may occur when nonspastic vascular segments are examined.
1.2.5 Treatment
1.2.5.1 Conservative treatment
The treatment strategy depends in principle on multiple factors and should be decided on an individual basis. Risk factors such as nicotine consumption, lipid disorders, hypertension, and diabetes should be eliminated or treated.
In patients with asymptomatic stenoses that are not hemodynamically relevant, invasive treatment is not currently recommended, but drug therapy with platelet inhibitors is recommended, possibly in combination with lipid-lowering agents.
Patients with symptomatic stenoses that are hemodynamically relevant initially receive drug treatment, and invasive therapy is only considered if symptoms recur. The WASID study found no benefit with warfarin administration in comparison with aspirin in patients with symptomatic intracranial stenoses. In comparison, the risk of stroke during the first year was 12% in the aspirin group and almost as high in the warfarin group at 11%; in the second year, the figures were 15% and 13%, respectively. However, as major hemorrhage only occurred in 3% of the patients in the aspirin group in comparison with 8% in the warfarin group, treatment with vitamin K antagonists is now obsolete. Treatment with dual platelet inhibition (e.g., aspirin and clopidogrel) should therefore be considered, particularly when an ischemic event has occurred during single antiplatelet treatment. Individual testing of drug efficacy is advisable in any case, as there is a high percentage (up to 30%) of low responders and nonresponders, although no data in this population that correlates responder rates and clinical events.
When ischemic symptoms recur during medication, the indication for PTA and, if appropriate, stent placement should be considered. A recently published study (the SAMMPRIS study) did not observe any clear benefits with an invasive approach using stenting—a finding that requires further research after optimization of patient selection and concomitant drug therapy.
As mentioned above, it is therefore absolutely imperative to differentiate between embolic and hemodynamically relevant stenoses. In stenoses that have hemodynamic effects, with clinical symptoms, conservative therapy is only appropriate in combination with endovascular therapy (PTA, possibly with stent assistance) in order to improve perfusion. If this is not technically possible, attention should be given to ensure that blood pressure is not reduced too much, to avoid negative effects on the collateral supply.
The treatment of intracranial vascular occlusions also depends on clinical symptoms. Conservative treatment for acute stroke includes normalization of general parameters (cardiovascular and pulmonary function, as well as fluid balance and metabolic parameters) and oxygenation. If a patient reaches hospital within the “thrombolysis window” (usually < 6 hours after the start of symptoms), systemic intravenous thrombolysis therapy (up to 4.5 hours after the initial symptoms) or local intra-arterial embolectomy or thrombolytic therapy can be carried out. The 4.5-hour time interval currently applies to systemic intravenous thrombolytic therapy (with recombinant tissue plasminogen activator, rt-PA). In all cases, the earlier the patient is treated, the better the clinical outcome is. In what is known as the “bridging approach,” intravenous treatment (two-thirds of the total dosage, with 10% of that as a bolus) is combined with intra-arterial therapy. The initial intravenous thrombolysis allows rapid initiation of treatment and may optimize the efficacy of the endovascular intra-arterial therapy.
1.2.5.2 Endovascular intra-arterial therapy
Endovascular intra-arterial therapy is indicated and in most cases possible for hemodynamically relevant intracranial stenoses, or for stenoses that cause recurrent arterioarterial embolism in spite of adequate platelet function inhibition. The endovascular procedure consists of dilation (percutaneous transluminal angioplasty, PTA) (Fig. 1.2-7), which can be combined with stent implantation (Figs. 1.2-8, 1.2-9, 1.2-11). To prevent thromboembolic events during possible stent implantation, the patients should receive dual platelet inhibition (e.g., aspirin and clopidogrel), starting if possible several days before the procedure. It is advisable here to have the efficacy of platelet inhibition tested in the laboratory in order to identify nonresponders and poor responders, who may represent up to 30% of the patients. These patients then have to be treated with a correspondingly higher dosage. Following stent implantation, long-term monotherapy with aspirin or clopidogrel is required after temporary dual therapy.
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
