Physician Assistants & Nurse Practitioners

Brittney Misercola, MSN, RN, FNP-C, CFRN

Brittney Misercola, APRN,FNP-C

Brittney Misercola, a board-certified family nurse practitioner, received her master's degree in nursing from Frontier Nursing University. Brittney has been in the central Texas area for many years. Prior to becoming a nurse practitioner, she was an emergency flight nurse in the Killeen area for several years. Her nurse practitioner background includes emergency medicine, neurology, and orthopedic surgery. Brittney loves the central Texas Hill Country and has a desire to work collaboratively with her patients to achieve their wellness goals.

Brittney loves spending time with her husband and two daughters, as well as traveling.


Nicole A. Busch, AGCNS-BC

Nicole A. Busch, AGCNS-BC

Nicole Busch is a board-certified clinical nurse specialist with a specialty in the adult through gerontology population. She initially completed undergraduate degrees in Business Management and Sociology from the University of Texas at Austin, but after several years of working in the business world, life guided her towards her passion of working in healthcare. She obtained her Masters in Nursing in 2015 from the University of Texas at Austin.

Post-graduate school, Nicole began her career as an advanced practice nurse with a focus in internal medicine, working with patients in the hospital, physical rehabilitation, and acute mental health settings.

Nicole is committed to helping patients achieve optimum functionality and quality of life by creating comprehensive pain management plans that fit the needs and lifestyles of those she treats.

Outside of work, Nicole enjoys traveling, photography, and spending time with her husband, Brian, and their dog, Otis.


Cassidy Lawrence, PA

Cassidy Lawrence, PA

Cassidy Lawrence hails from the great state of Virginia. She is a highly motivated board-certified physician assistant with 6 years' experience. She graduated from the Interservice Physician Assistant Program (IPAP) while serving as an active duty soldier in the United States Army, and she received her master of physician assistant studies in 2010 from the University of Nebraska Omaha Medical Center. 

Cassidy served in the Army for 9 years. Upon her exodus from the military she worked at San Antonio-based Family Practice Clinic for 2 years managing patients of all ages. She joined PSA in June 2016 and is based out of the Killeen/Copperas Cove locations serving the Bell County communities.

Cassidy’s areas of clinical interest include family practice, urgent care, and pain management.

Outside the office, Cassidy loves to spend time with her husband and beautiful daughter. She is an avid runner and enjoys health and fitness.


Amanda Carlisle, NP

Amanda Carlisle, NP

Amanda “Mandy” Carlisle is a Board Certified Family Nurse Practitioner accredited through the American Academy of Nurse Practitioners. She received her Bachelor’s Degree in Nursing from the University of Texas Health Science Center at San Antonio and her Master’s Degree in Nursing from Texas State University where she graduated with highest honors. She has over eighteen years of experience in nursing. She is an active member of the American Academy of Nurse Practitioners, Texas Nurse Practitioners, Austin Advanced Practice Nurses, and Sigma Theta Tau International Nursing Honors Society


Rebecca Messmore, FNP-BC PMNBC-RN

Rebecca Messmore, FNP-BC PMNBC-RN

Rebecca Messmore board-certified family nurse practitioner and board-certified psychiatric mental health registered nurse. She received her Master's Degree from Texas State University and her undergraduate degree from Nevada State College.

Rebecca grew up in Las Vegas, Nevada and relocated to the Austin area in 2009. She has experience as a nurse with home health, psychiatry, neurology, and has worked on medical-surgical and long term acute care units. Rebecca continues to work part time on inpatient children and adult psychiatry units and is a member of the Nurse Corps US Navy Reserves.

In her free time, Rebecca likes to spend time with her family, outdoors when possible.

Rebecca has an interest in helping patients to achieve reasonable pain management goals.


Angela Piel, MSN, APRN, FNP-C

Angela Piel, MSN, APRN, FNP-C

Angela Piel is board-certified Family Nurse Practitioner accredited through the American Academy of Nurse Practitioners. She graduated with her Master’s Degree from South University in Austin, TX with Highest Honors, maintaining a 4.0 GPA throughout her program. Prior to becoming a Nurse Practitioner, she worked in many areas of nursing, to include: Wound Care, Medical, Surgical, Trauma, Orthopedic, Intensive Care, and Emergency Nursing Units.

She was born and raised in Iowa, but has been a Texas resident since 2011. She is an Army veteran with 8 years of prior service. She has a passion for giving back to the military community, and loves having the opportunity to serve military members, veterans, and their families as a medical provider.

She is an active member of Sigma Theta Tau International Honor Society of Nursing, American Association of Nurse Practitioners, and Texas Nurse Practitioners.

Outside of work, Angela loves spending time with her husband and her son. She enjoys refurbishing old furniture pieces, building furniture, making home décor, traveling, and spending time with friends and family.


Cathryn Lisa Ortiz-Garnett, NP

Cathryn Lisa Ortiz-Garnett, NP

Cathryn Lisa Ortiz-Garnett is an Advance Practice Registered Nurse. Lisa is a graduate of Texas Health Science Center at San Antonio Graduate School of Biomedical Sciences with a Master of Science in Nursing in 1977 where she graduated Magnum Cum Lata, Phi Theta Kappa. Lisa comes to Pain Specialists of Austin with an extensive background in Neurosurgery, ICU and Trauma.

Lisa and her husband have moved to Central Texas from Brownsville where she has resided since 1989. They have purchased a house that was built in the 1800 and have enjoyed remodeling it and all that comes with a house of that age and time in history.

Lisa has 5 children and 5 grand children that she thoroughly enjoys spending every minute she can with.