AANS Neurosurgeon | Volume 28, Number 4, 2019


The Future of Neurosurgical Education Part I: Setting the Stage

Print Friendly, PDF & Email

I have always found articles that predict the future to be risible. The readers do not know if the author’s predictions are accurate and by the time “the future” arrives no one will remember what was written. This is how psychics and political pundits stay in business. So, when I agreed to write an article about the future of neurosurgical education, I felt a bit unscrupulous. Although I have participated in the trajectory of neurosurgery for 40 years, studied its history and speculated about its future, the reader should be cautioned that pontificating neurosurgeons belong to the same guild as psychics and political pundits. 

The Halsted Model

Until the 19th century, surgical training was haphazard with no standardized prerequisites, duration of training or curriculum. The surgical trainee learned solely through observation of a mentor and finished training when the mentor indicated readiness. However, as surgery evolved from a trade to a profession in the United States, the method of training surgeons also evolved, due largely to the influence of Harvey Cushing’s mentor, William Halsted. Halsted’s principles of surgical training include:

  • The need to understand the scientific basis of disease;
  • Repeated, supervised care of surgical patients to acquire skills in operative technique and medical management; and
  • Increasing responsibility during training, leading to independent practice.1

These principles have stood the test of time and I see no reason to abandon them. However, dramatic changes in the scope of practice, technology and societal expectations have changed how we apply these principles to neurosurgical training.

Neurosurgical Education 2000-2018

The first years of the 21st century saw a dramatic change in neurosurgical education. Residency training today, while continuing to honor the principles that Halsted proposed, is very different from residency training just 15 years ago. During this brief period of time we have:

Advancing Technology, Patient Expectations and Scope of Practice

Changes in neurosurgery resident training have also been driven by advancing technology, elevated patient expectations and the rapidly growing scope of neurosurgical practice. When I started my residency, neurosurgeons in training did one or two years of general surgery, followed by four or five years of neurosurgery. At that time, the operating microscope was the height of technology, while MRI scans, image guided operations, neuro-endovascular procedures and deep brain stimulator placement were not yet available. Only orthopedists put metal in the spine. The general neurosurgeon still roamed the earth and subspecialization was not a pressing issue. 

The dramatic advance in technology over the last 40 years has changed all of this, allowing neurosurgeons today to do a much wider range of procedures with better outcomes; however, this increase has made mastering all aspects of neurosurgery untenable. While the range of neurosurgical options has been steadily increasing, our patients are demanding to know more and more about their neurosurgeons’ credentials. In my experience, many more patients now recognize that the best neurosurgeon to treat their intracranial aneurysm is probably not the best neurosurgeon to treat their degenerative spine – and they expect documented subspecialty expertise for their particular problem. So, while the scope of global neurosurgical practice has increased, many individual neurosurgeon’s practices have become more focused. Rapidly advancing technology and changing patient expectations have resulted in ever increasing neurosurgical subspecialization and this trend is unlikely to be reversed in the future. 

Although no neurosurgeon now practices all aspects of neurosurgery, we still train neurosurgical residents as though they will. This dissonance between the scope of an individual’s neurosurgical practice and the scope of neurosurgical residency training, accreditation and certification needs is being addressed. Organized neurosurgery has responded in a variety of ways. The first is an attempt to define core neurosurgery – the cognitive and technical skills that each neurosurgeon must master to achieve certification as a neurosurgeon. 

The committee that developed the ACGME Milestones 2.0 for neurosurgery used an operational definition:

Core neurosurgery is the cognitive and technical skills that each neurosurgeon must master to care for neurosurgical patients until they can be seen by a subspecialist

The new Level 3 milestones are designed to correspond to the core cognitive and patient care skills needed by every neurosurgeon. The ACGME Residency Review Committee (RRC) for neurosurgery has also determined case minimums in all subspecialties that each graduating resident should obtain and the American Board of Neurological Surgery (ABNS) is working to define core neurosurgery by determining what knowledge base and patient care skills are needed to become an ABNS-certified neurosurgeon. Defining core neurosurgery will help to keep us together as a specialty, while recognizing that the neurosurgeons of today and tomorrow will obtain more extensive training in one or more subspecialty disciplines and focus their practices largely within these subspecialties. To keep our specialty intact and vibrant, the leaders of neurosurgical education must first recognize this emerging pattern that includes core neurosurgical training as well as a focused practice in one or two subspecialty areas, and then develop the infrastructure and processes to support this.

The Role of CAST

Ralph Dacey, then SNS President, appointed the CAST Task Force in 2012; Steve Giannotta, Volker Sonntag, Art Day and me. Our charge was to:

  • Develop and clarify advanced subspecialty training requirements beyond those of core neurosurgery residency training.
  • Determine the feasibility of enfolding fellowship training within the residency.
  • Develop, in concert with the ABNS, a process for certifying individuals as well as accrediting programs in neurosurgical subspecialties.

We sought advice from the American Association of Neurological Surgeons (AANS) and Congress of Neurological Surgeons (CNS) Sections, the RRC and the ABNS. CAST, which had previously been the Committee for Accreditation of Subspecialty Training, was renamed the Committee on Advanced Subspecialty Training, with clearly defined processes for the CAST accreditation and certification roles.

Principles of CAST Neurosurgical Fellowship Training

The task force produced the following principles of neurosurgical fellowship training:

  • Completion of an ACGME-accredited residency is sufficient to allow the practice of neurosurgery. 
  • CAST oversight of neurosurgical fellowships must serve the interest of our patients and our specialty by ensuring the quality of neurosurgical fellowship training.
  • Fellowships may be either enfolded into residency training or follow the completion of the neurosurgery residency program. In either case they must offer sufficient depth and breadth of training to provide a higher level of subspecialty expertise than that achieved during the core residency training.
  • The requirements for fellowships and fellows are established by CAST in consultation with the neurosurgical subspecialty sections. CAST will specify the duration and components of training and the requirements for facilities, faculty, affiliated services and minimum case material at the fellowship site.
  • Fellowships must have a defined curriculum and procedural objectives that correspond to the ACGME Level 5 Milestones in that subspecialty and must include scholarly activity with clear expectations of academic performance.
  • The duration of enfolded fellowship training and its position in the residency program may vary, depending on the subspecialty (e.g. neurocritical care fellowship training must total 12 months, which can occur in blocks of no less than four months during any post-graduate year, while subspecialties that require refined operative skills may only be enfolded in the residency if they occur after the chief resident year).
  • CAST may present practice track certificates and documents that indicate a neurosurgeon has completed a CAST-accredited fellowship. However, certification as a neurosurgeon is done only by the ABNS, which now also certifies individuals with focused practices in neurocritical care, CNS endovascular surgery and pediatric neurosurgery.2



1. Grillo, H.C. (1999). To impart this art: The development of graduate surgical education in the United States. Surgery. 125(1), 1-14.

2. Harbaugh, R. E. (2015). The 2015 AANS Presidential Address: Neurosurgery’s founding principles. Journal of Neurosurgery, 1351-1357.


Leave a Reply

Be the first to reply using the above form.