The patient was emergently brought to the neuroangiography suite. After induction with general anesthesia, right common femoral artery was obtained.

Given arch tortuosity seen on pre-operative CTA, a Simmons Select catheter (Penumbra, Alameda, California, USA) was chosen. After the right CCA was successfully catheterized, an angiogram was obtained which showed a 360-degree loop in a proximal CCA (Fig. 2). Under roadmap guidance, the BENCHMARK BMX 96 guiding catheter (Penumbra, Alameda, California, USA) was advanced over the Simmons and Terumo and into the CCA (Fig. 2A, B). The Simmons and Terumo were removed and manual aspiration of the proximal right CCA bifurcation thrombus was performed through the BMX. Under roadmap guidance, the BMX over the Berenstein Select catheter (Penumbra, Alameda, California, USA) and the Terumo guidewire were navigated into the right ICA (Fig. 2C). Angiographic evaluation showed an additional 360-degree loop in the right cervical ICA, and a proximal M1 occlusion intracranially (Fig. 2C).

The first pass of thrombectomy in the right M1 was performed using a RED72 aspiration catheter with the SENDit system (Penumbra, Alameda, California, USA) over the Synchro 2 microwire (Stryker, Kalamazoo, Michigan, USA) (Fig. 2D). The system was navigated through the cervical ICA loop and to the site of occlusion, where the RED72 catheter was advanced over the SENDit to the proximal clot face. Aspiration was initiated through the RED72 catheter and continued for 2 minutes. Post-first pass angiography showed interval revascularization of the right M1, with now an occlusion in the right M2 superior trunk (Fig. 2E). Simultaneously, the previously seen ICA loop was noted to have straightened, with development of severe vasospasm in this context (Fig. 2E). Verapamil was injected into the ICA through the BMX to relieve the vasospasm with minimal improvement. Given persistent spasm and straightening of the loop, gentle external neck manipulation was performed. While there was some improvement, the loop did not re-form and there appeared to be persistent spasm at the location. The decision was made to carefully cross the region with a microcatheter system with the intent to perform a second pass.

Under roadmap guidance, the Headway 21 over Synchro 2 was carefully navigated past the straightened ICA loop and region of vasospasm with minimal resistance. A microinjection was performed to confirm passage in the true lumen. Next, the 5 French Sofia aspiration catheter (Terumo Medical Corporation, Somerset, New Jersey, USA) was then carefully advanced over the Headway 21 and Synchro 2 past the stenotic segment and intracranially to the occluded right proximal M2 using the co-axial technique. This appeared to reform the pre-existing loop in the ICA (Fig. 2F). A second pass was performed via direct aspiration through the Sofia catheter in the M2 segment. The catheter was then slowly withdrawn from the patient under engine aspiration.

Post-second pass angiographic evaluation through the BMX showed Thrombolysis in Cerebral Infarction (TICI) score 2b reperfusion, resolution of vasospasm, and return of the pre-treatment configuration of the ICA loop (Fig. 2G, H). There was no residual thrombus in the CCA. A region of mild CCA stenosis was noted that did not appear flow-limiting (Fig. 2H).

An magnetic resonance imaging (MRI) was performed 24 hours later which demonstrated moderate infarct burden in the right MCA territory (Fig. 3), as well as asymptomatic, mild hemorrhagic transformation in the basal ganglia (parenchymal hematoma type 1, Fig. 4) [9,25]. The patient was discharged to a rehabilitation facility. At the time of discharge, her NIHSS was 5 for mild left upper extremity drift, left lower extremity drift to the bed, and facial droop.

While EVT is considered to be a safe and feasible procedure in elderly patients [12], several challenges can be encountered during the procedure due to age-related changes. Vascular tortuosity becomes more profound with age [4,28]. These anatomical changes increase the complexity of the case and navigation of endovascular tools. Furthermore, elderly patients tend to have greater stiffness and calcification in their vessels. Arterial stiffness was found to be a predictor of poor functional outcome in patients treated with EVT [11,17]. Our case presents the challenges of performing thrombectomy in a patient with severe carotid artery tortuosity, a common occurrence in elderly patients. Navigating this required optimal endovascular tools and delivery devices to achieve adequate recanalization.

The term tandem lesions is used to describe severe stenosis or occlusion of either the proximal CCA or ICA, in addition to an intracranial occlusion [14]. Proximal disease of the CCA and ICA can vary in its severity and features, posing unique challenges in EVT that require individualized approaches for management [5,16]. Two mainstay approaches are often considered. The first, often referred to as the anterograde approach, is through first using balloon angioplasty or stenting to treat the proximal lesion before moving on to intracranial thrombectomy. In contrast, the retrograde approach prioritizes intracranial thrombectomy first, if the proximal lesion can at least be crossed, before later addressing the proximal lesion after intracranial reperfusion is achieved [35]. While each approach has its own advantages and challenges, the aim is to address both lesions [3]. There is further controversy about the use of stenting the proximal lesion acutely versus in a delayed fashion [37]. Many practitioners opt to place a stent if the residual proximal stenosis is severe or if it subsequently occludes on delayed angiography, while deferring for a later time when it may be safer to initiate antiplatelet agents in cases with mild stable-appearing stenosis [3,20]. Thus, the optimal management of tandem lesions in EVT remains elusive and depends on several clinical, anatomic, and technical considerations.

Arterial tortuosity has been shown to be a predictor of procedural complication during EVT [18,30]. In our case, the patient had not only extreme CCA tortuosity but also a 360-degree ICA loop which must be navigated. Due to the anatomy of the vascular structures, multiple endovascular tools were considered for the optimal construct. To navigate through the supra-aortic tortuosity, we first selected a Simmons Select catheter, which allowed for the necessary flexibility and support to navigate into the CCA successfully. After a proximal CCA thrombus was aspirated, we then utilized an aspiration catheter system with the SENDit delivery device. Other available devices on the market include the Tenzing 7 (Route 92 Medical, San Mateo, CA, USA) and the Carrier (Balt, Montmorency, France). These devices are inserted into the aspiration catheter to reduce the ledge effect and improve navigation through tortuous vasculature [19]. For the second pass over a microcatheter system, we utilized an aspiration catheter with a softer tip, in this case Sofia, in order to navigate past the 360-degree loop in the ICA. Another approach, called the “tightrope technique,” has been described to straighten tortuous vessels with a stiff guidewire [22]. Due to the highly variable proximal anatomy and degree of tortuosity among patients, some cases may also require the use of the “grappling technique” with a stent retriever [13,26]. While initially described with an antiquated device, it can also be performed successfully with a stent retriever. By first navigating a microcatheter system beyond the intracranial occlusion and deploying a stent retriever at the site of occlusion, the stent retriever and its pusher wire can provide distal support and straighten the vasculature, allowing the passage of an aspiration catheter through tortuous segments, often in the region of the ophthalmic artery origin. The aspiration catheter can then be advanced to the proximal clot face for combined aspiration and stent retriever thrombectomy [36].

Vasospasm is a common complication in EVT, thought to occur due to mechanical irritation and stress to the vessels from device manipulation [1]. In our case, vasospasm was observed following the straightening of a cervical ICA loop during navigation intracranially for thrombectomy in the right M1 segment. The use of intra-arterial verapamil was partially effective in relieving the vasospasm. Verapamil is a non-dihydropyridine calcium channel blocker that relaxes vascular smooth muscle, thereby reducing spasm [6,23]. Verapamil is infused intra-arterially proximal to the region of vasospasm. Doses vary based on the clinic setting and severity of spasm but typically range from 10-30 mg. Slower infusion over a period of 5-10 minutes while monitoring vital signs can help prevent unwanted hemodynamic side effects. Other agents that are commonly employed include milrinone and nicardipine [7]. These agents are often infused intra-arterially over the course of several minutes proximal to region of spasm.

In our case, careful navigation of the devices through arterial loops resulted in straightening of a cervical ICA loop. Loop straightening can alter the true anatomy of the patient and result in complications such as dissection and vasospasm. In our patient, the ICA loop was straightened upon careful navigation of microcatheter system and softer aspiration catheter. Initially, straightening of the ICA loop was associated with the appearance of severe vasospasm. When there was only minimal improvement with intra-arterial verapamil and external massage of the neck, a decision was made to navigate through the affected region to perform a second pass of thrombectomy. After initially crossing the straightened loop and region of vasospasm, a microinjection was performed to confirm access to the true arterial lumen. It was then possible to advance a softer aspiration catheter over the microcatheter system through this region. Ultimately, it appeared that the flexible and smaller Sofia catheter may have helped to mechanically restore the ICA to its true pre-procedural state. There are limited reports of techniques to restore a straightened loop to its native state in the existing literature. Early reports include a description of open surgical approaches [21]. The paucity of existing literature may relate to the heterogenous anatomy and relatively rarity of an artery to fail to return to its native configuration after endovascular manipulation [10].