Neurosurgery Clinical Instructors

Mark G. Bigder, BA, HBK, MD, MPH
Cerebrovascular and Skull Base Neurosurgery

Dr Bigder was born and raised in Thunder Bay, Canada where he completed Bachelor of Arts in Psychology and Honours Bachelor of Kinesiology degrees through Lakehead University. He subsequently completed medical school and neurosurgical residency in Winnipeg at the University of Manitoba. During his residency, Dr Bigder completed a Master of Public Health degree in epidemiology at Harvard TH Chan School of Public Health. He has published research articles on Gamma Knife radiosurgery, microvascular decompression and various public health topics, and has presented his work at international conferences including the International Stereotactic Radiosurgery Society Congress, Congress of Neurological Surgeons and European Public Health Conference among others.

Dr Bigder has been involved in several leadership roles including serving as the Canadian Neurosurgical Society National Resident Representative, member of the Canadian Neurological Sciences Federation Scientific Planning Committee and member of the Canadian Neurosurgical Research Collaborative.

Dr Bigder, along with his wife Sara, together enjoy running, hiking and spending time in the outdoors with their daughter and two dogs. His love for travel and adventure has taken him on journeys to a number of destinations worldwide including the summits of Mt Batur, Cotopaxi, Kilimanjaro and Kala Patthar.


Mauricio Mandel Brigido, MD, PhD
Cerebrovascular and Skull Base Neurosurgery

Dr. Mandel obtained his medical degree from the University of São Paulo Medical School, Brazil. He received the “Prof. Dr. Edmundo Vasconcelos Award” as the best student on all surgical disciplines upon completion of medical school. He subsequently completed his neurosurgical residency at the Hospital das Clinicas of University of Sao Paulo Medical School, Brazil.

After his residency, Dr. Mauricio started a busy private practice at Hospital Israelita Albert Einstein, Sao Paulo, Brazil.

His clinical and research interests are focused on minimally invasive neurosurgery. Dr. Mauricio attended a Ph.D. program at the University of Sao Paulo, Brazil, where he discussed a doctoral thesis entitled “Employment of minimally invasive neurosurgical techniques for treatment of unruptured brain aneurysms of the anterior circulation.”  During his Ph.D. thesis, he described an innovative minimally invasive approach for the treatment of middle cerebral artery aneurysms (transpalpebral “eyelid” approach). He has published several peer-reviewed articles and has presented his work at different international conferences.

As Clinical Instructor at Stanford, Dr. Mauricio is currently concentrating on gaining operative exposure to cerebral revascularization procedures with Dr. Gary Steinberg.

Dr. Mandel, along with his wife Suzana, enjoys running, hiking and traveling. He also enjoys playing the cello. He has been a cellist in several university symphony orchestras in Sao Paulo.


Daniel R. Kramer, MD
Functional Neurosurgery

Daniel R. Kramer grew up in Oak Park, IL before completing his undergraduate degree at Northwestern University in cognitive science and philosophy.  He then completed his medical degree at the University of Pennsylvania and his neurosurgical training at the University of Southern California.

Dr. Kramer has a clinical interest in surgical treatments for movement disorders, epilepsy, and pain.  His research interests are focused on the interpretation of neural signals and the communication between brain areas, particularly to produce movement and somatosensation.  He works primarily on brain computer interface, where the human brain interfaces directly with machines to restore motor and sensory function to paralyzed individuals.

In his free time, he enjoys ultra-running, concerts, and snowboarding.


Yiping Li, MD
Cerebrovascular and Skull Base Neurosurgery

Dr. Li grew up in the Midwest where he obtained an undergraduate degree from the school of pharmacy at Purdue University and obtained his medical degree from Indiana University.  He then completed a neurosurgery residency at the University of Wisconsin where he also completed his neuroendovascular fellowship in 2017.

As clinical instructor at Stanford, Dr. Li is currently concentrating on the treatment of complex cerebrovascular diseases including ischemia, cerebral aneurysms, arteriovenous and cavernous malformations. During his time off, Dr. Li enjoys spending time outdoors hiking and camping with his wife and daughter.


Ahmed Mohyeldin, MD, PhD
Skull Base Surgery

Dr. Mohyeldin completed his undergraduate education at Emory University with a degree in neuroscience and behavioral biology.  Having been selected as an All-American Athlete, he was drafted to play professional soccer in Atlanta prior to medical school. Dr. Mohyeldin completed his medical education at George Washington University. During medical school he was awarded a grant from the American Association of Neurological Surgeons and from the Maryland Stem Cell Research Fund to pursue a post-doctoral research fellowship at Johns Hopkins University under the mentorship of Dr. Alfredo Quinones-Hinojosa. His research investigated developmental transcriptional programs coopted by brain cancer with a specific focus on chordomas and glioblastomas. During this time, he developed the first animal model for chordoma and identified the transcription factor brachyury as a novel therapeutic target, which is currently the focus of a major NIH clinical trial as well as multiple drug design studies for chordoma patients. Dr. Mohyeldin pursued his neurosurgical training at Ohio State University, during that time he was awarded the R25 grant from NIH to further pursue this work. After completing his residency, he remained at OSU and pursued a clinical fellowship with Dr. Daniel Prevedello and Ricardo Carrau in advanced skull base and endoscopic cranial surgery. He comes to the Neurosurgery Department to work with Dr. Juan Fernandez-Miranda and collaborate with leading basic scientists at Stanford to identify and target important transcriptional programs that maintain cancer stem cell populations in chordoma to find a meaningful cure for this disease.


Margaret Pain, MD
Pediatric Neurosurgery


Rahul Singh, MD
Comprehensive Spine Neurosurgery

Dr. Singh recently completed his neurological surgery residency at West Virginia University. He completed his Bachelors of Science in biochemistry and Medical Degree from Rutgers University.  He enjoys being outdoors and reading fiction.