Fibromuscular Dysplasia of the Internal Carotid Artery

Imaging of Non-atherosclerotic Vasculopathies

Non-atherosclerotic vasculopathies (NAVs) may present with various neurological symptoms ranging from headache, stroke, visual symptoms, and various types of intracranial hemorrhage. NAVs result from different etiologies which include collagenopathies, immunological, hematological, and infection mechanisms, and other rarer unidentifiable or idiopathic causes. NAV etiologies account for about 10–15% and 20–25% of adult and pediatric stroke cases, respectively, and therefore, diagnosing the underlying cause of NAV becomes clinically very important. Clinical diagnosis of NAV is challenging because the clinical presentation is very non-specific and overlapping with various other central nervous system disorders. Before the advent of non-invasive techniques, making a diagnosis of non-atherosclerotic vasculopathy as a cause of the stroke was very challenging. Today with newer techniques such as high-resolution magnetic resonance (MR), MR and computed tomography perfusion, and angiogram, there are number of pointers which can give us a lead about the non-atherosclerotic causes. Imaging may provide the first lead to the clinician regarding the diagnosis or possible differential diagnosis so that the targeted and focused biomarkers (blood, cerebrospinal fluid, or/and in some cases biopsies) may be obtained to clinch the diagnoses. The purpose of the article is to enumerate the causes, clinical features, and illustrate the imaging findings of the various non-atherosclerotic vasculopathic disorders and discuss “pearls” to their diagnosis. In this article, we have also discussed the latest advances in vascular imaging and elaborated on few uncommon non-atherosclerotic vasculopathies. These are very relevant clinically in the day-to-day practice for the radiologist, neurologist, and the neurointerventionalist.

A distinctive case of fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is a rare, non-inflammatory angiopathy, which can affect the brain supplying arteries. Usually, the diagnosis is based on conventional and/or MR angiography. We present a patient with multisegmental stenoses of the internal carotid artery (ICA) where the diagnosis of FMD is based on an eye-catching ultrasound finding.

Fibromuscular Dysplasia of Cervical and Intracranial Arteries

Fibromuscular dysplasia is an uncommon, segmental, nonatherosclerotic arterial disease of unknown aetiology. The disease primarily affects women and involves intermediate-sized arteries in many areas of the body, including cervical and intracranial arteries. Although often asymptomatic, fibromuscular dysplasia can also be associated with spontaneous dissection, severe stenosis that compromises the distal circulation, or intracranial aneurysm, and is therefore responsible for cerebral ischaemia or subarachnoid haemorrhage. Fibro-muscular dysplasia affects middle and distal portions of the internal carotid and vertebral arteries, and occasionally, intracranial arteries. Several pathological and angiographic patterns exist. The most frequent pathological type is medial fibromuscular dysplasia, which is associated with the ‘string of beads' angiographic pattern. Unifocal lesions are less common and can be associated with several pathological subtypes. The pathophysiology of the disease is widely unknown. Fibromuscular dysplasia may in fact result from various causes and reflect a non-specific response to different insults. The poor knowledge of the natural history and the lack of randomised trials that compared the different treatment options do not allow any satisfactory judgement to be made regarding the need for or the efficacy of any treatment.

Color Doppler imaging of cervicocephalic fibromuscular dysplasia

BACKGROUND

Fibromuscular dysplasia (FMD) is a possible cause of stroke, especially in middle-aged women. However, only few reports are available on ultrasonographic detection and monitoring.

METHODS

Among the 15,000 patients who underwent color Doppler imaging (CDI) of the cervicocephalic arteries during the study period, all cases fulfilling ultrasound criteria of FMD were included into the case series. Criteria of FMD were: 1. Segmental string-of-beads pattern, 2. Localization in the distal extracranial part of internal carotid artery (ICA) or vertebral artery (VA), and 3. (optional): Direct and/or indirect criteria of stenosis.

RESULTS

CDI detected FMD in 39 vessels (37 ICA and 2 VA segments) of 21 patients. 16 patients had bilateral manifestation on ICA, one of those also on VA, bilaterally. CDI disclosed 4 symptomatic high-grade ICA stenoses, 3 of them underwent endovascular treatment. 5 patients with moderate symptomatic ICA stenoses got medical treatment. In 6 patients FMD was the most likely cause of headache and in one patient FMD was diagnosed as a cause of vertigo.

CONCLUSIONS

CDI may be used for detection of cervicocephalic FMD. Due to the unfavourable localisation of FMD for CDI, the sensitivity of CDI is lower in comparison to angiography. However, high-grade FMD stenoses that require invasive treatment can be recognized on the basis of indirect hemodynamic criteria.

Tortuosity, kinking, and coiling of the carotid artery: expression of atherosclerosis or aging?

The etiology of carotid abnormalities is both congenital than acquired. The aim of this study was to clarify the role of aging and atherosclerosis in the acquired cases, and the role of these abnormalities in hemodynamic alterations and neurologic symptoms. Over a 1-year period the authors studied all the subjects undergoing carotid examination by continuous-wave and color-coded Doppler sonography at an Angiology Unit. They evaluated neurologic symptoms; risk factors for atherosclerosis; number, sites, and kinds of carotid abnormalities; atherosclerotic lesions; stenosis; hemodynamic alterations of the carotid; and other localizations of atherosclerotic diseases. There were 469 subjects: 272 (58%) with abnormalities (group 1) and 197 (42%) without abnormalities (group 2). The total number of abnormalities was 479 (104 tortuosities, 262 kinkings, and 113 coilings). The abnormalities were more prevalent in the elderly (P<0.001) and in women (P<0.001). In group 1 they found significant prevalences of hyperlipemia (P<0.001), hypertension (P<0.01), chronic cigarette smoking (P<0.01), and ischemic heart disease (P<0.05). Carotid atherosclerotic lesions were more prevalent in group 1 than in group 2 (P<0.001); among the patients with atherosclerotic carotid lesions, those in group 1 were older than those in group 2 (P<0.001). Tortuosity seemed to be associated with fewer hemodynamic alterations. The authors conclude that atherosclerosis, hypertension, and aging may play an important role in producing carotid abnormalities. The aging seemed more important than atherosclerosis. Only a prospective study of patients with carotid abnormalities and no atherosclerotic lesion will clarify the role of hemodynamics and neurologic symptomatology.

Diagnosis of stroke in young adults

The cause of stroke in a young adult can usually be ascertained with proper workup. One of the most common causes is atherosclerotic cerebrovascular disease, and cigarette smoking is an important risk factor in young adults. Several types of nonatherosclerotic cerebral vasculopathy can also result in premature cerebral infarction; these include cervicocephalic arterial dissection, nonpenetrating traumatic arterial disease, moyamoya disease, fibromuscular dysplasia, vasculitis, and migraine. Cardiac embolism may play a more important role than was previously thought, and hematologic disorders (eg, sickle cell disease, polycythemia rubra vera, coagulation problems) are known to predispose patients to stroke. A careful history of risk factors and a thorough neurologic and cardiovascular examination followed by adequate testing, including angiography, are essential to diagnosis.