Histopathologic Features of Intracranial Vascular Involvement in Fibromuscular Dysplasia, Ehlers-Danlos Type IV, and Neurofibromatosis I

Vessel Wall Imaging Features of Spontaneous Intracranial Carotid Artery Dissection

BACKGROUND AND OBJECTIVES

Intracranial dissection is an important cause of stroke often with nonspecific angiographic features. Vessel wall imaging (VWI) can detect dissections, but intracranial applications remain unvalidated by pathologic specimens. We sought to determine the ability of VWI to identify the rarely reported spontaneous intracranial carotid dissection (sICD) guided by postmortem validation.

METHODS

VWI features of sICD, validated by postmortem specimen analysis in 1 patient, included luminal enhancement within a hypoenhancing outer wall, narrowing the mid to distal ophthalmic (C6) segment, relatively sparing the communicating (C7) segment. VWI examinations were reviewed to identify patients (1) with matching imaging features, (2) no evidence of other vasculopathies (i.e., inflammatory, intracranial atherosclerotic disease [ICAD]), and (3) adequate image quality. These sICD VWI features were compared with those in patients with known ICAD causing similar narrowing of C6 and relative sparing of C7 by a Fisher exact test accounting for multiple samples.

RESULTS

Among 407 VWI examinations, 8 patients were identified with 14 sICDs, all women aged 30-56 years, 6 (75%) bilateral. All patients with sICD had risk factors of dissection (e.g., recently postpartum, fibromuscular dysplasia, and hypertension) and 3 (37.5%) had intracranial dissections elsewhere. Seven (87.5%) were diagnosed as moyamoya syndrome on initial angiography. Enhancing lesions varied from thin flap-like defects (n = 6) to thick tissue along the superolateral wall of the internal carotid artery, within the hypoenhancing outer wall. Compared with 10 intracranial carotid plaques in 8 patients with ICAD, sICD demonstrated stronger (84.6% vs 20.0%, p = 0.003-0.025) and more homogeneous (61.5% vs 0.0%, p = 0.005-0.069) enhancement and less positive remodeling (0.0% vs 60.0%, p = 0.004-0.09). T1 hyperintensity was identified in 5 sICDs in 3 patients but not identified in ICAD. Three patients with serial imaging (8- to 39.8-month maximum intervals) revealed little to no changes in stenosis, wall thickening, or enhancement.

DISCUSSION

sICD is distinguishable on VWI from ICAD by enhancement characteristics, less positive remodeling, and clinical parameters. These VWI features should raise suspicion especially in young women with risk factors of dissection. Temporal stability and a lack of T1 hyperintensity should not discourage diagnosing sICD.

Cerebral arteriopathies of childhood and stroke - A focus on systemic arteriopathies and pediatric fibromuscular dysplasia (FMD)

Systemic vascular involvement in children with cerebral arteriopathies is increasingly recognized and often highly morbid. Fibromuscular dysplasia (FMD) represents a cerebral arteriopathy with systemic involvement, commonly affecting the renal and carotid arteries. In adults, FMD diagnosis and classification typically relies on angiographic features, like the 'string-of-beads' appearance, following exclusion of other diseases. Pediatric FMD (pFMD) is considered equivalent to adult FMD although robust evidence for similarities is lacking. We conducted a comprehensive literature review on pFMD and revealed inherent differences between pediatric and adult-onset FMD across various domains including epidemiology, natural history, histopathophysiology, clinical, and radiological features. Although focal arterial lesions are often described in children with FMD, the radiological appearance of 'string-of-beads' is highly nonspecific in children. Furthermore, children predominantly exhibit intimal-type fibroplasia, common in other childhood monogenic arteriopathies. Our findings lend support to the notion that pFMD broadly reflects an undefined heterogenous group of monogenic systemic medium-or-large vessel steno-occlusive arteriopathies rather than a single entity. Recognizing the challenges in categorizing complex morphologies of cerebral arteriopathy using current classifications, we propose a novel term for describing children with cerebral and systemic vascular involvement: 'cerebral and systemic arteriopathy of childhood' (CSA-c). This term aims to streamline patient categorization and, when coupled with advanced vascular imaging and high-throughput genomics, will enhance our comprehension of etiology, and accelerate mechanism-targeted therapeutic developments. Lastly, in light of the high morbidity in children with cerebral and systemic arteriopathies, we suggest that investigating for systemic vascular involvement is important in children with cerebral arteriopathies.

Cerebellar Hemangioblastoma Mimicking Arteriovenous Malformation: A Case Report

Hemangioblastoma (HBM) is a tumor distinguished by the presence of stromal cells and small vessels. These stromal cells represent stem cells, which, due to the influence of the neoplasm, proliferate and differentiate into "vasoformative elements" that create new blood vessels. Hemangioblastomas resemble arteriovenous malformation (AVM) in imaging features, characterized by an apparent vascular blush, the presence of multiple feeding vessels, and evident draining veins observed on digital subtraction angiography (DSA). Our study presents a case of HBM in the right cerebellar hemisphere mimicking AVM. The patient had been diagnosed with AVM in the same location two years ago and managed with endovascular embolization. One month prior, the patient experienced severe headaches, imbalance, nausea, left ear fullness, blurry vision, and high blood pressure. The imaging feature suggests HBM rather than AVM. The patient next underwent sub-occipital craniotomy and tumor resection with external ventricular drainage (EVD) insertion. The histopathological report of the excised mass confirmed HBM. In conclusion, AVM and HBM rarely occur together. Recent research indicates that HBM and AVM have exact embryologic origins and need later genetic alterations to develop into symptomatic lesions. Further research is required to clarify the uncommon combination of these lesions.

A Comparative Study of the Etiology of Intracranial Vertebral Artery Dissection and Carotid Artery Dissection

BACKGROUND

Both extrinsic (trauma or violent movement) and intrinsic (structural abnormality, atherosclerosis, or hemodynamic instability) factors may result in arterial dissection. The role of these factors in the origin or progression of dissection remains unclear. This study aimed to characterize the clinical features, radiologic features, and outcomes of intracranial vertebral artery dissection compared with carotid artery dissection and to determine the major causative factors.

METHODS

Consecutive patients with craniocervical dissection (n=127) were retrospectively analyzed. Patients with intracranial vertebral artery dissection (n=77) and those with carotid artery dissection (n=35) were compared with respect to patient age, sex, cerebrovascular risk factors, laboratory indices, and radiologic features.

RESULTS

Intracranial vertebral artery dissection was the most common craniocervical arterial dissection in our cohort (n=77, 60.6%). Body mass index in the intracranial vertebral artery dissection group was significantly greater than that in carotid artery dissection group. Clinical manifestations of intracranial vertebral artery dissection included ischemic stroke (37.7%), dizziness or vertigo (39.0%), and headache or neck pain (44.2%). Two patients had a definite history of trauma. The frontal and lateral tortuosity ratios of the vertebral basilar artery were significantly greater while the vertex angle was smaller in the intracranial vertebral artery dissection group compared with carotid artery dissection group. A positive correlation between the tortuosity ratios and subarachnoid hemorrhage and a significant inverse correlation between the tortuosity ratios and lipid parameters (high-density lipoprotein; apolipoprotein A1) were identified.

CONCLUSIONS

Intrinsic causes may play a more important role in the development of intracranial vertebral artery dissection than carotid artery dissection.

Neurofibromatosis type 1, fibromuscular dysplasia, and ischemic stroke: an association lost in time? A case report

Neurofibromatosis Type 1 (NF1) is a rare cause of ischemic stroke (IS) in the general population. We report a case of a young patient with NF1 in whom IS was caused by fibromuscular dysplasia. An angiographic study demonstrated occlusion in the right internal carotid artery (ICA), just after its origin, and the left ICA, just before the intracranial portion, and brain magnetic resonance imaging showed the limits of an area of brain infarction in the right frontoparietal region. Despite these concomitant neuroimaging findings, this association is rare, and it is difficult to establish the contribution to the outcome made by each of these diseases, which treatment is the best to implement, or what prognosis is.

The complex genetic basis of fibromuscular dysplasia, a systemic arteriopathy associated with multiple forms of cardiovascular disease

Artery stenosis is a common cause of hypertension and stroke and can be due to atherosclerosis accumulation in the majority of cases and in a small fraction of patients to arterial fibromuscular dysplasia (FMD). Artery stenosis due to atherosclerosis is widely studied with known risk factors (e.g. increasing age, male gender, and dyslipidemia) to influence its etiology, including genetic factors. However, the causes of noninflammatory and nonatherosclerotic stenosis in FMD are less understood. FMD occurs predominantly in early middle-age women, a fraction of the population where cardiovascular risk is different and understudied. FMD arteriopathies are often diagnosed in the context of hypertension and stroke and co-occur mainly with spontaneous coronary artery dissection, an atypical cause of acute myocardial infarction. In this review, we provide a comprehensive overview of the recent advances in the understanding of molecular origins of FMD. Data were obtained from genetic studies using complementary methodological approaches applied to familial, syndromic, and sporadic forms of this intriguing arteriopathy. Rare variation analyses point toward mechanisms related to impaired prostacyclin signaling and defaults in fibrillar collagens. The study of common variation, mainly through a recent genome-wide association study, describes a shared genetic link with blood pressure, in addition to point at potential risk genes involved in actin cytoskeleton and intracellular calcium homeostasis supporting impaired vascular contraction as a key mechanism. We conclude this review with future strategies and approaches needed to fully understand the genetic and molecular mechanisms related to FMD.

Case Report of a Hemangioblastoma With Large Blood Vessels and Rare Vascular Anomalies: Is It Fibromuscular Dysplasia or Arteriovenous Malformation Association?

Hemangioblastoma is considered a benign neoplasm characterized by abnormal vasculature and stromal cells; several pathophysiological mechanisms have been proposed, such as genetic predisposition, hormonal factors, and arterial wall ischemia. Fibromuscular dysplasia is characterized by hyperplasia or thinning of the smooth muscle, elastic fibre destruction, fibrous tissue proliferation, and arterial wall disorganization. We present a cerebellar hemangioblastoma case not associated with Von Hippel Lindau syndrome. Histologically we evidenced big vessels with anomalies of the vascular walls corresponding to fibromuscular dysplasia, and those changes have not been described in these types of tumors. In this light, rare findings could be called vascular malformations or degenerative vascular changes, fibromuscular dysplasia or vascular anomalies. Arterio-venous malformation and hemangioblastoma pathology are rarely presented together. Notwithstanding, we could say that it is a stromal stem cell tumor in a varied stage of differentiation.

Contemporary management of scalp cirsoid aneurysm: A dual-trained neurosurgeon's perspective

OBJECTIVE

Scalp cirsoid aneurysms are subcutaneous arteriovenous fistulae fed by branches of the external carotid artery. They present with progressive scalp swelling and cosmetic deformities in addition to neuro-vascular symptoms. We evaluate the treatment and outcome of this rare vascular lesion with surgery and adjunctive endovascular embolisation performed by a dual-trained neurosurgeon.

METHODS

A retrospective analysis of 6 cases operated over a 16 year-period was performed which comprised of clinical data, radiology including angiography and pre-operative embolisation, surgical approaches, outcomes and complications.

RESULTS

6 patients with ages ranging between 26 and 51 years were operated in the study period. All the patients underwent surgical excision of the lesion, of which 2 had undergone pre-operative embolisation of the feeders. There was no recurrence in the follow-up period (Mean 4.7 years) following total excision of the lesions. One patient had post-operative wound dehiscence and another had migration of embolic material to lungs.

CONCLUSION

Surgery is the predominant treatment method for scalp cirsoid aneurysms. Various adjunctive endovascular procedures can be performed pre-operatively to minimise operative blood loss.Though lower recurrence is seen with surgery for the scalp AV fistula, embolisation performed in select cases can achieve curative results with appropriate techniques.

Role of the physical examination in the determination of etiology of ischemic stroke

The actual investigation of the body of a patient by the clinician in search for the signs of the disease beginning with the primary vital signs and continues with the careful and attentive observation of the patient. This article reviews the key findings in the physical examination of patients with ischemic stroke that have the potential to indicate the etiology of the infarct and to help to choose the use of ancillary tests. Through a systematic search of articles published in English related to the physical examination of patients with stroke, we identified key findings in the vital signs and classic components of the physical exam (appearance of the patient, auscultation, and eye examination) that have shown clinical significance when determining ischemic stroke etiology. We further suggest that the prompt identification of such findings can translate into better use of diagnostic tools and selection of ancillary confirmatory tests, thus, reducing the time to etiology based treatment and secondary prevention of ischemic stroke. in this manuscript, we aim to show that even though nowadays the clinical skills tend to be overlooked due to the overreliance on technology, the physical exam continues to be a valuable tool in the clinician armamentarium when facing the challenge of a patient with ischemic stroke.

NF2 deficiency accelerates neointima hyperplasia following vascular injury via promoting YAP-TEAD1 interaction in vascular smooth muscle cells

Neurofibromin 2 (NF2), a potent tumor suppressor, is reported to inhibit proliferation in several cell types. The role of NF2 in neointima hyperplasia after vascular injury is unknown. We explored the role of NF2 in proliferation, migration of vascular smooth muscle cell (VSMC) and neointima hyperplasia after vascular injury. NF2 phosphorylation was elevated in VSMC subjected to platelet-derived growth factor (PDGF)-BB and in artery subjected to vascular injury. Mice deficient for Nf2 in VSMC showed enhanced neointima hyperplasia after injury, increased proliferation and migration of VSMC after PDGF-BB treatment. Mechanistically, we observed increased nuclear p-NF2, declined p-Yes-Associated Protein (YAP), nuclear translocation of YAP after PDGF-BB treatment or injury. NF2 knockdown or YAP overexpression showed similar phenotype in VSMC proliferation, migration and neointima hyperplasia. YAP inhibition abolished the above effects mediated by NF2 knockdown. Finally, NF2 knockdown further promoted YAP-TEA Domain Transcription Factor 1 (TEAD1) interaction after PDGF-BB treatment. Inhibition of TEAD1 blocked PDGF-BB-induced VSMC proliferation and migration, which were not reversed by either NF2 knockdown or YAP overexpression. In conclusion, NF2 knockdown promotes VSMC proliferation, migration and neointima hyperplasia after vascular injury via inducing YAP-TEAD1 interaction.

An update on the central nervous system manifestations of neurofibromatosis type 1

Neurofibromatosis 1 (NF1) is an autosomal dominant genetic disorder that presents with variable phenotypes as a result of mutations in the neurofibromatosis type 1 (NF1) gene and subsequently, abnormal function of the protein product, neurofibromin. Patients with NF1 are at increased risk for central nervous system (CNS) manifestations including structural, functional, and neoplastic disease. The mechanisms underlying the varied manifestations of NF1 are incompletely understood, but the loss of functional neurofibromin, resulting in sustained activation of the oncoprotein RAS, is responsible for tumorigenesis throughout the body, including the CNS. Much of our understanding of NF1-related CNS manifestations is from a combination of data from animal models and natural history studies of people with NF1 and CNS disease. Data from animal models suggest the importance of both Nf1 mutations and somatic genetic alterations, such as Tp53 loss, for development of neoplasms, as well as the role of the timing of the acquisition of such alterations on the variability of CNS manifestations. A variety of non-neoplastic structural (macrocephaly, hydrocephalus, aqueductal stenosis, and vasculopathy) and functional (epilepsy, impaired cognition, attention deficits, and autism spectrum disorder) abnormalities occur with variable frequency in individuals with NF1. In addition, there is increasing evidence that similar appearing CNS neoplasms in people with and without the NF1 syndrome are due to distinct oncogenic pathways. Gliomas in people with NF1 show alterations in the RAS/MAPK pathway, generally in the absence of BRAF alterations (common to sporadic pilocytic astrocytomas) or IDH or histone H3 mutations (common to diffuse gliomas subsets). A subset of low-grade astrocytomas in these patients remain difficult to classify using standard criteria, and occasionally demonstrate morphologic features resembling subependymal giant cell astrocytomas that afflict patients with tuberous sclerosis complex ("SEGA-like astrocytomas"). There is also emerging evidence that NF1-associated high-grade astrocytomas have frequent co-existing alterations such as ATRX mutations and an alternative lengthening of telomeres (ALT) phenotype responsible for unique biologic properties. Ongoing efforts are seeking to improve diagnostic accuracy for CNS neoplasms in the setting of NF1 versus sporadic tumors. In addition, MEK inhibitors, which act on the RAS/MAPK pathway, continue to be studied as rational targets for the treatment of NF1-associated tumors, including CNS tumors.

Wilson Disease With Giant Splenic Artery Aneurysms Caused by Fibromuscular Dysplasia During Living Donor Liver Transplantation: A Case Report

Liver cirrhosis can cause splenic artery aneurysms (SAA) that pose a threat to patients undergoing liver transplantation. However, liver transplantation with multiple visceral artery aneurysms including giant SAA caused by arterial fragility has never been reported. We describe a 36-year-old man with decompensated liver cirrhosis due to Wilson disease that was complicated by giant SAA and multiple aneurysms in the bilateral renal arteries caused by fibromuscular dysplasia (FMD). The maximal diameter of the triple snowball-shaped SAA was 11 cm. We planned a 2-stage strategy consisting of a splenectomy with distal pancreatectomy to treat the SAA and subsequent living donor liver transplantation (LDLT) to address the liver cirrhosis. This strategy was selected to prevent fatal postoperative infectious complications caused by the potential development of pancreatic fistula during simultaneous procedures and to histopathologically diagnose the arterial lesion before LDLT to promote safe hepatic artery reconstruction. However, a postoperative pancreatic fistula did not develop after a splenectomy with distal pancreatectomy, and the pathologic findings of the artery indicated FMD. The patient underwent ABO-identical LDLT with a right lobe graft donated by his brother. Other than postoperative rupture of the aneurysm in the left renal artery requiring emergency interventional radiology, the patient has remained free of any other arterial complications and continues to do well at 2 years after LDLT.

Safety Assessment of Endovascular Treatment of Cerebral Aneurysms in Patients with Fibromuscular Dysplasia

Background

The prevalence of cerebral aneurysms is increased in fibromuscular dysplasia (FMD). The presence of FMD may serve as discouragement to elective endovascular aneurysm treatment. Outcomes of endovascular intervention for aneurysms through vessels affected by FMD have not been reported.

Methods

A prospectively maintained database of patients undergoing intracranial embolization was reviewed for patients with FMD who underwent endovascular aneurysm treatment.

Results

A total of 1,025 patients were screened and 31 (3.0%) had cerebrovascular FMD. These patients underwent a total of 43 embolization procedures; 27 of these procedures were performed through an affected vessel. All but 1 patient were female and the average age was 62 years. "String-of-pearls"-type FMD was the most common subtype (90%). The internal carotid arteries were more commonly affected (65%) than the vertebral arteries (48%). All patients underwent treatment of cerebral aneurysms, most of which (87%) were incidentally discovered; 6 patients (19%) also had incidental vessel dissection. The average aneurysm size was 7.1 mm. The morphology was saccular in 93% of the cases, and 86% were in the anterior circulation. The most commonly performed treatment was flow diversion (67%), in the majority of cases by pipeline embolization. Other procedures performed were coiling (19%), stent-coiling (12%), and intrasaccular flow disruption (2%). All but 1 procedure (98%) were successful. There were no major complications; 1 patient experienced a transient ischemic attack. Follow-up angiography was performed in 88% of the cases, without evidence for disease progression after treatment. The average time to last angiographic follow-up was 17 months (±13).

Conclusions

Elective embolization of intracranial aneurysms can be performed safely through vessels affected by FMD.

Subarachnoid Hemorrhage Because of Distal Superior Cerebellar Artery Dissection in Neurofibromatosis Type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a rare disease with an incidence of 1 in every 3000 births. Numerous studies have focused on the main function of NF1 as a tumor suppressor, whereas few have examined the cerebrovascular abnormalities observed in patients with NF1. It is worth noting that intracranial aneurysms are uncommon in this condition.

CASE DESCRIPTION

We report a case of NF1 with a dissection of the distal segment of the superior cerebellar artery. A 36-year-old woman presented with a distal superior cerebellar artery (SCA) dissection causing subarachnoid hemorrhage. Subsequently, because of the rich collateral blood flow distal to the dissection, N-butyl cyanoacrylate (NBCA) glue embolization was unsuccessful. Therefore, direct trapping of the artery was necessary. The patient was discharged after an uneventful postoperative period, and has remained without complications.

CONCLUSIONS

In the treatment of subarachnoid hemorrhage because of a distal SCA dissection in patients with NF1, NBCA glue embolization may be a safer option than microsurgery or coil embolization, in the acute phase, considering the possible vulnerability of the vessel wall, accessibility, morphology of the lesions, and the risk of developing unpredictable infarcts in the case of parent artery occlusion. However, regular reevaluation of the blood flow is necessary to monitor recurrence, given the rich collateral circulation.

A Review of the Genetics of Intracranial Berry Aneurysms and Implications for Genetic Counseling

Here we review the current understanding of the genetic architecture of intracranial berry aneurysms (IBA) to aid in the genetic counseling of patients at risk for this condition. The familial subtype of IBA, familial intracranial aneurysms (FIA), is associated with increased frequency of IBA, increased risk of rupture, and increased morbidity and mortality after rupture. Family history is the strongest predictor for the development of IBA. However, a genetic test is not yet available to assess risk within a family. Studies using linkage analysis, genome-wide association, and next-generation sequencing have found several candidate loci and genes associated with disease onset, but have not conclusively implicated a single gene. In addition to family history, a separate or concurrent diagnosis of autosomal dominant polycystic kidney disease is a strong genetic risk factor for IBA formation. We also discuss the relative risk for developing IBA in several Mendelian syndromes including vascular Ehlers-Danlos syndrome, Marfan syndrome, Neurofibromatosis Type I, and Loeys-Dietz syndrome.

Fatal spontaneous rupture of common iliac artery associated with fibromuscular dysplasia

A previously healthy 25-year-old man with no known risk factors was presented at the emergency room with a 3 h history of abdominal and loin pain. Physical examination and lab data showed no specific findings except tenderness, slight white cell count elevation and decreased haemoglobin level. The patient's condition deteriorated over the following hours and he died despite resuscitation attempts. Autopsy revealed a 2.5-cm longitudinal tear in the intima of the right common iliac artery, which formed a thrombosed false lumen extending to the abdominal aorta proximally and to the left common iliac artery. Histopathologic examination revealed the characteristic changes of fibromuscular dysplasia (FMD). FMD involving the common iliac arteries is extremely rare; only six cases have been reported previously, and only two of those included forensic findings. The presented case is the first case of FMD with intimal tearing in the right common iliac artery, with propagation to the left common iliac artery and abdominal aorta. When a previously healthy young adult without hypertension or other risk factors presents with acute abdominal and loin pain, systemic vascular disease should be on the list of differential diagnoses. Careful and complete evaluation of multiple arteries can be critical.

The defining pathology of the new clinical and histopathologic entity ACTA2-related cerebrovascular disease

INTRODUCTION

Smooth muscle cell contraction is an essential function of arteries and relies on the integrity of the actin-myosin apparatus. The tissue-specific α2-smooth muscle actin, encoded by ACTA2, is predominantly expressed in vascular smooth muscle cells. ACTA2 mutations predispose to development of aortic aneurysms and early onset coronary and cerebrovascular disease. Based on arteriographic findings, a distinct cerebrovascular disease has been proposed for ACTA2 heterozygous patients carrying the R179H mutation.

RESULTS

We present the first integrated analysis of a severely compromised patient with the R179H mutation and define the arterial pathology of ACTA2-related cerebrovascular disease. Histologically, striking morphological abnormalities were present in cerebral arteries of all sizes. Massive intimal smooth muscle cell proliferation, fragmentation of the elastic laminae and medial fibromuscular proliferation characterized large arteries whereas prominent vessel wall thickening, fibrosis and smooth muscle cell proliferation were unique changes in small arteries. The medial fibrosis and smooth muscle cell proliferation explain the characteristic radiologic appearance of "straight arteries" and suggest impaired function of mutant smooth muscle cells. Actin three-dimensional molecular modeling revealed critical positioning of R179 at the interface between the two strands of filamentous actin and destabilization of inter-strand bundling by the R179H mutation, explaining the severe associated phenotype.

CONCLUSIONS

In conclusion, these characteristic clinical and pathologic findings confirm ACTA2-related cerebrovascular disease as a new cerebrovascular disorder for which new therapeutic strategies need to be designed.