Research Profile: Christopher S. Ogilvy, MD and Ajith Thomas, MD

Christopher S. Ogilvy, MD

Professor of Neurosurgery, Harvard Medical School
Director, Brain Aneurysm Institute, BIDMC


Ajith Thomas

Ajith Thomas, MD

Associate Professor of Neurosurgery, Harvard Medical School
Co-Director, Brain Aneurysm Institute, BIDMC

Research Group

Abdulrhaman Alturki, MD
Luis Ascanio-Cortez, MD
Kohei Chida, MD
Alejandro Enriquez-Marulanda, MD
Christoph Griessenauer, MD
Raghav Gupta
Kimberly Kicielinski, MD
Georgios Maragkos, MD
Justin Moore, MD, PhD
Rouzbeh Motiei-Langroudi, MD
Mohamed Salem, MD

Research Focus

Clinical Research

Flow Diverter Technology

The Brain Aneurysm Institute has been at the forefront of introducing cutting edge technology, such as flow diverters and the new ATLAS stent. We have accumulated one of the largest experiences with flow diverter technology in the world and have been able to add substantially to understanding of the safety and efficacy of this device. Our publications in peer reviewed literature, which number about 25 this past year, are a reflection of this growing practice.

Anticoagulation regimens

For endovascular techniques, we have investigated the type of anticoagulation needed to enhance the safety of device delivery. We examined data from our own institution as well as a number of collaborative multi-institutional studies in an attempt to refine the antiplatelet agent regimens and radiographic follow-up for these individuals. We have documented that almost 30% of patients who are non-responders to Clopidogrel warrant treatment with Ticagrelor. By altering these patients’ antiplatelet regimen, stroke rates can be reduced dramatically when using intravascular flow diversion.

Management of Dural AV Fistulas

We have developed significant expertise in the management of both cranial and spinal dural AV fistulas. As part of this effort, we have introduced a new classification system for cavernous carotid fistulas based on venous drainage to guide treatment and prognosis.

Subarachnoid hemorrhage

We have also hypothesized that anti-angiogenic factors, such as soluble Fms-like tyrosine kinase-1 and soluble transforming growth factor co-receptor endoglin, are important contributors to the pathophysiology of delayed cerebral ischemia. Analysis of CSF from subarachnoid hemorrhage patients seems to confirm this hypothesis. The findings were published in World Neurosurgery.

Aneurysm Recanalization Stratification Scale

We have developed the Aneurysm Recanalization Stratification Scale, which uses accessible predictors including aneurysm-specific factors (size, rupture, and intraluminal thrombosis) and treatment-related features (treatment modality and immediate angiographic result) to predict retreatment risk after endovascular therapy.

Technological and Other Scientific Innovations

In collaboration with Conor Walsh, PhD, at the Harvard School of Engineering and Applied Sciences (SEAS), Dr. Thomas designed a hand-held, portable cranial drilling device that can be used with any diameter drill bit to create holes in the skull without endangering underlying brain tissue. The drill will make it safer for neurosurgeons to penetrate the skull for smaller probes such as intracranial pressure monitors.  It will allow healthcare professionals in allied specialties, such as trauma surgery, to place intracranial monitors safely. This project received the 2011 Excellence in Medical Device Design Award from SEAS.

Basic Science

In the laboratory, in collaboration with Christiane Ferran, MD, PhD, Dr. Thomas has been exploring the hypothesis that some of the limitations surrounding neural stem cell transplantation can be overcome by the addition of periventricular endothelial cells (PvEC) from the embryonic brain. This novel concept is the outgrowth of several recent studies in the area of angiogenesis and neurogenesis, where it is postulated that PvECs migrate in the embryonic brain in a similar manner to neurons, and have a reciprocal relationship in the development of neuronal networks and the vasculature that supports them.  Dr. Thomas’ project involves characterizing the molecular interactions between neural precursor cells and embryonic derived mouse brain periventricular endothelial cells to show enhanced bidirectional effects on neurogenesis and vasculogenesis.  This understanding will inform the optimal conditions for transplanting an appropriate combination of these cells within a mouse focal ischemia model. Publications have resulted from this collaboration, with more in the process.

Accomplishments 2016-2017

  • 2016 Excellence in Clinical Research Mentorship, Department of Surgery (Dr. Ogilvy)
  • 2017 Physician Champion Award, The Brain Aneurysm Foundation (Dr. Ogilvy)
  • Appointed Associate Member of the Broad Institute (Dr. Thomas)

Teaching, Training, and Education

  • G. Galbraith Lecture, The University of Alabama at Birmingham Department of Neurosurgery (Dr. Ogilvy)
  • BIDMC Site Director, combined BIDMC/Boston Medical Center Neurosurgical Residency Program (Dr. Thomas)
  • Fellowship Director, Endovascular and Operative Neurovascular Fellowship, BIDMC (Dr. Thomas)

Abstracts, Posters, and Exhibits

Griessenaeuer CJ, Chua M, Hanafy K, Tachie Y, Chen A, LeBlanc R, Patel A, Salem M, Karumanchi A, Ogilvy CS, Thomas A. Anti-angiogenic factor soluble fms-like Tyrosine Kinase-1 (sFlt-1) identifies patients at risk for severe cerebral vasospasm the first day after aneurysmal subarachnoid hemorrhage. Congress of Neurological Surgeons Meeting, Boston MA, 2017 (poster) Phan K, Dmytriw A, Griessenauer CJ, Moore J, Ogilvy CS, Thomas A. Endovascular thrombectomy alone versus combined intravenous thrombolysis and thrombectomy: A systematic review and Meta-analysis. Congress of Neurological Surgeons Meeting, Boston, MA, 2017 (poster)

Schmalz P, Sneh G, Alturki A, Stapleton CJ, Thomas A, Ogilvy CS. Outcome of combined endovascular and surgical treatment of unruptured anterior communicating artery aneurysm: Changing indications for intervention in the modern era. Congress of Neurological Surgeons Meeting, Boston, MA, 2017 (poster)

Adeeb N, Ogilvy CS, Hussain S, Hakeem S, Moore J, Foreman P, Dmytriw A, Gupta R, Limbucci N, Mangiafico S, Kumar A, Michelozzi C, Zhang Y, Pereira V, Matouk C, Harrigan M, Siddiqui A, Levy E, Renieri L, Marotta T, Cognard C, Thomas A. Incidence of branch occlusion and ischemic complications following pipeline embolization of posterior circulation aneurysm. Congress of Neurological Surgeons Meeting, Boston, MA, 2017 (poster)

Motiei-Langroudi R, Stippler M, Alturki A, Griessenauer E, Kasper E, Arle J, Alterman R, Ogilvy CS, Thomas A. Factors predicting the need for surgery of the opposite side after unilateral evacuation of bilateral chronic subdural hematomas. Congress of Neurological Surgeons Meeting, Boston, MA, 2017 (poster)

Selected Publications

Adeeb N, Griessenauer CJ, Foreman PM, Moore JM, Shallwani H, Motiei-Langroudi R, Alturki A, Siddiqui AH, Levy EI, Harrigan MR, Ogilvy CS, Thomas AJ. Use of platelet function testing before pipeline embolization device placement: A multicenter cohort study. Stroke 2017;48(5):1322-1330.

Griessenauer J, Adeeb N, Foreman PM, Gupta R, Patel AS, Moore J, Abud TG, Thomas AJ, Ogilvy CS, Baccin CE. Impact of coil packing density and coiling technique on occlusion rates for aneurysms treated with stent-assisted coil embolization. World Neurosurg  2016;94:157-166.

Griessenauer CJ, Ogilvy CS, Foreman PM, Chua MH, Harrigan MR, He L, Fusco MR, Mocco JD, Stapleton CJ, Patel AB, Sonig A, Siddiqui AH, Thomas AJ. Pipeline embolization device for small intracranial aneurysms: Evaluation of safety and efficacy in a multicenter cohort. Neurosurgery 2017;80(4):579-587.

Gupta R, Moore JM, Adeeb N, Griessenauer CJ, Patel AS, Chua MH, Thomas AJ, Ogilvy CS. Clinical presentation, progression, and treatment outcomes of moyamoya disease in the elderly. Acta Neurochir (Wien) 2016;158(12):2409–2414.

Gupta R, Moore JM, Griessenauer CJ, Adeeb N, Patel AS, Youn R, Poliskey K, Thomas AJ, Ogilvy CS. Assessment of dual-antiplatelet regimen for pipeline embolization device placement: A survey of major academic neurovascular centers in the United States. World Neurosurg 2016;96:285–292.

Ogilvy CS, Motiei-Langroudi R, Ghorbani M, Griessenauer CJ, Alturki AY, Thomas AJ. Flow diverters as useful adjunct to traditional endovascular techniques in treatment of direct carotid-cavernous fistulas. World Neurosurg 2017;105:812–817.