Neurosurgery Clinical Instructors

Maleeha Ahmad, MD, FRCS SN
Stereotactic Radiosurgery and Neuro-oncology

Maleeha Ahmad, M.D F.R.C.S S.N., is a British Neurosurgeon who graduated with Distinction from the University of Southampton School of Medicine, U.K.

Dr Ahmad completed her Neurosurgical residency with the Yorkshire and Humber Deanery - obtaining the  Membership and then the Fellowship of the Royal College of Surgeons of the United Kingdom. After her Board Certification in Neurological Surgery, Dr Ahmad undertook her first Fellowship at Weill Cornell Medical Center’s Skull Base Research Lab focusing on endoscopic and transcranial routes to the sellar and perisellar regions.  

Dr Ahmad then joined Geisinger Medical Center as their first Neurosurgical Oncology Fellow and junior Faculty, with focus on gliomas and brain metastases. In addition to increasing surgical autonomy, Dr Ahmad also incorporated the adjuvant use of the clinical application of tumor treating fields, robotics, laser interstitial thermal therapy and stereotactic radiosurgery to her clinical practice. Dr Ahmad then joined the University of Pittsburgh Medical Center hospital network as full time faculty.

In July 2020, Dr Ahmad joined the Department of Neurosurgery at Stanford University. Dr Ahmad is working with Dr Steven D.Chang - Professor and Vice Chairman of Strategic Development and Innovation in the Department of Neurosurgery at Stanford, and Co-Director of the Surgical Neuro-Oncology and Stanford Cyberknife Radiosurgery Programs.  Dr Ahmad’s work will focus on brain and spinal tumors and vascular neoplasms using an armamentarium of on-going clinical research effectiveness and trials, up to date neurosurgical adjuvant, combinatorial approaches and Cyberknife stereotactic radiosurgery and neuro-oncology.


Karam Paul Asmaro, MD, MS
Skull Base Surgery

Dr. Asmaro grew up in Ontario, Canada and completed his undergraduate education at Wayne State University in Detroit, Michigan with a dual degree in chemistry and biology, graduating summa cum laude and Phi Beta Kappa. He remained at his alma mater to complete a neuroscience master of science degree where his thesis focused on the oxidation products of dopamine and their implication on Parkinson’s disease. Following his graduate studies, he competed his medical education at Wayne State University School of Medicine during which he received funding for his research on stroke therapy and graduating with Alpha Omega Alpha honors. Dr. Asmaro pursued his neurosurgical training at Henry Ford Health System with a focus on skull base pathology. He joined the OMICs laboratory under the mentorship of Drs. Ana Castro and Houtan Noushmehr focusing on epigenetic epigenetic modifications of brain tumors. He was awarded the Congress of Neurological Surgery 2020 Resident Award for the highest ranked abstract on his Pituitary Epigenetic Liquid Biopsy work. During his residency, he also received the highest percentile nationwide on the American Board of Neurological Surgery’s Primary Examination alongside other honors and achievements.

Dr. Asmaro comes to Stanford University as a clinical instructor to work with Dr. Juan Fernandez-Miranda with an aim to gain specialized exposure to advanced surgical techniques to tackle complex brain tumors and identify novel treatment paradigms.

Outside of the hospital, he enjoys traveling, golfing, and hiking with his wife.


Andrew Gauden, B Med Sci (Hons), MBBS (Hons), MA, PhD, FRACS
Cerebrovascular Neurosurgery/Interventional Neuroradiology

Dr Andrew Gauden is an Australian Neurosurgeon who attained his Fellowship in Neurosurgery with the Royal Australasian College of Surgeons in 2020. Dr Gauden grew up in Tasmania, Australia, and completed his undergraduate medical degree at the University of Tasmania, graduating with first class honours. He then commenced training at the Royal Melbourne Hospital in 2009 and was admitted to the neurosurgical training programme in 2013.

In 2017 he completed a PhD in Clinical Medicine at Macquarie University in Sydney, Australia, under the supervision of Professor Marcus Stoodley.  Dr Gauden’s PhD research demonstrated a world-first successful treatment of arteriovenous malformations with the combined treatment of stereotactic radiosurgery and vascular targeting.  He has since received awards for this research from the American Association of Neurological Surgeons and the Neurosurgical Society of Australasia.

Dr Gauden has commenced work as clinical instructor in Cerebrovascular Surgery with the Department of Neurosurgery at Stanford under the supervision of Professor Gary Steinberg to gain exposure in the management of cerebrovascular disorders including, intracranial aneurysms, vascular malformations and ischaemic cerebrovascular disease.  He will follow this training with a further 2 years with the Department of Radiology and Division of Neurointerventional Radiology to gain exposure to the endovascular treatment of cerebrovascular disorders in order to become a dual-trained cerebrovascular neurosurgeon.

During his free time he has interests in hiking, outdoor rock climbing and fencing. He also studies Ancient History and in 2017 he was awarded a Masters of Arts majoring in Ancient History with Distinction from the University of Wales, Trinity St David.


Mark Krel, DO
Stereotactic, Functional and Epilepsy Neurosurgery

Dr. Krel completed his undergraduate and graduate training at the University of California, Irvine and at the University of Southern California. Having always had a strong passion for academia, he worked as a University faculty member at California State University Long Beach and Fullerton and Johns Hopkins University before pursuing his medical training at Western University of Health Sciences in Pomona, California and neurosurgery residency training at Riverside University Health System Medical Center treating the breadth of neurosurgical conditions across the spectrum of health delivery systems including Level I and II Trauma Centers, county safety-net hospitals, including the second busiest ER in California, HMO systems, and private hospitals and worked with patients in all life stages from newborns to advanced geriatrics. 

Dr. Krel joined the Stanford Neurosurgery team as a Clinical Instructor specializing in Stereotactic, Functional and Epilepsy neurosurgery focusing on the treatment and management of movement disorders, pain, epilepsy and deep brain surgeries. He has additional focus on the treatment of complex skull base conditions and brain tumors, general spine surgery, and the breadth of brain and spine trauma. He has published several scientific articles and book chapters on various topics in neurosurgery and has special interest in advancing the surgical treatment of functional disorders of the nervous system, in particular, the objective measurement of functional therapuetics and machine-brain interface as pertaining to the restoration of function.

In his spare time, Dr. Krel enjoys spending time with his children, cooking, soccer, golf, and playing music.


Daphne Li, MD
Pediatric Neurosurgery

Dr. Li grew up in Canada. She attended Vanderbilt University for her undergraduate training where she majored in neuroscience. Subsequently, she attended medical school at New York Medical College. Dr. Li completed her neurosurgical training at Loyola University Medical Center, during which time she spent a year under the mentorship of Dr. Amanda Saratsis at Ann and Robert H Lurie Children's Hospital investigating diffuse intrinsic pontine gliomas and liquid biopsy.  As a clinical instructor at Stanford, Dr. Li will be focused on pediatric neurosurgery. Outside of the hospital she enjoys travelling, staying active, and spending time with her family, husband and two dogs.


Arjun Pendharkar, MD
Cerebrovascular and Endovascular Neurosurgery

Arjun Pendharkar was born at Stanford Hospital and grew up in the Bay Area. He graduated from Cal Poly San Luis Obispo with a degree in Microbiology. At Cal Poly, Arjun worked in the lab of Dr. Michael Black where he studied Celiac Disease—cloning a novel strain of prophylactic Lactobacillus bacteria to cleave immunogenic gliadin peptides in the small intestine. Prior to attending medical school at Georgetown University, Arjun spent a year in the Department of Neurosurgery at Stanford in the labs of Dr. Raphael Guzman and Gary Steinberg studying intravascular neural stem cell therapy for stroke—specifically elucidating the difference between intra-arterial and intravenous injection. He subsequently completed his neurosurgery residency at Stanford including an NIH R25 and NREF funded postdoctoral fellowship in Dr. Steinberg’s lab studying motor circuit plasticity and optogenetic stimulation to promote recovery in a mouse model of stroke. Outside of medicine, Arjun enjoys traveling, skiing, and playing golf.


Vashisht Sekar MBBS DHMSA PhD FRCSEd (Neuro.Surg)
Neurosurgical Oncology and Radiosurgery

Vashisht (Vash) Sekar is a neurosurgeon trained in the United Kingdom. He grew up in Chennai, India and graduated with distinction from Kasturba Medical College in Manipal, India, widely regarded as one of the top medical schools in India. He then underwent a period of clinical and research training in cerebral blood flow haemodynamics and embolisation culminating with a PhD from the prestigious University of Manchester in the United Kingdom in 2014. During this period he also studied for a Diploma in the History of Medicine from the Worshipful Society of Apothecaries in London with an interest in renaissance and European Surgery and was elected as a Member of the Royal College of Surgeons of Edinburgh.

He subsequently underwent clinical Neurosurgical training in Leeds and Belfast culminating with  Fellowship of the Royal College of Surgeons of Edinburgh(Neurosurgery).

He has wide clinical and research interests in neurosurgical oncology including gliomas, skull base surgery and spine surgery. He will work on radiosurgical techniques and researching clinical outcomes of complex tumours and novel radiosurgical applications under the supervision of Dr Chang and Dr Meola.

Outside of work, he likes to spend time with his wife and daughters, when time permits paint, watch cricket ,world cinema and read history.


Timothy H. Ung, MD
Neurosurgical Neuro-Oncology and Stereotactic Radiosurgery

Dr. Ung was born in Denver, Colorado where he completed his undergraduate studies at the University of Colorado with a dual degree in Integrative Physiology and Molecular, Cellular, and Developmental Biology. After completing his undergraduate work, he completed his medical education at the University of Colorado School of Medicine. During his time in medical school, he was awarded a neurosurgery research fellowship at Columbia University in New York, New York. As the Bartoli brain tumor fellow, he was mentored by Dr. Jeffrey Bruce and Dr. Peter Canoll. His research focused on glioblastoma tumor heterogeneity, convection-enhanced delivery of therapeutics in malignant glioma, and the use of sodium fluorescein for the resection of high-grade gliomas. At the conclusion of his medical education, he was also inducted into the Gold Humanism Honor Society.

Dr. Ung then joined the University of Colorado where he is completing his neurosurgical training. During his residency, his research has been primarily focused on clinical outcomes in high-grade glioma, surgical techniques and outcomes in skull-based surgery, and applications of sodium fluorescein for the resection of neurosurgical tumors. His efforts have led to expanded applications of sodium fluorescein for the resection of spinal cord tumors and deep seeded brain lesions.

Dr. Ung comes to Stanford University as a neurosurgical neuro-oncology and stereotactic radiosurgery fellow. Under the mentorship of Dr. Steven Chang, he hopes to gain specialized training in the operative and radiosurgical management of brain and spine tumors. At the conclusion of his fellowship, he will return to Colorado where he will complete his neurosurgery residency. Dr. Ung hope to pursue a career in academic neurosurgery with a focus on the treatment of brain and spinal tumors.

Outside of the hospital, he enjoys spending time with his family, traveling, backcountry skiing, hiking and fly fishing.


Katherine E. Wagner, MD
Spine Neurosurgery

Dr. Wagner completed her undergraduate degree at Wellesley College, where she majored in chemistry. Her undergraduate research focused on utilizing nanoparticles to remove metal ions from water and other solutions. She also spent a summer researching sea turtles in Mexico. Dr. Wagner returned home to New Jersey and earned her medical degree at Rutgers New Jersey Medical School in Newark, New Jersey. At Rutgers, she helped manage a student run clinic, which also provided medical care at a homeless shelter. She assisted with health fairs in the community, providing HIV screening and visual exams several times a year. The New Jersey Medical School Alumni Association awarded her scholarships during her second, third, and fourth years. 

She proceeded to complete her neurosurgery residency training at Hofstra/Northwell Health in Long Island, New York. She spent an enfolded year working with Dr. Michael Schulder in a neuro-oncology fellowship. During that time she focused primarily on surgery for brain tumors, along with other techniques like laser interstitial thermal therapy (LITT) and stereotactic radiosurgery (SRS).  As a senior resident she developed a strong interest in spine surgery, including spinal oncology, neuro-navigation, exoscopic surgery, robotic surgery, and spinal instrumentation. Working with Dr. Jamie Ullman and others, Dr. Wagner published the Trauma section of Operative Neurosurgery's Essential Handbook for Medical Students. She also authored a chapter on spine trauma in the book Neurosurgery Fundamentals (Agarwal et al.). Outside of the hospital Dr. Wagner enjoys hiking and traveling. 


Benjamin Yim, MD
Cerebrovascular Surgery