1331 N 7th St #405 Phoenix, AZ 85006
Phone: (602) 254-3151

Advanced Practice Providers

Arizona Neurosurgery & Spine Specialists

The physicians and staff of Arizona Neurosurgery & Spine Specialists, PC, bring decades of healthcare experience, medical knowledge and exceptional patient care to the practice.


Manda L. Chatelain, ANP, ACNP

Manda Chatelain has been providing patient care as a nurse practitioner with Arizona Neurosurgery and Spine Specialists since January of 2003. She works in collaboration with the attending neurosurgeons performing consultations and daily hospital rounds. She participates in the development of our patients' individualized plans of care. Manda also serves as first assist in the operating room and works closely with a multi-disciplinary team to provide post operative care to our neurosurgical patients.

Manda earned a Bachelor of Science in Nursing from the University of Arizona, a Master of Science in Nursing from Arizona State University and a Post Masters Degree in Nursing from St Louis University. She is board certified by the American Nurses Credentialing Center as an Adult Nurse Practitioner and Acute Care Nurse Practitioner. She has completed training as a Registered Nurse First Assist via the National Institute of First Assisting and obtained the status of Certified Nurse of the Operating Room.


Melissa A. Leonard, PA-C

Melissa A. Leonard joined the Arizona Neurosurgery & Spine Specialists, PC staff in June 2012 as a Board Certified Physician Assistant. Her prior experience includes Cardiology and Family Practice. Melissa graduated with Honor from Drexel University in Philadelphia, Pennsylvania where she was awarded a Master’s of Health Science degree in 2008 with the Advanced Degree of Physician Assistant. Working with the attending neurosurgeons and our staff of advanced practice providers, Melissa provides a wide variety of care to our neurosurgical patients including hospital consultations, daily visits and serving as a first surgical assistant in the operating room.


Jessica Vo, PA-C

Jessica Thuy Vo is a board certified physician assistant, who joined Arizona Neurosurgery and Spine Specialist in December 2014. After graduating with honors from Loyola University Chicago with a B.S. in Pre-Medicine Studies, Psychology, and Spanish, she moved to Arizona to attend Midwestern University and earned her Master in Medical Science in Physician Assistant Studies in 2014. As a part of the physician-PA team, she works in close conjunction with the neurosurgeons to provide individualized care to our patients in the acute care setting. She completes patients' physical and history, helps with the treatment plan, performs bedside procedures, serves as first assist in the operating room, and manages post-operative care for our patients. She also enjoys mentoring physician assistant students. She is a proud Vietnamese-American, who is fluent in Vietnamese.

During her leisure time, she enjoys reading, hot yoga, and exploring the world. She joined Dr. David Wilson on a neurosurgery humanitarian trip to Vietnam in early 2018 and has a keen interest in continuing neurosurgical efforts overseas. She believes that in order to provide excellent and compassionate care to our patients, we should never lose our sense of humanity.


Sophia Guardiola, DNP, AGACNP

Sophia Guardiola, DNP, RN, AGACNP-BC is a board-certified Advanced Practice Nurse Practitioner with a subspecialty in Neurosurgery. Sophia earned her Doctor of Nursing Practice, Adult-Gerontology Acute Care Nurse Practitioner, from Rush University College of Nursing in Chicago, Illinois. She worked as a registered nurse in the intensive care setting for 10 years at Rush University Medical Center, where she completed her doctoral project that aimed to explore provider’s perceptions and attitudes towards palliative care in the surgical intensive care unit. During her training, she also collected clinical data for neurosurgical research and helped publish Patient’s Guide to Deep Brain Stimulator Placement. Upon graduation, she was a member of the Sigma Theta Tau International Honor Society of Nursing. Thereafter, Sophia moved to Phoenix, Arizona in 2015 for advanced nursing practice opportunities. She joined the AANS team in 2016, and provides evidence-based collaborative care to neurosurgical patients in the acute care setting.

She is a member of the American Association of Nurse Practitioners (AANP), Neurocritical Care Society (NCS), National Association of Hispanic Nurses (NAHN), American Association of Critical Care Nurses (AACN). She has Emergency Neurological Life Support (ENLS) and Fundamental Critical Care Support (FCCS) certification.


Heather Fett, ACNP

Heather Fett has been a nurse since 2010. She has been a Nurse Practitioner since 2017. Her other nursing experience includes: neurological and neurosurgical intensive care and telemetry at Banner University Medical Center, a level one trauma center. As a registered nurse Heather worked with the stroke support group at Banner University Medical Center and volunteered with the American Stroke Association Stroke Check. Heather is certified in Emergency Neurological Life Support and is a Certified Neuroscience Registered Nurse.

Education and Honors

  • 2018 National Institute of First Assisting – Registered Nurse First Assistant
  • 2017 Grand Canyon University – Acute Care Nurse Practitioner
  • 2010 Phoenix College – Associates in Nursing
  • 1998 Illinois State University – Bachelors of Science in Psychology

Karla D. Wax, FNP, AGACNP

Karla is a native to Arizona. She began her career in healthcare in 1989. Karla joined Arizona Neurosurgery and Spine Specialist (ANSS) in 2008 after earning her Family Nurse Practitioner degree through Grand Canyon University in Phoenix, AZ. As a nurse practitioner for ANSS, Karla works closely with the neurosurgeons and other advanced practice providers to ensure quality neurosurgical care and treatment within the hospital setting. She also assumes the role of first surgical assistant in the operating room. In 2012, Karla returned to St Louis University to obtain her post masters certification as a Gerontology Adult Acute Care Nurse Practitioner. Prior to becoming a nurse practitioner, Karla worked at The Barrow Neurological Institute in Phoenix, AZ as a register nurse. Her nursing experiences include neurosurgery post anesthesia care unit, neuroscience intensive care unit and nursing supervisor of a neuroscience intensive care unit. Karla is a member of the advance practice nursing committee at Banner Good Samaritan Hospital in Phoenix, AZ. Prior to her nursing career, Karla was a registered respiratory therapist.


Yun Chelsea Chen, MS, FNP-C, RNFA

Chelsea was born in Chengdu, China and moved to Phoenix at the age of six. She earned her Bachelor of Science degree in nursing from Arizona State University in 2010 and began her nursing career in the acute neurological unit at St. Joseph’s Hospital and Medical Center Barrow Neurological Institute. She spent five years taking care of post-surgical and epilepsy patients at the bedside, and eventually decided to pursue a master’s degree in nursing. In 2014, Chelsea completed a Master of Science degree in nursing from Grand Canyon University and obtained her family nurse practitioner certification. Later that year, Chelsea started working at Barrow Brain and Spine as a nurse practitioner. She then became certified as a surgical first assist in order to further her knowledge of the science and art of neurologic surgery. Chelsea joined the team at Arizona Neurosurgery and Spine Specialist in August of 2018 and is thrilled she is able to continue working with the esteemed physicians and their team in caring for neurosurgical patients and their families. When not working, Chelsea enjoys playing the cello and participating in outdoor activities such as hiking and horseback riding.

Chelsea is a member of several professional organizations, including the American Association of Nurse Practitioners and Sigma Theta Tau International Honor Society of Nursing.

  • RNFA, National Institute of First Assisting, 2015
  • FNP-C, American Academy of Nurse Practitioners, 2014
  • MSN, Family Nurse Practitioner, Grand Canyon University, 2011
  • BSN, Arizona State University, 2010
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