We tested the hypothesis that admission serum magnesium
levels are associated with extent of hemorrhage in patients with aneurysmal subarachnoid hemorrhage
Single-center prospective observational study.
Tertiary hospital neurologic ICU.
Patients with aneurysmal subarachnoid hemorrhage
Clinically indicated CT scans and serum laboratory studies.
Measurements and Main Results:
Demographic, clinical, laboratory, and radiographic data were analyzed. Extent of initial hemorrhage was graded semi-quantitatively on admission CT scans using the modified Fisher scale (grades: 0, no radiographic hemorrhage; 1, thin [< 1 mm in depth] subarachnoid hemorrhage
; 2, thin subarachnoid hemorrhage
with intraventricular hemorrhage; 3, thick [≥ 1 mm] subarachnoid hemorrhage
; 4, thick subarachnoid hemorrhage
with intraventricular hemorrhage). We used both ordinal (modified Fisher scale) and dichotomized (thick vs thin subarachnoid hemorrhage
) univariate and adjusted logistic regression models to assess associations between serum magnesium
and radiographic subarachnoid hemorrhage
severity. Data from 354 patients (mean age 55 ± 14 yr, 28.5% male, median admission Glasgow Coma Scale 14 [10–15]) were analyzed. Mean magnesium
was lower in patients with thick versus thin subarachnoid hemorrhage
(1.92 vs 1.99 mg/dL; p
= 0.022). A monotonic trend across categories of modified Fisher scale was found using analysis of variance and Spearman rank correlation (p
= 0.015 and p
= 0.008, respectively). In adjusted ordinal and binary regression models, lower magnesium
levels were associated with higher modified Fisher scale (odds ratio 0.33 per 1 mg/dL increase; 95% CI, 0.14–0.77; p
= 0.011) and with thick subarachnoid hemorrhage
(odds ratio 0.29 per 1 mg/dL increase; 95% CI, 0.10–0.78; p
These data support the hypothesis that magnesium
influences hemorrhage severity in patients with aneurysmal subarachnoid hemorrhage
, potentially through a hemostatic mechanism.