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​Translational and laboratory research are a central mission of the Division of Neurosurgery. The division has several collaborations with the UC San Diego School of Medicine, the Scripps Research Institute, the Salk Institute, and industry partners.

A significant portion of our research is focused on clinical investigations pertaining to the diagnosis and surgical treatment of patients with cerebrovascular diseases, including large cerebral vessel occlusions, aneurysms/arteriovenous malformations, and carotid stenosis.

Our group has curated a large institutional database of patients treated with endovascular techniques to identify areas for quality improvement and enable comparative cost-effectiveness research. Additionally, our group leads several prospective studies including a multi-site randomized clinical trial comparing methods of CSF drainage for aneurysmal SAH and the impact of carotid stenting in patients with carotid artery disease on neurocognition.

Cerebrovascular Research Group

 Prospective Studies

  • Antihypertensive effects of carotid stenting
  • Lumbar versus External Ventricular CSF Drainage after Aneurysmal Subarachnoid Hemorrhage: A Randomized Prospective Clinical Trial.

Retrospective Studies

  • Thrombectomy outcomes
  • Quality improvement protocols
    • Door to puncture time in ischemic stroke


  • Identifying biomarkers for traumatic brain injury
  • Utilizing 4D Flow MR Angiography to characterize vascular pathology

Institutional Database

  • Prospectively maintained
    • Carotid stenting & endarterectomy
    • Thrombectomy for large vessel occlusion
    • Aneurysm clipping and coiling
    • Arteriovenous malformation embolization and resection
    • Tumor embolization

Big Data

  • Healthcare disparities research
  • Comparative effectiveness research
  • Volume-outcome relationships

Cost Effectiveness Research/Health Services Research

  • Cost Effectiveness of surgical/endovascular treatment of neurovascular pathology


  • TL1 Long Term Training Grants
    • Arvin R. Wali
    • Michael G. Brandel
    • Peter Abraham

Medical Student Education

  • Masters in Clinical Research
    • Arvin R. Wali
    • Michael G. Brandel
    • Christian Lopez

Prior Cerebrovascular/Endovascular Fellows

  • J. Scott Pannell
  • Vincent Cheung
  • Jeff Steinberg
  • David Santiago--Dieppa
  • Robert Rennert

Medical Student Research Leaders and Academic Mentors

  • Arvin R. Wali
  • Michael G. Brandel
  • Christian Lopez

Publication Highlights

  1. Wali AR, Brandel MG, Santiago-Dieppa DR, Rennert RC, Steinberg JA, Hirshman BR, Khalessi AA. Markov Modeling for the Neurosurgeon: A Review of the Literature and Introduction to Cost-Effectiveness Research. Neurosurgical Focus. May 2018. In Press.
  2. Brandel MG, Rennert RC, Wali AR, Santiago-Dieppa DR, Steinberg JA, Lopez Ramos C, Abraham P, Pannell JS, Khalessi AA. The Impact of Preoperative Endovascular Embolization on Immediate Meningioma Resection Outcomes. Neurosurgical Focus. April 2018. In Press.
  3. Santiago-Dieppa DR, Steinberg JA, Brandel MG, Rennert RC, Cheung VJ, Wali AR, Olson SE, Khalessi AA, Pannell JS. The Balloon Bridge: A Novel Technique for Reaccessing a Carotid Artery Stent. World Neurosurg. 2018 Feb 23. PMID: 29482008
  4. Rennert RC, Steinberg JA, Cheung VJ, Santiago-Dieppa DR, Pannell JS, Khalessi AA. Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations. J Vis Exp. 2017 Oct 20;(128). PMID: 29155706
  5. Sack J, Steinberg JA, Rennert RC, Hatefi D, Pannell JS, Levy M, Khalessi AA. Initial Experience Using a High-Definition 3-Dimensional Exoscope System for Microneurosurgery. Oper Neurosurg (Hagerstown). 2017 Jun 29. PMID: 29106670
  6. Wali AR, Park CC, Santiago-Dieppa DR, Vaida F, Murphy JD, Khalessi AA. Pipeline embolization device versus coiling for the treatment of large and giant unruptured intracranial aneurysms: a cost-effectiveness analysis. Neurosurg Focus. 2017 Jun;42(6):E6. PMID: 28565986
  7. Sack J, Cheung V, Amaro D, Wali AR, Santiago-Dieppa DR, Pannell JS, Khalessi AA. Surgical Resection and Histopathological Analysis of a Thrombosed Giant Fusiform MCA Aneurysm After Initial Treatment with a Flow Diversion Construct. World Neurosurg. 2017 Jul;103:348-354. PMID: 28433850
  8. Abraham P, Scott Pannell J, Santiago-Dieppa DR, Cheung V, Steinberg J, Wali A, Gupta M, Rennert RC, Lee RR, Khalessi AA. Vessel wall signal enhancement on 3-T MRI in acute stroke patients after stent retriever thrombectomy. Neurosurg Focus. 2017 Apr;42(4):E20. PMID: 28366071
  9. Santiago-Dieppa DR, Hirshman BR, Wali A, Scott Pannell J, Alam Y, Olson S, Cheung VJ, Steinberg JA, Gupta M, Khalessi AA. The circle of Willis predicts the antihypertensive effects of carotid artery stenting. Neurosurg Focus. 2017 Apr;42(4):E18. PMID: 28366069
  10. Gupta M, Cheung VJ, Abraham P, Wali AR, Santiago-Dieppa DR, Gabel BC, Almansouri A, Pannell JS, Khalessi AA. Low-profile Visualized Intraluminal Support Junior Device for the Treatment of Intracranial Aneurysms. Cureus. 2017 Feb 17;9(2):e1037. PMID: 28357169

New Grants

​PI Name
​Research Title
​Funding Source


​Modulation of spinal neurodegenerative diseases in swine by stem cell grafting.

​NIH (Federal)


A Phase 1/2a Dose Escalation Study of AST-OPC1 in Subjects with Subacute Cervical Spinal Cord Injury
Asterias (Non-Federal)

Pilot Study of Clinical Safety and Feasibility of the PILGA-POLY-L-LYSINE Scaffold for the Treatment of Complete ASIA A Traumatic Acute Spinal Cord Injury 

In Vivo (Non-Federal)​