Neurointerventionalist
Associate Professor of Neuroradiology & Neurosurgery, University of Toronto
Fellowship Program Supervisor (Director), Interventional & Diagnostic Neuroradiology, Toronto Western Hospital (UHN)
I treat complex vascular diseases of the brain and spine through the blood vessels, and invent devices to do it better, safer or faster. I mentor fellows from around the world to become trusted leaders.
Pushing hard when it helps, holding back when it doesn’t, speaking honestly with you throughout.
“I spend my days in people’s heads but can’t read minds (yet), so I listen instead.”
Interventional neuroradiology, the work and how to build a career in it. Podcast Radiologists, episode 27 (University Medical Imaging Toronto).
Fellowship Supervisor (Director) of the Interventional Neuroradiology Program at Toronto Western Hospital (UHN) and the University of Toronto.
Former Head of the Division of Neuroradiology at University Health Network (2022 to 2025).
Course Director of PIKES, the pan-Canadian Karel ter Brugge educational symposium in interventional neuroradiology, neurology and neurosurgery.
Interventional neuroradiology staff at the Hospital for Sick Children (SickKids), with a Neurosurgery cross-appointment at the University of Toronto.
Former stroke-centre certification auditor, national board examiner and Editorial Board member (Journal of Neuroradiology).
Proctor and consultant for multiple medtech companies.
I have been a patient too. That vulnerability, and the worry about whether you will wake up the same, is an anxiety your family carries with you. Surrendering and trusting someone you barely know in that moment takes real courage. Each patient I counsel or operate on, whatever their story, is approached with the same care and focus as a member of my own family. I take a genuine interest in the person, not only the disease, and I listen for what is said and for what is not: a hesitation, a question left unasked, what a relative adds, how someone carries themselves in the room. I want every patient to feel, beyond any doubt, that they are cared for. Brain and spine diseases can be frightening, and when I study your chart and images, I do it with a deep sense of responsibility and compassion. That is the standard I hold myself to, and the one I try to pass on.
Many of the patients who reach me have been told their case is too difficult, or have already had a treatment that did not work. I do not give up easily, and I will keep looking for a way when others have stopped. That is how I have been able to treat, and often cure, people who were told nothing more could be done. Persistence is not the same as taking chances. I prepare meticulously, I put safety ahead of ambition, and I have learned to recognise when the wisest decision is not to proceed. I cannot promise a perfect outcome for everyone, but I can promise that every avenue will have been weighed with judgement and care.
Just as often, the right course is not to intervene at all. For many conditions, treatment risk, however small, can outweigh that of the disease's natural history, and careful observation with regular follow-up may be the wiser path. Knowing when not to treat is as much a part of the work as knowing how. And not every problem has a clear cause or a solution I can offer. With long-standing symptoms especially, I will look thoroughly, but I will be honest about what can and cannot be helped, rather than raise hopes I cannot meet.
Complications can occur. Medicine does not always go the way we hope. When it does not, I do not step back. I stay with the patient and the family, and I carry those moments with me.
I am still captivated, every time, when a catheter introduced through a tiny hole in the wrist or the groin reaches the deepest part of the brain. I love the puzzle of a difficult case, working it like a riddle and executing it with artful precision. I am drawn to the leading edge, and to helping develop the technology that takes us there.
Among the deepest joys of my work is mentoring. Teaching matters to me for the same reason the bedside does: putting the small, hard-to-teach details into words, so fellows understand and integrate them faster, growing into independent thinkers ready to face the unexpected with humility, judgement and creativity. Like a sensei, I love watching hesitant trainees blossom into sure-handed experts, their eyes widening with exhilaration at each transformative aha moment, as they turn into masters I may learn from as well.
After completing his training in Paris, my friend and co-fellow Dr Eugen Enesi built interventional neuroradiology in Albania from almost nothing, and I was glad to help where I could.
Some of the best in the field trained me, and gave me the room to push myself as far as I could. What I want now is simple: to keep building new tools with the engineers who bring them to patients, to help others treat neurovascular diseases well, and to give back to those who need it most.
If you are a physician with a complex or previously untreatable case, a trainee, or a builder working on the next tool, I would like to hear from you. Reach me at pascal.mosimann@uhn.ca or on LinkedIn.
For referrals. Physicians can refer a patient to our multidisciplinary neurovascular clinic and interventional neuroradiology service by fax at +1 416 603 4257, or by email. Patients: please ask your physician to send a referral.