Original ArticleThe Impact of Aneurysm Location on Incidence and Etiology of Hyponatremia Following Subarachnoid Hemorrhage
Introduction
Subarachnoid hemorrhage (SAH) resulting from aneurysm rupture affects up to 30,000 individuals per year in the United States and is associated with high mortality rates even with aggressive treatment.1 Hyponatremia is a common electrolyte abnormality in patients with aneurysmal subarachnoid hemorrhage (aSAH), occurring in approximately 40%–50% of all patients.2, 3 Usually this develops between days 4 and 10 after aSAH. It is associated with complications and worse outcomes, including vasospasm and longer hospital stays.2, 4 The syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting (CSW) contribute to most cases of hyponatremia following aSAH.5
It has been suggested that aneurysm location could affect the risk of developing hyponatremia after aSAH; however, some studies have not found this to be the case.6 To date, no studies have examined the effect of aneurysm location on the etiology of hyponatremia. Thus, we sought to determine whether incidences of SIADH and CSW differed between patients with aneurysms of the anterior circulation or posterior circulation. We hypothesized that patients with ruptured anterior circulation aneurysms would be more likely to develop SIADH given the closer proximity of the aneurysm to the hypothalamic-pituitary-adrenal axis. Given that the 2 conditions have divergent treatments, knowledge of such an association would be important. We also investigated whether aneurysm location is associated with development of hyponatremia after aSAH, given that prior studies have reported mixed results.6, 7
Section snippets
Materials and Methods
After obtaining Institutional Review Board approval (#949325-1), a retrospective review of all patients who presented with spontaneous SAH within the last 6 years in a prospectively maintained institutional database was performed. Data were recorded without personal identifiers, and informed consent was not required. Patients were included in the study if they developed hyponatremia, defined as at least 1 measured sodium value <135 mEq/L before postbleed day (PBD) 14. Patients who had
Results
A total of 331 patients with spontaneous SAH over the past 6 years were identified. Of 331 patients, 63 were excluded because there was no identified aneurysm, 45 were excluded because they died within 5 days of admission, and 97 patients did not develop hyponatremia within 14 days of admission. Three further patients were excluded because of a history of congestive heart failure, and 1 patient was excluded because of end-stage renal disease. This left 114 patients included in the hyponatremia
Discussion
Hyponatremia is the most common electrolyte abnormality in aSAH and warrants aggressive treatment. Numerous studies have demonstrated the association of hyponatremia with vasospasm and prolonged hospital courses.2, 4, 6, 10 Although 1 study showed a higher rate of hyponatremia in anterior communicating artery aneurysms,7 others suggested that aneurysm location is not associated with hyponatremia.6, 11 It remains unclear if aneurysm location is associated with different etiologies of
Conclusions
Differentiating between SIADH and CSW in hyponatremic patients is a clinical challenge that is complicated by a lack of reliable methods for assessing volume status. In our cohort of patients who developed hyponatremia after aSAH, an association between anterior circulation aneurysms and SIADH trended toward, but did not reach, statistical significance. This association warrants further study in a larger cohort. In our cohort, the presence of a ruptured anterior communicating artery aneurysm
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2019, Neurosurgery Clinics of North AmericaCitation Excerpt :After all of the ADH stored in the damaged part of the posterior pituitary gland has been released, the second phase ceases, but clinical DI will not be apparent if there is still functional ADH neuronal cell bodies in the hypothalamus that continue to secrete stimulated ADH, albeit at a lower magnitude.46 CSW is a rare condition, which is predominantly associated with subarachnoid hemorrhage,49,50 but can also rarely occur after pituitary surgery.33,51 This condition is characterized by polyuria, hypovolemia, and natriuresis, leading to hyponatremia.
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2019, World NeurosurgeryCitation Excerpt :Our cutoff value for hyponatremia of <135 mmol/L conformed to the widely reported definition of hyponatremia in studies investigating this matter in patients with SAH since 1996.4-6,18-21 Some studies have described a correlation between SAH caused by aneurysms of the anterior circulation and a greater prevalence of hyponatremia.22,23 Furthermore, studies have shown a greater occurrence of hyponatremia in patients with poor-grade SAH and those with higher Fisher grade.24
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.