I write to clarify some points regarding a paper recently published in the Canadian Journal of Neurological Sciences on the history of cerebrovascular surgery in Canada. 1 Edward Archibald, of McGill University, was Canada's first neurosurgeon, and one of the first neurosurgeons in the world. 2 Archibald trained in Neurosurgery at Queen Square, London, with Victor Horsley, in 1906, after which he became the dedicated neurosurgeon at the Royal Victoria Hospital, in Montreal. He published many papers on neurosurgical topics, and a magisterial, 300-page treatise on the practice of neurosurgery in 1908, 3 which rivaled Cushing's own text, published in the same year. Archibald was a founding member of the Society of Neurological Surgeons (SNS) (1920), with Harvey Cushing and 13 other pioneers of North-American neurosurgery. Archibald continued to practice neurosurgery until he recruited Wilder Penfield to McGill University as his replacement, in 1928. At that time, and on the recommendation of Ernest Sachs and Charles Frazier, Archibald became the first senior member of the SNS. Arthur Elvidge was trained in neurosurgery by Archibald, Wilder Penfield, and William Cone, and he joined the latter two as the third neurosurgeon at the Montreal Neurological Institute (MNI). Elvidge introduced cerebral angiography in North America in 1934, after learning the technique from Egas Moniz in Lisbon; and he published the first North-American monograph on its use-most notably as an aid in the diagnosis of arteriovenous malformations (AVM)-in 1937. 4 He was also the first to demonstrate the occlusion of an internal carotid artery by angiography, and to correlate it with contralateral hemiplegia. 5 Elvidge was the first neurosurgeon to clip an anterior circulation aneurysm, in 1946. 6 Francis Echlin, working toward a Master's degree under Penfield's supervision, discovered that experimental vasospasm can result in cortical infarction, in 1939. Eric Peterson and I, at the University of Ottawa, were the first to describe a chronic experimental model of subarachnoid hemorrhage, in cats and monkeys, in 1973. 7,8 Peterson was also the first to treat a carotid-cavernous fistula by endovascular means, in 1969, reaching the lesion through the ophthalmic vein. 9 William Feindel, Lucas Yamamoto, and Charles Hodge, from the MNI, developed the techniques of intraoperative fluorescein angiography and intraoperative radioisotope blood flow studies, which they used as an aid in the treatment of cerebral AVMs. Using these techniques they described the intra-cerebral steal syndrome associated with these lesions. Leblanc and his collaborators at the MNI quantitated the hemodynamic and metabolic aspects of the intra-cerebral steal syndrome using positron emission tomography, and Leblanc and Meyer were the first to demonstrate the usefulness of functional imaging in the treatment of AVMs. 10,11 Further details on the contributions of the MNI in the field of neurovascular surgery, and of neurology and neurosurgery in general, can be found in Feindel and ...