Shirley was born and raised in the town of Rutherglen, Scotland, and obtained a B.Sc. (Hons) in Biology (Microbiology) at Glasgow College of Technology (now Glasgow Caledonian University, Scotland) and a Ph.D. at the University of St Andrews, Scotland. In 1992 she moved to the United States to complete post-doctoral training at the Vollum institute, Oregon Health & Sciences University (OHSU), Portland, Ore.

Dr. McCartney joined the OHSU Department of Neurological Surgery, in 1997 as a research assistant and in 2001 was appointed to senior research assistant. She was appointed to the faculty as an instructor in 2003, an assistant professor in 2004, and associate professor in 2014. In 2020 Dr. McCartney was appointed to a position of Research Administrator.

Dr. McCartney collaborates with Dr. Kim Burchiel on trigeminal neuralgia research and a diagnostic artificial network for facial pain, and Drs. Maria Fleseriu and Chris Yedinak on neuroendocrine clinical research.

Her responsibilities as an educator include teaching and directing faculty and staff of the Department of Neurological Surgery, on OHSU institutional review board policies, clinical trial management, and academic publishing ethics.

Dr. McCartney, currently serves as director of neurological surgery clinical research (clinical trials and investigator initiated clinical research), and manages a team of research coordinators. She also edits, manages and administers clinical and academic publishing material. 

Dr. McCartney is a Shin Shin Toitsu Aikido 5th Dan, and has been teaching and training Ki principles and Aikido for over 34 years.