17 Endovascular Options to Treat Iatrogenic Vascular Injury and Tumor Involvement of the Skull Base

Vascular injuries are rare but potentially fatal complications of both open microsurgical and endoscopic surgery for skull base tumors. Although ICA injury occurs in <2% of cases of pituitary adenomas,1 ^{,​ 2} treatment of these vascular injuries is markedly challenging. Historically, ICA injuries that could not be primarily repaired required vessel sacrifice with or without attempted high-flow bypass, a treatment strategy that contributes to the morbidity associated with the injuries.^{2 ,​ 3 ,​ 4 ,​ 5 ,​ 6} Vascular injuries may be immediately apparent intraoperatively or can present in a delayed fashion, days to even years after the index surgery.^{1 ,​ 2 ,​ 6 ,​ 7 ,​ 8 ,​ 9}

In general, the ideal strategy for managing ICA injury during skull base surgery is prevention. This requires a combination of anatomical knowledge, experience, and adherence to established surgical principles. Primary repair of vascular injuries, particularly during endonasal approaches, is very challenging because of the long working corridor, limited surgical freedom, and limitations in available instrumentation. Recently, dedicated teaching efforts using both live courses and simulator models have been designed to help prepare surgeons to manage endonasal ICA injuries intraoperatively.^{10 ,​ 11 ,​ 12 ,​ 13} However, the combination of the challenging anatomy and technical limitations currently prevents definitive primary repair of ICA injuries in a majority of these cases.

Various endovascular options have been used to treat iatrogenic ICA injuries after endonasal and open microsurgical skull base surgery. These options differ for injuries that are immediately evident and require emergent treatment^{2 ,​ 3 ,​ 4 ,​ 6 ,​ 8 ,​ 14 –​ 20} and those that present in a delayed fashion after surgery,^{2 ,​ 5 ,​ 7 ,​ 9 ,​ 21 –​ 27} radiosurgery,^{26 ,​ 28} or medical management.²⁹

Acute injuries with active extravasation require immediate treatment. Traditionally, ICA hemorrhage control was accomplished via vessel sacrifice. However, this was often performed at the cost of ICA territory perfusion. This technique has also been used for injuries that present in a delayed fashion if the patient is determined to be tolerant of vessel occlusion after BTO.

As endovascular treatment technologies have evolved, so too have the treatment options and strategies for iatrogenic ICA injuries. In 2013, Gardner et al3 reported on seven ICA injuries during endonasal cases that occurred over a 13-year period. They proposed an endovascular treatment algorithm that involved the use of covered stents or coil sacrifice of the ICA to treat pseudoaneurysms or lacerations with active hemorrhage, respectively. Additional studies have reported favorable outcomes treating acute injuries with covered stents to control bleeding and preserve vessel patency.^{17 ,​ 18 ,​ 19 ,​ 20} With the advent of flow-diverting devices, potential treatment options have expanded further and cases of iatrogenic ICA injuries have been successfully treated with these devices.^{14 ,​ 15} When using flow-diverting devices, covered stents, and stent-assisted coiling techniques, the need for antiplatelet therapy must be considered.

In 2016, Sylvester et al² reported on seven patients with an ICA injury after endonasal surgery who were treated with endovascular therapy, and these authors performed a comprehensive review of the literature. Combining their patients’ data with the available published data, they identified 105 total patients with ICA injuries after endonasal surgery who received endovascular treatment. Of these, 46 patients were treated with ICA sacrifice, 28 with focal embolization of the lesion with or without stent assistance, and 31 with parent vessel reconstruction via a covered stent or flow-diverter device. They found that ICA sacrifice provided durable hemorrhage control but carried a relatively high rate of persistent neurological complication (22%). Lesion coil embolization with or without stent assistance was likewise successfully accomplished but carried a high rate of technical complication (31 and 22%, respectively) and resulted in new or persistent neurologic deficits. Endoluminal reconstruction via a covered stent or flow-diverting device was successfully used for select cases. Although the cases for which this technique was used were carefully selected for this therapy, endoluminal reconstruction produced favorable results with a relatively low complication rate. Based on these data, the authors propose a treatment algorithm that takes into account numerous factors including vascular anatomy, injury characteristics, response to BTO, and relative risk of dual antiplatelet therapy (DAPT). Combining the treatment strategies discussed above with our own institutional experience, we propose a similar treatment algorithm (Fig. 17.1). If an iatrogenic injury occurs that cannot be readily repaired, the injury is packed off to limit bleeding. Regardless of whether the bleeding appears to be controlled by surgical packing, the patient is taken immediately to the angiography suite. The first critical decision-making branch point is to determine whether the patient is a candidate for DAPT. DAPT is required for any covered stent, stent-assisted coiling, or flow-diverter treatment. Of course, the use of DAPT puts patients at a higher risk for postoperative hematoma, and the use of these agents must be weighed against the benefits of the attempted endovascular repair. If the bleeding is controlled with packing and there is no angiographic evidence of active extravasation or large pseudoaneurysm, it may be reasonable to consider delaying treatment until DAPT can be initiated; however, proceeding with treatment urgently is favored, even with the risk of initiating DAPT earlier. Factors that may make patients poor candidates for DAPT are a large residual tumor volume that may predispose them to hematoma development from disrupted tumor vasculature or injuries resulting from trauma.^{2 ,​ 30}

If a patient has been determined to be not a candidate for DAPT, but emergent intervention is required, BTO evaluation is recommended next. Because patients with iatrogenic ICA injuries remain intubated and under general anesthesia, the BTO must be completed and interpreted without neurological examination. In these scenarios, the determination of whether the patient can tolerate occlusion must be made on the basis of radiographical and electrophysiological data (discussed below). If the patient can tolerate occlusion, vessel sacrifice can be performed endovascularly using coils with or without liquid embolysates or microvascular plugs. If the patient cannot tolerate occlusion and active extravasation is noted at the injury site and if DAPT is contraindicated for the patient, a high-flow extracranial to intracranial bypass is needed to supplement blood flow before the ICA is sacrificed. In this situation, if a pseudoaneurysm is identified, it can be treated with primary coiling, if possible, or with high-flow bypass followed by vessel sacrifice.

If a patient is deemed an acceptable candidate for DAPT, the endovascular treatment selected is on the basis of angiographic findings. All patients are heparinized during the procedure. Because these patients were not treated with DAPT before stent placement, we use intraoperative intravenous and intra-arterial administration of abciximab, followed postoperatively by aspirin and clopidogrel. Our group recently showed that this strategy was not associated with an increased risk of perioperative thromboembolic complications.³¹ We typically continue DAPT for 6 months to allow time for endothelialization of the stent and then repeat angiography. If no in-stent thrombosis is noted, we then consider discontinuing clopidogrel and maintaining the patient on an aspirin regimen. With regard to treatment selection for the ICA injury, if active extravasation is noted, the injury is treated by placing a covered stent across the site of injury. Traditional covered stents, such as those used to treat extracranial carotid injuries and pseudoaneurysms, can be difficult to place in the intracranial circulation. However, smaller covered stents, such as the Jostent (Abbott Vascular Devices, Abbott Medical, Abbott Park, IL), can be delivered through catheters capable of navigating through the cranial ICA and can be used to treat iatrogenic ICA injuries and cavernous carotid fistulas.^{20 ,​ 32 ,​ 33 ,​ 34} If a pseudoaneurysm is noted, the endovascular treatment options include deployment of a covered stent, stent-assisted coiling, or deployment of a flow-diverter device. The specific treatment selected should be based on the patient’s individual injury and the operator’s discretion. In general, stent-assisted coiling or flow-diverter placement is favored, because of the technical nuances involved with the deployment of covered stents and because they are associated with an increased risk of thromboembolic complications. If these techniques are unsuccessful, BTO followed by ICA sacrifice is recommended either with or without high-flow bypass based on the results of the BTO, as discussed above. Depending on the type of endovascular repair performed and the severity of the injury, short-term follow-up angiograms may be warranted. These may be particularly necessary in the situations where a stent was placed across a pseudoaneurysm to ensure stabilization of the lesion. Regardless of technique used, 6-month follow-up vascular imaging is prudent.

As the technology and experience with flow-diverting devices continues to progress, endoluminal reconstruction techniques may continue to improve outcomes for these challenging cases. Additional techniques have also been reported. Cobb et al35 reported an iatrogenic ICA injury that was repaired primarily after an endovascular balloon was inflated at the injury site during an intraoperative angiogram.³⁵

Regardless of the endovascular treatment strategy selected, timely recognition of the event and effective communication between the teams involved are essential. If an iatrogenic injury occurs, the surgical team should immediately alert the anesthesia team, so that they can prepare for blood pressure augmentation and necessary fluid resuscitation and transfusions. If primary control or repair of the injury cannot be achieved immediately, the surgical team should inform the endovascular team, conveying important details, including the side, site, mechanism, and likely extent of the injury, and ask them to have an angiography suite prepared. In cases that have a higher risk for a carotid artery injury (such as surgery for tumors encasing the carotid, revision surgeries, etc.), it is of paramount importance to discuss this elevated risk with all the teams involved and to have a plan in place before beginning surgery. We recommend that an endovascular team be available whenever central skull base surgery is to be performed. Furthermore, it is recommended that high-risk procedures be performed exclusively at institutions with immediately available endovascular services, such as comprehensive stroke centers.

Skull base vascular injuries are not limited only to the ICA. Cases of posterior cerebral artery injury following endonasal and open surgery have also been reported.36 ^{,​ 37 ,​ 38}

17.3.1 Case Example

One example is a case of a hemorrhagic posterior communicating artery (PComA) pseudoaneurysm after endoscopic endonasal surgery. A 41-year-old man was diagnosed with a midline intracranial dermoid cyst and underwent endoscopic endonasal resection (Fig. 17.2a). No vascular injury was noted during surgery. On postoperative day 9, the patient experienced a sudden-onset severe headache and neurologic decline from a subarachnoid hemorrhage. An angiogram demonstrated a right PComA pseudoaneurysm (Fig. 17.2b). Vertebral artery injection demonstrated robust filling of bilateral posterior cerebral arteries (Fig. 17.2c), and the pseudoaneurysm was treated with coil embolization with focal sacrifice of the distal PComA (Fig. 17.2d). The patient did not experience any neurologic complication associated with this treatment.

Related posts:

Bypass in the Treatment of Skull Base Tumors Dealing with Vascular Injury During Middle Fossa Surgery Simulation and Training—Preparing for Vascular Injury Dealing with Major Intraoperative Vascular Injury Extracranial Anterior Cranial Base Surgery for Vascular Tumors Extracranial Lateral Cranial Base Vascular Tumor Surgery

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