Inclusion Criteria1. Patient with acute cerebral ischemia due to ICA or MCA occlusion,
2. Patient's clinical attending physician plans mechanical embolectomy procedure as part of routine clinical care.
3. Age 21-95.
Exclusion Criteria1. Severe renal impairment with creatinine 3.0 or higher,
2. Myasthenia gravis,
3. Second or third degree heart block without a pacemaker in place,
4. Technical inability to navigate microcatheter to target clot,
5. Patient already enrolled in another experimental treatment trial. Exclusion criteria 1-3 are all contraindications to magnesium therapy.