Bleeding risk of cerebrovascular malformations in hereditary hemorrhagic telangiectasia

Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an underrecognized and underdiagnosed autosomal-dominant angiodysplasia that has an estimated prevalence of 1 in 5000 individuals, with variable clinical presentations even within family members with identical mutations. The most common manifestations are telangiectasias of the skin and nasal mucosa. However, HHT can often be complicated by the presence of arteriovenous malformations and telangiectasias in the lungs, brain, gastrointestinal tract, and liver that are often silent and can lead to life-threatening complications of stroke and hemorrhage. This article reviews HHT for the pulmonologist, who is not uncommonly the first practitioner to encounter these patients.

Neurological involvement in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by epistaxis, telangiectases, and multi-organ vascular dysplasia. Head and neck localizations of HHT are recurrent, frequent associated with serious complications. The aim of this study was to describe the clinical and imaging patterns of neurological involvement in HHT and to discuss the role of interventional radiology in the management of HHT patients. Based on a multidisciplinary experience of twenty years at our center, we report here the different aspects of neurological involvement of HHT. Depending on the genetic type of the disease, vascular abnormalities may affect different organs. The knowledge of neurological involvement according to specific localization of HHT makes detection easier. As cerebral or spinal arteriovenous fistula may be present in patients with epistaxis or pulmonary arteriovenous malformations (PAVMs), radiologists should be able to detect high-risk lesions and prevent related complications. Finally, we review indications and techniques of embolization for hemorrhagic lesions and emphasize that endovascular therapies are very effective and safe in experienced hands. Head and neck imaging is commonly used for the diagnosis of HHT. Imaging plays also a key role for patient evaluation before treatment as pluridisciplinary management is needed.

Natural history of brain capillary vascular malformations in hereditary hemorrhagic telangiectasia patients

BACKGROUND AND PURPOSE

Brain capillary vascular malformations (CVMs) are known to occur with relatively high frequency in hereditary hemorrhagic telangiectasia (HHT) patients. These lesions are thought to have a benign natural history but this has not been systematically studied. The purpose of our study was to examine the natural history of CVMs in a consecutive series of HHT patients.

MATERIALS AND METHODS

Consecutive patients with untreated CVMs receiving serial imaging were included. Baseline data including demographics, HHT gene mutations, and Curacao diagnostic criteria were collected. The primary outcome was rupture on follow-up. A secondary outcome was new focal neurological deficit or seizure related to the lesion.

RESULTS

22 patients with 42 CVMs were included. Mean age was 45.9±16.9 years. 18 patients (81.8%) were women and 4 (18.2%) were men. 19 patients (86.4%) had definite HHT and 3 patients (13.6%) had probable HHT. Mean follow-up was 4.6±3.7 years. There were a total of 100.2 patient years of follow-up and 222.5 lesion years. No lesions ruptured on follow-up and no patient had focal neurological deficits or seizures related to the lesions.

CONCLUSIONS

Our study found that CVMs in HHT patients have a benign natural history as no patients had hemorrhage or other symptoms related to these lesions. These findings should be confirmed in additional multicenter longitudinal studies.

Hemorrhage Risk in Pediatric Patients with Multiple Intracranial Arteriovenous Malformations

BACKGROUND/AIMS

This study aims to characterize the clinical features, treatment strategies, and annual hemorrhage incidence rate of pediatric patients with multiple arteriovenous malformations (MAVM).

METHODS

The PubMed and EMBASE databases and the arteriovenous malformations (AVM) database at the Johns Hopkins Hospital were searched for reports of pediatric patients (under 21 years of age) with MAVM. Data related to demographics, clinical features, management, and treatment outcomes were analyzed using descriptive statistics. Twenty-four pediatric patients met the inclusion criteria.

RESULTS

The annual hemorrhage incidence rate was 2.1%. The most common presenting features were neurological deficit (38%) and hemorrhage (21%). Treatment with embolization has become the most frequently used modality. In patients undergoing staged treatment of MAVM, hemorrhage of an untreated nidus (n = 1), visualization of a new nidus (n = 2), or disappearance of a draining vein (n = 1) occurred.

CONCLUSION

The annual hemorrhage incidence rate for pediatric patients with MAVM approaches the upper range of previously reported hemorrhage rates for solitary AVM. A staged approach to treating MAVM requires close follow-up as changes to the remaining nidi may occur during the latency period. Limitations of this study include its small sample size and reporting bias.

Hemorrhage risk and clinical features of multiple intracranial arteriovenous malformations

The aim of this report is to examine clinical characteristics, treatment strategies, and annual hemorrhage incidence rate for patients with multiple arteriovenous malformations (MAVM). The PubMed and EMBASE databases and the arteriovenous malformations (AVM) database at The Johns Hopkins Hospital were searched to identify patients with MAVM. Data related to demographics, clinical features, management, and treatment outcomes were analyzed with descriptive statistics. Thirty-eight patients met the inclusion criteria. The annual hemorrhage incidence rate was 6.7%. Surgical intervention remained the most common single-modality treatment from 1949-2011. Between 1990 and 2011, multiple-modality treatment strategies (36% of cases) were employed more frequently. The most common presenting features were neurological deficit (74%) and hemorrhage (63%). In patients undergoing staged treatment of MAVM, hemorrhage of an untreated nidus (n=5), visualization of a new nidus (n=9), and disappearance of an untreated nidus (n=2) were observed. Limitations of this study include small sample size and reporting bias. The annual hemorrhage incidence rate for MAVM patients was approximately two- to three-fold greater than the reported annual hemorrhage rates for solitary AVM. Combining different treatment modalities has become the most common management strategy. The potential instability of remaining nidi with staged or incomplete treatment necessitates close follow-up in these cases.

Genetic markers and their influence on cerebrovascular malformations

Cerebrospinal vascular malformations are a group of anomalies affecting the arterial wall, the capillary arteriovenous interface, or the venous and lymphatic structures. Heritability and family studies allow identification of mutations in single genes associated with rare familial conditions causing cerebral or spinal vascular malformations, as is the case in hemorrhagic hereditary telangiectasia diseases. This article reviews the genetic and epigenetic influences increasingly reported in recent years as causal factors or triggers involved in the formation and growth of cerebromedullary vascular malformations.

How to manage patients with hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia is a rare systemic autosomal dominantly inherited disorder of the fibrovascular tissue with a wide variety of clinical manifestations. Diagnosis is based on the clinical Curaçao criteria or molecular genetic testing. Dilated vessels can develop into telangiectases or larger vascular malformations in various organs, calling for an interdisciplinary approach. Epistaxis and gastrointestinal bleeding can result from these vascular defects. Various conservative and interventional treatments have been described for these conditions. However, no optimal therapy exists. Treatment can become especially difficult due to progressive anaemia or when anticoagulant or anti-thrombotic therapy becomes necessary. Screening for pulmonary arteriovenous malformations (PAVM) should be performed in all confirmed and suspected patients. Treatment by percutaneous transcatheter embolotherapy and antibiotic prophylaxis is normally effective for PAVM. Cerebral or hepatic vascular malformations and rare manifestations need to be evaluated on a case-by-case basis to determine the best course of action for treatment.

Hemorrhage rates from brain arteriovenous malformation in patients with hereditary hemorrhagic telangiectasia

BACKGROUND AND PURPOSE

Hereditary hemorrhagic telangiectasia (HHT) is a systemic disease characterized by mucocutaneous telangiectasias, epistaxis, and arteriovenous malformations (AVMs). Intracranial hemorrhage (ICH) rates in this population are not well described. We report ICH rates and characteristics in HHT patients with brain AVMs (HHT-BAVMs).

METHODS

We studied the first 153 HHT-BAVM patients with follow-up data enrolled in the Brain Vascular Malformation Consortium HHT Project. We estimated ICH rates after BAVM diagnosis.

RESULTS

The majority of patients were women (58%) and white (98%). The mean age at BAVM diagnosis was 31±19 years (range, 0-70), with 61% of cases diagnosed on asymptomatic screening. Overall, 14% presented with ICH; among symptomatic cases, 37% presented ruptured. During 493 patient-years of follow-up, 5 ICH events occurred yielding a rate of 1.02% per year (95% confidence interval, 0.42-2.44%). ICH-free survival differed significantly by ICH presentation (P=0.003); ruptured cases had a higher ICH rate (10.07%; 95% confidence interval, 3.25-31.21%) than unruptured cases (0.43%; 95% confidence interval, 0.11-1.73%).

CONCLUSIONS

Patients with HHT-BAVM who present with hemorrhage are at a higher risk for rehemorrhage compared with patients with BAVM detected presymptomatically.

Neurovascular manifestations in hereditary hemorrhagic telangiectasia: imaging features and genotype-phenotype correlations

BACKGROUND AND PURPOSE

Hereditary hemorrhagic telangiectasia is an autosomal dominant disease that presents in 10%-20% of patients with various brain vascular malformations. We aimed to report the radiologic features (phenotype) and the genotype-phenotype correlations of brain vascular malformations in hereditary hemorrhagic telangiectasia.

MATERIALS AND METHODS

Demographic, clinical, genotypic, and imaging information of 75 patients with hereditary hemorrhagic telangiectasia with brain arteriovenous malformations enrolled in the Brain Vascular Malformation Consortium from 2010 to 2012 were reviewed.

RESULTS

Nonshunting, small, superficially located conglomerates of enhancing vessels without enlarged feeding arteries or draining veins called "capillary vascular malformations" were the most commonly observed lesion (46 of 75 patients; 61%), followed by shunting "nidus-type" brain AVMs that were typically located superficially with a low Spetzler-Martin Grade and a small size (32 of 75 patients; 43%). Direct high-flow fistulous arteriovenous shunts were present in 9 patients (12%). Other types of vascular malformations (dural AVF and developmental venous anomalies) were present in 1 patient each. Multiplicity of vascular malformations was seen in 33 cases (44%). No statistically significant correlation was observed between hereditary hemorrhagic telangiectasia gene mutation and lesion type or lesion multiplicity.

CONCLUSIONS

Depending on their imaging features, brain vascular malformations in hereditary hemorrhagic telangiectasia can be subdivided into brain AVF, nidus-type AVM, and capillary vascular malformations, with the latter being the most common phenotype in hereditary hemorrhagic telangiectasia. No genotype-phenotype correlation was observed among patients with this condition.

Rare manifestations in a case of Osler-Weber-Rendu disease

Osler-Weber-Rendu disease (OWRD) is a rare vascular dysplasia that presents most commonly with epistaxis. The most dreaded complication, however, is an intracranial haemorrhage. We present a patient with two rare manifestations of OWRD, subdural haematoma and portal venous hypertension, both seldom reported in the literature. The patient made a full recovery and continues to do well at this time.

Optimal management of hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), also known by the eponym Osler-Weber-Rendu syndrome, is a group of related disorders inherited in an autosomal dominant fashion and characterized by the development of arteriovenous malformations (AVM) in the skin, mucous membranes, and/or internal organs such as brain, lungs, and liver. Its prevalence is currently estimated at one in 5,000 to 8,000. Most cases are due to mutations in the endoglin (HHT1) or ACVRLK1 (HHT2) genes. Telangiectasias in nasal and gastrointestinal mucosa generally present with recurrent/chronic bleeding and iron deficiency anemia. Larger AVMs occur in lungs (~40%-60% of affected individuals), liver (~40%-70%), brain (~10%), and spine (~1%). Due to the devastating and potentially fatal complications of some of these lesions (for example, strokes and brain abscesses with pulmonary AVMs), presymptomatic screening and treatment are of utmost importance. However, due to the rarity of this condition, many providers lack an appreciation for the whole gamut of its manifestations and complications, age-dependent penetrance, and marked intrafamilial variation. As a result, HHT remains frequently underdiagnosed and many families do not receive the appropriate screening and treatments. This article provides an overview of the clinical features of HHT, discusses the clinical and genetic diagnostic strategies, and presents an up-to-date review of literature and detailed considerations regarding screening for visceral AVMs, preventive modalities, and treatment options.

Cerebral vascular malformations in hereditary hemorrhagic telangiectasia

Object

Hereditary hemorrhagic telangiectasia (HHT) is a hereditary disorder characterized by mucocutaneous telangiectasias, frequent nosebleeds, and visceral arteriovenous malformations (AVMs). Few reports have outlined the prevalence of the various cerebral vascular malformations found in patients with HHT. The authors set out to define the prevalence of cerebral vascular malformations in a population of HHT patients who underwent imaging with 3-T imaging (MRI/MR angiography [MRA]) of the brain.

Methods

A retrospective review of prospectively collected data was carried out using a database of 372 HHT patients who were seen and examined at the Georgia Regents University HHT Center and screened with 3-T MRI/MRA. Data were tabulated for numbers and types of vascular malformations in this population.

Results

Arteriovenous malformations were identified in 7.7%, developmental venous anomalies in 4.3%, and cerebral aneurysms in 2.4% of HHT patients. The HHT AVMs tended to be supratentorial, small, and cortical in this series, findings consistent with other recent studies in the literature. An arteriovenous fistula, cavernous malformation, and capillary telangiectasia were identified in 0.5%, 1%, and 1.9% of HHT patients, respectively.

Conclusions

Few studies have investigated the prevalence of the various vascular malformations found in HHT patients screened with 3-T MRI/MRA of the brain. Hereditary hemorrhagic telangiectasia AVMs are more likely to be multiple and have a tendency toward small size and cortical location. As such, they are often treated using a single-modality therapy.

Brain arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia: clinical presentation and anatomical distribution

BACKGROUND

Hereditary hemorrhagic telangiectasia is an autosomal dominant genetic disease with a wide array of vascular malformations involving multiple organs. Brain arteriovenous malformations can lead to intracranial hemorrhage and are often diagnosed only after patients become symptomatic. Early diagnosis and interventional treatment may prevent neurologic sequelae or death. Because of the rarity of defined cases, the spectrum of presentations in children with brain arteriovenous malformations and hereditary hemorrhagic telangiectasia has not been explored in detail. Here, we report our experience in children with hereditary hemorrhagic telangiectasia and brain arteriovenous malformations regarding both disease manifestations at presentation and the spectrum of brain arteriovenous malformation manifestations.

METHODS

A retrospective review of demographics, clinical manifestations, and brain magnetic resonance imaging/computed tomography scan findings in 115 patients with confirmed hereditary hemorrhagic telangiectasia (HHT) was conducted using the Hospital for Sick Children's HHT Clinic database for the years 1997-2012.

RESULTS

Eleven patients (four girls and seven boys) were diagnosed with hereditary hemorrhagic telangiectasia and brain arteriovenous malformations during this period. Five patients initially presented with epistaxis, four presented with intracranial hemorrhage, and two were asymptomatic with a positive family history of confirmed hereditary hemorrhagic telangiectasia. Although all children had an index case with hereditary hemorrhagic telangiectasia in the family, in three patients, hereditary hemorrhagic telangiectasia was not diagnosed before the child's presentation with intracranial hemorrhage. Multiple brain arteriovenous malformations were found in five patients, with one patient having bithalamic arteriovenous malformations.

CONCLUSIONS

This study highlights the importance of both family history and early clinical signs to prompt further diagnostic testing to avoid intracranial hemorrhage from brain arteriovenous malformations in children with hereditary hemorrhagic telangiectasia.

Role of transthoracic contrast echocardiography in the clinical diagnosis of hereditary hemorrhagic telangiectasia

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) can be diagnosed according to the four clinical Curaçao criteria, including the presence of pulmonary arteriovenous malformations (PAVMs). In the past few years, transthoracic contrast echocardiography (TTCE) replaced chest high-resolution CT (HRCT) imaging for the screening of PAVMs. The objective of this study was to determine whether the presence of any pulmonary shunt on TTCE can be accepted as a new clinical Curaçao criterion in diagnosing HHT.

METHODS

Between 2004 and 2012, we included 487 first-degree relatives of known HHT-causing mutation carriers who underwent both TTCE and chest HRCT imaging to screen for PAVMs. A quantitative three-point grading scale was used to differentiate among minimal, moderate, or extensive pulmonary shunt on TTCE (grade 1-3). Genetic testing was performed in all people and considered the gold standard for the diagnosis of HHT.

RESULTS

Chest HRCT imaging demonstrated PAVMs in 114 of 218 patients (52.3%) with a pulmonary shunt on TTCE. The addition of any pulmonary shunt on TTCE to the current clinical Curaçao criteria increased the number of positive criteria in 92 of 487 individuals (18.9%), which increased the sensitivity in diagnosing HHT from 88% to 94% at the expense of a decreased specificity from 74% to 70%. Accepting only pulmonary shunt grades ≥ 2 on TTCE as a diagnostic criterion for HHT enhanced the number of positive criteria in 30 (6.2%) individuals, which led to an increased sensitivity of 90% with no decrease in specificity (74%).

CONCLUSIONS

The addition of only pulmonary shunt grades ≥ 2 on TTCE to the current clinical Curaçao criteria increases its sensitivity without affecting specificity in the diagnosis of HHT.

Endothelial signaling and the molecular basis of arteriovenous malformation

Arteriovenous malformations occur when abnormalities of vascular patterning result in the flow of blood from arteries to veins without an intervening capillary bed. Recent work has revealed the importance of the Notch and TGF-β signaling pathways in vascular patterning. Specifically, Notch signaling has an increasingly apparent role in arterial specification and suppression of branching, whereas TGF-β is implicated in vascular smooth muscle development and remodeling under angiogenic stimuli. These physiologic roles, consequently, have implicated both pathways in the pathogenesis of arteriovenous malformation. In this review, we summarize the studies of endothelial signaling that contribute to arteriovenous malformation and the roles of genes implicated in their pathogenesis. We further discuss how endothelial signaling may contribute to vascular smooth muscle development and how knowledge of signaling pathways may provide us targets for medical therapy in these vascular lesions.

Ruptured large basilar artery aneurysm associated with an arteriovenous malformation in hereditary hemorrhagic telangiectasia

A 53-year-old woman presented with intracranial hemorrhage caused by a ruptured cerebral aneurysm. Digital subtraction angiography revealed a large aneurysm arising from the top of the basilar artery and a Spetzler-Martin grade 3 arteriovenous malformation. Endovascular embolization of the aneurysm was completed with a slight neck remnant. Medical examination confirmed that she suffered from hereditary hemorrhagic telangiectasia (HHT). HHT is a rare autosomal dominant disorder characterized by multiple mucocutaneous telangiectasia and associated vascular malformations. This case suggests that the prognosis for HHT patients with treatable aneurysms should be as good as that of healthy individuals. Consequently, neurosurgeons should suspect underlying HHT in all patients with cerebral vascular malformations.

Giant calcified thrombosed varices secondary to a pial arteriovenous fistula associated with hereditary hemorrhagic telangiectasia

A 28-year-old woman presented with an unusual case of giant thrombosed varix with calcified walls that had mass effects secondary to a pial single-channel arteriovenous fistula (AVF) associated with hereditary hemorrhagic telangiectasia (HHT). She consulted our hospital for chronic headache. She had been diagnosed with HHT based on genetic testing when her 3-year-old son presented with subarachnoid hemorrhage due to spinal AVF. Imaging studies revealed pial single-channel AVF with multiple varices. The varices in the right frontal lobe were over 6 cm in diameter and had laminar thromboses and calcified walls. Because of the mass effect, direct surgical flow disconnection was performed followed by removal of the varices using an internal decompression technique. Postoperatively, the patient was discharged with no neurological symptoms and no longer suffered chronic headache. Intracerebral varices are occasionally associated with high-flow AVF, and usually treated by interrupting the feeding arteries leaving the varices intact. This extremely rare case of intracerebral giant thrombosed varices with calcified wall and mass effect indicates that surgical removal of varices should be considered.

Left atrial appendage closure for stroke prevention in patients with atrial fibrillation and hereditary hemorrhagic telangiectasia

Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting millions of individuals worldwide, and a major risk factor for disabling cerebral embolic stroke. Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant inherited disorder, characterized by vascular abnormalities with high-bleeding tendency and therefore intolerance for oral anticoagulation. We report a case of percutaneous closure of the left atrial appendage, which might be a good alternative strategy instead of chronic oral anticoagulation to protect patients with high-risk AF and HHT from cerebral embolic strokes.

Spinal arteriovenous fistulas in children with hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant angiodysplasia with high penetrance and variable expression. The manifestations of HHT are often age related, and spinal arteriovenous fistula (AVF) may be the initial presentation of HHT in young children. Because spinal AVFs are rarely reported, however, screening is not incorporated into current clinical recommendations for the treatment of patients with HHT. The authors describe 2 cases of children younger than 2 years of age with acute neurological deterioration in the context of a spinal AVF and in whom HHT was subsequently diagnosed. One patient presented with intraventricular and subarachnoid hemorrhage and the other with acute thrombosis of an intramedullary varix. These cases highlight the potential for significant neurological morbidity from a symptomatic AVF in very young children with HHT. Given the lack of data regarding the true incidence and natural history of these lesions, these cases raise the question of whether spinal cord imaging should be incorporated into screening recommendations for patients with HHT.

Brain arteriovenous malformation multiplicity predicts the diagnosis of hereditary hemorrhagic telangiectasia: quantitative assessment

BACKGROUND AND PURPOSE

The purpose of this study was to quantitatively estimate the relationship between multiplicity of brain arteriovenous malformations (bAVMs) and the diagnosis of hereditary hemorrhagic telangiectasia (HHT).

METHODS

We combined databases from 2 large North American bAVM referral centers, including demographics, clinical presentation, and angiographic characteristics, and compared patients with HHT with non-HHT patients. Logistic regression analysis was performed to quantify the association between bAVM multiplicity and odds of HHT diagnosis. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated to determine accuracy of bAVM multiplicity for screening HHT.

RESULTS

Prevalence of HHT was 2.8% in the combined group. bAVM multiplicity was present in 39% of patients with HHT and was highly associated with diagnosis of HHT in univariate (OR, 83; 95% CI, 40-173; P<0.0001) and multivariable (OR, 86; 95% CI, 38-195; P<0.001) models adjusting for age at presentation (P=0.013), symptomatic presentation (P=0.029), and cohort site (P=0.021). bAVM multiplicity alone was associated with high specificity (99.2%; 95% CI, 98.7%-99.6%) and negative predictive value (98.3%; 95% CI, 97.6%-98.8%) and low sensitivity (39.3%; 95% CI, 26.5%-53.2%) and positive predictive value (59.5%; 95% CI, 42.1%-75.2%). Positive and negative likelihood ratio was 51 and 0.61, respectively, for diagnosis of HHT. HHT bAVMs were also more often smaller in size (<3 cm), noneloquent in location, and associated with superficial venous drainage compared with non-HHT bAVMs.

CONCLUSIONS

Multiplicity of bAVMs is highly predictive of the diagnosis of HHT. The presence of multiple bAVMs should alert the clinician to the high probability of HHT and lead to comprehensive investigation for this diagnosis.

Capillary telangiectasias: clinical, radiographic, and histopathological features

Object

Brain capillary telangiectasias (BCTs) are small, clinically benign, angiographically occult lesions that are usually incidental findings. Large capillary telangiectasias have not been reported previously as most BCTs are very small. Symptomatic BCTs are also rare, with few reports in the literature. The authors review the clinical manifestations, imaging, and histopathological characteristics of BCTs to further elucidate the diagnostic and clinical features of these vascular malformations.

Methods

The authors completed a retrospective radiological review of all cases of BCTs in the neuroradiology database at the University of Utah involving patients treated between January 1993 and December 2007. The MR imaging scans were reviewed, and the BCT was measured in 2 dimensions. They arbitrarily chose > 1 cm to define a large BCT as a majority of these lesions were smaller than that. The medical chart and the electronic database were used to gather each patient's clinical information.

Results

One hundred thirty patients were identified in the archived neuroradiology database of capillary telangiectasias. Cases involving 105 patients with definite capillary telangiectasias were reviewed, and from these, 7 patients were identified to have a large capillary telangiectasia measuring > 1 cm. Upon further review, 2 of these patients were identified as having symptoms likely related to their capillary telangiectasia. These 2 cases are reported in the article. No patients with smaller BCTs were found to have symptoms related to their lesion.

Conclusions

Brain capillary telangiectasias are small vascular malformations that rarely cause symptoms. They are often overlooked on imaging because of their clinically benign nature; however, they have been misdiagnosed as glial tumors in the past. Specific MR imaging sequences (T1-weighted postcontrast and gradient refocused echo) are valuable in aiding diagnosis, as histopathological diagnosis is often not possible. These cases highlight that BCTs can cause symptoms, a finding that may actually be related to the size of the lesion (28.6% of large BCTs in this series were symptomatic, whereas none of the small ones were).

Hereditary haemorrhagic telangiectasia: pathophysiology, diagnosis and treatment

Hereditary haemorrhagic telangiectasia, inherited as an autosomal dominant trait, affects approximately 1 in 5000 people. The abnormal vascular structures in HHT result from mutations in genes (most commonly endoglin or ACVRL1) whose protein products influence TGF-ß superfamily signalling in vascular endothelial cells. The cellular mechanisms underlying the generation of HHT telangiectasia and arteriovenous malformations are being unravelled, with recent data focussing on a defective response to angiogenic stimuli in particular settings. For affected individuals, there is often substantial morbidity due to sustained and repeated haemorrhages from telangiectasia in the nose and gut. Particular haematological clinical challenges include the management of severe iron deficiency anaemia; handling the intricate balance of antiplatelet or anticoagulants for HHT patients in whom there are often compelling clinical reasons to use such agents; and evaluation of apparently attractive experimental therapies promoted in high profile publications when guidelines and reviews are quickly superseded. There is also a need for sound screening programmes for silent arteriovenous malformations. These occur commonly in the pulmonary, cerebral, and hepatic circulations, may haemorrhage, but predominantly result in more complex pathophysiology due to consequences of defective endothelium, or shunts that bypass specific capillary beds. This review will focus on the new evidence and concepts in this complex and fascinating condition, placing these in context for both clinicians and scientists, with a particular emphasis on haematological settings.

Hereditary hemorrhagic telangiectasia: from molecular biology to patient care

SUMMARY

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by severe and recurrent nosebleeds, mucocutaneous telangiectases, and, in some cases, life-threatening visceral arteriovenous malformations of various types, including pulmonary, hepatic, cerebral, and spinal. Gastrointestinal telangiectases are frequent and may cause severe bleeding. HHT type 1 results from mutations in ENG on chromosome 9 (coding for endoglin), and HHT type 2 results from mutations in ACVRL1 on chromosome 12 (coding for activin receptor-like kinase 1). Mutations of either of these two genes account for most clinical cases. In addition, mutations in MADH4 (encoding SMAD4), which cause a juvenile polyposis/HHT overlap syndrome, have been described, and recently, an HHT3 locus on chromosome 5 (5q31.3-5q32) has been reported. The mutated genes in HHT encode proteins that modulate transforming growth factor-beta superfamily signaling in vascular endothelial cells. Management of patients has changed considerably in the last 20 years, in terms of both treatment and the prevention of complications. The goal of this review was to describe the underlying molecular and cellular physiopathology, explore clinical and genetic diagnostic strategies for HHT, and present clinical management recommendations in order to treat symptomatic disease and to screen for vascular malformations.

Comparison of 2 approaches for determining the natural history risk of brain arteriovenous malformation rupture

Estimating risk of intracranial hemorrhage (ICH) for patients with unruptured brain arteriovenous malformations (AVMs) in the natural course is essential for assessing risks and benefits of treatment. Traditionally, the survival period starts at the time of diagnosis and ends at ICH, but most patients are quickly censored because of treatment. Alternatively, a survival period from birth to first ICH, censoring at the date of diagnosis, has been proposed. The authors quantitatively compared these 2 timelines using survival analysis in 1,581 Northern California brain AVM patients (2000-2007). Time-shift analysis of the birth-to-diagnosis timeline and maximum pseudolikelihood identified the point at which the 2 survival curves overlapped; the 95% confidence interval was determined using bootstrapping. Annual ICH rates per 100 patient-years were similar for both the birth-to-diagnosis (1.27, 95% confidence interval (CI): 1.18, 1.36) and the diagnosis-to-ICH (1.17, 95% CI: 0.89, 1.53) timelines, despite differences in curve morphology. Shifting the birth-to-diagnosis timeline an optimal amount (10.3 years, 95% CI: 3.3, 17.4) resulted in similar ICH survival curves (P = 0.979). These results suggest that the unconventional birth-to-diagnosis approach can be used to analyze risk factors for natural history risk in unruptured brain AVM patients, providing greater statistical power. The data also suggest a biologic change around age 10 years influencing ICH rate.

Brain abscess and hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder that can lead to serious central nervous system complications including hemorrhage, ischemia, and infection. Symptoms can be mild, making diagnosis problematic. Fifty-three prior cases of HHT and brain abscess are described, in addition to two new cases. The clinical manifestations and current methods for diagnosis and management of patients with HHT are reviewed. Early recognition of HHT is important because screening in these patients and affected family members may help prevent complications. In addition, advancements in imaging, surgical techniques, antibiotics, and genetic testing may improve outcomes.

Estimates of maternal risks of pregnancy for women with hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu syndrome): suggested approach for obstetric services

OBJECTIVES

Hereditary haemorrhagic telangiectasia (HHT) affects 1 in 5-8000 individuals. Pregnancy outcomes are rarely reported. The major reason is that most women do not have their HHT diagnosed prior to pregnancy. Using a large well-characterised series, we studied all pregnancies known to have occurred in HHT-affected women, whether or not their diagnosis was known at the time of pregnancy. Our aim was to estimate rates and types of major complications of HHT in pregnancy, to guide management decisions.

DESIGN

Cohort study, with prospective, retrospective and familial components.

SETTING/POPULATION

Tertiary referral centre population.

METHODS

All 262 pregnancies in the 111 women with HHT and pulmonary arteriovenous malformations (PAVMs) reviewed between 1999 and 2005 were studied. Eighty-two women (74%) did not have a diagnosis of HHT/PAVM at the time of pregnancy. 222 pregnancies in their 86 HHT-affected relatives were also studied.

MAIN OUTCOME MEASURES

PAVM bleed, stroke and maternal death.

RESULTS

Thirteen women experienced life-threatening events during pregnancy: 1.0% (95% CI 0.1-1.9) of pregnancies resulted in a major PAVM bleed; 1.2% (0.3-2.2%) in stroke (not all were HHT related); and 1.0% (0.13-1.9%) in maternal death. All deaths occurred in women previously considered well. In women experiencing a life-threatening event, prior awareness of HHT or PAVM diagnosis was associated with improved survival (P = 0.041, Fisher's exact test).

CONCLUSIONS

Most HHT pregnancies proceed normally. Rare major complications, and improved survival outcome following prior recognition, means that pregnancy in a woman with HHT should be considered high risk. Recommendations for pregnancy management are provided.

Treatment of multiple arteriovenous malformations in pediatric patients with hereditary hemorrhagic telangiectasia and spontaneous hemorrhage. Report of two cases

Due to inheritance of an autosomal dominant genetic mutation, patients with hereditary hemorrhagic telangiectasia (HTT) have an increased risk of harboring a cerebral arteriovenous malformation (AVM). They are also significantly more likely to have multiple AVMs. The natural history of AVMs in patients with HHT as well as their rate of hemorrhage is not clearly defined. Furthermore, spontaneous regression of such lesions has been reported. Treatment of cerebral AVMs in patients with HHT presents a particular challenge, especially with detection of incidental lesions following screening of asymptomatic patients. The management of HHT in two pediatric patients in whom hemorrhaging from a cerebral AVM occurred but who also had other lesions is presented here. Both patients were treated with stereotactic radiosurgery.

Experiences in the management of brainstem hematomas

The purpose of this study was to present our experience in the management of spontaneous brainstem hematomas (BSH). Records of 58 consecutive patients were reviewed, including demographic data, symptoms, Glasgow Coma Scale, treatment, intraoperative findings (in surgical cases), and outcome according to the Glasgow Outcome Scale. Fifteen patients were comatose (GCS 4 or less): 11/15 patients were treated conservatively. Four patients with accompanying acute occlusive hydrocephalus were treated by placement of an external ventricular drainage. None survived. In nine patients (60%), arteriosclerosis and/or long-standing arterial hypertension were known and arteriopathic BSH was suspected. Forty-three patients were not comatose: 37 patients showed no impairment of consciousness (GCS 15), 6 patients presented with mild disturbance of conscious state (GCS 13), progressing to coma (GCS 8) in 1. In the majority (36/43) of the non-comatose patients (83.7%) cavernoma could be revealed and removed surgically. In six patients (14%), an atypically located arteriopathic BSH was assumed and treated medically. One patient had an underlying brainstem arteriovenous malformation and was treated radiosurgically. Many arteriopathic BSH cause immediate coma indicating direct and irreversible damage of midpontine structures. Thus, we suggest not to proceed to surgery, even if the bleeding is accompanied by acute hydrocephalus. The majority of BSH not resulting in immediate coma are caused by underlying cavernomas. In these cases surgery should be considered.

Unusual giant cerebral venous varix associated with brain abscess: variant of hereditary hemorrhagic telangiectasia--case report

A 35-year-old man suffered secondary generalized tonic-clonic convulsions due to a large brain abscess. Neuroimaging incidentally revealed another tumor-like lesion. Cerebral angiography confirmed that the lesion was an unusual giant venous varix associated with a high-flow pial arteriovenous fistula (AVF) and showed one more small arteriovenous malformation (AVM). Pulmonary AVF, which can cause brain abscess, was also detected. Surgical ligation of the AVF and removal of the small AVM via individual craniotomies resulted in successful extirpation of the cerebrovascular malformations. Although the typical mucocutaneous symptoms were absent in this patient, the combination of arteriovenous anomalies was highly suggestive of hereditary hemorrhagic telangiectasia.

[Pulmonary arteriovenous malformations - association with hereditary hemorrhagic telangiectasia. Clinical cases and family screening]

Pulmonary arteriovenous malformations are a rare disorder associated to hereditary hemorrhagic telangiectasia in over 50 % of the cases. Clinical presentation, diagnostic work-up, therapeutic options and prognosis are reviewed by the authors. Pulmonary arteriovenous malformations are known to have considerable morbidity and mortality, their treatment being advisable as well as their screening among family members, especially if the index case is diagnosed with both pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia. To this moment prospective studies establishing the best diagnostic work-up for the patients and their families are lacking. The authors report two pulmonary arteriovenous malformations cases in a family with hereditary hemorrhagic telangiectasia. Patient's diagnosis led to family screening which resulted in the identification of pulmonary arteriovenous malformations in two family members and pulmonary disease exclusion in four patients previously known to have hereditary hemorrhagic telangiectasia.

Hereditary Hemorrhagic Telangiectasia (HHT) in Dentistry: A Literature Review

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal-dominantly-inherited vascular dysplasia characterized by age-dependant incomplete penetrance and variable expressivity, with clinical manifestations consisting in epistaxis, mucocutaneous telangiectases, gastrointestinal bleeding and arteriovenous malformations (AVMs), which affects approximately ½ million people world-wide. It affects males and females of all racial and ethnic groups. Up to 1/3 of HHT patients have multiple organ involvement, which can be disabling and/or life threatening. HHT can be treated successfully if correctly diagnosed. Morbidity of HHT is often due to complications of AVMs, such as stroke or haemorrhage, also known to occur in children. Many authors have reported successful new therapeutical options for AVMs, which have resulted in a significant decrease of life-threatening complications and HHT morbidity. Since early diagnosis permits an appropriate care of affected subjects, a very sensitive mutation screening technique is required to identify the mutation carriers among all at-risk individuals belonging to HHT-families. There may be one or more genes that cause HHT but, if so, they are quite rare. Currently, scientists are trying to better understand exactly how the abnormal gene can interfere with normal blood vessel formation and promote the phenotype of HHT, so that better treatments for the symptoms of HHT can be developed.

Association of a polymorphism of the ACVRL1 gene with sporadic arteriovenous malformations of the central nervous system

OBJECT

Important central nervous system (CNS) manifestations in patients with hereditary hemorrhagic telangiectasia (HHT) include arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). Hereditary hemorrhagic telangiectasia is caused by germline mutations of two genes: ENG (HHT Type 1) and ACVRL1 (HHT Type 2). The ENG gene variations have been associated with the formation of intracranial aneurysms. The authors studied whether sequence variations in ACVRL1 or ENG are associated with the development of clinically sporadic arteriovenous dysplasias and aneurysms of the CNS.

METHODS

The coding sequence (in 44 patients with AVMs and 27 with aneurysms) and the 5' end and the polyA site (in 53 patients with AVMs) of the ACVRL1 gene were analyzed for sequence variations using direct sequencing and single-strand conformational polymorphism analysis. One ENG and three ACVRL1 gene polymorphisms were genotyped using restriction enzyme-based analysis in 101 patients with sporadic AVMs and DAVFs of the CNS, 79 patients treated for intracranial aneurysms, and 202 control volunteers. The authors identified a statistically significant association between the IVS3 -35A/T polymorphism in intron 3 of the ACVRL1 gene and the development of AVMs and DAVFs (p = 0.004; odds ratio [OR] 1.73; 95% confidence interval [CI] 1.19-2.51; after adjustments for age and sex), but not aneurysms (crude OR 0.82; 95% CI 0.55-1.18).

CONCLUSIONS

The results of this study link ACVRL1 (HHT Type 2 gene) to the formation of the clinically sporadic variants of vascular malformations of the CNS most commonly seen in patients with HHT, that is, AVMs and DAVFs.

A pulmonary right-to-left shunt in patients with hereditary hemorrhagic telangiectasia is associated with an increased prevalence of migraine

INTRODUCTION

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal-dominant vascular dysplasia with a high prevalence of pulmonary arteriovenous malformation (PAVM). Recent studies report an increased prevalence of migraine in patients with a cardiac right-to-left shunt. The aim of our study was to evaluate whether there is also an increased prevalence of migraine in patients with a pulmonary right-to-left shunt (PAVM).

METHODS

All patients with HHT referred to our hospital till April 2004 with or without PAVM and with or without migraine were included in the study.

RESULTS

In total, 538 HHT patients (41.6% men; mean age +/- SD, 39.3 +/- 18.6 years) could be included. PAVM was present in 208 patients (38.7%; mean age, 39.3 +/- 17.6 years). Significantly more women were present in the PAVM subgroup compared to the non-PAVM subgroup, 65.4% vs 53.9% (p = 0.009). Migraine occurred in 88 patients with HHT, a prevalence of 16.4%. The prevalence of migraine in women with HHT was significantly higher compared to men, 19.4% vs 12.1%, respectively (p = 0.03) The prevalence of migraine in patients with PAVM was 21.2%, which was significantly higher then in patients without PAVM, 13.3% (p = 0.02). The occurrence of PAVM in the patients with migraine is significantly higher than in those without migraine, 50.0% vs 36.4%, respectively (p = 0.02).

CONCLUSION

This study showed a higher prevalence of PAVM in patients with migraine and HHT. The right-to-left shunt due to the PAVM might play a causal role in the pathogenesis of migraine in patients with HHT. This needs to be determined in further studies.

Clinical symptoms according to genotype amongst patients with hereditary haemorrhagic telangiectasia

BACKGROUND

Hereditary haemorrhagic telangiectasia (HHT) is a dominantly inherited disease, characterized by a wide variety of clinical manifestations, including epistaxis, gastrointestinal (GI) bleeding, pulmonary arteriovenous malformations (PAVMs) and neurological symptoms. HHT is a genetically heterogeneous disorder involving at least two loci; HHT 1 mapping to chromosome 9 q 34.1 (ENG) and HHT 2 mapping to chromosome 12 q 31 (ALK-1).

OBJECTIVE

To evaluate and describe the diversity of clinical manifestations in a Danish population of HHT patients with known HHT 1 or HHT 2 subtype.

DESIGN

Prospective clinical examination with genetic evaluation and follow-up.

SETTING

Investigation centre was Odense University Hospital. All HHT patients in the County of Fyn were included.

METHODS

HHT family members were invited to a clinical examination including registration of HHT manifestations, screening for PAVM and neurological evaluation. Blood tests were performed for analysis of disease-causing mutation, and clinical manifestations in the HHT subtypes were compared. The survival of the patients was studied in the follow-up period.

RESULTS

Included in the study were 73 HHT patients representing 18 families. In 14 of the families we identified a disease-causing mutation. Thirty-nine patients (from 10 families) had HHT1 and 16 HHT patients from four families had HHT2.

CONCLUSION

Amongst patients with HHT1 genotype the prevalence of PAVM was higher than amongst HHT patients with HHT2 genotype. HHT1 patients had experienced more severe GI bleeding than HHT2 patients. There was no significant difference in severity of epistaxis or age at debut. Finally the mortality over a 90-month observation period was not significantly increased.

Hereditary hemorrhagic telangiectasia in children: endovascular treatment of neurovascular malformations: results in 31 patients

Hereditary hemorrhagic telangiectasia (HHT) is a heterogeneous disease that can present with a variety of clinical manifestations. The neurovascular complications of this disease, especially in children, may be potentially devastating. The purpose of this article was to review the therapeutic results of endovascular treatment of neurovascular malformations in children. A total of 31 patients under the age of 16 were included in this retrospective analysis. All children were treated in a single center. Twenty children presented with 28 arteriovenous (AV) fistulae, including seven children with spinal AV fistulae and 14 children with cerebral AV fistulae (one child had both a spinal and cerebral fistulae). Eleven children had small nidus-type AV malformations. All embolizations were performed employing superselective glue injection. Follow-up ranged between 3 and 168 months (mean 66 months). A total of 115 feeding vessels were embolized in 81 single sessions, resulting in a mean overall occlusion rate of the malformation of 77.4% (ranging from 30 to 100%). Two of 31 patients (6.5%) died as a direct complication of the embolization procedure; two patients (6.5%) had a persistent new neurological deficit; eight patients (26.7%) were clinically unchanged following the procedure; in 13 patients (41.9%) an amelioration of symptoms but no cure could be achieved; and six patients (19.4%) were completely asymptomatic following the endovascular procedure. In the surviving patients morphological complete occlusion was possible in twelve patients (38.7%); therapy is still not completed in six patients. Since the natural history of neurovascular manifestations of HHT in children is associated with high morbidity and mortality, therapeutic intervention is mandatory. In most instances a morphological target can be identified; therefore, even partial and staged treatment can be performed. Our results demonstrate that in 27/31 patients these targeted interventions resulted in stabilizing the disease, ameliorating the symptoms or even complete resolution. The endovascular approach employing glue as the embolizing agent represents a safe and efficient way to control the neurovascular phenotypes of HHT.

Genotype-phenotype relationship in hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterised by vascular malformations in multiple organ systems, resulting in mucocutaneous telangiectases and arteriovenous malformations predominantly in the lungs (pulmonary arteriovenous malformation; PAVM), brain (cerebral arteriovenous malformation; CAVM), and liver (hepatic arteriovenous malformation; HAVM). Mutations in the ENG and ALK-1 genes lead to HHT1 and HHT2 respectively. In this study, a genotype-phenotype analysis was performed. A uniform and well classified large group of HHT patients and their family members were screened for HHT manifestations. Groups of patients with a clinically confirmed diagnosis and/or genetically established diagnosis (HHT1 or HHT2) were compared. The frequency of PAVM, CAVM, HAVM, and gastrointestinal telangiectases were determined to establish the genotype-phenotype relationship. The analysis revealed differences between HHT1 and HHT2 and within HHT1 and HHT2 between men and women. PAVMs and CAVMs occur more often in HHT1, whereas HAVMs are more frequent in HHT2. Furthermore, there is a higher prevalence of PAVM in women compared with men in HHT1. In HHT1 and HHT2, there is a higher frequency of HAVM in women. HHT1 has a distinct, more severe phenotype than HHT2. There is a difference in the presence of symptoms between men and women. With these data, genetic counselling can be given more accurately when the family mutation is known.

Manifestations of hereditary hemorrhagic telangiectasia in children and adolescents

The medical literature provides little information on manifestations of hereditary hemorrhagic telangiectasia (HHT) in children. The presented investigation was initiated to analyze early presenting symptoms in HHT, which should help to make the diagnosis at a young age and thus prevent potential complications from occult visceral arteriovenous malformations (AVM), which have commonly been described in HHT. A series of 15 children and adolescents with a suspicious diagnosis of HHT were examined clinically for typical signs and symptoms of the disorder. If the diagnosis of HHT seemed to be likely, recommendations for non-invasive screening procedures were given. Screening was directed at the detection of occult visceral AVMs. Main outcome measures were the definition of principal signs of HHT in children and adolescents. Family history was positive for HHT in 13 persons. The principal sign of recurrent epistaxis was present in 10/15 individuals and the earliest age of onset with regard to epistaxis was 4 years. Cutaneous vascular lesions were present in 5/15 patients. Screening for AVMs was performed in six individuals and revealed vascular lesions of the brain in two patients and vascular lesions of the lung in two patients. Gastrointestinal hemorrhages were present in one infant. Based on these findings, diagnosis of HHT seemed likely in ten individuals and unlikely in five individuals. Signs and symptoms of HHT in children and adolescents may be discrete, but are detectable at an earlier age than previously thought. Clinical examinations in children from HHT families may help identify candidates who will benefit from molecular genetic testing or screening imaging studies.