Ultrasound Criteria for Diagnosing Spontaneous Cervical Artery Dissections

Abstract

Spontaneous dissection of brain-supplying cervical arteries, which also includes findings after minor injuries, is one of the main causes of ischaemic strokes in young adults. Strokes due to dissection are usually due to arterio-arterial embolism. They are rarely the first symptom of dissection because an intraluminal thrombus must first develop. Therefore, early diagnosis of dissection can contribute to stroke prevention – through immediate therapy with anticoagulants or antiplatelet drugs. This article describes the diagnostic criteria and typical findings of spontaneous dissection, in which no dissecting membrane is to be expected as in aortic dissection. Traumatic dissections following blunt or penetrating injuries also present with different findings. Examiners should be aware of possible differential diagnoses whose ultrasound image may mimic a dissection. A frequently occurring but avoidable cause of misdiagnosis is idiopathic carotidynia. Ultrasound also enables differentiation between dissection and vasculitis or carotid web and detection of normal variants such as fenestration of the vertebral artery. Further possibilities for misdiagnosis may arise in the presence of a variant of the ascending pharyngeal artery or in extracranial vasospasm. The different imaging techniques for the detection of a dissection are complementary, as false-negative findings occur with all techniques; no method serves as the gold standard. In any case, ultrasound can make an important contribution to the detection of a dissection, and it is worth knowing the diagnostic criteria.

Ultrasound assessment of brain supplying arteries (extracranial)

“…B. das "Advanced (Superb) Microvascular Imaging" zur Beurteilung der Plaque-Perfusion und der potenziel- eccentrically located low-echo mural hematoma in the distal section. The stenosis maximum is usually too far distal to graduate the stenosis [30]. Proximal CCA dissections should be promptly evaluated for suspected aortic dissection if diagnosed for the first time.…”

“…PITFALLS ( [30,33,33] KEY TAKEAWAYS ▪ All findings should be understandable based on the image and curve documentation ▪ The multiparametric approach to ICA stenosis grading is based on both peak systolic and diastolic flow velocities and B-scan morphologic criteria; in high-grade stenoses, it is additionally based on indirect criteria and the presence of collateral circulation. ▪ A multiparametric approach enables grading of high-grade ICA stenosis in 10 % increments ▪ Intima-media thickness (IMT) is determined in a plaque-free region 2 cm proximal to the bulb in the CCA on the posterior vessel wall ▪ In B-mode imaging, atherosclerotic plaques are described using echogenicity, internal structure, and surface ▪ The origin of the vertebral artery from the subclavian artery is a predisposition site for stenosis ▪ Criteria for stenosis of the vertebral artery at the origin from the subclavian artery is an anglecorrected PSV > 120 cm/s ▪ There is hypoplasia of the VA with an absolute lumen diameter ≤ 2.0-2.5 mm in several segments or a diameter ratio compared to the opposite side > 1:1.7 ▪ Higher-grade stenosis of the subclavian artery leads to a subclavian steal syndrom of the ipsilateral vertebral artery ▪ Criteria of a subclavian steal syndrome of the VA include systolic deceleration (grade 1) of the flow profile, alternating flow (grade 2), or completely retrograde flow (grade 3) in the VA…”

“…A double lumen, on the other hand, is rare. In the case of a high-grade luminal narrowing at the level of the atlas loop, a "sloshing phenomenon" can be detected in the V2 segment [30]. Hematoma-related vascular narrowing must not be confused with large vessel vasculitis, which is often concentric and longer in distance (▶ Fig.…”

“…Ein doppeltes Lumen ist hingegen selten. Bei einer hochgradigen Lumeneinengung in Höhe der Atlasschlinge kann im V2-Segment ein "Schwapp-Phänomen" nachgewiesen werden [30]. Die hämatombedingte Gefäßeinengung darf nicht mit einer Großgefäß-Vaskulitis verwechselt werden, welche häufig konzentrisch und längerstreckig ausgeprägt ist (▶ Abb.…”

Neurologische Ultraschalldiagnostik – ein Update

“…Typischer sonografischer Befund einer ACI-Dissektion ist eine langstreckige, spitz zulaufende Stenose mit einem exzentrisch gelegenen echoarmen Wandhämatom im distalen Abschnitt der ACI. Das Stenosemaximum liegt meist zu weit distal, um eine Stenosegraduierung vornehmen zu können [12].…”