Neuroscience Research Program

Image of R. Loch Macdonald

R. Loch Macdonald

MD, University of British Columbia; PhD, University of Alberta


Scientist in the Keenan Research Centre of the Li Ka Shing Knowledge Institute of St. Michael's Hospital

Head, Division of Neurosurgery, Department of Surgery, St. Michael's Hospital

Keenan Endowed Chair in Surgery,

Professor, Department of Surgery, University of Toronto

Scientist, Labatt Family Centre of Excellence in Brain Injury and Trauma Research, Keenan Research Centre in the Li Ka Shing Knowledge Institute of St. Michael’s Hospital

Member, Institute of Medical Science, University of Toronto

Research Interests

Subarachnoid Hemorrhage, Cerebral Blood Flow, Cerebral Aneurysms, Cerebral Vascular Malformations, Vascular Biology

Contact Information

Phone: 416-864-5393
Fax: 416-864-5634

Macdonald, R. L., Higashida, R. T., Keller, E., Mayer, S. A., Molyneux, A., Raabe, A., Vajkoczy, P., Wanke, I., Bach, D., Frey, A., Marr, A., Roux, S., & Kassell, N. (2011). Clazosentan, an endothelin receptor antagonist, in patients with aneurysmal subarachnoid haemorrhage undergoing surgical clipping: a randomised, double-blind, placebo-controlled phase 3 trial (CONSCIOUS-2). The Lancet Neurology, 10(7), 618-625.

Ibrahim, G. M., Weidauer, S., & Macdonald, R. L. (2011). Interobserver variability in the interpretation of computed tomography following aneurysmal subarachnoid hemorrhage: Clinical article. Journal of neurosurgery, 115(6), 1191-1196.

Ibrahim, G. M., Weidauer, S., Vatter, H., Raabe, A., & Macdonald, R. L. (2012). Attributing hypodensities on CT to angiographic vasospasm is not sensitive and unreliable. Stroke, 43(1), 109-112.

Macdonald, R. L., Higashida, R. T., Keller, E., Mayer, S. A., Molyneux, A., Raabe, A., Vajkoczy, P., Wanke, I., Bach, D., Frey, A., Nowbakht, P., Roux, S., & Kassell, N (2012). Randomized trial of clazosentan in patients with aneurysmal subarachnoid hemorrhage undergoing endovascular coiling.Stroke, 43(6), 1463-1469.

Zoerle T, Ilodigwe D, Wan H, Lakovic K, Sabri M, Ai J, Macdonald RL (in press) Pharmacologic prevention of cerebral vasospasm in experimental subarachnoid hemorrhage: systematic review and meta-analysis. Journal of Cereb Blood Flow & Metabolism

Sabri, M., Ai, J., Lakovic, K., D’abbondanza, J., Ilodigwe, D., & Macdonald, R. L. (2012). Mechanisms of microthrombi formation after experimental subarachnoid hemorrhage. Neuroscience.

My major research interests are in the field of aneurysmal subarachnoid hemorrhage and complications of it such as angiographic vasospasm, microcirculatory dysfunction and delayed cerebral ischemia. My laboratory studies causes of delayed neurological deterioration after subarachnoid hemorrhage using animal models and testing hippocampal electrophysiology and function, animal behavior, learning and memory and changes in gene expression and function. We also are studying mechanisms of large artery and microcirculatory vasospasm after aneurismal subarachnoid hemorrhage and effects of intracerebral and subdural hemorrhage on the brain. All of this work is laboratory-based but I also am involved in multiple clinical trials and patient-based studies conducted testing similar hypotheses. We also are developing an international repository of individual patient data of patients with aneurysmal subarachnoid hemorrhage, that includes now more than 12,000 patients and that we use to ask questions about clinical trial design, management, and outcome of these patients.

We generally have several students working towards postgraduate degrees in both laboratory and clinical
research as well as undergraduate summer students and medical students working on various projects.