Moyamoya disease complicated with renal artery stenosis and nephrotic syndrome: reversal of nephrotic syndrome after nephrectomy

Moyamoya Vasculopathy and Moyamoya-Related Systemic Vasculopathy: A Review With Histopathological and Genetic Viewpoints

Systemic vasculopathy has occasionally been reported in cases of moyamoya disease (MMD). Since the pathological relationship between moyamoya vasculopathy (MMV) and moyamoya-related systemic vasculopathy (MMRSV) remains unclear, it was examined herein by a review of histopathologic studies in consideration of clinicopathological and genetic viewpoints. Although luminal stenosis was a common finding in MMV and MMRSV, histopathologic findings of vascular remodeling markedly differed. MMV showed intimal hyperplasia, marked medial atrophy, and redundant tortuosity of the internal elastic lamina, with outer diameter narrowing called negative remodeling. MMRSV showed hyperplasia, mainly in the intima and sometimes in the media, with disrupted stratification of the internal elastic lamina. Systemic vasculopathy has also been observed in patients with non-MMD carrying the RNF213 (ring finger protein 213) mutation, leading to the concept of RNF213 vasculopathy. RNF213 vasculopathy in patients with non-MMD was histopathologically similar to MMRSV. Cases of MMRSV have sometimes been diagnosed with fibromuscular dysplasia. Fibromuscular dysplasia is similar to MMD not only in the histopathologic findings of MMRSV but also from clinicopathological and genetic viewpoints. The significant histopathologic difference between MMV and MMRSV may be attributed to a difference in the original vascular wall structure and its resistance to pathological stress between the intracranial and systemic arteries. To understand the pathogeneses of MMD and MMRSV, a broader perspective that includes RNF213 vasculopathy and fibromuscular dysplasia as well as an examination of the 2- or multiple-hit theory consisting of genetic factors, vascular structural conditions, and vascular environmental factors, such as blood immune cells and hemodynamics, are needed.

Research progress of moyamoya disease combined with renovascular hypertension

Moyamoya disease (MMD) is an idiopathic cerebrovascular disease which was first described by Suzuki and Takaku in 1969. Moyamoya disease is a non-atherosclerotic cerebrovascular structural disorder. MMD has been found all over the world, especially in Japan, Korea, and China. In recent years, many reports pointed out that the changes of vascular stenosis in patients with moyamoya disease occurred not only in intracranial vessels, but also in extracranial vessels, especially the changes of renal artery. Renovascular hypertension (RVH) is considered to be one of the important causes of hypertension in patients with moyamoya disease. The pathogenesis of moyamoya disease combined with renovascular hypertension is still unclear, and the selection of treatment has not yet reached a consensus. This article reviews the latest research progress in epidemiology, RNF213 gene, pathomorphology, clinical characteristics and treatment of moyamoya disease combined with renovascular hypertension, in order to provide reference for clinical workers.

Moyamoya disease with refractory hypertension associated with peripheral arterial stenosis in the renal parenchyma

Moyamoya disease (MMD) has long been known to be associated with hypertension. While renal artery stenosis (RAS) is considered one of the causes of hypertension with MMD, most hypertension causes remain unexplained. A boy with MMD was diagnosed with renovascular hypertension (RVH) due to left-sided RAS by angiography. Although nephrectomy on the affected side for unilateral RVH was performed, hypertension poorly improved. Histopathological examination of the resected specimens revealed that the vascular lumen not only of the renal artery but also of peripheral vessels in the renal parenchyma was narrowed. He developed end-stage renal disease caused by multiple wasp stings and received a kidney transplant from a living donor with his remaining right kidney resected. His hypertension improved dramatically just after the operation. In histopathological findings, the narrowed vascular lumen was also observed in the resected right renal parenchyma similar to that in the left kidney. In our case, these pathological findings were the same as those of major vessels previously reported in MMD patients. Immunohistochemical staining with anti-renin antibody on bilateral intrinsic kidneys was strongly revealed in the Juxtaglomerular apparatus. He has been normotensive with the minimum amount of amlodipine since transplantation and resection of his intrinsic right kidney. This is the first report to show the possibility that peripheral arterial stenosis in the renal parenchyma due to MMD would result in refractory hypertension. If MMD patients have hypertension of unknown origin without significant RAS, it should be considered that the etiology may be peripheral arterial stenosis in the renal parenchyma.

Comparison of clinical outcomes and characteristics between patients with and without hypertension in moyamoya disease

OBJECTIVE

Our study aimed to compare the disparity of patients with moyamoya disease (MMD) between hypertension group and non-hypertension group. And we attempt to explore the risk factors for MMD with hypertension.

METHODS

We retrospectively analyze 542 adult patients with moyamoya disease admitted to our hospital from 2009 to 2016. In view of inclusion criteria, we divided patients with moyamoya disease into two groups (hypertension group and non-hypertension group) and summarized their clinical characteristics. Furthermore, we explore the risk factors for unfavorable outcomes in hypertension group.

RESULTS

Of 542 adult patients with moyamoya disease, we identified 156 patients (28.8%) with hypertension and 386 patients (71.2%) without hypertension. During follow-up, we hold the views that the prognosis of non-hypertension group was obviously better than hypertension group (P = 0.005) and the complications were prone to occurring to patients with hypertension (P = 0.037). In the multivariate analysis, severe hypertension (OR, 2.746; 95% CI, 1.096-6.822; P = 0.031) and no anti-hypertensive medication (OR, 0.342; 95% CI, 0.131-1.895; P = 0.029) were the independent predictors for postoperative unfavorable outcomes. The common surgical modalities of moyamoya disease (direct and indirect bypass) had no significant difference in future unfavorable outcomes prevention in adult MMD patients with hypertension.

CONCLUSIONS

We suggested severe hypertension and no anti-hypertensive medication as the independent risk factors for unfavorable clinical outcomes in adult MMD with hypertension.

Efficacy of Antihypertensive Therapy in a Child with Unilateral Focal Fibromuscular Dysplasia of the Renal Artery: A Case Study and Review of Literature

Background: Fibromuscular dysplasia (FMD) is one of the important etiologies of renovascular hypertension in children. It is usually resistant to multiple antihypertensive agents and can cause extreme elevation in blood pressures, which can lead to end organ damage if not promptly diagnosed and treated. Treatment options include medical management with antihypertensive agents, balloon or stent angioplasties, surgical revascularization, and nephrectomy. The aim of the study was to review the efficacy of antihypertensive therapy only in the management of FMD in a very young child. Methods: This is a retrospective chart study with review of literature. Results: Here, we report a 22-month-old toddler who presented with severe resistant hypertension and cardiomyopathy who was found to have focal FMD of the right renal artery. She also presented with proteinuria, hyponatremia that was probably secondary to pressure natriuresis, hypokalemia, hyperaldosteronism, and elevated plasma renin activity. The stabilization of blood pressures was done medically with the usage of antihypertensive medications only, without the need for angioplasty or surgical revascularization. Conclusions: We demonstrate that surgical intervention may not always be necessary in the treatment of all cases of FMD, especially in a small child where such intervention may be technically challenging and lead to potential complications. Hence, medical management alone may be sufficient, at least for the short-term, in small children with controlled hypertension and normal renal function, with surgical intervention reserved for FMD with medication-refractory hypertension and/or compromised renal function.

Renal agenesis and external iliac artery stenosis in an infant with moyamoya disease

We describe a 14-month-old girl who presented with arterial ischemic stroke due to moyamoya disease, unilateral renal agenesis and external iliac artery stenosis. The association of moyamoya disease with renal agenesis and external iliac artery stenosis has not been described before. This report expands the spectrum of moyamoya disease and suggests that moyamoya disease may have an intrauterine onset.

Moyamoya disease with renal artery and external iliac artery stenosis

Moyamoya disease is a rare, progressive occlusive disease of the cerebral vasculature, mainly involving internal carotid and proximal cerebral arteries with development of fine collateral vascular network in brain. Coexistence of renal vascular lesion with cerebral vascular lesion has rarely described and association with external iliac and femoral vascular stenosis is not known to the best of our knowledge. This is the first case of renovascular hypertension with Moyamoya disease being reported in India with involvement of other extra cranial vessels.

Prevalence of stenoocclusive lesions in the renal and abdominal arteries in moyamoya disease

OBJECTIVE

The extracranial involvement of moyamoya disease has been reported in several studies. The main purpose of this study was to determine the prevalence of stenoocclusive lesions in the renal and major abdominal arteries in moyamoya disease.

MATERIALS AND METHODS

Abdominal angiography was performed in 73 patients with idiopathic moyamoya disease. The findings of abdominal angiography were retrospectively reviewed for the presence and appearance of stenosis in the renal and other major abdominal arteries.

RESULTS

Four (5%) of 73 patients presented with unilateral renal artery stenosis. Three patients had moderate stenosis, and one patient had mild stenosis. In the three patients with moderate stenosis, the renal artery stenosis was located in the proximal region of the main branch. Two patients (3%) with moderate stenosis of the unilateral renal artery had renovascular hypertension. No statistically significant differences were observed in age, sex, and the cerebral angiographic stage between patients with and without renal artery stenosis. No stenosis was found in the abdominal aorta or celiac, superior mesenteric, common hepatic, splenic, and proximal common iliac arteries. No occlusions were found in any abdominal arteries.

CONCLUSION

The prevalence of renal artery stenosis in patients with moyamoya disease was 5% (4/73). Involvement of the proximal region of the renal artery was dominant. No stenosis was found in other abdominal arteries.

Interventional radiology for renovascular hypertension in children

Pediatric renovascular hypertension is an uncommon but important clinical problem. Atherosclerosis is rare in children, who typically suffer from fibromuscular dysplasia, neurofibromatosis type 1, Williams syndrome, or certain other rare conditions. Children with renovascular disease often have involvement of other arteries including the aorta and mesenteric and cerebral vessels. The pediatric interventional radiology service has a vital role in the diagnosis, evaluation, and treatment of renovascular hypertension. Renal vein renin sampling appears to be more useful in children than in adults, because their arterial disease is more often bilateral and segmental. Diagnostic angiography is still superior to less-invasive methods of imaging the renal arteries, especially the smaller branches. Interventional options include angioplasty, stenting, and ethanol ablation. Angioplasty is almost always technically successful and usually gives a worthwhile clinical improvement. Stenting is only used in children when angioplasty fails. Ethanol embolization may be appropriate in children with focal renin-producing areas that are untreatable by angioplasty.

Renal artery stenosis and nephrotic syndrome: a rare combination in an infant

We describe an uncommon pediatric finding of unilateral renal artery stenosis, which presented as nephrotic syndrome, hypertension, failure to thrive, and hyponatremia. The child was a previously well 8-month-old male who looked well but had mild periorbital edema with severe hypertension. After 3 days of captopril therapy, the nephrotic-range proteinuria significantly improved. However, the hypertension persisted. Renal imaging revealed a small left kidney with reduced parenchymal uptake and no significant excretion. A renal angiogram demonstrated left renal artery stenosis with increased left renal vein renin activity. The hypertension resolved within 24 h of a left nephrectomy, but non-nephrotic-range proteinuria persisted for 8 months post operatively. Pathology of the left kidney was consistent with fibromuscular dysplasia. Although a few glomeruli (1%) had changes consistent with focal segmental glomerulosclerosis, such a few abnormal glomeruli were unlikely to account for the nephrotic syndrome. Hypertension-induced changes in the unaffected right kidney probably caused the nephrotic-range proteinuria.