Objectives-To compare the diagnosis and prognosis of extracranial versus intracranial vertebral artery dissections without intracerebral haemorrhage. Methods-Twenty two vertebral artery dissections were defined by intra-arterial angiography and classified in two groups: group 1, nine extracranial dissections (seven patients) and group 2, 13 intracranial dissections (nine patients), involving the basilar artery in five cases. Bilateral dissections were found in 38% of the population. Before angiography, all the patients had been investigated by continuous wave Doppler, colour coded Doppler, and transcranial Doppler. Mean follow up was 44 months. Results-The two most important symptoms of both dissections (81% of patients) were unbearable pain preceding stroke and progressive onset of stroke within a few hours. Severe ultrasonic abnormalities were present in 94% of the patients whereas specific ultrasonic signs (segmental dilation with eccentric channel) were rare (19%) in both groups. Major strokes and brainstem strokes represented respectively 67% and 78% in intracranial versus 43% and 29% in extracranial dissections. Severe sequelae (permanent disabling motor or cerebellar deficit) were more often associated with intracranial (44%) than with extracranial dissections (14%). No recurrence of dissection and no cerebral haemorrhage were found under heparin. Significant factors of poor outcome (P< 0.05) were the initial severity of the stroke and the bilateral location of dissections. Conclusion-The combination of a pain and a progressive onset of the stroke, corroborated by ultrasonic findings, could have helped to recognise most of these types of dissections. Intracranial dissections have a poorer prognosis than extracranial dissections.

An international consensus meeting to determine criteria for the quantification of stenosis of the extracranial internal carotid artery was held in Paris on December 2 and 3, 1994. A review of the literature and expert analysis of validity and reproducibility led to the following recommendations: Intra-arterial X-ray angiography: At present, two main methods of quantification are being evaluated, the distal and the local method, the former being the better validated. The latter method, on the other hand, is better able to represent moderate lesions at the level of the carotid bulb. Therefore, it is suggested that a ratio between the stenosis and the common carotid artery should also be established. X-ray angiography prior to carotid endarterectomy can be avoided if ultrasound and MR angiography concur in identifying severe stenosis provided that intracranial vessels are without relevant disease. Ultrasound Doppler duplex methods can quantify the degree of extracranial carotid artery stenosis in terms of both diameter reduction according to the criteria established by recent surgical studies (NASCET – distal degree of stenosis – and ECST – local degree of stenosis – as well as residual area in cross-sections. The latter is more suitable since hemodynamic effect, local increase of velocity, and pressure drop are taken into consideration. Technical requirements (carrier frequency 4–5 MHz, Doppler angle inferior to 60°, sample volume ≧5 mm) call for a combination of three validated criteria. Maximum Doppler shift/flow velocities measured at the narrowest point of the stenosis and the degree of poststenotic flow disturbances should be examined. In systole, a value of 4 kHz (120 cm/s) (f0 = 4 MHz), identifies most stenoses >50% in local diameter reduction and as in end-diastole, a value of 4.5 kHz (135 cm/s) identifies stenoses of >80%. Carotid ratio: The systolic velocity ratio should be recorded between the site of the stenosis and the common carotid artery obtained 3 cm below the bifurcation. This limits the influence of general hemodynamic factors unrelated to the stenosis such as the cardiac output. A threshold value of >1.5 determines stenoses of >50% and a threshold value of >4, stenoses of >70%. Area ratio: The ratio between the total arterial lumen in cross-section and the minimal residual lumen should be determined by echotomography and additional color Doppler flow imaging. In addition there are indirect criteria, such as asymmetry of pulsatility of the common carotid artery and middle cerebral artery signals as well as inverted flow of the ophthalmic artery which distinguish moderate from high-degree stenoses (>80% diameter reduction). Magnetic resonance angiography (MRA): With this method, a diameter ratio using the distal degree of stenosis is recommended with data obtained from transverse source images in addition to transverse T1 sequences. MRA is a complement to ultrasonic methods, particularly in cases of calcified stenoses and for the analysis of intracranial vessels.

An international consensus meeting to determine criteria for the characterization of extracranial carotid artery stenosis was held in Paris on December 13–14, 1996. Recommendations are the following if the degree of the stenosis and the precise location of the stenosis are well defined. Ultrasonic Doppler duplex methods describe the composition and the surface topography of carotid plaques. Echogenicity (from anechoic to hyperechoic), surface (from smooth to cavitated) and texture (from homogeneous to heterogeneous) are the features to be estimated as plaque thickness and length. Echogenicity is standardized against blood (anechoic), mastoid muscle (isoechogenic) or bone (hyperechogenic cervical vertebrae). Luminal surface is classified into three classes: regular, irregular (0.4–2 mm depth) and ulcerated (>2 mm depth with a well-defined back wall at its base and a color Doppler injection). Texture is a function of pixle size and, in a given region of interest, reflects the variability of the grey scale values. Recommended technical requirements are frequency- and amplitude-modulated color Doppler flow imaging, carrier frequency >5 MHz capable of insonating up to 4 cm and retrievable documentation of relevant findings. Computed tomographic angiography permits three-dimensional rendering of the size and extent of the plaque and allows to recognize calcifications, deposits, plaque isodense to muscle and ulcers >2 mm in size. Angiography may identify gross calcifications and large ulcers defined in two classes: 1 – large (2 mm depth by 2 mm width) and 2 – complex with multiple craters. Magnetic resonance imaging with or without angiography may play a role in the future. In vitro studies show that MR can demonstrate plaque components such as fibrosis, calcification, hemorrhage and necrotic core, but current technical limitations related to resolution and motion artifacts prevent this from being implemented in vivo. Pathological studies require en bloc surgery. Component areas should be calculated from their length and width, and ulcerations measured from their width. The risk of cerebrovascular ischemia is clearly related to the degree of stenosis. Factors of individual importance for higher risk include in descending importance: evidence of progression, surface ulceration and low echogenicity. Texture is still under investigation as a prognostic factor.

Background: The prevalence of fibromuscular dysplasia (FMD) in patients with cervical artery dissection (CAD) is unknown. Our objectives were to assess the risk of CAD recurring as a stroke or a transient ischemic attack and the association of these events with FMD. Methods: We prospectively included and followed 103 consecutive patients who had been admitted for a CAD. The median follow-up was 4 years (range 4 months to 10 years). The main criteria for inclusion were a mural hematoma demonstrated by cervical magnetic resonance imaging and/or signs suggesting CAD on 2 other investigations. FMD was diagnosed on the so-called string of beads pattern by digital subtraction angiography. Results: Five patients had CAD recurrence (60% occurred late). Four of these 5 patients had FMD. In 4 patients, CAD recurrence involved another cervical artery. Conclusion: The rate of symptomatic CAD recurrence was 1% per year and was often related to FMD.

The purpose of this prospective study was to assess the value of continuous wave Doppler velocimetry, standard duplex scanning and color Doppler flow imaging in the diagnosis of carotid dissections. From 1975 to 1993, 42 patients (mean age, 44 +/‐ 14 years) were admitted to the University Hospital of Angers for a carotid dissection studied first by ultrasonography, then defined by angiography. Five cases were bilateral. Continuous wave Doppler examination revealed signs of severe obstruction of the carotid arteries in 96% of the cases (occlusion, extensive submandibular tight stenoses, significant slowdowns in the carotid and ophthalmic vessels, retrograde ophthalmic blood flow). Standard duplex scanning suggested dissection in 72% of the cases (tapering stenoses or occlusion, segmental ectasis, tubular vessel, peripheral residual channel, or rare irregular "membrane"). Color Doppler flow imaging suggested a dissection in 82% of the cases. This method has the advantage of underlining the peripheral channel, the double lumen, and the dissecting hematoma, which often is hypoechoic. The ultrasonic methods (continuous wave Doppler combined with color Doppler flow imaging) failed only when they are performed late and when moderate or segmental intrapetrosal dissections were present. These ultrasonic investigations would thus appear to be useful for early diagnosis of carotid dissections.