Oisin O'Neill, MD, FRCSI, FACS

503-935-8500
Areas of Focus: 
Brain & Spine Tumors
Cerebrovascular Neurosurgery
General Neurosurgery/Complex Spine
Peripheral Nerve Surgery
Intraoperative MRI technology

About Me

Dr. O’Neill is a board-certified neurosurgeon in the United States as well as in the European Union. He completed his medical training at the Royal College of Surgeons in 1985 and his neurosurgery training started in Richmond and Beaumont hospitals in Dublin, Ireland. In 1988, Dr. O’Neill and his family immigrated to the United States where he received neurosurgery training at the University of Washington and at Oregon Health & Sciences University. In 1991 he was examined and admitted as a Fellow of the Royal College of Surgeons in Ireland. Dr. O’Neill’s particular interests are in the treatment of brain tumors, stereotactic radiosurgery, and in the surgical treatment of the vascular pathology of the brain. Dr. O'Neill has extensive peer-reviewed publications and book chapters.

My Work

Office Locations: 
Hospitals Served: 
Legacy Emanuel Medical Center
Providence Portland Medical Center
Providence St. Vincent Medical Center
Specialties: 
Areas of Focus: 
Brain & Spine Tumors
Cerebrovascular Neurosurgery
General Neurosurgery/Complex Spine
Peripheral Nerve Surgery
Intraoperative MRI technology

Education & Honors

Board Certification: 
Neurosurgery
Education & Training: 
  • Chief of Department of Neurosurgery & Neurology, Providence St. Vincent Hospital, Portland, OR, 2017
  • Clinical Instructor, Neurosurgery, Oregon Health & Science University, 1995
  • Attending Neurosurgeon, Oregon Health & Science University, Portland, OR, 1995
  • Fellowship, Neurovascular/Interventional, Oregon Health & Science University, Portland, OR, 1993
  • Residency, Neurosurgery, Oregon Health & Science University, Portland, OR, 1994
  • Residency, Surgery & Neurosurgery, University of Washington, Seattle, WA, 1988
  • Senior House Office, Neurosurgery, St. Laurence Hospital/Beaumount Hospital, Dublin, Ireland, 1988
  • MD, Royal College of Surgeons, Dublin, Ireland, 1985
Honors: 
  • David Gault Medal in Obstetrics and Gynecology, 1984
  • 2nd Place, Lyons/Fitzsimons Prize in Surgery, 1985
  • Fellow of the Royal College of Surgeons, Dublin Ireland, 1991
  • Portland Monthly Magazine, "Top Doctors," 2008
  • Portland Monthly Magazine, "Top Doctors," 2009
  • Portland Monthly Magazine, "Top Doctors," 2016
  • Consumers Research Council of America, Top Surgeons, 2003
  • Consumers Research Council of America, Top Surgeons, 2009
Publications: 
  • E. Graham, Kathryn & H. Samuels, Mary & M. Nesbit, Gary & M. Cook, David & R O'Neill, O & L. Barnwell, Stanley & Loriaux, Lynn. (1999). Cavernous Sinus Sampling Is Highly Accurate in Distinguishing Cushing’s Disease from the Ectopic Adrenocorticotropin Syndrome and in Predicting Intrapituitary Tumor Location 1. The Journal of clinical endocrinology and metabolism. 84. 1602-10. 10.1210/jcem.84.5.5654.
  • Kuether, TA & O'Neill, Oisin & M. Nesbit, Gary & L. Barnwell, Stanley. (1998). Endovascular Treatment of Traumatic Dural Sinus Thrombosis: Case Report. Neurosurgery. 42. 1163-6; discussion 1166. 10.1097/00006123-199805000-00129.
  • A. Kuether, Todd & R. O'Neill, Oisin & M. Nesbit, Gary & L. Barnwell, Stanley. (1996). Direct Carotid Cavernous Fistula after Trigeminal Balloon Microcompression Gangliolysis: Case Report. Neurosurgery. 39. 853-5; discussion 855. 10.1097/00006123-199610000-00042.
  • M. Nesbit, Gary & Clark, Wayne & R. O'Neill, Oisin & L. Barnwell, Stanley. (1996). Intracranial intraarterial thrombolysis facilitated by microcatheter navigation through an occluded cervical internal artery. Journal of neurosurgery. 84. 387-92. 10.3171/jns.1996.84.3.0387.
  • Clark, Wayne & L. Barnwell, Stanley & Nesbit, Gary & R O'Neill, O & L. Wynn, Michael & Coull, Bruce. (1995). Safety and Efficacy of Percutaneous Transluminal Angioplasty for Intracranial Atherosclerotic Stenosis. Stroke; a journal of cerebral circulation. 26. 1200-4. 10.1161/01.STR.26.7.1200.
  • R. O'Neill, Oisin & L. Barnwell, Stanley & J. Silver, David. (1995). Middle Meningeal Artery Aneurysm Associated with Meningioma: Case Report. Neurosurgery. 36. 396-8. 10.1097/00006123-199502000-00022.
  • R O'Neill, O & Joseph H. Piatt, Jr & Mitchell, Peter & Roman-Goldstein, Simon. (1995). Agenesis and Dysgenesis of the Sacrum: Neurosurgical Implications. Pediatric neurosurgery. 22. 20-8. 10.1159/000121295.
  • R. O'Neill, Oisin & Gilliland, Grant & Delashaw, Johnny & Purtzer, Thomas. (1995). Transorbital penetrating head injury with a hunting arrow: Case report. Surgical neurology. 42. 494-7. 10.1016/0090-3019(94)90079-5.
  • L Barnwell, S & Clark, Wayne & Nguyen, Tung & R O'Neill, O & L Wynn, M & Coull, Bruce. (1994). Safety and efficacy of delayed intraarterial urokinase therapy with mechanical clot disruption for thromboembolic stroke. AJNR. American journal of neuroradiology. 15. 1817-22.
  • R. O'Neill, Oisin & Delashaw, Johnny & P. Phillips, Jack. (1994). Subperiosteal hematoma of the orbit associated with subfrontal extradural hematoma: Case report. Surgical neurology. 42. 308-11. 10.1016/0090-3019(94)90398-0.
  • L. Barnwell, Stanley & R. O'Neill, Oisin. (1994). Endovascular Therapy of Carotid Cavernous Fistulas. Neurosurgery clinics of North America. 5. 485-95. 10.1016/S1042-3680(18)30515-1.
  • R O'Neill, O & Roman-Goldstein, Simon & Joseph H. Piatt, Jr. (1994). Sacral Agenesis Associated with Spinal Cord Syrinx. Pediatric neurosurgery. 20. 217-20. 10.1159/000120792.
  • R. O’Neill, Oisin & Burchiel, Kim. (1991). Role of the Sympathetic Nervous System in Painful Nerve Injury. Neurosurgery clinics of North America. 2. 127-36. 10.1016/S1042-3680(18)30762-9.
Other Activities: 
  • Register, General Medical Council of Ireland
  • Member, American Association of Neurosurgeons
  • Member, Association of Northwest Physicians
  • Member, Southwest Oncology Group
  • Diplomat, American Board of Neurological Surgeons, 2000
  • Fellow, American College of Surgeons
  • Fellow, American Association of Neurosurgeons