Clinical Neurosurgery Research Group (CNRG)

Overview

CNRG was founded in 2022 by medical and pre-medical students and is advised by faculty in the Department of Neurosurgery at MGH. Our members have specialized roles that promote a highly coordinated research workflow. The vision at CNRG is to establish a collaborative environment between individuals at all stages in their neurosurgery training through research initiatives, longitudinal mentorship, and clinical opportunities. Our mission is to advance the field of neurosurgery by producing rigorous and impactful research while raising the next generation of neurosurgeons through mentorship, exposure, and a dedication to collaboration.

Research Projects

We coordinate multiple projects simultaneously across three areas: Clinical Neurosurgery (novel imaging and treatment approaches including navigated intraoperative ultrasound); Medical Education (developing and evaluating tools for neurosurgery training, including a sub-internship academy); and Global Neurosurgery and Leadership (assessing methods for professional development and mentorship on a global scale, including the annual Mission Brain Hackathon).

Faculty Advisors

Brian Nahed, MD, MSC

Dr. Brian Nahed is a neurosurgeon specializing in Brain Tumors (Glioblastoma, Low Grade Gliomas, Meningiomas, Metastatic Brain Tumors) and Brain Mapping / Intraoperative Imaging. He is Director of Neurosurgery Residency Program at MGH and Harvard Medical School and Associate Professor of Neurosurgery.

Dr. Nahed specializes in brain tumors of the eloquent cortex (language and motor areas of the brain) which require awake surgery, language and motor mapping, and subcortical stimulation. Dr. Nahed specializes in intraoperative technology and minimally invasive procedures to treat brain tumors aggressively and safely.
Born in New York, Dr. Nahed attended UCLA where he majored in Neuroscience, graduating Phi Beta Kappa and with the department's Highest Honors. He attended the Yale School of Medicine where he was awarded the Doris Duke Clinical Research Fellowship and graduated with honors. Dr. Nahed completed his neurosurgery residency at the Massachusetts General Hospital; where Dr. Nahed completed a postdoctoral fellowship with Drs. Daniel Haber and Shyamala Maheswaran in the MGH Cancer Center.

Dr. Brian Nahed was recruited to the MGH Department of Neurosurgery, MGH Brain Tumor Center, and Harvard Medical School in 2011. Dr. Brian Nahed's research focuses on developing the first blood based test to diagnose and monitor brain tumors. In collaboration with Drs. Haber, Maheswaran, and Stott, Dr. Nahed published the first evidence of circulating tumor cells in the blood of patients with glioblastoma. Drs Nahed and Stott run an NIH funded laboratory developing the first blood test for patients with brain tumors.

As the Director of the MGH Neurosurgery Residency Program, he has led neurosurgical education. He serves on the Executive Committee of the Congress of Neurological Surgeons and the CNS/AANS Executive Committee For Brain Tumors. He is Co-Chair of the CNS Leadership Institute. He is an active member of the American Association of Neurological Surgeons and Council State Neurological Societies. Dr. Nahed serves as the lead neurotrauma consultant for the National Football League (NFL).

Bryan Choi, MD, PhD

Dr. Bryan Choi, MD, PhD is an attending neurosurgeon in the Department of Neurosurgery and the Stephen E. and Catherine Pappas Center for Neuro-Oncology. He specializes in surgical care for patients with benign and malignant brain tumors. Born in Cleveland, Ohio, Dr. Choi graduated summa cum laude from Harvard College and attended Duke University School of Medicine, where he completed dual MD and PhD training in the field of tumor immunology under the guidance of Drs. John Sampson and Darell Bigner. During his neurosurgery residency at the Massachusetts General Hospital, he pursued a postdoctoral fellowship in the laboratory of Dr. Marcela Maus, focused on developing CAR T-cell therapies for cancer. He has published broadly, holds several patents, and has lectured internationally on immune-based treatments for brain tumors. Dr. Choi was recruited to join the faculty of the MGH Brain Tumor Center and Harvard Medical School where he is currently in active practice. He also leads a research laboratory with the goal of developing the next generation of cell therapies and clinical trials in neuro-oncology.

Ganesh Shankar, MD, PhD

Dr. Ganesh Shankar is a board-certified neurosurgeon at the Massachusetts General Hospital. He completed his neurosurgery residency at Mass General and a fellowship in complex spine surgery at the Cleveland Clinic. His clinical specialization encompasses the evaluation and surgical management of all spine pathologies, ranging from degenerative disorders, primary and metastatic spine tumors, intradural pathologies, spine infections, and spine trauma. His surgical approaches include minimally invasive techniques. He specializes in complex spine procedures requiring revision surgery and correction of spine deformities.

Dr. Shankar also performs research on bone biology and molecular determinants of primary and metastatic spine neoplasms. He serves as the Neurosurgical Director of Biospecimen Banking for the Department of Neurosurgery. His research has been recognized by awards from the American Association of Neurologic Surgeons, Congress of Neurological Surgeons, Joint Section on Disorders of the Spine and Peripheral Nerves, and AO Spine North America.

William Curry, MD

Dr. William Curry is an attending in the Department of Neurosurgery and in the Pappas Center for Neuro-oncology. He provides surgical care for patients with benign and malignant tumors of the brain, skull-base, and spine.

Dr. Curry is a graduate of Harvard College, attended Cornell University Medical College in New York City and trained in Neurosurgery at Massachusetts General Hospital. He has been on the neurosurgical faculty at Mass General Hospital since 2004. He is a national leader in the neurosurgical care of patients with tumors of the brain, skull-base, and spine. He is highly skilled in both open and endoscopic/minimally invasive techniques and is known for his ability to handle the most advanced surgical challenges. Dr. Curry leads and participates in multiple clinical trials for patients with brain tumors and is particularly interested in the development of cellular and immune-based therapies for malignant tumors. He is an integral part of the Pappas Center for Neuro-oncology, the MGH/MEEI Cranial Base Center, and the Harris Chordoma Center at Massachusetts General Hospital.

Student Members

Mercy Mazurek - Team Lead

Mercy Mazurek is an MD candidate at Harvard Medical School where she serves as Team Lead of CNRG. She graduated Phi Beta Kappa from the University of Virginia with a B.S. in Biochemistry. As an undergraduate, she conducted clinical research in the Neurology Department to develop an AI mobile application to detect stroke in low-resource settings as well as worked on subsampling PET imaging in a computational medical physics lab. After graduation, she spent three years at Yale leading the first deployment of the Hyperfine low-field, portable MRI brain scanner across clinical settings. She is currently conducting research with Dr. G. Rees Cosgrove at Brigham and Women's Hospital, leading projects on treatment outcomes, patient selection, and lesion characteristics in a cohort of 700+ patients treated with MR-guided focused ultrasound thalamotomy. Her research spans intraoperative neuroimaging, neuro-oncology, surgical education, MR-guided focused ultrasound, and global neurosurgery, with a focus on leveraging multimodal neuroimaging to guide neurosurgical procedures and expand access to advanced neuroimaging methods. Her work has been published in Nature Communications, JAMA Neurology, Science Advances, Stroke, and Operative Neurosurgery, among others, with 1,200+ citations.

Zsombor Gal - Technology Lead

Zsombor graduated from Princeton University summa cum laude, majoring in Molecular Biology with a Certificate in Neuroscience and will graduate Harvard Medical School with his MD in May 2026. He is an incoming resident in the combined MGB Neurosurgery Residency Program. Zsombor co-founded the Clinical Neurosurgery Research Group at MGH and conducted research across BWH and Boston Children's Hospital, contributing to the most comprehensive global neurosurgery workforce assessment to date, a multivariable outcomes analysis of salvage surgery for recurrent brain metastases, and two original chapters and three updated chapters for the ISPN Guide, with numerous peer-reviewed publications and presentations at CNS, AANS, and WFNS. In June 2025, he traveled to The Gambia to support the MGB-EFSTH neurosurgical partnership, leading data collection for a prospective AI-assisted ward care study in collaboration with OpenAI and serving as first author on a case report describing the first epilepsy surgery performed in the country. Prior to medical school, he received the Sigma Xi Book Award for Outstanding Thesis Research, the United States Presidential Scholar Award, and the Jack Kent Cooke Foundation Graduate Scholar Award.

Nikki Pérez – Personnel and Operations Lead

Nicole “Nikki” Perez, BA is a MD candidate at Harvard Medical School with a passion for neurosurgical oncology and global neurosurgery. She serves as US Regional Chair of Research for the Mission:Brain organization, founding member of the Clinical Neurosurgery Research Group at MGH, Steering Team Student Lead for the 2025-2030 Boston Declaration Initiative, and founding member and technical co-lead for the International Society of Global Neurosurgery (ISGNS). Through her work with Mission:BRAIN, she has co-organized several annual global hackathon events and leads an international peer mentorship program that aims to expand access to neurosurgical research opportunities in low-resource settings. At MGB, she has also helped to develop and lead educational programming, such as the Neurosurgery Pre-Clerkship Bootcamp, Neurosurgery Sub-Internship Bootcamp, and MGB Surgical Leadership Day. Upon her graduation from Harvard in May 2026, Nikki will join the Barrow Neurological Institute as a neurosurgery resident. At the BNI, she plans to continue her work with Barrow Global developing affordable, sustainable, and humanistic innovations that improve patient care both within and beyond the operating room.

Timothy West – Administrative Lead

Timothy is an MD candidate and Cornelius Vanderbilt Scholar at the Vanderbilt University School of Medicine. Prior to medical school, Timothy graduated with honors from The Johns Hopkins University with a Bachelors of Science in Neuroscience before spending multiple years as a clinical researcher with MGH Neurosurgery, where his work focused on intraoperative technology and decision-making in addition to global neurosurgery and neurosurgical education. His work includes several peer-reviewed publications and presentations at the CNS and AANS. In 2023, he received the Elekta Tumor Section Award from the AANS/CNS Section on Tumors for his work on navigated intraoperative ultrasound. Timothy is a founding member of CNRG and also serves as North America Regional Director of Mission:Brain and Executive Team Lead for the Mission:Brain Global Neurosurgery Hackathon. He also played key roles in Mission:Brain’s successful efforts to build the first neurosurgical infrastructure in Sierra Leone and continues to lead initiatives to procure and supply neurosurgical equipment to under-resourced clinics worldwide.

Alexander Wang – Member

Alexander is a third-year medical student at Case Western Reserve School of Medicine. He was born in Vancouver, Canada and graduated magna cum laude with departmental honors from UCLA with a Bachelor of Science in Neuroscience. In college, he was awarded the Arnold B. Scheibel Scholarship for his undergraduate research investigating correlates of traumatic brain injury. In medical school, he has been granted the Jack and Fay Netchin Medical Student Research Fellowship awarded by the American Brain Tumor Association, the Warren Selman Medical Student Research Fellowship by University Hospitals Department of Neurosurgery, and the Case Comprehensive Cancer Center Medical Student Training Award. He is also the vice president of the American Association for Neurological Surgeons chapter at CWRU SOM. He is interested in immunotherapy for glioblastoma and is actively involved in ongoing research investigating steroid-induced barriers to active immunotherapy in myeloid cells.

Ethan Wetzel – Member

Ethan is a medical student at Harvard Medical School. Originally from Modesto, CA, Ethan attended the University of California, Los Angeles where he graduated summa cum laude and received the Neuroscience Department’s Highest Research Distinction. As an undergraduate, Ethan pursued his passion for neuro-oncology and neurosurgery in the Lai Laboratory where he worked to improve the standard of care for glioma patients by identifying radiographic criteria to differentiate true tumor progression from pseudoprogression. Ethan also cofounded the Institute of Neuro Innovation, a non-profit organization aimed at improving access to care for under-resourced patients with neurological diseases. After graduation, Ethan continued his neuro-oncology work in the Cahill Lab where he focused on exploiting metabolic vulnerabilities of IDH-mutant gliomas. As a medical student Ethan is passionate about continuing to improve the care of brain tumor patients, while ensuring access to care.

Publications

View all CNRG publications

Peer-Reviewed Publications

1. Mazurek MH, Maguire AJ, Sixkiller JD, et al. Use of a Novel Intraoperative Neurocognitive Monitoring Task During Awake Craniotomy for Tumor Resection in the Language-Dominant Parietal Lobe. Oper Neurosurg. Published online February 18, 2026. doi:10.1227/ons.0000000000001933
2. West TR, Perez NA, Adubofour K, et al. Protocol for the systematic reduction of sterile surgical instrument waste: a single-institution prospective implementation and analysis. J Neurosurg. 2025;144(3):729-738. Published 2025 Dec 26. doi:10.3171/2025.8.JNS251183
3. Mazurek MH, Bassa MJ, Padayachy L, et al. An International Course on Intraoperative Ultrasound in Neurosurgery: Evaluation of a Multi-center, Hands-on Courses in Promoting Familiarity and Use of Intraoperative Ultrasound in Neurosurgery. World Neurosurg. Published online September 29, 2025. doi:10.1016/j.wneu.2025.124524
4. Wetzel EA, Fournier G, Huckins D, et al. Emergency TeleNeurosurgery Physician Consultation Program and Associated Health Care Utilization Benefits. Neurosurgery. Published online December 16, 2025. doi:10.1227/neu.0000000000003883
5. Gal ZT, Wetzel EA, Nahed BV, et al. Efficacy of bone-modifying agents in preventing vertebral complications of multiple myeloma: a systematic review and meta-analysis. Spine J. 2026;26(4):806-820. doi:10.1016/j.spinee.2025.10.018
6. Perez NA, Gal ZT, Muñoz W, et al. Early exposure to neurosurgery: promoting early specialty interest through a single-day resident-driven neurosurgical course for preclinical students. J Clin Neurosci. 2025;141:111612. doi:10.1016/j.jocn.2025.111612
7. Gal ZT, Nanda P, Hsueh B, et al. Sub-Internship Academy: Implementation and Evaluation of Single-Day Resident-Driven Focused Sub-Internship Preparation Course. World Neurosurg. 2025;193:533-542. doi:10.1016/j.wneu.2024.09.127
8. Razak SS, West TR, Tunsiricharoengul S, et al. International Hackathon as a Tool to Augment Education, Collaboration, and Innovation in Global Neurosurgery. Neurosurgery. 2024;95(2):480-486. doi:10.1227/neu.0000000000002991
9. West TR, Mazurek MH, Perez NA, et al. Navigated Intraoperative Ultrasound Offers Effective and Efficient Real-Time Analysis of Intracranial Tumor Resection and Brain Shift. Oper Neurosurg. 2025;28(2):148-158. doi:10.1227/ons.0000000000001250

Oral Presentations

1. Gal Z, Gabriel D, Wetzel E, See AP, Hogue G. Nontraumatic atlantoaxial rotatory subluxation (Grisel's syndrome) in the pediatric population: a systematic review and management algorithm. Presented at: Congress of Neurological Surgeons Annual Meeting; 2025 Oct 11–15; Los Angeles, CA.
2. Wang A, West T, Perez N, Mazurek M, Gal Z, Wetzel E, Choi B, Salvucci M, Nahed B. A single-institution analysis of removed instruments after implementing a protocol designed to minimize neurosurgical instrument waste. Presented at: Congress of Neurological Surgeons Annual Meeting; 2025 Oct 11–15; Los Angeles, CA.
3. West T, Mazurek M, Perez N, Wang A, Wetzel E, Gal Z, Choi B, Nahed B. Navigated intraoperative ultrasound with rigid image fusion decreases neuronavigation inaccuracies following brain shift. Presented at: Congress of Neurological Surgeons Annual Meeting; 2025 Oct 11–15; Los Angeles, CA.
4. Wetzel E, Holt G, Stehr P, Li L, Wang A, Mazurek M, Perez N, West T, Gal Z, Razak S, Nahed B. Decreased race reporting in clinical trials after 2016: analysis of 10,384 participants across 162 studies. Presented at: American Association of Neurological Surgeons Annual Meeting; 2025 Apr 25–28; Boston, MA.
5. Gal ZT, Nanda P, Hsueh B, Robertson FC, Razak S, Mazurek M, West T, Perez N, Jones PS, Coumans J, Nahed BV. Sub-internship academy: implementation and evaluation of single-day resident-driven focused sub-internship preparation course. Presented at: Congress of Neurological Surgeons Annual Meeting; 2023 Sep 9–13; Washington, DC.
6. West T, Mazurek M, Razak SS, Gal Z, Perez N, Burrows A, Choi B, Nahed B. Impact of navigated intraoperative ultrasound on brain shift and gross tumor resection. Presented at: Congress of Neurological Surgeons Annual Meeting; 2023 Sep 9–13; Washington, DC.

Poster Presentations

1. Wetzel E, Fournier G, West T, Gal Z, Perez N, Mazurek M, Wang A, Stapelton C, Nahed B. Emergency teleneurosurgery physician consultation program and associated healthcare utilization benefits. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2025 Oct 11–15; Los Angeles, CA.
2. Mazurek M, Maguire A, Sixkiller J, West T, Perez N, Wang A, Wetzel E, Gal Z, Ritzl E, Choi B, Rapalino O, Nahed B. Use of a novel intraoperative neurocognitive monitoring task during awake craniotomy resection for tumors in the language-dominant parietal lobe. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2025 Oct 11–15; Los Angeles, CA.
3. Gal Z, Wetzel E, Nahed B, Saylor P, Hirsch J, Marciscano A, Raje N, Tobert D, Yee A, Shankar G. Zoledronate as the most effective agent for vertebral fracture prevention in multiple myeloma: a network meta-analysis. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2025 Oct 11–15; Los Angeles, CA.
4. Gal ZT, Wetzel EA, West TR, Razak SS, Nahed BV, Shankar GM. Efficacy of bone-modifying agents in preventing vertebral complications of multiple myeloma: a systematic review and meta-analysis. Poster presented at: American Association of Neurological Surgeons Annual Meeting; 2025 Apr 25–28; Boston, MA.
5. Razak S, Gal Z, Wetzel E, West T, Nair-Kanneganti A, Leavitt L, Punchak M, Navarro Garcia de Llano JP, Hassan T, Perez N, Wang A, Mazurek M, Lawton M, Nahed B, Quiñones-Hinojosa A. Fostering global neurosurgical innovation and collaboration through virtual hackathons. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2024 Sep 28–Oct 2; Houston, TX.
6. Perez N, West T, Mazurek M, Wetzel E, Wang A, Gal Z, Razak S, Choi B, Rapalino O, Nahed B. Automated diffusion tensor imaging (DTI) tractography in patients with multifocal gliomas reveals changes in white matter architecture with glioma infiltration. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2024 Sep 28–Oct 2; Houston, TX.
7. Razak S, Wang A, Smith C, Safa A, West T, Perez N, Mazurek M, Gal Z, Wetzel E, Li L, Shankar G, Choi B, Curry W, Stapleton C, Salvucci M, Nahed B. Comparative cost analysis of autologous and synthetic skull implants for cranioplasty using time-driven activity-based costing. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2024 Sep 28–Oct 2; Houston, TX.
8. Perez N, West T, Adubofour K, Li L, Gal Z, Mazurek M, Razak S, Salvucci M, Nahed B. Protocol to reduce neurosurgical instrument waste: evaluation of a prospective single institution intervention. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2024 Sep 28–Oct 2; Houston, TX.
9. Razak S, West T, Wang A, Wetzel E, Li L, Mazurek M, Gal Z, Perez N, Wang A, Coumans J, Plotkin S, Barker F, Rapalino O, Iliopoulos O, Nahed B. Delineating growth dynamics and surgical indicators in VHL-associated and sporadic hemangioblastomas. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2024 Sep 28–Oct 2; Houston, TX.
10. Perez N, Gal Z, Muñoz W, Hsueh B, Nanda P, Nahed B. Early exposure to neurosurgery: evaluation of a single-day resident-driven neurosurgical course for pre-clerkship students. Poster presented at: Congress of Neurological Surgeons Annual Meeting; 2024 Sep 28–Oct 2; Houston, TX.