Magnesium Sulfate and Neuroprotection

To the Editor: We read with great interest the article from Wilkes et al. (1) reporting that correcting ionized plasma magnesium during cardiopulmonary bypass in patients undergoing coronary artery bypass grafting (CABG) reduces the risk of postoperative cardiac arrhythmia. In their article, Wilkes and colleagues mention some of the systemic effects of magnesium sulfate administration and the underlying cellular mechanisms. But they fail to mention its neuroprotective effects. Magnesium sulfate has major neuroprotective effects in experimental head trauma models (2), spinal cord ischemia (3), and ischemia after middle cerebral artery occlusion (4). Cardiopulmonary bypass for CABG is complicated by postoperative neurocognitive decline (5), possibly related to diffuse ischemic brain damage. By competing with Ca2+, magnesium reduces the ischemia-related rise in intracellular Ca2+, thereby preventing cell death. In the brain, magnesium causes a dose-dependent vasodilation of pial arterioles, dilates the basilar artery, and improves cortical blood flow during middle cerebral artery occlusion. In patients undergoing cardiopulmonary bypass for CABG, administration of magnesium sulfate to correct ionized plasma magnesium may also play a beneficial role in perioperative neuroprotection. Dr. Wilkes does not wish to respond.