Our Providers

Dr. Messiha is double board-certified in anesthesiology and pain medicine. He has an interest and background in multimodal pain management, utilizing interventional, medical, physical, and psychological therapies to treat the person as a whole. He is a graduate of the Pennsylvania State University College of Medicine and completed his general surgery internship at Harbor-UCLA Medical Center. After completing his anesthesiology residency at Case Western Reserve University/Metrohealth Medical Center in Cleveland, Ohio, Dr. Messiha completed a pain medicine fellowship at the University of Pittsburgh Medical Center. Dr. Messiha and his family are happy to be back home in Southern California, and he looks forward to building long-term relationships with his patients and providing the highest level of care to improve their quality of life.

Dr. Joshua Barnhill is double board certified in Anesthesiology and Pain Medicine. He grew up in in St. Louis, MO where he graduated medical school from Saint Louis University. Following graduation, he served over ten years in the United States Navy. Dr. Barnhill strongly believes each patient deserves a customized approach and multimodal treatment strategy tailored to their goals to achieve functional improvement. He treats complex regional pain syndrome, cancer pain, migraines, and musculoskeletal pain conditions, including back pain, neck pain, myofascial pain, neuropathic pain, joint pain, and post-surgical pain using traditional and advanced therapies.

Adina was born and raised in Garden Grove, California. She is very personable, outgoing, and knowledgeable! She received a Bachelor of Science in Biochemistry/Cell Biology at UCSD. Adina went on to USC where she received a Master’s of Science in Physician Assistant Studies. After spending a few years practicing in Orthopedic Surgery, she continued on to broaden her experience in Primary Care and Urgent Care settings. Adina enjoys spending her free time with her family and friends.