Potential risk of artificial cerebrospinal fluid solution without magnesium ion for cerebral irrigation and perfusion in neurosurgical practice.

The effect of irrigation with artificial cerebrospinal fluid (CSF) containing various magnesium ion (Mg(2+)) concentrations on vasospastic arteries was investigated in the dog. Cerebral vasospasm was induced by the experimental subarachnoid hemorrhage model in 15 beagle dogs. Cisternal irrigation was performed for 1 hour via a microcatheter placed in the cisterna magna with commercially available artificial CSF (ARTCEREB®) with physiological concentration of Mg(2+) (2.2 mEq/l) (ACM group, n = 5), ARTCEREB solution without Mg(2+) (ACR group, n = 5), and ARTCEREB solution with higher Mg(2+) concentration (5 mEq/l) (ACMM group, n = 5). CSF electrolyte concentrations and the diameters of the basilar and vertebral arteries were measured. In the ACM group, no changes were detected in either CSF Mg(2+) concentration or arterial diameters. In the ACR group, the CSF Mg(2+) decreased significantly to 0.8 ± 0.07 mEq/l from the baseline value of 1.4 ± 0.03 mEq/l, and both basilar and vertebral artery diameters were significantly decreased to 0.61 ± 0.18 mm and 0.57 ± 0.23 mm from their baseline values of 0.74 ± 0.22 mm and 0.68 ± 0.17 mm, respectively. In the ACMM group, the CSF Mg(2+) significantly increased to 2.4 ± 0.15 mEq/l from the baseline value of 1.4 ± 0.05 mEq/l, and both basilar and vertebral artery diameters were significantly increased to 0.84 ± 0.19 mm and 0.90 ± 0.22 mm from their baseline values of 0.71 ± 0.21 mm and 0.69 ± 0.24 mm, respectively. Irrigation with artificial CSF solution without Mg(2+) causes vasoconstriction of the cerebral artery. Irrigation with artificial CSF with appropriate Mg(2+) concentration is essential, especially in patients with subarachnoid hemorrhage.