Using expanding balloon stents to treat intracranial arteriosclerotic stenoses requires precise measurement of the vascular diameter in order to avoid possible overexpansion and rupture of intracranial arteries. However, precise measurement is not always technically reliable, and self-expanding stents were therefore developed that have markedly reduced the complication rate, as they are more flexible and no balloon remodeling is needed. Self-expanding stents can adapt to varying vascular diameters and adjustment of critical stent radial forces allows secondary remodeling of the vessels after the vascular plaque has been broken through using PTA.
Fig. 1.2–7a-d A 71-year-old patient with unilateral symptoms on the right side in a case of left-sided carotid T-occlusion (a). During thrombus aspiration with a Penumbra® catheter, the left carotid flow area was recanalized (b). Multiple aspiration of small thrombus fragments (c). The vessels were successfully reopened (d).
Fig. 1.2–8a-c A 57-year-old patient with unilateral brachiofacial symptoms on the left side in a case of right-sided occlusion of the main trunk of the middle cerebral artery (a). During intra-arterial abciximab (ReoPro®) administration, with stenting required for a subtotal internal carotid artery ostial stenosis on the left side and supplementary rt-PA administration, patency of the middle cerebral vessels was restored (b). Small areas of infarction are demarcated on the follow-up CT after 24 hours (c, arrows).
Fig. 1.2–9a-e A 56-year-old patient with high-grade stenosis of the vertebral artery on the left, on time-of-flight magnetic resonance angiography (MRA) (a, arrow), with recurrent TIAs and a hypoplastic vertebral artery on the right ending at the PICA. The corresponding digital subtraction angiography (DSA) image (b). A Pharos® stent at the level of the stenosis, with the balloon inflated (c). Imaging of the stent in the bone window (d). Normalization of the vascular caliber after complication-free stenting (e).
Fig. 1.2–10a, b A 72-year-old patient who suddenly became comatose, with distal occlusion of the basilar artery (a). Recanalization of the posterior flow area during thrombus aspiration using a Penumbra® catheter (arrow: catheter tip) (b).
The intervention should be carried out with the patient under general anesthesia. Access is obtained via the route of least risk, usually the femoral artery. A microballoon catheter is introduced via a guide catheter positioned in the internal carotid artery or vertebral artery, the balloon positioned at the site of the stenosis, and percutaneous transluminal angioplasty (PTA) is carried out. In a second step, a self-expanding microstent catheter is advanced using a wire exchange maneuver. After optimal placement at the previously stenotic vascular segment, the stent is released by withdrawing the microcatheter. With balloon-mounted stents, prior PTA is not required, as this takes place during the stent deployment (Fig. 1.2-15).
A multicenter prospective study (the Wingspan study) reported good treatment results, with a fatal ipsilateral stroke rate of 7% within 6 months. During the same period, the repeat stenosis rate (with a stenosis grade of > 50%) was low at 7.5% and the patients affected remained without neurological symptoms. A multicenter study in the United States has also reported successful treatment, with technical success and a low periprocedural risk. The primary end point of stroke or death within 30 days after the intervention or ipsilateral stroke after 30 days was observed in 15.7% of the patients and in most cases was associated with withdrawal of platelet inhibition or recurrent stenosis.
In cases of acute vascular occlusion, local therapy nowadays consists of mechanical extraction of the embolus/thrombus.
The mechanical procedures mainly used today include aspiration via wide-lumen, highly flexible catheters that are advanced as far as the vascular occlusion (Fig. 1.2-10a) and a stent retriever system (Figs. 1.2-13, 1.2-14). The efficacy of these systems depends on the consistency of the thrombus/embolus and the arterial access. The systems are sometimes used in combination. Rapid mechanical recanalization of occluded intracranial arteries can be achieved in more than 90% of cases. All of the mechanical procedures can be combined with intra-arterial thrombolysis therapy or platelet inhibition with administration of glycoprotein receptor antagonists.
Fig. 1.2–11a-d A 77-year-old patient with high-grade stenosis of the middle cerebral artery trunk on the left side (a), with recurrent infarction in the middle cerebral artery flow area during dual medication. A Wingspan® stent at the level of the stenosis with an exchange wire in place in an M2 branch (b). Normalization of the vascular caliber after complication-free stenting (c). Three-dimensional imaging of the stent on Xper-CT (d).
Fig. 1.2–12a-f An 82-year-old patient with multiple cervical and intracranial vascular stenoses, with recurrent TIAs in the posterior flow area and a principal finding of high-grade basilar artery stenosis (a, MPR on CTA, arrow). The patient had declined endovascular therapy. Three months later, there was acute hemiplegia on the right side, with dysarthria and bilaterally disturbed eye movements during dual medication. The cause was a proximal basilar artery occlusion (b) following earlier stenosis. It was only possible to pass the stenosis after balloon dilation, with contrast imaging of the distal occluded basilar artery (c). During local thrombolytic therapy with rt-PA, the posterior flow area reopened distally (d). Due to persistent relevant stenosis (e), stenting was carried out at the same time. The Wingspan® stent is seen at the level of the stenosis, with the exchange wire in place (f). In these conditions, there was normalization of the vessels in the posterior flow area and a tolerable occlusion of the right posterior cerebral artery with an anterior fetal supply.
Fig. 1.2–14a, b A 51-year-old patient with acute right-sided hemiparesis and aphasia, with occlusion of the main trunk of the middle cerebral artery on the left (a). After the thrombus had been passed with a microcatheter and a Solitaire® stent had been