in the vertebral artery, with a risk of overestimating stenoses:
Inadequate perfusion of the contralateral vertebral artery (e.g., due to aplasia, hypoplasia, stenosis, occlusion, dissection) with hyperperfusion of the artery being examined
Hyperperfusion of the vertebral arteries when collaterals via the posterior communicating branch are compensating for obstructive carotid processes
Arteriovenous malformations in the vertebrobasilar flow area
Measurement of the relevant parameters, e.g., after extrasystoles, with a compensatory pause, or in cases of absolute arrhythmia after a longer RR interval, or with an increased ejection volume in patients with aortic insufficiency or marked bradycardia
Differential diagnoses in cases of flow deceleration in the vertebral artery, with a risk of underestimating stenoses:
Distal vertebrobasilar flow obstruction (high pulsatility, and reduced diastolic flow in particular)
Hypoplasia or dilatory arteriopathy in the vertebral artery
Marked cerebral microangiopathy or raised intracranial pressure with disturbed distal outflow (with identical bilateral findings)
When measurements are carried out during hemodynamically compromising tachycardic heart action
In cases of proximal high-grade flow obstructions
Findings in occlusions of the extracranial vertebral artery:
Vessel not identifiable (in continuous-wave mode, occlusion may only be suspected, however)
Possible hyperperfusion of the contralateral vessel
Arterial lumen definitely demonstrated on duplex ultrasound, without PW Doppler or color signals
Demonstration of distal inflow collaterals possible
Findings in occlusions of the intracranial vertebral artery:
Markedly increased extracranial pulsatility, with reduced diastolic flow in one vertebral artery that may amount to pendular flow (caution: outflow into a dilated PICA may lead to a normal Doppler signal when there is a distal vertebral artery occlusion)
Possible hyperperfusion of the contralateral artery
Course of the vertebral artery not capable of being imaged transnuchally
Vertebral artery compression syndrome (often suspected, but actually a rare finding) characterized by:
Rotatory vertigo and nystagmus
Capable of being reproducibly triggered by head rotation
Can be stopped by a return movement
Clear hypoplasia in one vertebral artery (duplex ultrasound evidence)
Movement-dependent, hemodynamically compromising compression of a normal-lumen vertebral artery (Doppler and duplex ultrasound evidence possible), so that with relevant hypoplasia of a vertebral artery and suspicious clinical findings, an attempt should be made to provoke symptoms during Doppler/duplex ultrasound examination of various segments of the normal-lumen vertebral artery
1.1.6 Treatment
1.1.6.1 Conservative treatment
Medical treatment is indicated in both internal carotid artery stenosis and vertebral artery stenosis, in order to limit atherosclerotic progression and reduce the risk of a neurological event. This treatment recommendation is independent of the decision on whether to offer interventional or surgical revascularization therapy. Treatments currently available include inhibition of platelets using acetylsalicylic acid (ASA), dipyridamole plus acetylsalicylic acid, or clopidogrel. In addition, treatment with statins is advised due to their anti-inflammatory and thus plaque-stabilizing effect in other vascular territories. Medical treatment alone is recommended in patients with stenosis of the internal carotid artery who either have a low risk of stroke (symptomatic stenoses < 50%, asymptomatic stenoses < 60%) or who are at high perioperative or peri-interventional risk due to comorbid conditions, or who have a limited life expectancy.
Drug treatment was the only form of therapy available for cerebral ischemia in the posterior flow region prior to the advent of endovascular approaches. Unfortunately, there is still a lack of data from randomized studies comparing drug treatment with surgical or interventional therapy for extracranial stenoses of the vertebral artery. The results of the Vertebral Artery Stenting Trial (VAST), which is currently still recruiting, will probably be able to provide important information. At present, 180 patients with symptomatic vertebral artery stenosis > 50% have been randomly assigned either to endovascular treatment (stent implantation) or to the conservatively treated group in the study.
1.1.6.2 Endovascular treatment
Patient preparation
General patient history
Medication and allergy history
Complete neurological evaluation, plus National Institutes of Health Stroke Scale (NIHSS)
in the vertebral artery, with a risk of overestimating stenoses:
