Neurovascular surgery: the way forward—an Australian perspective

Introduction

Endovascular treatment of neurovascular pathology has seen widespread growth in Australia, but the nature and degree of implementation has been highly variable across the country and even within local networks. While national open surgical case numbers have not seen a clear decline in absolute terms, the expansion of endovascular treatment, the growing surgeon workforce and greater trainee positions mean that there is a reduction in relative terms. This trend presents a challenge to training our next generation of open neurovascular surgeons. Although Australian neurosurgical trainees and neurosurgeons face few regulatory obstacles in obtaining experience and qualification in endovascular techniques, very few have done so. This likely reflects a range of historical, cultural and political factors.

Australian geography and workforce

The population of Australia and New Zealand are approximately 27 million and 5 million respectively, with a collective landmass of about 8 million square kilometres. Continental US and Europe have a similar landmass but population densities over ten times higher. Most of the Australian population, virtually all of the neurosurgical units and the 293 practicing neurosurgeons are focused at the major coastal cities that are quite widely dispersed (1).

The Australian health system depends on both the public and private sector, creating a structural and cultural middle ground between a UK and US style system. Although there is a large public sector that accommodates most acute admissions and emergency surgery (86%), the private sector is responsible for the bulk of elective surgical work performed in Australia (70%) (2). As the private sector accounts for most surgical activity, it also has a strong influence on clinical practice and culture.

The degree of centralisation is highly variable across the country. Some states such as Western Australia have very centralised care for neurosurgery, with all of their ~3 million population directed to one neurosurgical service. By comparison, New South Wales, with a population of ~8 million has a fragmented series of networks with eleven neurosurgical units in close proximity; of which there are six centres within a 60 km radius that offer aneurysm surgery.

Australian training and neurovascular exposure

There are currently 54 accredited neurosurgical trainees dispersed across the 27 accredited neurosurgical training units of Australia and New Zealand. The number of registrars in unaccredited or non-training posts is not well documented.

Typically 3–4 years of ‘unaccredited’ neurosurgical experience are completed prior to successful selection to the Surgical Education and Training (SET) program. The SET trainee then completes 5–9 years of formal training across a minimum of 3 units across the country. The forced rotation to different centres, and typically different states is to ensure depth, breadth, and consistency of training.

Recently, it was calculated that between 2008 and 2018, the typical Australian trainee exposure to aneurysm treatment had increased, largely due to the growth in the endovascular treatment of aneurysms, both ruptured and unruptured. In the same study, it was determined that the typical SET trainee would be exposed to the microsurgical treatment of about 90 aneurysms during training. This number remained roughly stable over the 10-year observation period as the decline in surgically managed ruptured aneurysms was offset by a growth in the number elective microsurgically treated aneurysms (3).

These numbers would suggest that trainee exposure hasn’t declined, however, anecdotally the nature of that exposure has changed. Trainees are unlikely to obtain much experience as a primary surgeon, and very few obtain competence. Historically satisfactory clip repair of an anterior circulation aneurysm was a competency that required achievement prior to completion of training. This is now considered an advanced competency that is no longer a barrier. Instead, trainees must have shown competency in at least 5 of 8 advanced competencies, reflecting the move toward more subspecialised skillsets for both individuals and units alike.

Fellowship training and accreditation

A formal neurovascular fellowship is not required to perform neurovascular surgery in Australia, however, it is increasingly becoming an expectation in order to undertake neurovascular cases, or simply a requirement for those wanting to obtain competence that was not achieved upon completion of training.

The challenge for most units is to maintain the skills of a selected number of surgeons to allow competency and provision of an effective service. This has seen formal or informal subspecialisation within units. There are very few units therefore which have sufficient volume of open vascular cases to offer a dedicated neurovascular fellowship position, and only two that are accredited by the Royal Australasian College of Surgeons (RACS). Most open neurovascular trained surgeons in Australia have obtained their fellowship experience internationally.

In contrast to open neurovascular surgery, there exists a formalised accreditation body for interventional neuroradiology: the Conjoint Committee for recognition of training in Interventional NeuroRadiology (CCINR). This committee was formed through collaboration between peak Australian bodies representing Radiology, Neurology, and Neurosurgery. CCINR registration requires practitioners to have met a standardised level of training, experience and currency, and is a prerequisite for most neurointerventional appointments and Medicare reimbursement for mechanical thrombectomy in ischaemic stroke. The CCINR requires a 2-year competency-based fellowship training program independent of specialty background.

Each year there are about 10 CCINR accredited fellowships available in Australia. Although these programs are open to neurosurgeons, neurologists and radiologists the vast bulk of those in training are radiologists. Currently there are 71 CCINR accredited neuroendovascular specialists in Australia and 3 in New Zealand; of which a 9 are neurosurgeons, 12 are neurologists and 50 are radiologists (4). Notably all 9 dual-trained open-endovascular surgeons have received their endovascular training internationally. No surgeon completed their endovascular training domestically.

Trends and challenges of neurovascular training

Despite a population that is growing and aging, and a neurosurgical workforce that is expanding, the number of microsurgical aneurysm cases being performed nationally has remained stagnant at about 900 cases each year. Although the number of endovascularly treated aneurysms was also ~900 in 2008, by 2023 that number has almost doubled (2). The ratio of endovascular to surgically treated aneurysms reflects regional variation in skillset, resources, staffing and culture. Nationwide 42% of aneurysms are treated surgically, but that varies from 14% (Western Australia) to 65% (Tasmania) (3).

The volume of surgically resected arteriovenous malformations within Australia has remained relatively unchanged over the last two decades, at about 180–200 cases per year. The number of bypass procedures has increased from about 40 cases per year in 2010 to 60 cases per year in 2023, with the vast majority being superficial temporal artery to middle cerebral artery (STA-MCA) bypass (2).

Despite the concentration of neurosurgical centres into major cities, there still exist a number of neurosurgical units with capacity to perform microsurgery but no available on-site endovascular treatment option. Until recently, this included Far North Queensland, Tasmania and some neurosurgical units of Sydney, which understandably would experience some bias toward surgical treatment. As thrombectomy for stroke becomes an expected standard of care, it is predictable that we will see expansion of thrombectomy services and endovascular specialists to regional centres. It is predictable therefore that there will be further shift away from surgical management.

Discussion

As Australia has no centralised neurovascular database, audit or accreditation body, the currently heterogeneous regional practice patterns are likely to continue for the foreseeable future. Scope of practice limitation will not be enforced by RACS, but is increasingly becoming a part of local hospital credentialing.

In Australia, subarachnoid haemorrhage remains the domain of a neurosurgeon, and these patients continue to be admitted under their care. There is however a gradual and growing presence of interventional radiology, interventional neurology and neurocritical care specialists in the management of these patients, particularly in units where microsurgery is an uncommon occurrence. While greater multispecialty interest and involvement enrich patient care, there is also the potential that surgeons become less involved in patent care and potentially even transition from the principal admitting team to a consulting service.

In units that demonstrate a strong bias toward endovascular treatment of aneurysms, neurosurgical trainees typically do not see increased exposure to endovascular procedures despite recent changes by the neurosurgical SET board to encourage trainee exposure to these techniques: endovascular procedures have been included in the surgical logbook and endovascular competency can now be assessed by any CCINR specialist, not just surgeons. Although it may be possible for neurosurgical trainees to scrub with neurologists and radiologists, there are few examples where this occurs. Neurosurgical trainees face many obstacles to accessing endovascular cases: priority given to non-surgical trainees, scheduling clashes with on-call or other operating theatre commitments, local hospital accreditation, indemnity concerns, historical protocols or culture. Even when the endovascular specialist is a surgeon, these barriers may prove prohibitive.

Although there is the capacity to undergo dual training within Australia, it seems highly unlikely that we will see a major shift in practice patterns. For a dual-trained surgeon to achieve and maintain excellence with the full spectrum of endovascular and open neurovascular techniques would require high case volumes and a degree of centralisation we are not likely to see. This reality may in part explain the relatively low uptake of endovascular training amongst Australian neurosurgeons.

Ensuring quality neurovascular care will therefore continue to require a multidisciplinary team (MDT) approach. The days of “clip-versus-coil” have passed. There is a well-established role for both treatment modalities, and the optimal patient management is achieved by careful consideration of all options and local capability. A simple application of a “coil-first” approach does not constitute an MDT discussion.

While centralisation and higher volume helps achieve better outcomes, this benefit is undermined without a robust and engaged surgical service. It is well established that higher surgical volume is associated with better surgical outcomes (5). Anderson et al. showed that endovascular outcomes following aneurysm treatment correlated more strongly with local microsurgical volume than with the endovascular volume (6). This highlights the importance of surgeon engagement, robust MDT and achieving optimal individualised treatment selection.

An MDT cannot be effective if there is a significant imbalance of technical skill, understanding or respect. Just as it is important for microsurgeons to have exposure to the endovascular techniques, it is important for endovascular specialists to have trained with and developed an appreciation for the capabilities of microsurgery. The fragmentation of the Australian neurovascular landscape therefore poses challenges to the quality of microsurgical training, endovascular training and effective MDT. How this growing challenge is to be overcome is yet to be seen.

Conclusions

Training the next generation of Australian neurovascular surgeons will continue to be a challenge that is largely reliant upon international fellowships. Looking forward, Australia’s lack of centralisation, minimal subspecialisation, vast geography, and historical practice patterns will likely maintain the status quo. Embracing the inclusion of endovascular techniques in neurosurgical training has many potential benefits but it is unlikely that we will see a large workforce of hybrid neurovascular surgeons. It is probable that we will continue to see semi specialised surgeons offering microsurgery and radiologists providing the bulk of endovascular care, highlighting the continued importance of the MDT approach.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editor (Christos Tolias) for the series “State of Neurovascular Surgery. The Way Forward” published in AME Surgical Journal. The article has undergone external peer review.

Peer Review File: Available at https://asj.amegroups.com/article/view/10.21037/asj-24-46/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-24-46/coif). The series “State of Neurovascular Surgery. The Way Forward” was commissioned by the editorial office without any funding or sponsorship. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Neurosurgical Society of Australasia. NSA Workforce Snapshot Report [Internet]. 2024. Available online: nsa.org.au/Public/Public/Information/Public/Publications.aspx
2. AIHW. Australian Institute of Health and Welfare. Australia’s hospitals at a glance [Internet]. 2024. Available online: https://www.aihw.gov.au/reports/hospitals/australias-hospitals-at-a-glance
3. Huang H, Limb R, Lai LT. Is it time to rethink microsurgical training for the treatment of intracranial aneurysms in Australia? J Clin Neurosci 2023;108:95-101. [Crossref] [PubMed]
4. CCINR. Register of Australian and New Zealand INRs [Internet]. 2024. Available online: www.ccinr.com.au/register
5. Davies JM, Lawton MT. Improved outcomes for patients with cerebrovascular malformations at high-volume centers: the impact of surgeon and hospital volume in the United States, 2000-2009. J Neurosurg 2017;127:69-80. [Crossref] [PubMed]
6. Anderson IA, Kailaya-Vasan A, Nelson RJ, et al. Clipping aneurysms improves outcomes for patients undergoing coiling. J Neurosurg 2018;130:1491-7. [Crossref] [PubMed]