Weill Cornell Medicine provides a highly competitive, demanding environment for neurosurgery residents. Our seven-year program produces some of the top neurosurgeons in the country. About the Program

John Chae, MD
Full Bio
John Chae received his MD this year from Weill Cornell Medical College, where he was a member of Alpha Omega Alpha, the national medical student honor society. During his tenure at Weill Cornell, John was awarded the 2019 Siegel Family Student Prize for high academic achievement and leadership as well as the 2018 Marcus M. Reienberg, M.D. Award in Community Service. He received a Bachelor of Arts in chemistry from Williams College, where he was a member of Phi Beta Kappa. John has been an active member of the Weill Cornell Medicine AANS Neurosurgery Interest Group, where he twice directed the Medical Student Neurosurgery Training Camp, and helped organize a medical student publication group. John has served as a mentor with HPREP, designed to boost medical school enrollment rates of underrepresented groups. Among his research projects are several conducted under the mentorship of Dr. Jeffrey Greenfield on congenital brain malformations, including the creation of a novel pathophysiology-based classification system.

Andrew Garton, MD
- Now Available: Intracranial Arteriovenous Malformations, Essentials for Patients and Practitioners
- Thank a Resident Day 2023
- WCM Medical Student Rachael Han Awarded Best Chiari Paper at Peds Section 2022
- Dr. Garton Awarded Resident Traveling Fellowship
- Covid on the Cover of World Neurosurgery
- Match Day 2019: New Residents in Neurological Surgery
Full Bio
Andrew Garton is a chief resident, having completed his undergraduate degree at the University of Michigan and his medical education at the Columbia University College of Physicians and Surgeons, where he was a member of both the medical student honor society Alpha Omega Alpha and the Gold Humanism Honor Society. During residency, he completed a CAST-accredited fellowship in endovascular neurosurgery, including a focus on pediatric cerebrovascular neurosurgery that involved rotating at Boston Children's Hospital. His publications have included first-author manuscripts in Neurosurgery, Journal of Neurosurgery, Stroke, Journal of Neurointerventional Surgery, Journal of Neurooncology, and World Neurosurgery. In his free time, he enjoys running, cycling, rock climbing, hiking, and cocktail-making.

Sergio Guadix, MD
Full Bio
Dr. Guadix received his MD in 2023 from Weill Cornell Medical College, where he was a member of Alpha Omega Alpha, the medical student honor society. During his time here at Weill Cornell, Dr. Guadix has gotten to know the neurosurgeons well. He has conducted research in endovascular neurosurgery alongside Dr. Jared Knopman, worked on imaging studies in craniosynostosis with Dr. Caitlin Hoffman, and co-authored a series of academic papers on neurosurgery during Covid and another paper on stereotactic radiosurgery with Dr. Susan Pannullo.
Dr. Guadix took a year off from his medical studies to work under the mentorship of Dr. Mark Souweidane as the Rudin Medical Student Fellow in Pediatric Neuro-oncology, researching enhanced drug delivery systems for pediatric brain tumors. He was awarded the 2022 ChadTough Defeat DIPG Foundation Gamechanger Grant to continue those studies. Dr. Guadix received his bachelor’s degree in cognitive science from the University of Pennsylvania, then completed a yearlong post-baccalaureate pre-medical program at Johns Hopkins University before attending Weill Cornell Medical College.

Natasha Kharas, MD, PhD
Full Bio
Dr. Natasha Kharas received her MD and PhD degrees from McGovern Medical School at the University of Texas Health Science Center at Houston. A native New Yorker, Natasha earned her undergraduate degree in neural science (with highest honors) from NYU before enrolling in the MD/PhD program at McGovern, where she was elected to the medical student honor society Alpha Omega Alpha. Dr. Kharas has been working with Dr. Casey Halpern’s lab at Stanford University to examine the role of intracranial stimulation in epilepsy, and with Dr. David Sandberg at McGovern on a translational research project examining the safety and pharmacokinetics of injecting the chemotherapy drug panobinostat directly into the fourth ventricle to treat posterior fossa tumors in children. She received an NIH F31 grant for her PhD dissertation research, which examined the neural underpinnings of how sleep improves cognitive performance; she also performed research that examined the neural basis for how unconscious visual stimuli alter behavior.

Alexandra Giantini Larsen, MD
- Dr. Larsen Wins 2024 Gaposchkin Prize for Resident Research
- Now Available: Intracranial Arteriovenous Malformations, Essentials for Patients and Practitioners
- Dr. Larsen Wins Top Honor at NYSN Resident Research Night
- Dr. Giantini-Larsen Named 2023-2024 Neurosurgery Publications Resident Deputy Fellow
- Dr. Larsen Awarded Grants to Boost Diversity in Neurosurgery
- Thank a Resident Day 2023
- WCM Medical Student Rachael Han Awarded Best Chiari Paper at Peds Section 2022
- Dr. Justin Schwarz Wins Stieg Award for Resident Education
- Covid on the Cover of World Neurosurgery
- Match Day 2019: New Residents in Neurological Surgery
Full Bio
Alexandra Giantini Larsen is a graduate of Harvard Medical School, where she was vice president of the AANS medical student chapter and co-president of the Harvard Medical School chapter of the Association of Women Surgeons. She earned her bachelor’s degree with honors in Molecular and Cellular Biology at Johns Hopkins University.
Dr. Larsen spent a year as a Howard Hughes Medical Institute Medical Research Fellow in the laboratory of Dr. E. Antonio Chiocca, Chair of Neurosurgery at Brigham and Women's Hospital in Boston, where her research was focused on viral therapies for glioblastoma. She also has spent time as a researcher in the Vascular Biology Program at Boston Children's Hospital with Dr. Edward Smith and in the Brain Tumor Stem Cell Laboratory at Johns Hopkins Hospital with Dr. Alfredo Quinones-Hinojosa. She was an observer in our own department during her college years, when we recognized her emerging talents, and we are delighted to have her join us for her residency.

Lily McLaughlin, MD
Full Bio
Lily McLaughlin received her MD in 2024 from Georgetown University School of Medicine, where she was a member of the Gold Humanism Honor Society. We met Lily last summer, when she completed a sub-internship month that showed her to be extremely talented, responsible, and committed to patient care. Prior to medical school, Lily earned a master’s degree in biomedical studies at Drexel University after completing her bachelor’s degree in biology at Villanova. She has co-authored numerous academic research papers, many of them with colleagues from Memorial Sloan Kettering, where she spent three years as a clinical research associate. She has researched and presented on healthcare disparities and participated in mentoring programs and community health initiatives.

Kate Rosen, MD
Full Bio
Kate Rosen was raised by two teachers and grew up in Salem, Oregon, on a healthy diet of art museums, hiking trips, and Tom Petty. As an undergraduate she attended Santa Clara University, where she studied chemistry, biology, and public health while also working as a volunteer EMT. After graduating, she worked in quality improvement at Stanford Children's Health using clinical informatics and systems-based thinking to improve healthcare. She then received her MD from the Oregon Health & Science University School of Medicine, where she was a member of Alpha Omega Alpha, the national medical student honor society, and of the Gold Humanism Honor Society, which recognizes senior medical students for excellence in compassionate clinical care. Dr. Rosen has been a mentor to students under-represented in medicine and is one of the founders of The Differentialists, a student group formed to build diagnostic reasoning skills. Her research has included studying delayed cerebral ischemia after pituitary macroadenoma resection, and her study of fluid overload in pediatric ICU patients was named Best Abstract by a Trainee at the annual meeting of the American Academy of Pediatrics (AAP). She strives to specialize in neuro-oncology, with a focus on clinical trials and immunotherapy. In her free time Dr. Rosen likes to run marathons and climb mountains.

David Sykes, MD
Full Bio
David Sykes received his MD in 2024 from Duke University School of Medicine, where he was a Medical Student Member of both the AANS and CNS and was awarded an AO Spine Young Investigator Research Grant Award. Before medical school, David earned his bachelor’s degree in biochemistry and music from Washington University in St. Louis. He has conducted clinical research in the spine division at Duke and has worked in the Brain Tool Lab, where medicine and engineering come together in the development of novel technologies. He has co-authored many peer-reviewed articles, primarily on spinal tumors, injuries, and degeneration, and has studied the use of advanced technologies such as augmented reality in neurosurgery. David completed a sub-internship with us last year and proved himself to be both talented and collaborative.

Nalini Tata, MD, MPP
Full Bio
Dr. Nalini Tata received her medical degree from Northwestern University’s Feinberg School of Medicine, where she was elected to the Alpha Omega Alpha medical student honor society, with a concurrent Master of Public Policy (MPP) degree from the Harvard Kennedy School of Government. Dr. Tata received her undergraduate degree in neurobiology from Brown University, then earned a Master of Philosophy degree from the University of Cambridge in England before enrolling in medical school. As a student researcher with Dr. Rees Cosgrove at Brigham and Women’s Hospital, she helped study asleep DBS practices and outcomes. She has also written about ethics and philosophy of neurosurgical practice during and beyond the time of the Covid-19 pandemic with Dr. Nader Dahdaleh at Northwestern Memorial Hospital.

Umberto Tosi, MD
- New Study Shows Brain Surgery for Colloid Cysts is Cognitively Safe
- Dr. Tosi Wins Second Place at NY Society of Neurosurgery's Resident Research Night
- Dr. Tosi Presents Award-Winning Abstract at CNS 2024
- Dr. Tosi Wins 2024 Apuzzo Award
- Thank a Resident Day 2023
- Covid on the Cover of World Neurosurgery
- Two Papers Show Disparities in Neurosurgical Research and Outcomes
- Match Day 2020: Weill Cornell Medicine Neurological Surgery Welcomes Newest Residents
Full Bio
Umberto Tosi received his medical degree with Honors in Research from Weill Cornell Medical College in 2020. As a medical student, Dr. Tosi worked in the laboratory of Dr. Mark Souweidane of the Children's Brain Tumor Project, investigating novel drug delivery technologies in treating pediatric gliomas. During his tenure as a medical student he was awarded an Alex's Lemonade Stand Foundation POST Grant and the Rudin Pediatric Neuro-oncology Fellowship; upon graduation he won the Harold G. Wolff Research Prize for his work.
As a resident, Umberto has further developed his interest in neurosurgical oncology. He focused his attention to both skull base surgical approaches, under the mentorships of Dr. Souweidane, Schwartz, and Ramakrishna, and tumor biology and development of novel therapeutics, under the mentorship of Dr. Tabar, at Memorial Sloan Kettering.
Dr. Tosi grew up in Italy, then earned his bachelor’s degree summa cum laude from the University of Pennsylvania, double majoring in Biological Basis of Behavior and Chemistry. He was inducted in Phi Beta Kappa in 2015. He completed his Honors Thesis under the supervision of Dr. Jeannie Chin at Jefferson University, investigating the role of early epileptiform activity in the development of epigenetic dysregulation in Alzheimer’s Disease models. In addition to publishing his research with numerous members of the department, Dr. Tosi has mentored medical students in a variety of subjects.