Temporal Profile of the Effects of Intracisternal Injection of Magnesium Sulfate Solution on Vasodilation of Spastic Cer
Purpose: The temporal profiles of the effects of intracisternal injection of magnesium sulfate (MgSO4) on vasodilation and cerebrospinal fluid (CSF) magnesium ion (Mg2+) concentration were investigated in the canine subarachnoid hemorrhage (SAH) model.
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Abstract Purpose: The temporal profiles of the effects of intracisternal injection of magnesium sulfate (MgSO4) on vasodilation and cerebrospinal fluid (CSF) magnesium ion (Mg2+) concentration were investigated in the canine subarachnoid hemorrhage (SAH) model. Method: Cerebral vasospasm was induced using the twohemorrhage model in seven female beagles. On day 7, 0.5 ml/kg of 15 mmol/l MgSO4 in Ringer solution was injected into the cerebellomedullary cistern. Angiography was performed on day 1 (before SAH), and before and 1, 3, and 6 h after the intracisternal injection on day 7. CSF Mg2+ was measured at the same time. Results: The diameters of the basilar artery (BA), vertebral artery (VA), and superior cerebellar artery (SCA) before the intracisternal injection on day 7 were 0.59 0.15, 0.41 0.17, and 0.35 0.17 mm, respectively, and were significantly decreased (p < 0.01) compared with the baseline diameters on day 1. The BA diameters at 1 h (0.74 0.16 mm) and 3 h (0.73 0.13 mm), the VA diameter at 1 h (0.64 0.14 mm), and the SCA diameter at 3 h (0.54 0.08 mm) after the injection were significantly increased (p < 0.05). The CSF Mg2+ concentration was significantly increased (p < 0.01) at 1 h (3.59 0.76 mEq/l) and 3 h (2.00 0.31 mEq/l) after the injection compared with the baseline value (1.35 0.23 mEq/l). Conclusions: The reversible effect of intracisternal MgSO4 solution injection on the spastic artery depends on maintenance of the optimal CSF Mg2+ concentration. Keywords Cerebrospinal fluid Magnesium ion Vasospasm Subarachnoid hemorrhage
K. Mori (*), T. Yamamoto, Y. Nakao, and T. Esaki Department of Neurosurgery, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka, 410-2295, Japan e-mail: [email protected] M. Miyazaki, Y. Hara, and Y. Aiko Department of Radiology, Juntendo University Shizuoka Hospital, Izunokuni, Shizuoka, Japan
Introduction Delayed cerebral vasospasm remains one of the major determinants of final neurological outcome even after advanced modern intravascular and open aneurysm procedures in patients with subarachnoid hemorrhage (SAH). Administration of calcium channel blockers is a promising method to prevent or ameliorate cerebral vasospasm based on the biological etiology [1]. Recent prospective studies of continuous intravenous administration of magnesium sulfate (MgSO4) in patients with aneurysmal SAH have failed to show any vasodilatory effect [5, 7]. The blood–brain barrier is relatively impermeable to serum magnesium ion (Mg2+), so higher blood concentration of Mg2+ may not be reflected in increased cerebrospinal fluid (CSF) Mg2+ concentration. However, higher extracellular Mg2+ concentration in vitro causes vasodilation of spastic cerebral vessels [6]. Therefore, intracisternal administration of Mg2+ may reverse cerebral vasospasm caused by SAH. We previously found that intracisternal infusion of MgSO4 solution improved reduced cerebral blood flow after experimental SAH in rats using a quantitative autoradiographic method [2], and that
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