologic devastation.

Incidence, clinical manifestations, and course of water and electrolyte metabolism disturbances following transsphenoidal pituitary adenoma surgery: a prospective observational study

OBJECT

The authors prospectively studied the incidence, spectrum of clinical manifestations, course, and risk factors of water and electrolyte disturbances (WEDs) following transsphenoidal pituitary adenoma surgery.

METHODS

From the preoperative day to the 14th postoperative day, 57 successive patients undergoing transsphenoidal adenomectomy were monitored daily for body weight, balance of fluids, serum electrolytes, plasma osmolality, plasma antidiuretic hormone (ADH) levels, urinary sodium excretion, urinary osmolality, and subjective sensation of thirst. The type of adenoma operated on and the intraoperative manipulation of the neurohypophysis were also recorded.

RESULTS

Fifty-seven patients (mean age 55 years, 61.4% females) harbored 30 clinically hormone-inactive and 27 hormone-secreting pituitary adenomas. Postoperative WED occurred in 75.4% of the patients: in 38.5% as isolated diabetes insipidus (DI); in 21% as isolated hyponatremia; and in 15.7% as combined DI-hyponatremia. The maximum of medians of diuresis (5.750 L) in patients with isolated DI occurred on postoperative Day 2. Nadir of medians of hyponatremia (132 mmol/L) in patients with isolated hyponatremia occurred on postoperative Day 9. In patients with combined DI-hyponatremia, maximum of medians of diuresis (5.775 L) occurred on the 2nd day and nadir of medians of hyponatremia (130 mmol/L) on the 10th postoperative day. Altogether, 8.7% of the patients had to be treated with desmopressin because of DI persisting for >3 months. Of all the patients with hyponatremia, 42.8% were treated by transient fluid-intake restriction due to an IH of <130 mmol/L with or without clinical symptomatology. Transient acute renal failure occurred in one of these patients. Generally, the occurrence of postoperative WEDs was linked to the intraoperative manipulation of the neurohypophysis. Increased thirst correlated significantly with DI (p=0.001 and 0.02, respectively) and decreased thirst with the hyponatremic episode in patients with combined DI-hyponatremia (p=0.003). Decreased urine osmolality correlated significantly with the presence of DI (p=0.023). Electrolyte-free water clearance and urinary Na+ excretion were not correlated with DI and hyponatremia. Antidiuretic hormone was not suppressed during hyponatremia.

CONCLUSIONS

Water and electrolyte disturbances occurred in the majority of patients undergoing transsphenoidal adenomectomy and were usually transient. Diabetes insipidus is more frequent than hyponatremia. Diabetes insipidus usually occurs during the 1st postoperative day and resolves in the majority of cases within 10 days. In few patients, DI may persist and require therapy with ADH analogs. Hyponatremia usually occurs at the end of the 1st postoperative week and resolves in most cases within 5 days. Very few patients will need treatment other than fluid-intake restriction to avoid serious complications. Thus, careful monitoring of the WEDs in patients undergoing transsphenoidal pituitary adenoma surgery is mandatory for the first 10 postoperative days.

Natriuretic Peptides, Antidiuretic Hormone and Hyponatraemia after Acute Craniocerebral Injury

We investigated the physiological mechanisms involved in central hyponatraemia in patients with acute craniocerebral injury (ACI). We measured blood concentrations of natriuretic peptides, antidiuretic hormone (ADH), and endogenous digitalis-like substance (EDLS), blood and urine sodium concentrations, and the plasma and urine osmolality in 68 patients with ACI and 24 healthy control subjects. A total of 27 ACI patients were hyponatraemic and the majority of these had grievous or severely grievous craniocerebral injuries. Blood concentrations of EDLS and ADH in hyponatraemic ACI patients were significantly higher compared with normonatraemic ACI patients and control subjects. Blood EDLS and sodium concentrations were negatively correlated with each other, whereas EDLS was positively correlated with urine sodium concentration and with urine osmotic pressure. Hyponatraemic ACI patients require different treatment based on the cause of their central hyponatraemia, so it is important to undertake a comprehensive analysis of each patient's physiological status.

Volume and electrolyte management

Osmolality is the primary determinant of water movement across the intact blood-brain barrier (BBB), and we can predict that reducing serum osmolality would increase cerebral oedema and intracranial pressure. Brain injury affects the integrity of the BBB to varying degrees. With a complete breakdown of the BBB, there will be no osmotic/oncotic gradient, and water accumulates (brain oedema) consequentially to the pathological process. In regions with very moderate BBB injury, the oncotic gradient may be effective. Finally, osmotherapy is effective in brain areas with normal BBB; hypertonic solutions (mannitol, hypertonic saline) dehydrate normal brain tissue, with a decrease in cerebral volume and intracranial pressure. In patients with brain pathology, volume depletion and/or hypotension greatly increase morbidity and mortality. In addition to management of intravascular volume, fluid therapy must often be modified for water and electrolyte (mainly sodium) disturbances. These are common in patients with neurological disease and need to be adequately treated.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The systemic implications of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is analogous to a pathophysiological watershed, disrupting brain integrity and function and precipitating an array of systemic derangements including cardiovascular, respiratory, endocrine, hematological, and immune dysfunction. Extracerebral organ dysfunction is closely linked to the magnitude of the primary neurological insult, suggesting neurogenic, neuroendocrine and neuroimmunomodulatory mechanisms. Systemic organ involvement is associated with increased mortality and neurological impairment, even after adjustment for other outcome predictors such as the severity of the initial neurological injury. This may be a reflection of secondary brain injury precipitated by hypoxemia, circulatory failure, fever, or hyperglycemia, all of which have been linked to adverse clinical outcomes. Interventions to avert or reverse these and other perturbations need to be tested in clinical trials as they represent opportunities to improve survival and neurological recovery in patients with SAH.

Hyponatremia and Comparison of NT-pro-BNP Concentrations in Blood Samples from Jugular Bulb and Arterial Sites after Traumatic Brain Injury in Adults: A Pilot Study

BACKGROUND

Hyponatremia after traumatic brain injury (TBI) may influence neurological function and treatment. A causal relationship between elevated serum concentrations of Type B natriuretic peptide (BNP) and hyponatremia has been implied after subarachnoid hemorrhage and other neurosurgical disorders, although the source of BNP has not been identified. We evaluated if hyponatremia and increased BNP occur after TBI and if BNP is produced/released by the brain within 24 h after injury.

RESULTS

NT-proBNP was measured in concomitant jugular venous and arterial blood samples within 24 h after TBI. NT-proBNP was elevated in both samples in six patients (24%). One patient (4%) showed an increased jugular NT-proBNP concentration above a normal arterial concentration, suggesting a brain source. In the other 24 patients the difference between jugular and arterial NT-proBNP was not statistically significant. Hyponatremia (< or =136 mEq/l) also occurred in six patients (24%), but only two (8%) had both increased arterial NT-proBNP and hyponatremia. In both the urine sodium was slightly elevated above normal, but not statistically different from other patients. The difference in serum sodium between hypo- and normo-natremic groups was significant, but mean NT-proBNP and jugular:arterial NT-proBNP differences were not.

CONCLUSIONS

In this pilot study BNP is elevated within 24 h after TBI in some patients. However, it does not originate from the brain and increased NT-proBNP concentrations are not consistently associated with hyponatremia or increased urinary sodium loss.

Traumatic brain injury: intensive care management

Traumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. The modern management of severe TBI has fallen into the domain of a multidisciplinary team led by neurointensivists, neuroanaesthetists, and neurosurgeons and is based on the avoidance of secondary injury, maintenance of cerebral perfusion pressure (CPP), and optimization of cerebral oxygenation. In this review, we will discuss the intensive care management of severe TBI with emphasis on the specific measures directed at the control of intracranial pressure and CPP.

Recent advances in surgical and intensive care management of subarachnoid hemorrhage

There have been considerable advancements in the medical and surgical management of subarachnoid hemorrhage (SAH) resulting from the rupture of the intracranial aneurysms in the past three decades. While developments in anesthesia and critical care management and recently introduced neuroprotective agents had a considerable effect on the improvement of the medical treatment strategies, advancements in the microsurgical techniques together with the evolvements in the field of interventional neuroradiology have improved surgical therapy. The aim of this paper is to review some of the recent advancements in the surgical and critical care management.

Endocrine problems in critically ill children: an overview

The endocrine system maintains a delicate balance of physiologic processes including growth and sexual maturation, energy production and utilization, fluid and electrolyte balance, and circulatory function. Although endocrine regulation of growth and sexual maturation is a significant issue in general pediatrics, disorders of energy production and utilization, fluid and electrolyte balance, and circulatory function are the endocrine causes of critical illness in children. Care of the child with critical endocrine disease requires an understanding of endocrine pathophysiology, keen history taking and assessment skills, and knowledge of the pharmacology of synthetic hormone treatment. This article will provide an overview of common endocrine problems encountered in critically ill children with attention to endocrine problems that are unique to pediatrics and that may pose diagnostic and treatment dilemmas for healthcare providers without experience or education in pediatric critical care.

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