The pros and cons of radial access in neurointerventional surgery

radial access neurointerventional surgery
Pascal Jabbour (L), Kareem El Naamani

As the adoption of radial access across the world of neurointerventional surgery begins to pick up pace, Pascal Jabbour and Kareem El Naamani (Thomas Jefferson University, Philadelphia, USA) take a look at both sides of the coin in this relatively new alternative to the transfemoral approach.

The neurointervention field has witnessed immense technological advancements in the treatment of neurovascular diseases since the introduction of the Guglielmi detachable coils in 1991.1 One revolutionary milestone was the introduction of the radial access, which gained popularity in the neurointerventionist community—especially after several cardiology studies proved its safety and overall reduced morbidity and mortality.2-4

Although the radial access site has inherent limitations, the decreased risk of access site and periprocedural complications demonstrated in the cardiac literature prompted neurointerventionists to pursue a “radial-first” strategy in their practice. With the introduction of radial access, many studies were conducted in the neurovascular field to assess its efficacy, safety profile, and feasibility, and compare these parameters to those of the conventional femoral access in order to address the limitations, push for more advancements, and ensure that patient safety remains the top priority.5,6

Advantages of radial access

Transradial access provides several advantages at the anatomical, safety, financial and feasibility levels. First, the radial artery is more superficial than the femoral artery, and is not in close proximity to any critical structures that are susceptible to injury during the procedure.7 Moreover, because of the dual blood supply to the hand, direct injury to the radial artery, such as thrombosis or dissection, is less detrimental to the patient.8 The transradial approach is particularly advantageous in complex arch anatomies. In patients with bovine arches, the common origin of the innominate artery and the left common carotid artery (CCA) allows direct navigation of the left CCA without the need to form the Simmons catheter in the aortic arch.9

Also, in other cases, where the navigation of elongated and tortuous aortic arches (type II or III) poses a challenge to the femoral approach, transradial confers a technically favourable, alternative direct catheterisation without the need for reforming.10,11 Compared to the femoral approach, the radial approach also provides a more straightforward access to the posterior circulation, which reduces time to revascularisation in the setting of vertebrobasilar strokes.12 In our recent large, single-centre case series involving diagnostic and interventional neuroendovascular procedures via radial access, we showed that there was no significant difference in access site complications between transradial and transfemoral approaches—which signifies that complex treatments can be effectively carried out via radial access.6

Another advantage of radial access is that haemostasis can be achieved without the need for a vascular closure device.7 As patient comfort is pivotal, and taking into consideration the current climate in which patients have the benefit of choosing among many treatment options, radial access has gained a strong patient preference due to the ability of patients to ambulate directly after the procedure compared to post-femoral access procedures, which require bedrest for an extended period of time.13 Because of this, patients require less postprocedural nursing care and shorter hospital stay, which in turn reduces hospital costs.13 Other high-risk patients, such as the elderly, patients on blood thinners, pregnant patients, the severely obese, and patients with iliofemoral atherosclerotic disease, may also benefit from radial access due to reduced radiation exposure and fewer access site complications.14,15

Left transradial access and distal transradial access are also additional refinements that expanded our armamentarium for unique anatomical limitations.16,17 The left vertebral artery is left-dominant in most patients and subclavian tortuosity has higher incidence on the right side. The left radial approach provides easier and more advantageous access in these cases.18-20 As for distal transradial access, studies have not only shown that this approach is associated with lower rates of radial artery occlusion and hand ischaemia, but also—because hand supination is not required for these procedures—left-sided access becomes more comfortable with the hand draped across the body in a neutral position.21-24

Disadvantages of radial access

Although low risk, several complications are associated with the transradial access, such as radial artery spasm (RAS), occlusion and perforation, which may result in forearm haematoma or compartment syndrome. Rarer complications include pseudoaneurysm, arteriovenous fistula formation or sterile abscess formation.5,25,26 RAS has been reported to occur in 4–20% of transradial procedures27, with risk factors including small radial artery diameter, repetitive friction and manipulation, patient pain and anxiety, and guidewire entrance into a side branch.5,28-30 When RAS manifests at the beginning of a procedure, it prevents further access, which results in a transfemoral conversion or procedure failure. On the other hand, if RAS occurs post-cannulation, vasodilators are administered through the sheath or guide.31

When it comes to radial artery occlusion (RAO), the incidence varies between 1% and 6% of procedures, and is associated with female gender, low body mass index, high sheath to radial artery diameter ratio, diabetes and occlusive haemostasis—depending on compression time and pressure.32-34 Although RAO is asymptomatic due to the aforementioned dual blood supply, persistence of RAO may render the radial artery unviable for future radial access procedures.21 Other limitations for radial access are anatomical in nature and range from radial artery anomalies, tortuosity, arteria lusoria, and subclavian tortuosity, to aortic arch types.5,10

One radial artery anomaly is high-bifurcation radial origin, which requires the interventionist to navigate an elongated, smaller radial artery diameter, increasing the risk for RAS.5 Another anomaly is a radial artery loop, which may be accompanied by a recurrent radial artery branch at its apex, increasing the risk of perforation if a wire was advanced into the recurrent radial artery.35,36 Although subclavian tortuosity poses a challenge, using the left radial access overcomes such obstacles.15,19

Another challenge is an aberrant right subclavian artery, also known as arteria lusoria, which has an incidence of 0.6–1.4%, and causes repetitive entry of the guidewire into the descending aorta.5,37 While mentioned previously that the radial approach provides easier access in patients with type III aortic arch, in some cases—where the brachiocephalic artery is too inferior—selecting the descending aorta may be challenging, and reforming the catheter in the CCA or ascending aorta may be necessary.10 Lastly, some other concerns regarding radial access include the lack of familiarity with a novel technique, increased radiation exposure in operators in the beginning of their learning curve, and lack of devices designed specifically for radial artery dimensions.38-40

The future of radial access

Although transfemoral catheterisation for neuroendovascular procedures remains the primary access route for most patients, interest in radial access is growing. The two landmark studies in cardiac literature—the RIVAL and MATRIX studies of more than 7,000 patients—showed that radial access is associated with a 60% reduction in vascular complications, as well as significant decreases in all-cause mortality and net adverse clinical events.2,41

As for the neurointervention community, radial access has proven to be safe, effective, feasible and, most importantly, preferred by patients.5,6,10,12-14,16,38 Many centres around the USA, like ours, have introduced radial access training in their fellowship programmes to ensure that future neurosurgeons are transradial- and transfemoral-trained. Also, our centre was the first in the country to perform a transradial robotic-assisted carotid stenting. This not only proves that the scope of radial access is expanding, but also that the transradial approach is here to stay. However, along the journey, it is of utmost importance to address the limitations of radial access via technological advancements, learning curves, and randomised controlled trials—since the main goal of any medical revolution is patient care and safety.



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Pascal Jabbour is the head of the Division of Neurovascular and Endovascular Neurosurgery in the Department of Neurological Surgery at the Sidney Kimmel Medical College at Thomas Jefferson University in Philadelphia, USA. He is also the Angela and Richard T Clark Distinguished Professor of Neurological Surgery and, as a dually trained vascular neurosurgeon, he performs both endovascular and open procedures.

Kareem El Naamani is a postdoctoral research fellow in the Department of Neurosurgery at Thomas Jefferson University Hospital in Philadelphia, USA. He finished his medical education at the Lebanese American University in Beirut, Lebanon and is currently pursuing his goal of becoming a board-certified neurosurgeon.


DISCLOSURES: Jabbour is a consultant for Balt, Cerenovus, Cerus Endovascular, Medtronic, Microvention and Q’Apel.


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