Cerebrovascular Manifestations of Hereditary Hemorrhagic Telangiectasia

Personalised stroke evaluation and management: tailoring individualised patient care for hereditary haemorrhagic telangiectasia

SummaryHereditary haemorrhagic telangiectasia (HHT) has an estimated prevalence of 1 in 5000-8000 individuals globally with pulmonary arteriovenous malformations (PAVMs) affecting approximately 15%-50% of HHT patients. Ischaemic stroke is a known complication of PAVMs that affects ≤30% of patients with PAVMs. Studies have shown that patients with PAVMs have ischaemic stroke a decade earlier than routine stroke. The predominant mechanism of ischaemic stroke in HHT patients is paradoxical embolism due to PAVMs, but most HHT-related PAVMs are asymptomatic. Additionally, HHT is often underdiagnosed in patients and poses a challenge to physicians due to its rarity. We present a case of a patient with ischaemic stroke who was subsequently diagnosed with HHT and found to have a PAVM on further evaluation. This case highlights the importance of using an individualised patient-centred stroke evaluation and screening for PAVMs in patients who had a stroke with possible or suspected HHT and definite HHT.

Prevalence and Characteristics of Intracranial Aneurysms in Hereditary Hemorrhagic Telangiectasia

BACKGROUND AND PURPOSE

The association between hereditary hemorrhagic telangiectasia and intracranial aneurysms remains controversial. This study evaluated the prevalence and characteristics of intracranial aneurysms in patients with hereditary hemorrhagic telangiectasia with brain vascular malformations.

MATERIALS AND METHODS

Between 2007 and 2021, patients enrolled in the Brain Vascular Malformation Consortium with definite hereditary hemorrhagic telangiectasia, the presence of brain vascular malformations, and available angiographic studies of the brain were retrospectively reviewed. Angiographic features of intracranial aneurysms and their relationship to coexisting brain vascular malformations were analyzed. We also examined the association between baseline clinical features and the presence of intracranial aneurysms.

RESULTS

One hundred eighty patients were included. A total of 14 intracranial aneurysms were found in 9 (5%) patients, and 4 intracranial aneurysms were considered flow-related aneurysms. Patients with intracranial aneurysms were significantly older than patients without intracranial aneurysms (mean, 48.1 [SD, 18.2] years versus 33.5 [SD, 21.0] years; P = .042). If we excluded flow-related intracranial aneurysms, the prevalence of intracranial aneurysms was 3.3%. All intracranial aneurysms were in the anterior circulation, were unruptured, and had an average maximal diameter of 3.9 (SD, 1.5) mm. No intracranial aneurysms were found in pediatric patients with hereditary hemorrhagic telangiectasia. No statistically significant correlation was observed among other baseline demographics, hereditary hemorrhagic telangiectasia features, and the presence of intracranial aneurysms.

CONCLUSIONS

The prevalence of intracranial aneurysms in this large cohort study is comparable with that in the general population and might be increased slightly due to hemodynamic factors associated with shunting brain vascular malformations.

Localized conditional induction of brain arteriovenous malformations in a mouse model of hereditary hemorrhagic telangiectasia

BACKGROUND

Longitudinal mouse models of brain arteriovenous malformations (AVMs) are crucial for developing novel therapeutics and pathobiological mechanism discovery underlying brain AVM progression and rupture. The sustainability of existing mouse models is limited by ubiquitous Cre activation, which is associated with lethal hemorrhages resulting from AVM formation in visceral organs. To overcome this condition, we developed a novel experimental mouse model of hereditary hemorrhagic telangiectasia (HHT) with CreER-mediated specific, localized induction of brain AVMs.

METHODS

Hydroxytamoxifen (4-OHT) was stereotactically delivered into the striatum, parietal cortex, or cerebellum of R26CreER; Alk12f/2f (Alk1-iKO) littermates. Mice were evaluated for vascular malformations with latex dye perfusion and 3D time-of-flight magnetic resonance angiography (MRA). Immunofluorescence and Prussian blue staining were performed for vascular lesion characterization.

RESULTS

Our model produced two types of brain vascular malformations, including nidal AVMs (88%, 38/43) and arteriovenous fistulas (12%, 5/43), with an overall frequency of 73% (43/59). By performing stereotaxic injection of 4-OHT targeting different brain regions, Alk1-iKO mice developed vascular malformations in the striatum (73%, 22/30), in the parietal cortex (76%, 13/17), and in the cerebellum (67%, 8/12). Identical application of the stereotaxic injection protocol in reporter mice confirmed localized Cre activity near the injection site. The 4-week mortality was 3% (2/61). Seven mice were studied longitudinally for a mean (SD; range) duration of 7.2 (3; 2.3-9.5) months and demonstrated nidal stability on sequential MRA. The brain AVMs displayed microhemorrhages and diffuse immune cell invasion.

CONCLUSIONS

We present the first HHT mouse model of brain AVMs that produces localized AVMs in the brain. The mouse lesions closely resemble the human lesions for complex nidal angioarchitecture, arteriovenous shunts, microhemorrhages, and inflammation. The model's longitudinal robustness is a powerful discovery resource to advance our pathomechanistic understanding of brain AVMs and identify novel therapeutic targets.

Etiologies of Brain Arteriovenous Malformation Recurrence: A Focus on Pediatric Disease

Pediatric brain arteriovenous malformations are a major cause of morbidity and mortality, with the harmful effects of this disease compounded by the additional disability-years experienced by children with ruptured or other symptomatic arteriovenous malformations. In addition to the risks shared with their adult counterparts, pediatric patients frequently experience recurrence following radiographic cure, which presents an additional source of morbidity and mortality. Therefore, there is a need to synthesize potential mechanisms contributing to the elevated recurrence risk in the pediatric population and discuss how these translate to practical considerations for managing these patients.

Evaluating the Quality, Readability, and Activity of Online Information on Brain Arteriovenous Malformations

Introduction Brain arteriovenous malformations (AVMs) are vascular deformities created by improper connections between arteries and veins, most commonly in the brain and spinal cord. The management is complex and patient-dependent; further understanding of patient education activities is imperative. Internet access has become more ubiquitous, allowing patients to utilize a large database of medical information online. Using Google Trends (GT) (Google LLC, Mountain View, CA, USA), one can see the public interest in a particular topic over time. Further, when presented with numerous search results, patients may not be able to identify the highest-yielding resources, making objective measures of information quality and readability imperative. Methods A GT analysis was conducted for "hereditary hemorrhagic telangiectasia," "cerebral aneurysm," and "arteriovenous malformation". These relative search volumes (RSV) were compared with the 2017 to 2019 annual USA AVM diagnosis quantity for correlation. These RSVs were also compared with the 2017 to 2019 annual USA deaths due to cerebral hemorrhagic conditions. One search was conducted for "brain arteriovenous malformation". Since most users looking for health information online use only the first page of sources, the quality and readability analyses were limited to the first page of results on Google search. Five quality tools and six readability formulas were used. Results Pearson's correlation coefficients showed positive correlations between USA AVM RSVs and annual AVM deaths per capita from 2017 to 2019 (R2=0.932). The AVM annual diagnosis quantity and AVM RSVs showed a strong positive correlation as well (R2=0.998). Hereditary hemorrhagic telangiectasia and cerebral aneurysms had strong positive correlations between their RSVs and their corresponding annual diagnoses in the 2017 to 2019 time period (R2=0.982, R2=0.709). One-way ANOVA, for USA's 2004 to 2021 AVM RSVs and 2004 to 2019 deaths per capita, displayed no month-specific statistically significant repeating pattern (all p>0.483). The DISCERN tool had four websites that qualified as "poor" and five as "good." The average score for the tool was "good." The Journal of the American Medical Association (JAMA) benchmark scores were very low on average, as four websites achieved zero points. There was a wide variance in the currency, relevance, authority, accuracy, and purpose (CRAAP) scores, indicating an inconsistent level of webpage reliability across results. The patient education materials assessment tool (PEMAT) understandability (86.6%) showed much higher scores than the PEMAT actionability (54.6%). No readability score averaged at or below the American Medical Association (AMA)-recommended sixth-grade reading level. Conclusion These GT correlations may be due to patients and families with new diagnoses researching those same conditions online. The seasonality results reflect that no prior research has detected seasonality for AVM diagnosis or presentation. The quality study showed a wide variance in website ethics, treatment information quality, website/author qualifications, and actionable next steps regarding AVMs. Overall, this study showed that patients are routinely attempting to access information regarding these intracranial conditions, but the information available, specifically regarding AVMs, is not routinely reliable and the reading level required to understand them is too high.

Multidisciplinary coordinated care of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease)

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease, is a rare disorder with a case prevalence as high as one in 5000, causing arteriovenous malformations in multiple organ systems. HHT is familial with autosomal dominant inheritance, with genetic testing allowing confirmation of the diagnosis in asymptomatic kindreds. Common clinical manifestations are epistaxis and intestinal lesions causing anemia and requiring transfusions. Pulmonary vascular malformations predispose to ischemic stroke and brain abscess and may cause dyspnea and cardiac failure. Brain vascular malformations can cause hemorrhagic stroke and seizures. Rarely, liver arteriovenous malformations can cause hepatic failure. A form of HHT can cause juvenile polyposis syndrome and colon cancer. Specialists in multiple fields may be called to care for one or more aspects of HHT, but few are familiar with evidence-based guidelines for HHT management or see a sufficient number of patients to gain experience with the unique characteristics of the disease. Primary care physicians and specialists are often unaware of the important manifestations of HHT in multiple systems and the thresholds for their screening and appropriate management. To improve familiarity, experience, and coordinated multisystem care for patients with HHT, the Cure HHT Foundation, which advocates for patients and families with this disease, has accredited 29 centers in North America with designated specialists for the evaluation and care of patients with HHT. Team assembly and current screening and management protocols are described as a model for evidence-based, multidisciplinary care in this disease.

Neuropilin-1 deficiency in vascular smooth muscle cells is associated with hereditary hemorrhagic telangiectasia arteriovenous malformations

Patients with hereditary hemorrhagic telangiectasia (HHT) have arteriovenous malformations (AVMs) with genetic mutations involving the activin-A receptor like type 1 (ACVRL1 or ALK1) and endoglin (ENG). Recent studies have shown that Neuropilin-1 (NRP-1) inhibits ALK1. We investigated the expression of NRP-1 in livers of patients with HHT and found that there was a significant reduction in NRP-1 in perivascular smooth muscle cells (SMCs). We used Nrp1^SM22KO mice (Nrp1 was ablated in SMCs) and found hemorrhage, increased immune cell infiltration with a decrease in SMCs, and pericyte lining in lungs and liver in adult mice. Histologic examination revealed lung arteriovenous fistulas (AVFs) with enlarged liver vessels. Evaluation of the retina vessels at P5 from Nrp1^SM22KO mice demonstrated dilated capillaries with a reduction of pericytes. In inflow artery of surgical AVFs from the Nrp1^SM22KO versus WT mice, there was a significant decrease in Tgfb1, Eng, and Alk1 expression and phosphorylated SMAD1/5/8 (pSMAD1/5/8), with an increase in apoptosis. TGF-β1–stimulated aortic SMCs from Nrp1^SM22KO versus WT mice have decreased pSMAD1/5/8 and increased apoptosis. Coimmunoprecipitation experiments revealed that NRP-1 interacts with ALK1 and ENG in SMCs. In summary, NRP-1 deletion in SMCs leads to reduced ALK1, ENG, and pSMAD1/5/8 signaling and reduced cell death associated with AVM formation.

OUP accepted manuscript

Paediatric intracranial dural arteriovenous shunts have clinical presentations and evolutions, with angiographic characteristics that differ from those described in adults. We report our experience concerning their therapeutic management, emphasizing the relevance of early diagnosis and appropriate treatment for satisfactory neurocognitive development. Using a prospective database, we reviewed the clinical and radiological data of all children with dural arteriovenous shunts managed between 2002 and 2020. Dural shunts were categorized into three types: dural sinus malformations with arteriovenous shunts; infantile dural arteriovenous shunts; and adult-type dural arteriovenous shunts. Therapeutic strategies and outcomes were analysed depending on lesional subtypes. Modified Rankin Scale for the paediatric population was assessed pre-treatment and at last follow-up. Twenty-eight patients [16 girls (57.1%); 12 boys (42.9%)] were included: 17 dural sinus malformation [10 boys (58.8%); seven girls (41.2%)], three infantile shunts [three girls (100%)], eight adult-type shunts [four girls (50%)]; four boys (50%)], with a mean age of 19.2 ± 36.6 months at presentation. Twelve (42.9%) had a modified Rankin Scale score of 0–2, four (14.3%) had a score of 3, three (10.7%) had a score of 4 and eight (28.6%) had a score of 5. Embolization was performed in 22 children [78.6%; 12 girls (54.5%); 10 boys (45.5%)]. Fifteen patients could be cured (68.2%): 11 dural sinus malformations (73.3%), four adult-type lesions (100%) but no infantile shunt. Mean post-treatment follow-up was 39.5 months (max. 139 months): 14 patients (63.6%) presented a modified Rankin Scale score of 0–2 and eight (36.4%) had a score ≥3. In the dural sinus malformation group, the modified Rankin Scale score was improved in 11 patients (73.3%) and unchanged in three (20%). Only one patient with infantile subtype (33.3%) improved clinically. In the adult-subtype group, all children (100%) improved. Of six untreated patients [four girls (66.7%); two boys (33.3%)], four with adult-subtype shunts showed uneventful evolutions, one with dural sinus malformation died, and therapeutic abortion was conducted in an antenatally diagnosed dural sinus malformation. Paediatric dural fistulas comprise different subtypes with variable clinical courses. Proper diagnosis is mandatory for optimal therapeutic strategies within appropriate therapeutic windows.

Imaging to intervention: a review of what the Interventionalist needs to Know about Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a disorder that affects 1 in 5000-10,000 people worldwide and can result in devastating complications such as cerebral abscess, stroke, massive hemorrhage, and even death. HHT is an autosomal dominant disorder that leads to the formation of abnormal communication between the arteries and veins with a resultant spectrum of vascular anomalies. The disorder affects many organ systems and thus requires a dedicated multidisciplinary approach. Interventional radiologists are vital members of this team providing expertise not only in disease management, but in complex embolotherapy, helping to maintain the health of these patients. This article reviews clinical manifestations, screening guidelines, diagnostic criteria, and endovascular management of HHT.

Pearls & Oy-sters: Cerebral Abscess Secondary to Pulmonary Arteriovenous Malformation in Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant condition which is linked to a myriad of neurological complications arising from vascular malformations of the brain, spinal cord, and lungs. Our case describes a previously healthy 3-year-old male who presented to hospital with fever of unknown origin and was found to have a brain abscess stemming from a pulmonary arteriovenous malformation (PAVM). This etiology was identified after a period of diagnostic delay; the medical team was suspicious for a proximal embolic source due to the presence of multiple tiny infarcts seen on MRI brain, but transthoracic echocardiogram and head and neck angiogram were unremarkable. Fortunately, an enhanced CT chest was performed, identifying a moderately-sized PAVM. PAVMs are associated with intracranial abscesses due to shunting and loss of the normal filtering effects of the lung capillary bed. Impaired pulmonary filtration can permit paradoxical thromboemboli and septic microemboli to enter systemic circulation, predisposing patients with PAVMs to cerebral abscess and ischemic stroke. Screening for PAVMs with contrast enhanced echocardiogram or enhanced CT chest may be considered in patients with cryptogenic brain abscess or recurrent embolic stroke of unknown origin. PAVMs are often associated with hereditary hemorrhagic telangiectasia (HHT). As many features of HHT have delayed clinical manifestation, genetic testing for HHT should be considered in patients with PAVM, even in the absence of other clinical features. In our case, genetic testing returned positive, confirming a new diagnosis of HHT type 1.

Pathogenesis and therapy of arteriovenous malformations: A case report and narrative review

Arteriovenous malformations (AVMs) are abnormal communications between arteries and veins that lack intervening capillary beds. They have been described in almost every organ in the body, emerging sporadically or as part of well-described syndromes. Hereditary hemorrhagic telangiectasia (HHT) is a rare, progressive, and lifelong disease characterized by AVMs and recurrent hemorrhaging. In the last 2 decades, significant advances have been made in understanding the pathogenesis of this condition. The accumulation of knowledge has led to a natural evolution of therapy, from open surgery to endovascular procedures, and now to a role for medications in certain AVMs. Here, we review a case of HHT and describe the most up-to-date clinical practice, including diagnosis of HHT, subtypes of HHT, and medical therapy.

The Role of BMP Signaling in Endothelial Heterogeneity

Bone morphogenetic proteins (BMPs), which compose the largest group of the transforming growth factor-β (TGF-ß) superfamily, have been implied to play a crucial role in diverse physiological processes. The most intriguing feature of BMP signaling is that it elicits heterogeneous responses from cells with equivalent identity, thus permitting highly context-dependent signaling outcomes. In endothelial cells (ECs), which are increasingly perceived as a highly heterogeneous population of cells with respect to their morphology, function, as well as molecular characteristics, BMP signaling has shown to elicit diverse and often opposite effects, illustrating the innate complexity of signaling responses. In this review, we provide a concise yet comprehensive overview of how outcomes of BMP signaling are modulated in a context-dependent manner with an emphasis on the underlying molecular mechanisms and summarize how these regulations of the BMP signaling promote endothelial heterogeneity.

Arteriovenous Malformations in the Setting of Osler-Weber-Rendu: What the Radiologist Needs to Know

Osler-Weber-Rendu, also known as Hereditary Hemorrhagic Telangiectasia, is an autosomal dominant disease with phenotypic manifestations that include pulmonary, cerebrospinal, hepatic, and other visceral arteriovenous malformations (AVMs). Pulmonary AVMs can result in hypoxemia, hemoptysis, or stroke due to paradoxical embolism. The mainstay of treatment is transcatheter embolization. Central nervous system and abdominal visceral AVMs contribute to morbidity of the disease. Radiologists should be familiar with the imaging manifestations and treatment algorithm of AVMs in Osler-Weber-Rendu to effectively guide patient care.

Cerebral Arteriovenous Malformations in Pediatric Patients with Hereditary Hemorrhagic Telangiectasia: Re-evaluating Appearance, Bleeding Risk, and Treatment Necessity in a Selective Meta-analysis

Pediatric patients suffering from cerebral nidal arteriovenous malformations are a unique population due to the rare occurrence of the disease. Diagnosis of hereditary hemorrhagic telangiectasia (HHT) in children is a rare event and mainly restricted to coincidental detection from screening of possibly afflicted family members. In patients with HHT, it is well known that the incidence of cerebral vascular malformations (CVMs) is higher than expected when compared with the nonafflicted population. Even though CVMs comprise a variety of different distinct anatomical and radiographic entities (e.g., capillary telangiectasia, nidal arteriovenous malformation [AVM], cavernous malformation, dural or pial as well as mixed fistula, and vein of Galen malformation), they are mostly summarized and analyzed all in one category due to the low number of individual cases identified in single centers. Nevertheless, the best treatment algorithm will likely vary significantly between different CVMs as does the clinical presentation and the natural course of the CVM. It is therefore the objective of this article to focus on nidal AVMs in pediatric patients suffering from HHT. To this end, we performed a systematic selective literature research to estimate incidence, clinical and radiological appearance, as well as classification according to established grading system, and to evaluate the necessity of treatment of these lesions in light of their respective outcomes. Our line of arguments explains why we recommend to follow these lesions expectantly and suggest to keep pediatric patients under surveillance with sequential scans until they reach adulthood.

The Roles of TGF-β Signaling in Cerebrovascular Diseases

Cerebrovascular diseases are one of the leading causes of death worldwide, however, little progress has been made in preventing or treating these diseases to date. The transforming growth factor-β (TGF-β) signaling pathway plays crucial and highly complicated roles in cerebrovascular development and homeostasis, and dysregulated TGF-β signaling contributes to cerebrovascular diseases. In this review, we provide an updated overview of the functional role of TGF-β signaling in the cerebrovascular system under physiological and pathological conditions. We discuss the current understanding of TGF-β signaling in cerebral angiogenesis and the maintenance of brain vessel homeostasis. We also review the mechanisms by which disruption of TGF-β signaling triggers or promotes the progression of cerebrovascular diseases. Finally, we briefly discuss the potential of targeting TGF-β signaling to treat cerebrovascular diseases.

De novo arteriovenous shunts after endovascular cure of cerebrospinal macro arteriovenous fistulas. A role for the vasa vasorum?

BACKGROUND AND PURPOSE

Macro-arteriovenous fistulas (MAVFs) are arteriovenous shunts draining into a giant venous ectasia. They can be treated by surgery or embolisation. Angiographic controls are usually performed rapidly after treatment in order to prove the cure of the lesion but no long term angiographies are generally scheduled. We wanted to control the stabilities of such lesions at follow-up.

METHOD

Clinical history and imaging of ninety-five patients with high flow shunts draining into venous ectasias (MAVFs, Vein of Galen malformations and dilatations) were reviewed.

RESULTS

De novo arteriovenous shunts related to angiogenesis involving vasa vasorum developed in three patients with MAVFs at various intervals. Genetic underlying conditions as HHT or RASA 1 mutations were suspected in each patient.

CONCLUSIONS

Neo-angiogenesis can occur after cure of MAVFs. Long term imaging follow-ups should be considered as the natural history of such recurrent shunts is currently unknown.

Clinical presentation and treatment paradigms of brain arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is characterized by recurrent spontaneous epistaxis, mucocutaneous telangiectases, and multisystem arteriovenous malformations (AVMs). Brain AVMs typically present at birth and are identified in approximately 10-20% of patients with HHT. A retrospective review was undertaken of all HHT patients with known single or multiple brain AVMs treated at our institution. Thirty-nine patients with brain AVM(s) were diagnosed with HHT. Most patients presented with at least one Curaçao criterion. A total of 78 brain AVMs were identified in 39 patients. Two-thirds of patients had solitary brain AVMs, whereas 33% of patients harbored at least two lesions (range: 2-16). Brain AVMs of the supratentorial cerebral hemispheres comprised 83% of all lesions, whereas infratentorial lesions accounted for only 17%. Of the 55 brain AVMs assigned Spetzler-Martin grading, the majority of patients were Grade 1 (73%), and 23% and 4% were Grades 2 and 3, respectively. Patients were treated with surgery alone (51%), embolization alone (6%), embolization followed by surgery (9%), stereotactic radiosurgery (11%), stereotactic radiosurgery followed by surgery (3%), or observation (20%). Of patients who underwent genetic analysis, 62% possessed mutations in ENG (HHT type 1), whereas 38% had mutations in ACVRL1 (HHT type 2). This robust patient cohort of brain AVMs in 39 patients with HHT advances the collective understanding of this disease's varied presentation, diagnostic workup, genetic underpinnings, and available treatment options.

Clinical presentation and treatment paradigms in patients with hereditary hemorrhagic telangiectasia and spinal vascular malformations

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder that causes angiodysplasia and results in mucocutaneous telangiectasias and arteriovenous malformations of organs. Although central nervous system vascular malformations can occur anywhere along the neuraxis, spinal vascular malformations are rare. We present our experience with the presentation and management of spinal vascular malformations in patients with HHT. Of the more than 800 patients with the diagnosis of HHT screened at our institution from 1995 through 2017, four patients with spinal vascular malformations (age range 1 month-77 years; 2 male, 2 female) were identified, three of whom came to clinical attention after significant neurological deterioration from previously unknown malformations. A review of the literature including our patients demonstrated 29 total spinal arteriovenous fistulas (AVFs) in 28 HHT patients (69% male). The lesions were located predominantly in the thoracic spine (65.5%). Three lesions were not treated, 17 were treated with embolization, 6 were surgically resected, and 3 were treated with embolization and surgery. In 14 cases, the patients presented with hemorrhage of the AVF. Overall, 79% of patients achieved complete or near-complete occlusion, with 75% reporting improvement in neurological function. Discovery of spinal lesions often occurs after neurological decline because current screening protocols do not include evaluation of the patient for spinal lesions. Most patients benefit from intervention, which is tailored to the characteristics of the patient and their malformation. Given the often-severe neurological deficit encountered at presentation, we favor a protocol that screens HHT patients for spinal vascular malformations.

The roles of endoglin gene in cerebrovascular diseases

Endoglin (ENG, also known as CD105) is a transforming growth factor β (TGFβ) associated receptor and is required for both vasculogenesis and angiogenesis. Angiogenesis is important in the development of cerebral vasculature and in the pathogenesis of cerebral vascular diseases. ENG is an essential component of the endothelial nitric oxide synthase activation complex. Animal studies showed that ENG deficiency impairs stroke recovery. ENG deficiency also impairs the regulation of vascular tone, which contributes to the pathogenesis of brain arteriovenous malformation (bAVM) and vasospasm. In human, functional haploinsufficiency of ENG gene causes type I hereditary hemorrhagic telangiectasia (HHT1), an autosomal dominant disorder. Compared to normal population, HHT1 patients have a higher prevalence of AVM in multiple organs including the brain. Vessels in bAVM are fragile and tend to rupture, causing hemorrhagic stroke. High prevalence of pulmonary AVM in HHT1 patients are associated with a higher incidence of paradoxical embolism in the cerebral circulation causing ischemic brain injury. Therefore, HHT1 patients are at risk for both hemorrhagic and ischemic stroke. This review summarizes the possible mechanism of ENG in the pathogenesis of cerebrovascular diseases in experimental animal models and in patients.

Cerebral hemorrhage in monozygotic twins with hereditary hemorrhagic telangiectasia: case report and hemorrhagic risk evaluation

The authors present a case of monozygotic twins with hereditary hemorrhagic telangiectasia (HHT) who experienced cerebral arteriovenous malformation (AVM) hemorrhage at a very young age. The clinical variables influencing HHT-related AVM rupture are discussed, and questions surrounding the timing of screening and intervention are explored. This is only the second known case of monozygotic HHT twins published in the medical literature, and the youngest pair of first-degree relatives to experience AVM-related cerebral hemorrhage. Evidence guiding the screening and management of familial HHT is lacking, and cases such as this underscore the need for objective and validated protocols.

Pulmonary Arteriovenous Malformations Are Associated with Silent Brain Infarcts in Hereditary Hemorrhagic Telangiectasia Patients

BACKGROUND AND PURPOSE

There is a high prevalence of right-to-left shunting pulmonary arteriovenous malformations (PAVMs), which are stroke risk factors, in hereditary hemorrhagic telangiectasia (HHT) patients. While the prevalence of ischemic complications in HHT patients is known, the prevalence of silent brain infarcts (SBI) remains unknown. The purpose of this study was to determine the prevalence and risk factors for SBI in HHT patients.

MATERIALS AND METHODS

Our institutional HHT database was queried to identify HHT patients who received a baseline screening brain MRI from January 2000 to February 2017. This study group was further refined by excluding patients who had a history of clinical ischemic disease as defined by having a stroke or transient ischemic attack (TIA). Brain MRIs were reviewed for SBI. Baseline data on demographics, Curacao criteria, presence of PAVMs, and cardiovascular risk factors were collected. The primary outcome was SBI prevalence. We also examined which baseline patient characteristics were associated with SBI through univariate chi-square and Student t tests and multivariate logistic regression analyses.

RESULTS

Three hundred fifty three consecutive HHT patients from January 2000 to February 2017 with a screening brain MRI and no prior history of stroke/TIA were included. SBI prevalence was 9.9% (35/353). SBI patients were more likely to have PAVMs than non-SBI patients (80.6 vs. 53.1%, p = 0.005). The median age was 66 in the SBI group and 52 in the non-SBI group (p = 0.006). SBI patients had higher prevalence of hyperlipidemia (34.3 vs. 9.8%, p < 0.0001), hypertension (48.6 vs. 22.0%, p = 0.005), and tobacco use (25.7 vs. 9.8%, p = 0.005). No patients under 30 had SBI. In the 60-69 age group, the prevalence of SBI was 18.8% with rates of 28.6% in the PAVM group and 10.5% in the non-PAVM group. For patients ≥70 years old, the prevalence of SBI was 21.4% overall and 27.6% in the PAVM group and 10.5% in the non-PAVM group. On multivariate analysis, PAVMs (OR 3.62, 95% CI 1.46-10.40) and increasing age (OR 1.04, 95% CI 1.01-1.07) were independently associated with SBI.

CONCLUSIONS

Overall, a similar 10% SBI prevalence in the HHT cohort was noted as compared to the general population. However, the prevalence of SBI was higher in HHT patients with PAVMs when compared to that of the general population, particularly among patients than 60 years old. These findings highlight the need to accurately identify, and when appropriate, treat PAVMs in the HHT population especially given the multiple significant, clinical consequences of SBI.

Cervical spine arteriovenous fistula associated with hereditary haemorrhagic telangiectasia

Reported is a case of a man aged 55 years who presented with progressive spastic paraparesis. Examination demonstrated multiple cutaneous telangiectases. Subsequent development of upper limb weakness, acute urinary retention and eventual respiratory compromise resulted in the requirement for intensive care unit admission and mechanical ventilation. MRI spine revealed diffuse T2 hyperintensity in the cervical cord with enhancement and cord expansion. Immunomodulatory therapy for a presumed diagnosis of transverse myelitis yielded no response, so a vascular aetiology was suspected. Spinal angiography demonstrated an arteriovenous fistula involving the upper cervical cord. Endovascular embolisation was successfully performed and a marked clinical improvement was achieved. Cervical arteriovenous fistulas can cause progressive myelopathy, subarachnoid haemorrhage and brainstem dysfunction. Management typically comprises endovascular embolisation or surgical interruption. A clinical diagnosis of hereditary haemorrhagic telangiectasia was also made in this case, and spinal arteriovenous fistula formation has been associated with this condition.

Hereditary haemorrhagic telangiectasia: to transplant or not to transplant - is there a right time for liver transplantation?

BACKGROUND & AIMS

Hereditary haemorrhagic telangiectasia is characterized by arterio-venous malformations (AVM). It frequently involves the liver without clinical symptoms, but may lead to biliary ischaemia, portal hypertension, or fatal high-output heart failure. The indication of liver transplantation is controversial.

METHODS

Herein, we report the case of a 65-year-old female patient with a 'double Osler syndrome' consisting of hereditary haemorrhagic telangiectasia (HHT) and type I hereditary angioedema diagnosed at the age of 25 and 22 years respectively.

RESULTS

Hereditary angioedema was treated with danazol for several decades until multiple hypoechogenic liver masses were detected. Albeit danazol treatment was replaced by C1 esterase inhibitor infusions, hepatocellular carcinoma was diagnosed at the age of 64 and the patient was listed for liver transplantation. HHT was marked by recurrent epistaxis until the age of 63 when severe intestinal bleeding occurred. At the age of 65, severe dyspnoea (NYHA class IV) developed and rapidly progressive high-output cardiac failure was diagnosed. Despite argon plasma coagulation to control bleeding from intestinal angiodysplasia, and treatment with bevacizumab to inhibit angiogenesis, the patient died from severe gastrointestinal bleeding associated with cardiogenic shock at the age of 66 before being transplanted.

CONCLUSION

The indication to list this patient for liver transplantation was debated several times before the diagnosis of hepatocellular carcinoma because of good general condition and low MELD score. Precise guidelines for screening and management of patients with hepatic HHT need to be better defined.

Prevalence and characteristics of brain arteriovenous malformations in hereditary hemorrhagic telangiectasia: a systematic review and meta-analysis

OBJECTIVE Patients with hereditary hemorrhagic telangiectasia (HHT) are known to suffer from high rates of cerebral arteriovenous malformations (AVMs). The authors performed a systematic review and meta-analysis of the literature examining prevalence rates, characteristics, and clinical presentation of cerebral AVMs in the HHT population. METHODS To identify studies on AVM prevalence and characteristics in the HHT population, 4 databases (MEDLINE, EMBASE, Scopus and Web of Science) were searched by a reference librarian with over 30 years experience in systematic reviews and meta-analysis. The search period was January 1, 1990-March 2016. The following search terms were used: hereditary hemorrhagic telangiectasia, Osler-Weber-Rendu syndrome, AVM, brain AVM, arteriovenous malformation, arteriovenous fistula, prevalence, and epidemiology. The authors identified studies that examined the prevalence rates, characteristics, and clinical presentation of cerebral AVMs in patients with HHT. They assessed overall AVM prevalence rates as well as prevalence rates by age, sex, HHT type, and country/region. They also systematically reviewed the characteristics of AVMs, including rupture status, location, clinical presentation, angioarchitecture, and Spetzler-Martin grade. Data were analyzed using a random-effects meta-analysis model. RESULTS Thirty-nine studies were included in this meta-analysis. Thirty studies examined brain AVM prevalence rates in various HHT patient populations, and 18 studies examined AVM clinical and angiographic characteristics (9 studies examined both prevalence rates and AVM characteristics). The prevalence of brain AVMs in HHT patients was 10.4% (95% CI 7.9%-13.0%) with no significant difference between males (8.5%, 95% CI 4.9%-12.0%) and females (11.0%, 95% CI 5.9%-16.1%). Patients with HHT Type 1 (HHT1) had a significantly higher brain AVM prevalence (13.4%, 95% CI 9.5%-17.4%) compared with those with HHT Type 2 (HHT2) (2.4%, 95% CI 1.0%-3.8%) (p < 0.0001). In 55.2% (95% CI 38.3%-72.1%) of cases, the AVMs were symptomatic. Spetzler-Martin grade was 2 or less in 86.9% (95% CI 67.5%-95.2%) of patients. CONCLUSIONS The prevalence of brain AVMs in the HHT population is about 10%. HHT1 patients are significantly more likely to have brain AVMs than HHT2 patients. Most AVMs in the HHT population are symptomatic. The Spetzler-Martin grade for these lesions is 2 or less in nearly 90% of patients.

Neurovascular Manifestations of Hereditary Hemorrhagic Telangiectasia: A Consecutive Series of 376 Patients during 15 Years

BACKGROUND AND PURPOSE

Hereditary hemorrhagic telangiectasia is associated with a wide range of neurovascular abnormalities. The aim of this study was to characterize the spectrum of cerebrovascular lesions, including brain arteriovenous malformations, in patients with hereditary hemorrhagic telangiectasia and to study associations between brain arteriovenous malformations and demographic variables, genetic mutations, and the presence of AVMs in other organs.

MATERIALS AND METHODS

Consecutive patients with definite hereditary hemorrhagic telangiectasia who underwent brain MR imaging/MRA, CTA, or DSA at our institution from 2001 to 2015 were included. All studies were re-evaluated by 2 senior neuroradiologists for the presence, characteristics, location, and number of brain arteriovenous malformations, intracranial aneurysms, and nonshunting lesions. Brain arteriovenous malformations were categorized as high-flow pial fistulas, nidus-type brain AVMs, and capillary vascular malformations and were assigned a Spetzler-Martin score. We examined the association between baseline clinical and genetic mutational status and the presence/multiplicity of brain arteriovenous malformations.

RESULTS

Three hundred seventy-six patients with definite hereditary hemorrhagic telangiectasia were included. One hundred ten brain arteriovenous malformations were noted in 48 patients (12.8%), with multiple brain arteriovenous malformations in 26 patients. These included 51 nidal brain arteriovenous malformations (46.4%), 58 capillary vascular malformations (52.7%), and 1 pial arteriovenous fistula (0.9%). Five patients (10.4%) with single nidal brain arteriovenous malformation presented with hemorrhage. Of brain arteriovenous malformations, 88.9% (88/99) had a Spetzler-Martin score of ≤2. Patients with brain arteriovenous malformations were more likely to be female (75.0% versus 57.6%, P = .01) and have a family history of hereditary hemorrhagic telangiectasia (95.8% versus 84.8%, P = .04). The prevalence of brain arteriovenous malformation was 19.7% in endoglin (ENG) mutations and 12.5% in activin receptor-like kinase (1ACVRL1) mutations.

CONCLUSIONS

Our study of 376 patients with hereditary hemorrhagic telangiectasia demonstrated a high prevalence of brain arteriovenous malformations. Nidal brain arteriovenous malformations and capillary vascular malformations occurred in roughly equal numbers.