Elsevier

World Neurosurgery

Volume 110, February 2018, Pages e621-e626
World Neurosurgery

Original Article
The Impact of Aneurysm Location on Incidence and Etiology of Hyponatremia Following Subarachnoid Hemorrhage

https://doi.org/10.1016/j.wneu.2017.11.058Get rights and content

Background

Hyponatremia is the most common electrolyte abnormality in patients with aneurysmal subarachnoid hemorrhage (aSAH). Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting (CSW) are the most common etiologies. Whether or not the location of the ruptured aneurysm is associated with the etiology of hyponatremia is unknown. We sought to determine whether or not the incidence of SIADH and CSW after aSAH differed based on aneurysm location.

Methods

Retrospective analysis of 335 consecutive patients who presented with aSAH at a single institution was performed. Patients were included if they developed hyponatremia before postbleed day 14. Electronic health records were reviewed to obtain data regarding aneurysm location, treatment, etiology of hyponatremia, and modified Rankin Scale score at hospital discharge.

Results

Inclusion criteria were met by 114 patients. There were 67 (59%) anterior circulation aneurysms and 47 (41%) posterior circulation aneurysms. Of patients, 85 (75%) had hyponatremia owing to SIADH, 14 (12%) had CSW, and 15 (13%) did not fit either etiology. SIADH was more common than CSW in anterior circulation aneurysms (90%) compared with posterior circulation aneurysms (75%). This trended toward, but did not reach, statistical significance (P = 0.08). More severe Hunt and Hess grades were associated with the development of CSW rather than SIADH (P = 0.002).

Conclusions

SIADH is much more common than CSW in patients with aSAH. Anterior circulation aneurysms may be associated with a higher rate of SIADH than posterior circulation aneurysms.

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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    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.

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