Meet the Doctors
Brian L. Day, D.C.
Dr. Day graduated from Life Chiropractic College West with honors in 1994. He holds a license in 4 states, and has treated countless patients. He has been certified in disability ratings for many years, as well as performing peer review for many insurance companies.
Dr. Day’s experience in Chiropractic is vast. He has treated numerous auto accident victims, as well as many different types of workers compensation cases.
After many years as a chiropractor, Dr. Day remains enthusiastic and loves to meet, and treat, new patients. “This is the perfect career for me,” he states.
He has developed a reputation for being detailed, systematic and meticulous. These are traits required not only for patient care but for the many aspects that parallel patient care and treatment.
Dr. Day has, on many occasions, been an expert witness for auto accident victims, as well as a patient advocate for workers’ compensation patients. He has spent countless hours studying common and uncommon injuries relating to auto accidents. Dr. Day understands the importance of being current on the latest research, as it will have a direct impact on treatments, as well as the case as a whole.
Dr. Day’s mission is to provide patients with the best treatments available for their particular condition. He understands that you have a choice in your healthcare, and wants all his patients to feel that they made the right choice. His commitment is indisputable. He was the first to offer transportation to his patients in his previous location, whom had difficulty getting to his office due to pain limitations. This service expanded as Dr. Day realized that many patients who needed care sometimes had difficulty getting to the clinic. One Stop Injury Center is currently working with the Nevada department of transportation to offer this type of service here in Las Vegas and Henderson, NV. He has volunteered his time and services to many local sports organizations, as well as the local Boys and Girls club.
Helping to create healthier lives, and to preserve the natural state of balance, is a rewarding life. “I absolutely love what I do, and love to help people in any way I can” states Dr. Day. “I am so excited to practice in Las Vegas and Henderson, NV, my wife and I absolutely love it here, and my daughter is a graduate from UNLV.”
The name he chose for the clinic “One Stop Injury Center” was meant to express how he feels about his job and his patients. “Our patients come before anything else, we are patient advocates and proud of it.”
Brian K. Fife, DC
Dr. Brian Fife is a Las Vegas native and chiropractic physician with more than 31 years of clinical experience specializing in the diagnosis, treatment, and medical evaluation of spinal and musculoskeletal injuries, particularly those resulting from motor vehicle collisions and other traumatic events. He is the Founder and Clinic Director of One Stop Injury Center – North (formerly Advanced Chiropractic Specialists) and has helped tens of thousands of patients throughout Southern Nevada recover from injury and restore function.
Dr. Fife completed his undergraduate studies while serving in the United States Army, attending the University of Maryland and later the University of Nevada, Las Vegas. He earned his Doctor of Chiropractic degree from the Los Angeles College of Chiropractic, graduating Magna Cum Laude in 1994. His academic honors include placement on the Dean’s List, the National Dean’s List, and induction into the Delta Sigma Honorary Scholastic Society for the Healing Arts.
In 1998, he was designated as an Independent Chiropractic Examiner by the American Board of Independent Medical Examiners (ABIME) and as a Permanent Disability Examiner by the State of Nevada. Over the course of his career, he has performed well over a thousand independent medical examinations and disability evaluations, providing expert medical analysis regarding injury causation, permanent impairment ratings, treatment necessity, and long-term prognosis.
His treatment and evaluations are based on objective clinical findings, diagnostic imaging, and established medical and chiropractic guidelines. He has completed Accident Reconstruction for the Medical Professional through Texas A&M University and has extensive training in the interpretation of MRI and advanced diagnostic imaging. He regularly lectures on the diagnosis and treatment of motor vehicle accident injuries and continues advanced education to remain current with developments in spinal and musculoskeletal care.
In addition to his clinical work, he has dedicated many years to serving youth in the Las Vegas Valley as a Scoutmaster and Commissioner with the Boy Scouts of America and as a youth baseball coach for 17 years. While attending UNLV, he became one of the first certified Personal Fitness Trainers in the Las Vegas Valley, providing fitness, nutrition, and sports injury rehabilitation training. He maintains a high level of personal fitness and is an avid outdoorsman.
Dr. Fife continues to focus on the accurate diagnosis, prognosis, treatment, and evaluation of traumatic spinal and musculoskeletal injuries, utilizing objective clinical findings, diagnostic imaging, and established medical and chiropractic guidelines to guide both patient care and injury assessment.
David Wagner, BS, DC
Dr. David Wagner was born in Covina, California and after four years in the United States Marine Corps obtained a Bachelor of Science degree from the University of Nevada Las Vegas in 1998. He then attained his Doctor of Chiropractic degree from the Southern California University of Health Sciences in 2001. Dr. Wagner operated a private practice in Temecula, California until 2023 before relocating to Henderson, Nevada with his wife and two children.
Having worked at a large surgical hospital for 6 years he observed the myriad of conditions that could be helped conservatively. He has since gained significant experience in nonsurgical treatment of many musculoskeletal conditions such as those related to auto accidents, sports injuries, chronic pain syndromes, sciatica, headaches and more.
John Gerber, DC
Dr. John Gerber graduated from Parker Chiropractic University in 1994 and has been a Chiropractor in the Las Vegas area for 30 years. Having played basketball from grade school through college, he enjoys working with athletes. At 14 years of age, Dr. Gerber moved with his family from Wisconsin to Phoenix, AZ where he met the love of his life. When she started looking into Chiropractic, he realized the chiropractic philosophy is how he lives his life, and that is what he wanted to do also. He continued his education with sports injury conservative treatment, wanting to help people return to their favorite activity and avoid surgery whenever possible.
When not working, you will find him at the gym (with his eye on the basketball court) or walking/running with his dogs.
Katharine Gerber, DC
Dr. Katharine Gerber graduated from Parker Chiropractic University in 1994 and has been a Chiropractor in the Las Vegas area for 30 years. She loves working with pregnant women and babies, helping entire families live heathier and more active lives. Dr. Gerber was born in Tucson, AZ and grew up in Phoenix, AZ knowing she wanted to be a doctor. Coming from a long line of medical doctors, but not wanting to prescribe meds or cut people open, she knew there had to be a better way. Dr. Gerber takes great pride in helping patients through acute injury care where pain meds and muscle relaxers are the standard of medical care.
When not working, you will find her at the gym, practicing what she preaches to patients or in the kitchen preparing healthy meals for family and friends.
Jordean Lea, D.C.
Dr. Lea was born in Sacramento, CA but he has spent most of his life growing up in a small town in southern Illinois. In 2012, he moved to Las Vegas to attend UNLV and where he studied Biochemistry. Eventually moving back to the St. Louis area to be closer to friends and family, he discovered the world of chiropractic care. In 2019, he began his chiropractic journey at Logan University.
During school, he participated in many sport medicine clubs and organizations that helped shape his skills with adjusting and many soft-tissue techniques. Even though he now mostly works with personal injury cases, he utilizes his sports medicine techniques to provide the best care possible to all his patients.
When Dr. Lea isn’t at work, he enjoys exploring new places and restaurants around the city. He also enjoys just lounging at home reading or watching movies. When the weather is nice, he prefers to be outdoors whether it be running and biking around the neighborhood or hiking and camping at the many national parks in and around Nevada.
Matthew A. Carissimi, DC
Dr. Matt Carissimi has over 14 years of experience treating patients with musculoskeletal injuries. Raised in New York, he earned his Bachelor’s degree in Biology from Binghamton University, State University of New York (SUNY Binghamton) in 2007 before receiving his Doctorate in Chiropractic from New York Chiropractic College in 2011.
Before relocating to the Las Vegas Valley, Dr. Carissimi practiced in Pennsylvania, where he worked extensively in multidisciplinary settings alongside medical and chiropractic physicians, providing collaborative care for injured patients. He now brings his skills, knowledge, and experience to serve patients at One Stop Injury Center – North.
Dr. Carissimi is skilled in a variety of chiropractic techniques, including chiropractic manipulation, manual therapy, physiotherapy, and kinesiotaping. He focuses on patient-centered, evidence-based care, developing individualized treatment plans aimed at restoring function and improving quality of life following injury.
Outside the clinic, he enjoys running, weight training, hiking, and spending time with his wife and young son.
Chandler R. Medina, D.C.
Dr. Medina graduated from Parker University in Dallas, Texas with highest honors in 2020. He holds a license in the state of Nevada and has experience treating many different types of patients, including athletes and auto accidents.While in chiropractic school, Dr. Medina had the opportunity to work with athletes in the Sports Performance Program as well as work in multidisciplinary setting treating veterans at the North Texas VA Hospital. He was involved in multiple clubs and activities while in school and was also a tutor.
Dr. Medina was first introduced to chiropractic in high school when a low back injury sidelined him at the end of the football season. After many different forms of treatment, he tried chiropractic and found relief for his pain. With continued treatment he was able to continue to play until college. When his football career was over, he decided to change career paths and work towards becoming a chiropractor in order to help others in the same way.
“It was rewarding to be able to see how chiropractic can change someone’s life and how big of an improvement they can have in their quality of life. Originally from Colorado, Dr. Medina is brand new to the Las Vegas and Henderson, NV area and Nevada. “I have really enjoyed living here and working with such great people.”
Rachel L. Brooks, DC
Dr. Rachel Brooks was born in Fort Worth, Texas, and raised in Las Vegas. She earned a Bachelor’s degree in Kinesiology with Honors from the University of Nevada, Las Vegas in 2019, and a Doctorate in Chiropractic Cum Laude from Parker University in Dallas in 2023. After completing her education, she returned to Las Vegas and joined One Stop Injury Center – North, (formerly Advanced Chiropractic Specialists), where she has been practicing for three years, specializing in the evaluation and treatment of spinal and musculoskeletal injuries resulting from motor vehicle accidents and personal injuries. She continues to expand her expertise through continuing education in the evaluation and treatment of traumatic musculoskeletal injuries, MRI interpretation, diagnosis, and whiplash management.
Dr. Brooks first experienced chiropractic care following a car accident, where she saw firsthand how targeted treatment can support the body’s natural healing process. Inspired by her recovery, she is dedicated to helping patients restore function and improve quality of life after injury.
She is proficient in Diversified, Activator, and Thompson Chiropractic Techniques and is a member of the International Chiropractic Pediatric Association (ICPA). She is also certified in the Webster Technique, a gentle, specialized approach for expecting mothers that aligns the pelvis, relieves surrounding muscle and ligament tension, and reduces nervous system stress during pregnancy. Dr. Brooks provides patient-centered, evidence-based care, focused on treating the underlying cause of injury to promote long-term recovery rather than simply alleviating symptoms.
Rosa Armenta, D.C.
Dr. Rosa Armenta is a licensed chiropractor in Nevada with over 20 years of clinical experience providing comprehensive, patient-centered care. She earned her Doctor of Chiropractic degree from Cleveland Chiropractic College and holds a Master of Business Administration in Healthcare Management from Western Governors University.
She has extensive experience evaluating and treating patients injured in motor vehicle collisions, workplace accidents, and slip-and-fall incidents. Her approach emphasizes thorough documentation, objective findings, accurate diagnosis, and evidence-based treatment protocols to support both clinical recovery and medico-legal reporting.
Dr. Armenta is a Certified Independent Chiropractic Examiner (CICE) and completed the NIRSAT™ certification in 2024, demonstrating advanced competency in performing Permanent Partial Disability (PPD) ratings using the AMA Guides to the Evaluation of Permanent Impairment, 5th Edition.
Dr. Armenta utilizes diversified chiropractic adjustments, rehabilitative exercise, physiotherapy modalities, manual therapy, and holds a Certificate in Cupping Therapy. She is committed to delivering individualized, evidence-informed care to help patients recover efficiently and return to optimal function.
Fluent in Spanish, Dr. Armenta effectively serves a diverse patient population. She believes every patient should be treated like a family member — with compassion, respect, and personalized attention — ensuring each individual feels supported throughout their recovery process.
Jason S. Stirrup, D.C.
Dr. Stirrup was born and raised in San Antonio, Texas. Growing up he always knew he would either follow in his parent’s footsteps by going into the medical field, like his mother who retired as a nurse from the VA hospital, or as a teacher like his father who retired from the Texas public school system as a high school English teacher. Little did he know he would eventually end up doing both. He initially decided to pursue psychiatry, and later on realized there had to be a more fulfilling career waiting for him. So, he earned his bachelor’s degree in psychology with a minor in health, and then he commissioned into the United States Army as an Officer where he would serve 10 years working in logistics, while he patiently waited for the right career to catch his attention.
After returning from a deployment in Afghanistan, Dr. Stirrup recalled seeing the wounded soldiers on the side of the parade field as they greeted the returning soldiers. It was at that moment he knew he had to pursue a career in medicine that would help to rehabilitate people, and give them the best second chance at life.
After leaving active duty, Dr. Stirrup went into the Army Reserves and earned his personal training certification, completed his second bachelors degree in Exercise sports science, with a concentration in Physical therapy, and followed by a third bachelors in Human Biology and eventually his Doctorate in Chiropractic Medicine.
In addition to Dr. Stirrup’s passion for treating patients, he also enjoys education. He teaches part time as an Anatomy and Physiology Professor at Nevada State University. When he is not treating patients and teaching students, Dr. Stirrup spends his free time training and competing in international bicycle races and occasional 5ks, spending time with family, friends, and his beautiful black lab Maddison, as well as finding various avenues to foster his creativity.
Although Dr. Stirrup started, and later pivoted, from his initial desire for psychiatric medicine, he still acknowledges the importance of the brain when treating patients and makes an effort to educate himself and others on the importance of mental health.