Introduction: Delayed cerebral ischemia by vasospasm is a potential sequeala of acute subarachnoid hemorrhage from ruptured intracranial aneurysm. It has been proposed that magnesium may alter this course by affecting tone of cerebral vasculature and antagonizing NMDA receptors. The ongoing phase 3 Magnesium in Aneurysmal Subarachnoid Hemorrhage (MASH) trial is investigating the ability of magnesium to affect ischemic events and improve neurologic outcomes. We investigate whether magnesium infusions affect development of severe symptomatic vasospasm as measured by need for endovascular spasmolysis.
Methods: The hospital course of 230 serial patients with SAH were analyzed retrospectively. Care was standardized through ICU protocols, including magnesium infusions. Serum magnesium levels were measured for all patients. Vasospasm was monitored by serial clinical examination, transcranial dopplers (TCD), CT angiogram and cerebral angiography.
Results: The 230 patients with SAH in this study were followed by daily TCD measurements. Therapeutic cerebral angiography was performed on 33 patients (14%) found to have elevated cerebral blood flow velocity by TCD combined with clinical findings suggestive of vasospasm. The peak serum magnesium did not significantly differ between patients who met criteria for requiring angiography for vasospasm and those who did not (3.3meq/L ± 1.2 vs 3.4meq/L ± 1.2, respectively). Similarly, the change in serum magnesium did not differ between these two groups (1.7 meq/L ± 1.3 vs 1.6meq/L ± 1.3). Furthermore, there was no statistically significant correlation between duration of vasospasm and serum magnesium (R2= -0.01).
Conclusions: In this retrospective analysis of patients with SAH from ruptured intracranial aneurysm, there was no significant effect of serum magnesium level on risk of vasospasm, duration of vasospasm, or number of treatments by angiography. These results support emerging data from other groups that magnesium infusion may not affect risk of delayed cerebral ischemia and ultimately long term neurologic outcomes.
Patient Care: Defining prophylaxis for subarachnoid hemorrhage-induced vasospasm continues to be an evolving territory. Magnesium infusions are used frequently, but the ability to prevent severe vasospasm remains unclear. This study indicates that the use of magnesium, despite the low cost, may not be well substantiated.
Learning Objectives: By the conclusion of this session, participants should be able to assess the contribution of magnesium infusions to preventing severe vasospasm.