Who We Are

At the Napa Pain Institute, our mission is to inspire hope and contribute to the health and well-being of our community here in the Bay Area by bringing more than three decades of experience in whole-patient care to the management of chronic pain. Our work is driven by our core value: the needs of our patients come first.

Our Story

The Napa Pain Institute was founded in 1992 by Dr. Eric Grigsby, a national leader in the field of Pain Management who has devoted his life to advancing techniques and treatment methods to alleviate chronic pain.

The Napa Pain Institute is a part of Neurovations, a patient care and innovation company. Today, Neurovations is a national leader in medical device and pharmaceutical innovation, clinical research, and a world-class education program focusing on pain and neuroscience. Dr. Grigsby is deeply connected to the healthcare community through our non-profit HealthRoots Foundation.

At the Napa Pain Institute, our providers seek a thorough understanding of the origin of patients’ pain issues and offer the latest techniques for the treatment of chronic pain. Through integrated clinical practice, research, and education, our caring, committed team are your partners in whole-patient health care, offering world-class treatment and support for those suffering from a range of debilitating chronic illnesses that result in ongoing pain.

Meet Our PHysicians

Dr. Eric J. Grigsby, MD, MBA

Dr. Melanie D. Johansson, MD, FACEP

Meet Our Staff


Kristine Fields


Darla Harrison, COO

Hilary Cromwell, RN

Danielle Pense, CBSPD

Real Stories of Hope & Healing

Our Patients share their journeys

David B.

“She changed the quality of my life so drastically and in such a positive way I can honestly tell people that she and Napa Pain Institute changed my life.”

Carolyn C.

“I highly, highly recommend Napa Pain Institute for anyone dealing with chronic or acute pain. They will find you a solution. And they are all wonderful.

Bruce F.

“I would easily give them and their facility the highest rating. They care and you are always treated with respect”.

Jeff B.

"I transferred to Napa Pain Institute 3 years ago and it was the best thing I have ever done."

Eric Grigsby, MD, MBA

CEO & Founder of Neurovations

Dr. Eric Grigsby enjoys a national reputation for excellence in the field of Pain Management. He has a background as a researcher, teacher and clinician and brings over 30 years of clinical experience to the Napa Pain Institute. Dr. Grigsby attended elementary and secondary school in his hometown of Knoxville, Tennessee, and received a Bachelor’s Degree in Biology and Economics from Brown University in Providence, Rhode Island. He formed an interest in Pain Management as a career while working at Boston Children’s Hospital in the Department of Orthopedic Surgery.

After graduating from Boston University Medical School in 1984, Dr. Grigsby trained in General Surgery, Anesthesiology, and Pain Management at the Mayo Clinic in Rochester, Minnesota. He was invited to join the Medical Staff and teach at the Mayo Medical School until moving to California in 1989. The Dean of the University of California at Davis Medical Center then invited Dr. Grigsby to establish their first Pain Management Center, where he served as Medical Director until 1992. Following his post at UC Davis, Dr. Grigsby established his private Pain Management practice in Napa, California.

Today, he and his staff of over 50 professionals consult with patients throughout Northern California and the western United States.  More recently, Dr Grigsby completed his Masters in Business Administration from Duke University’s Fuqua School of Business. He speaks nationally on topics such as non-operative treatment of spinal disorders, the safe use of medications for the treatment of pain, and the legal and regulatory issues relating to the proper treatment of patients with chronic illness.


Dr. Johansson comes to us as a fellowship-trained and board-certified pain management specialist with nearly a decade of experience. She completed her fellowship training at Walter Reed National Military Medical Center in Bethesda, MD where she then became the associate program director of the pain medicine fellowship and an assistant professor of military and emergency medicine. She graduated from the Virginia Commonwealth University School of Medicine in Richmond, Virginia, was Pre-medicine at San Diego State University, and received her BSN from Marquette University in Milwaukee, Wisconsin.

Her breadth of experience comes from a full career of serving in the United States Navy where she was the recipient of multiple academic and military service awards including a Meritorious Service Medal, three Navy Commendation Medals, and numerous other individual, unit, and campaign awards. She has multiple published works and is the founding member of a military Pain Medicine Special Interest Group with the American Society of Regional Anesthesia.

In her free time, Dr. Johansson enjoys traveling, is newly married, loves dogs, and enjoys cooking and baking, as well as other creative pursuits. She has a particular interest in advanced procedural techniques for chronic pain relief and the effects of lifestyle on pain and healing. She looks forward to continuing our mission of providing our patients with the best care, every day.


Gordon Iwasaki is a physician assistant with over twenty years of experience. He began his career in orthopaedics and industrial medicine. He has been working in pain management over the past seven years.

Mr. Iwasaki was raised in South San Jose and attended UC San Diego for his undergraduate degree. Later, he attended Charles Drew University in Los Angeles for his physician assistant studies and obtained his master’s from University of Nebraska. He has been residing throughout Southern California in Los Angeles, Riverside, and San Diego counties. He returns to Northern California to be closer to his family.

He remains a diehard 49ers and SF Giants fan and enjoys exercising and spending time with his canine companions and listening to music.

Kristine Fields

Clinic Manager

Kristine Fields brings over a decade of experience in healthcare administration to her role as Clinic Manager at the Napa Pain Institute. With a passion for delivering exceptional patient care and optimizing operational efficiency, Kristine oversees all aspects of clinic operations, from scheduling and patient relations to staff management and regulatory compliance.

Known for her strong leadership skills and dedication to excellence, Kristine collaborates closely with the medical team to ensure that every patient receives personalized and compassionate care. She is committed to staying abreast of the latest developments in pain management to provide the highest level of service to patients at the Napa Pain Institute.


We welcome Helen Cheung to the Napa Pain Institute as a Physician’s Assistant. Helen is a graduate of the Betty Irene Moore School of Nursing at UC Davis, and has a Bachelor of Science in Nursing from the University of Wisconsin-Madison. She is also certified in BLS and Adult ACLS. Her past education includes a Wisconsin State RN license, which she held until February 2021, and adult ventilator certification until 2020.

Helen has gained extensive experience as a returning student PA at the Jerold Phelps Community Hospital (SoHum Clinic) in Humboldt County, where she performed physical exams, delivered oral presentations, engaged in patient education, and fostered therapeutic relationships with patients under the direct supervision of an MD. She also performed specific procedures such as splinting and wound care, and performed PAP smears and biopsies. Additionally, Helen gained valuable experience at the UCDH Cypress Building – Bariatric Surgery, where she observed and participated in pre- and post-op visits, patient education, morning rounds, and performed surgical scrub and intra-operative assistance.

Helen has also gained experience in urgent care, the emergency department, endocrinology, diabetes & metabolism, Hansen Family Health Center, and pediatric clinics, as well as the CORE Medical Clinic. In all of these settings, she has performed patient assessments, delivered oral presentations, and assisted with medication prescriptions, imaging and lab orders, and documentation. She has also performed various procedures, including wound closure, suture removal, incision and drainage of skin abscesses, and pelvic exams. Through her experiences, Helen has developed a passion for providing quality patient care and expanding her clinical competency.

Darla Harrison

Chief Operating Officer

Darla Harrison serves as the Chief Operating Officer (COO) of Neurovations and Napa Pain Institute, bringing extensive expertise in healthcare management and operations to her role. With a proven track record of strategic leadership and operational excellence, Darla oversees the day-to-day operations of all business divisions, ensuring seamless coordination and alignment with strategic objectives.

Her commitment to optimizing patient care, fostering innovation, and driving organizational growth has been instrumental in advancing Neurovations and Napa Pain Institute’s mission to deliver cutting-edge treatments and compassionate care in the field of pain management. Darla has been with Neurovations for thirty years and is dedicated to enhancing healthcare delivery and outcomes for patients across the continuum of care.

HIlary Cromwell, RN

Nursing Administrator

Hilary Cromwell, RN, brings a wealth of expertise and dedication to her role as Nurse Manager at the Napa Surgery Center. With a background in nursing spanning over ten years, Hilary exemplifies a commitment to excellence in patient care and clinical leadership. Her role entails overseeing the nursing staff, ensuring adherence to best practices, and maintaining the highest standards of patient safety and satisfaction.

Known for her compassionate approach and meticulous attention to detail, Hilary plays a pivotal role in facilitating smooth operations and positive patient experiences at the Napa Surgery Center. She holds a Bachelor’s degree in Nursing and remains dedicated to ongoing professional development to uphold the center’s reputation for exceptional care and outcomes.

Danielle Pense, CBSPD

Facilities Manager

Danielle Pense serves as the Facilities Manager at the Napa Surgery Center, where she brings her expertise in facility management and operations to ensure the smooth functioning of the operating room and surgery center. Danielle is dedicated to maintaining a safe, efficient, and welcoming environment for patients, staff, and visitors. She assists in surgery with a focus on instrument sterilization. Danielle is also the technical manager for ultrasound, EKG and X-ray.

Other responsibilities include overseeing maintenance, safety protocols, and regulatory compliance to uphold the highest standards of facility operations. Known for her proactive approach and attention to detail, Danielle plays a crucial role in optimizing the functionality, efficiency and appearance of the Napa Surgery Center. She remains committed to delivering excellence in facility management to support the center’s mission of providing exceptional surgical care to patients.

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