Clinical significance of cerebral aneurysm in renovascular hypertension due to fibromuscular dysplasia: two cases in siblings

Low frequency of cervicocranial artery involvement in Japanese with renal artery fibromuscular dysplasia compared with that of Caucasians

BACKGROUND

Fibromuscular dysplasia (FMD), which usually affects the renal artery, also affects the carotid, vertebral, and intracranial arteries. Previous studies have shown a high prevalence of concomitant renal artery and cervicocranial lesions in FMD patients. However, the analyzed subjects were mostly Caucasians in Western countries.

METHOD

We performed a retrospective analysis to examine the prevalence of cervicocranial vascular lesions in Japanese FMD patients with renal artery involvement at a single institution. The presence of cervicocranial lesions was evaluated by Doppler echography and magnetic resonance angiography. We compared this prevalence with that reported in the literature.

RESULT

Thirty-one Japanese FMD patients with renal artery lesions were studied. The mean age was 30 ± 12 years, 71% were women, and 16% were smokers; all patients were Asians and had hypertension. Multifocal, tubular, and unifocal types of renal lesions were found in 52, 35, and 13% of patients, respectively. Bilateral renal lesions were found in 13% of patients. None of the patients had a cervical vascular lesion associated with FMD. Only two patients (8%) had a lesion in the intracranial artery, of which one was a known case of moyamoya disease.

CONCLUSION

These findings suggest that cervical artery involvement and intracranial artery involvement are not common in renal FMD patients in Japan, which is in contrast to the data reported for Caucasian patients in Western countries. Ethnic differences could influence the occurrence of cervicocranial lesions. A study with a larger sample size should be performed to validate these findings.

Retinal Manifestations in Fibromuscular Dysplasia

Fibromuscular dysplasia of the arteries (FMD) is a segmental angiopathy which may produce obstruction of the carotid, cerebral, renal, mesenteric, coronary or iliac arteries. Except for lesions related to arterial hypertension, retinal manifestations have not yet been reported. This paper describes the case of a 10-year-old boy with progressive deafness, a history of an unexplained stroke and progressive occlusions of the retinal arterioles in the fundus periphery. This resulted in retinal neovascularization and recurrent retinal and vitreous hemorrhages. Despite repeated photo- and cryocoagulation the eyes progressed to a tractional retinal detachment which was successfully treated by vitrectomy and scleral buckling. The diagnosis of FMD was made on the basis of a histopathological examination of a temporal artery biopsy. The child also presented an asymptomatic but severe aneurysmal dilatation of the aorta and CT scan and MRI showed dilated cerebral arteries. The father of our patient had died at the age of 27 years either from myocardial infarction or rupture of a dissecting aortic aneurysm. He was highly myopic and had lost one eye from retinal detachment. The younger brother of our patient also presents aneurysmal dilatation of the aorta and tortuous cerebral vessels. Ocular examination is still normal. The findings in this family are compatible with an autosomal dominant inheritance with variable expression.

Fibromuscular Dysplasia of Bilateral Brachial Arteries

Fibromuscular dysplasia (FMD) is a noninflammatory, nonatherosclerotic disease of the vascular system, that can affect intima, media, or adventitia. The dysplasia in these layers leads to decrease in the lumen and increased turbulence leading to diminished flow through the affected portion. The treatment of FMD thus far has been either surgical and/or interventional. The authors describe a patient who presented with painful digits and who was found to have bilateral brachial artery FMD and was treated with balloon angioplasty with complete resolution of symptoms.

Low yield of genetic testing for known vascular connective tissue disorders in patients with fibromuscular dysplasia

Patients with fibromuscular dysplasia (FMD) may have clinical features consistent with Mendelian vascular connective tissue disorders. The yield of genetic testing for these disorders among patients with FMD has not been determined. A total of 216 consecutive patients with FMD were identified. Clinical characteristics were collected and genetic test results reviewed for abnormalities in the following genes: transforming growth factor-β receptor 1 and 2 (TGFβR1 and TGFβR2), collagen 3A1, fibrillin-1, smooth muscle α-actin 2, and SMAD3. A total of 63 patients (63/216; 29.2%) were referred for genetic counseling with testing performed in 35 (35/63; 55.6%). The percentage of patients with a history of arterial or aortic dissection, history of aortic aneurysm, systemic features of a connective tissue disorder, and a family history of sudden death was significantly larger in the group that underwent genetic testing (62.9% vs 18.2%, p < 0.001; 8.6% vs 1.7%, p = 0.02; 51.4% vs 17.1%, p < 0.001; and 42.9% vs 22.7%, p = 0.04, respectively). Two patients were found to have distinct variants in the TGFβR1 gene (c.611 C>T, p.Thr204lle and c.1285 T>C, p.Tyr429His). The yield of genetic testing for vascular connective tissue disorders was low in a high-risk subset of FMD patients. However, two patients with a similar phenotype had novel and distinct variants in the TGFβR1 gene, a finding which merits further investigation.

Intracranial aneurysms and arterial hypertension: a review and hypothesis

BACKGROUND

Intracranial aneurysms and systemic arterial hypertension coexist in a high percentage of patients. The relationship between intracranial aneurysms and hypertension is poorly defined.

METHODS

Therefore, we reviewed the role of hypertension in the pathogenesis of saccular aneurysms as previously reported in clinical, experimental, and autopsy studies.

RESULTS

Among 24 relevant clinical and/or autopsy studies, the mean incidence of pre-existing hypertension was 43.5% in aneurysm patients compared to 24.4% in the normal population. Although definitive evidence is lacking, data from multiple types of investigations indicate that systemic arterial hypertension creates a greater risk for the development of intracranial aneurysms than previously believed. The underlying pathophysiological mechanism(s) are also poorly defined.

CONCLUSIONS

We propose a unifying hypothesis: Endothelial injury, occlusion of the vasa vasorum, and disruption of the synthesis of collagen and elastin are likely the most important factors in initiating the development of aneurysms. Chronic hypertension potentially affects all of these factors. Consequently, chronic hypertension may cause intimal thickening, necrosis of the tunica media, changes in the compositional matrix, and degeneration of the internal elastic lamina to develop in the arterial wall. These structural changes could cause a focal weakening in the arterial wall with resultant bulging. This theory accounts for the high incidence of intracranial aneurysms in the absence of any known associated hereditary or connective-tissue disease. Nor does it exclude the possibility of other etiological factors. From the perspective of prevention, however, it offers clear opportunities for prophylaxis.

Familial syndrome of progressive arterial occlusive disease consistent with fibromuscular dysplasia, hypertension, congenital cardiac defects, bone fragility, brachysyndactyly, and learning disabilities

We report on 4 of 9 sibs with a syndrome of stenosis of the renal arteries and chronic hypertension, variable stenosis or occlusion of cerebral, abdominal and probably coronary arteries due to suspected fibromuscular dysplasia, congenital cardiac abnormalities, brachydactyly and syndactyly of the hands and feet, and increased bone fragility consistent with a mild form of osteogenesis imperfecta. Three affected individuals have had mild to moderate learning disabilities. The parents and the remaining 5 sibs have normal hands and feet and no history of excessive fractures. Individual components of this syndrome may appear as isolated conditions, including fibromuscular dysplasia, brachydactyly, syndactyly, and osteogenesis imperfecta, and are autosomal dominant traits in many cases. Explanations for this familial occurrence include autosomal recessive inheritance, autosomal dominant inheritance with decreased penetrance, or parental gonadal mosaicism for a mutation involving a single gene or several contiguous genes.

Possible familial origin of multifocal renal artery fibromuscular dysplasia

OBJECTIVE

To describe phenotypes and estimate the prevalence of familial cases of renal artery fibromuscular dysplasia (FMD).

PATIENTS AND SETTING

One hundred and four unrelated hypertensive patients (94 women) with renal artery fibromuscular dysplasia documented on angiography and classified as having multifocal or unifocal lesions. Familial cases were defined as those with angiographic evidence of renal artery FMD in at least one sibling.

RESULTS

Eighty-one patients had multifocal and 16 had unifocal FMD. Both types of stenosis were present in seven patients. Fifty-four patients had bilateral FMD, including the seven patients with both unifocal and multifocal lesions. The 16 patients with unifocal FMD were younger, more likely to be men, and more commonly had unilateral stenoses, stenoses exceeding 75% and a small ischemic kidney than the 81 patients with multifocal lesions. Eleven cases were identified as familial on the basis of FMD having been documented in at least one sibling (eight sibling pairs and three trios). All probands were women and exhibited multifocal lesions. FMD was more often bilateral in familial than it was in apparently sporadic cases.

CONCLUSIONS

Multifocal FMD was mostly found in women and unifocal FMD in young men with more severe stenosis and kidney ischemia. The documented prevalence of familial cases was 11% in this series, the true prevalence being probably higher because only a few siblings were examined by angiography. Familial cases all exhibited the multifocal type and were more commonly bilateral than were sporadic cases.

Hypertensive cerebrovascular disease and the renin-angiotensin system

BACKGROUND

Arterial hypertension is the leading cause of cardiovascular disease and is associated with an increased risk of stroke and heart attack. These complications have been largely attributed to the remodeling of the arterial wall, including accelerated atherosclerosis occurring in hypertensive patients. Although the risk of haemorrhagic stroke seems to be directly related to the level of blood pressure elevation, no such tight relationship has been found between blood pressure levels and atherosclerosis. This observation has led to the concept that a number of genetic, humoral, and cellular factors may be involved in atherogenesis in hypertensive patients.

SUMMARY OF REVIEW

The experimental and clinical evidence concerning the role of the renin-angiotensin system in cardiovascular remodeling and atherogenesis of the cerebrovascular bed as well as the data supporting an association between angiotensin II and thrombotic stroke are examined.

CONCLUSIONS

The contribution of the renin-angiotensin system to the pathogenesis of accelerated carotid artery atherosclerosis and particularly of cerebrovascular disease remains to be definitively proven. However, the bulk of experimental and clinical data are consistent with the hypothesis that the renin-angiotensin system may play a detrimental role.

Fibromuscular dysplasia and aneurysm formation in the brachial artery

A patient with isolated right brachial artery aneurysms is presented. As a young woman these had been misdiagnosed, leading to inappropriate surgery and a subsequent brachial artery aneurysm produced median nerve neuropraxia. Resection of the aneurysm and bypass relieved these symptoms and the aetiology was fibromuscular dysplasia. The literature on fibromuscular dysplasia and aneurysms of the brachial artery are reviewed.

Familial association of intracranial aneurysms and cervical artery dissections

BACKGROUND AND PURPOSE

The familial occurrence of intracranial aneurysms and cervical artery dissections has been described in different families and supports the hypothesis that a primary arteriopathy may play a role in the pathogenesis of these disorders. Although the basis for this arteriopathy is generally not believed to be similar among cases of intracranial aneurysms and cervical artery dissections, several similarities exist in the epidemiology of these disorders and a common underlying arterial abnormality may be suspected.

SUMMARY OF REPORTS

The medical records of all 175 patients with spontaneous dissections of the cervical arteries who were seen at the Mayo Clinic between 1970 and 1989 were reviewed to identify families in which intracranial aneurysms and cervical dissections coexisted. Three families were identified in which intracranial aneurysms and cervical artery dissections were observed among siblings. These families are described in detail.

CONCLUSIONS

The familial occurrence of intracranial aneurysms and cervical artery dissections within the same families provides support to the importance of a common underlying arteriopathy in the pathogenesis of both these disorders. The underlying vascular defect may, at least in some cases, be inherited.