Cerebral salt wasting syndrome: review

Multiple electrolyte disorders in a neurosurgical patient: solving the rebus

BACKGROUND

It is important to ensure an adequate sodium and volume balance in neurosurgical patients in order to avoid the worsening of brain injury.Indeed, hyponatremia and polyuria, that are frequent in this patient population, are potentially harmful, especially if not promptly recognized.Differential diagnosis is often challenging, including disorders, which, in view of similar clinical pictures, present very different pathophysiological bases, such as syndrome of inappropriate antidiuresis, cerebral/renal salt wasting syndrome and diabetes insipidus.

CASE PRESENTATION

Here we present the clinical report of a 67-year-old man with a recent episode of acute subarachnoid haemorrhage, admitted to our ward because of severe hyponatremia, hypokalemia and huge polyuria.We performed a complete workup to identify the underlying causes of these alterations and found a complex picture of salt wasting syndrome associated to primary polydipsia. The appropriate diagnosis allowed us to correct the patient hydro-electrolyte balance.

CONCLUSION

The comprehension of the pathophysiological mechanisms is essential to adequately recognize and treat hydro-electrolyte disorders, also solving the most complex clinical problems.

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.

A case of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with lupus erythematosus in the central nervous system

We report on a case of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with lupus erythematosus in the central nervous system (CNS). A 73-year-old woman with essential hypertension suddenly demonstrated consciousness disturbance. Upon her admission, laboratory data showed significant hyponatremia (114 mEq/L) and a lack of body fluid loss. Diminished free water excretion (urine osmolality 684 mOsm/kg) and normal urine Na excretion (FENa 1.70 %) were consistent with the diagnosis of SIADH, which was confirmed by an inappropriately high concentration of plasma antidiuretic hormone (ADH) (15.3 pg/mL at 256 mOsm/kg of plasma osmolality). The hyponatremia was corrected by a combination of oral water intake restriction and saline infusion with furosemide administration until the 20th hospital day. Simultaneously, the presence of exudative pleural effusion in both chest cavities, suggesting the existence of pleuritis, and high titer of anti-nuclear antibody (ANA, 5120×) and anti-double-strand DNA antibody (6500 IU/mL), indicated the subclinical development of systemic lupus erythematosus (SLE), although the diagnostic criteria were not satisfied at that time. On the 34th hospital day, the sudden onset of unknown consciousness disturbance confirmed the diagnosis of SLE as CNS lupus. In previous case reports on SLE and/or SIADH, a few cases in which SLE and SIADH developed concomitantly regularly showed high immunological activities, as in our case. Some common pathophysiological bases might be involved in the concomitant appearance of those disorders.

[The syndrome of inappropriate antidiuresis]

The syndrome of inappropriate antidiuresis (SIAD; formerly the syndrome of inappropriate secretion of antidiuretic hormone) is the most frequent cause of hyponatremia. A strong association exists between mortality and hyponatremia, which reflects the severity of the underlying disease. In SIAD, hyponatremia is associated with normovolaemia but the assessment of extracellular volume can be difficult. Clinical features are mainly neurological and can lead to death but mechanisms of adaptation can limit cerebral oedema. The notion of mild asymptomatic hyponatremia was questioned by the observation of subclinical neurocognitive impairment, a greater risk of falls and fractures. Aetiologies are classified into six groups: neurologic disorders, infections mainly cerebral, meningeal and pulmonary, drugs in particular antidepressants, tumors, genetic causes, and idiopathic. Symptomatic acute hyponatremia is a therapeutic emergency that is not specific of SIAD. When hyponatremia is asymptomatic, fluid restriction with salt intake is generally sufficient but urea can be an alternative. In chronic SIAD, there is currently no recommendation. Fluid restriction is not always feasible; urea has proved its efficacy, its good tolerance and its long-term harmlessness. Vaptans have demonstrated their good tolerance and their efficacy on the correction of hyponatremia from SIAD in studies subgroups, for moderate hyponatremia and asymptomatic patients. In the only study having compared vaptans and urea, efficacy and tolerance were similar. Because of the cost difference between vaptans and urea and while waiting for follow-up studies, urea appears at present as the first-line treatment of hyponatremia in SIAD.

Clinical analysis of electrolyte imbalance in thalamic hemorrhage patients within 24 h after admission

We have observed that patients with thalamic hemorrhage are more likely to have electrolyte disturbances than those with non-thalamic hemorrhage. Here, we are attempting to provide some comprehensive information on electrolyte disturbances in patients with thalamic hemorrhage. Retrospectively, 67 patients with thalamic hemorrhage (TH group) and 256 with non-thalamic hemorrhage (N-TH group) were found from computer tomography images. Electrolytes of these patients were tested within 24 h after hospitalization. Chi-square test was used to compare the incidence of electrolyte imbalance. Serum K+ levels were found to be abnormal in 37.31% of the patients in the TH group and 24.21% in the N-TH group, and the difference was significant (p<0.05). Such a difference was also observed for the levels of serum Na+ and Cl+. Incidences of abnormal serum K+ (p<0.05), Na+ (p<0.01) and Cl(-) (p<0.01) levels were different among thalamic hemorrhage, basal ganglia area hemorrhage and lobar hemorrhage patients. In the TH group, the mortality of patients with electrolyte disturbances (42.50%) was higher than that of patients with normal electrolyte levels (14.81%, p<0.05). The incidence of electrolyte imbalance is higher in patients with thalamic hemorrhage than in those with non-thalamic hemorrhage. The reason may be partly related to the location of the hemorrhage. Electrolyte disturbance may contribute to the higher mortality of patients with thalamic hemorrhage.

Management of hyponatraemia

Hyponatraemia (serum sodium level < 135 mmol/litre) is the most common electrolyte abnormality among hospitalized patients. A prevalence rate as high as 15-30% has been reported among patients admitted to acute and intensive care units (Hoorn et al, 2004; Jaber et al, 2006). Evidence suggests an increase in mortality associated with even a mild degree of hyponatraemia (Waikar et al, 2009). Besides its significance as a potential cause of morbidity and mortality, hyponatraemia could also serve as a useful indicator for undiagnosed underlying pathology such as endocrine disorders or malignancy. A systematic approach towards the clinical assessment and interpretation of biochemical abnormalities is vital to facilitate the diagnosis and management of hyponatraemia. The optimal treatment of hyponatraemia should take into account its severity, duration and mode of clinical presentation. Overzealous correction could result in irreversible neurological complications.

The syndrome of inappropriate antidiuresis: pathophysiology, clinical management and new therapeutic options

Hyponatremia is a marker of different underlying diseases and it can be a cause of morbidity itself; this implies the importance of a correct approach to the problem. The syndrome of inappropriate antidiuresis (SIAD) is one of the most common causes of hyponatremia: it is a disorder of sodium and water balance characterized by urinary dilution impairment and hypotonic hyponatremia, in the absence of renal disease or any identifiable non-osmotic stimulus able to induce antidiuretic hormone (ADH) release; according to its definition, it is diagnosed through an exclusion algorithm. SIAD is usually observed in hospitalized patients and its prevalence may be as high as 35%. The understanding of the syndrome has notably evolved over the last years, as reflected by the significant change in the name, once the syndrome of inappropriate secretion of ADH (SIADH), today SIAD. This review is up to date and it analyses the newest notions about pathophysiological mechanisms, classification, management and therapy of SIAD, including vaptans.

[Incidence of hyponatremia and its causes in neurological patients]

INTRODUCTION

Hyponatremia is considered the most frequent electrolyte disorder found in hospitalized patients and seems to be a prognostic factor during hospitalization.

METHODS

A prospective observational study was carried out in consecutive neurological patients admitted to our hospital over a 3-month period. Blood and urinary ionogram and osmolality were determined at entry and 3-5 days after admission in all patients with hyponatremia.

RESULTS

Of the 130 patients admitted, 19 (14.6%) had hyponatremia. The causes of hyponatremia were as follows: inappropriate fluid replacement in 4 patients (21%), antihypertensive drugs in 4 (21%), syndrome of inappropriate secretion of antidiuretic hormone in 4 (21%), cerebral salt wasting syndrome in 2 (10%), and edematous status caused by liver disease in one and digestive loss in one (5%) each. Mortality was one (5%) and 0 (0%) among patients with and without hyponatremia, respectively.

CONCLUSION

Hyponatremia is common in hospitalized neurological patients and can be misdiagnosed as a worsening of the main illness.

Cerebral salt wasting syndrome in a patient with primary CNS lymphoma

BACKGROUND

In patients with severe central nervous system (CNS) diseases, life-threatening hyponatremia results from two main causes: the syndromes of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW). Clinical manifestations of the two conditions may be similar but their pathogeneses are fundamentally diverse. Distinguishing SIADH from CSW is based on the differential diagnoses of dilutional hyponatremia due to an excessive amount of water in the body (SIADH) and depletional hyponatremia caused by extensive natriuresis (CSW).

METHODS AND RESULTS

We report the case of a 48-year-old, previously healthy male with a diffuse large B-cell lymphoma affecting the area of the basal ganglia and the right part of the thalamus and oppressing the third brain ventricle. After admission to the Department of Hemato-oncology, the patient was soporous and laboratory tests revealed severe serum hyponatremia, hypochloremia, hypoosmolality and marked polyuria with normal serum levels of urea, creatinine, glucose and calcium. Urinalysis showed high specific gravity of the urine and extreme wasting of sodium, chloride and kalium ions. Overall fluid balance was negative. After the first chemotherapy cycle, the CT scan confirmed regression of the tumour site. This was accompanied by patient's improved cognition as well as decreased polyuria and urine electrolyte excretion. Eventually, it was concluded that the diagnosis was cerebral salt wasting syndrome.

CONCLUSION

We noted a so far unpublished case of a 48-year-old male with the diagnosis of primary CNS lymphoma (DLBCL) affecting deep structures of the brain and associated with CSW.

Cerebral salt wasting syndrome following atlantoaxial fracture dislocation in Down syndrome

We describe cerebral salt wasting syndrome (CSWS) in a 5-year-old female child with Down syndrome who had acute myelopathy secondary to chronic atlantoaxial subluxation and fracture dislocation of the odontoid process. The patient developed hyponatraemia associated with excessive urine output and elevated urine sodium concentration following her injury. An administered volume-for-volume replacement of urine loss with 0.9% sodium chloride resulted in an excellent outcome. This patient illustrates the importance of ascertaining CSWS in children with spinal cord disorders, in addition to the syndrome of inappropriate antidiuretic hormone (SIADH) secretion and diabetes insipidus (DI) commonly encountered following a central nervous system (CNS) injury, as the specific treatment approaches is clearly associated with an excellent outcome.

Electrolyte and salt disturbances in older people: causes, management and implications

Salt and electrolyte disturbances are commonly encountered in older patients. A sound understanding of the underlying physiological and pathological mechanisms underpinning the predisposition of older people to the common electrolyte imbalances can help clinicians minimize their considerable associated morbidity and mortality. This review focuses on the more common and clinically relevant salt and electrolyte disorders of older people. The epidemiology, causes, symptoms, diagnosis and treatment of hyponatraemia, hypernatraemia, hyperkalaemia, hypokalaemia and calcium and phosphate imbalance in old age are covered from a clinician's perspective.