Tonsillar Loop Dissection Causing Embolic Stroke and Internal Carotid Artery Occlusion: Mechanical Stentriever Thrombectomy, Angioplasty, and Telescoping Flow Diverter Stent-Assisted Arterial Reconstruction (Thrombectomy First, Retrograde Revascularization)

Proximal carotid artery dissections can be treated with conventional carotid stents. However, high cervical and skull base dissections are often more difficult to treat due to the tortuosity or redundancy of the carotid artery. Loops, coils, and kinks in the cervical internal carotid artery (ICA) have been defined as “carotid redundancy,” which has been shown to increase the risk of dissection. High locations and tortuous arterial segments are difficult to access with conventional carotid stents due to their relative stiffness. Balloon expandable (coronary) stents can be used for this indication, but they also have limited flexibility and poor apposition to the vessel wall in tortuous anatomy. They are highly porous and therefore have a limited ability to retain thrombus. Due to the inadequate wall coverage of these stents in the target vessel, their flow diversion effect is not sufficient to ultimately eliminate a dissecting pseudoaneurysm from the circulation. In recent years, flow-diverting stents have been found to be more suitable for the treatment of dissections in tortuous anatomies, mainly due to their flexibility, low porosity, and remarkable adaptation to the vessel wall. A 32-year-old woman, mother of a 2-year-old child, had an unremarkable medical history except for depression treated with escitalopram. She was admitted to the emergency department 2 h after sudden onset of speech changes that worsened during her hospitalization. On admission, she initially had moderate pure motor dysphasia (nonfluent dysphasia affecting naming and repetition), which then progressed to reduced, fragmentary, echoic, and perseverative speech with frequent hesitations and pauses. She also developed new comprehension difficulties and right arm weakness. The patient had no history of uncontrolled vascular risk factors or medications. Her husband recalled that 1 week earlier she had complained of left orbital discomfort and visual changes in the left eye that may have corresponded to episodes of amaurosis fugax. She had complained of neck pain 3 days before admission. Neurological examination for suspected left hemispheric ischemia revealed a baseline National Institutes of Health Stroke Scale (NIHSS) score of 4, which increased to 7 as her symptoms worsened. Cranial CT obtained after clinical progression of the left hemisphere stroke showed normal brain parenchyma (automated ASPECTS 10). CT perfusion (CTP) maps showed a discrete left prefrontal region of hypoperfusion with reduction of cerebral blood flow to <30% of expected (core) in a 6 ml volume and an extended 37 ml area corresponding to the left middle cerebral artery (MCA) supply territory with time-to-maximum extent >6 s (penumbra). The total mismatch difference was 31 ml and the mismatch ratio was 6.2. CT angiography (CTA) showed a flame-shaped occlusion of the left cervical ICA and occlusion of the left anterior insular branch of the MCA. There was a complete tonsillar loop in the right ICA. The patient received intravenous thrombolysis without clinical improvement and was transferred from the emergency department to the neuroangiography suite for endovascular treatment. The endovascular procedure was designed to regain access across the occluded left ICA for intracranial stentriever-assisted mechanical thrombectomy (MT) followed by ICA angioplasty and flow diverter stent-assisted arterial reconstruction. At the end of the procedure, we confirmed recanalization of the ICA and complete parenchymal reperfusion. The patient was successfully extubated 3 h after the procedure and was able to speak with full comprehension after 8 h. Post-procedural cranial CT ruled out hemorrhagic complications and suggested a hypodense region in the left prefrontal area. She had a very good clinical course with improvement of her NIHSS to 0 at 2 days, corresponding to a modified Rankin Scale (mRS) score of 0 at discharge. Because difficult access anatomy is common in patients undergoing emergency thrombectomy, it is important for the treating physician to be prepared for unusual situations to increase the likelihood of successful revascularization. This chapter focuses on carotid redundancy, carotid dissection, and emergency arterial revascularization with flow-diverting stents.