Cerebrovascular Malformations in a Pediatric Hereditary Hemorrhagic Telangiectasia Cohort

De Novo Brain Vascular Malformations in Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Approximately 10% of people with hereditary hemorrhagic telangiectasia (HHT) have brain vascular malformations (VMs). Few reports describe de novo brain VM formation. International HHT Guidelines recommend initial brain VM screening upon HHT diagnosis in children but do not address rescreening. We aimed to confirm whether brain VMs can form de novo in patients with HHT.

METHODS

The Brain Vascular Malformation Consortium HHT project is a 17-center longitudinal study enrolling patients since 2010. We analyzed the database for de novo VMs defined as those detected (1) on follow-up neuroimaging in a patient without previous brain VMs or (2) in a location distinct from previously identified brain VMs and reported those in whom a de novo VM could be confirmed on central neuroimaging review.

RESULTS

Of 1909 patients enrolled, 409 (21%) had brain VMs. Seven patients were recorded as having de novo brain VMs, and imaging was available for central review in four. We confirmed that three (0.7% of individuals with brain VMs) had de novo brain VMs (two capillary malformations, one brain arteriovenous malformation) with intervals of six, nine, and 13 years from initial imaging. Two with de novo brain VMs were <18 years. The fourth patient, a child, did not have a de novo brain VM but had a radiologically confirmed increase in size of an existing brain arteriovenous malformation.

CONCLUSIONS

Brain VMs can, albeit rarely, form de novo in patients with HHT. Given the potential risk of hemorrhage from brain VMs, regular rescreening in patients with HHT may be warranted.

Current Practice: Rationale for Screening Children with Hereditary Hemorrhagic Telangiectasia for Brain Vascular Malformations

BACKGROUND

Hereditary hemorrhagic telangiectasia is an autosomal dominant vascular dysplasia characterized by mucocutaneous telangiectasias, recurrent epistaxis, and organ vascular malformations including in the brain, which occur in about 10% of patients. These brain vascular malformations include high-flow AVMs and AVFs as well as low-flow capillary malformations. High-flow lesions can rupture, causing neurologic morbidity and mortality.

STATE OF PRACTICE

International guidelines for the diagnosis and management of hereditary hemorrhagic telangiectasia recommend screening children for brain vascular malformations with contrast enhanced MR imaging at hereditary hemorrhagic telangiectasia diagnosis. Screening has not been uniformly adopted by some practitioners who contend that screening is not justified. Arguments against screening include application of short-term data from the adult A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) trial of unruptured sporadic brain AVMs to children with hereditary hemorrhagic telangiectasia as well as concerns about administration of sedation or IV contrast and causing patients or families increased anxiety.

ANALYSIS

In this article, a multidisciplinary group of experts on hereditary hemorrhagic telangiectasia reviewed data that support screening guidelines and counter arguments against screening. Children with hereditary hemorrhagic telangiectasia have a preponderance of high-flow lesions including AVFs, which have the highest rupture risk. The rupture risk among children is estimated at about 0.7% per lesion per year and is additive across lesions and during a lifetime. ARUBA, an adult clinical trial of expectant medical management versus treatment of unruptured brain AVMs, favored medical management at 5 years but is not applicable to pediatric patients with hereditary hemorrhagic telangiectasia given the life expectancy of a child. Additionally, interventional, radiosurgical, and surgical techniques have improved with time. Experienced neurovascular experts can prospectively determine the best treatment for each child on the basis of local resources. The "watch and wait" approach to imaging means that children with brain vascular malformations will not be identified until a potentially life-threatening and deficit-producing intracerebral hemorrhage occurs. This expert group does not deem this to be an acceptable trade-off.

Prevalence and Predictors of Hereditary Hemorrhagic Telangiectasia and Capillary-Malformation Arteriovenous Malformation Syndrome Among Children with Neurovascular Malformations

OBJECTIVE

To investigate the prevalence and predictors of hereditary hemorrhagic telangiectasia (HHT) and capillary-malformation arteriovenous malformation (CM-AVM) syndrome among children with no prior personal or family history of these diseases who presented with an arteriovenous shunt lesion.

STUDY DESIGN

A retrospective chart review was completed on patients aged 0 through 21 years with arteriovenous shunt lesions evaluated at our Cerebrovascular Center. Diagnosis of definite or suspected HHT or CM-AVM was based on clinical features and genetic testing. Associations between final diagnosis and type and number of lesions, epistaxis, telangiectasias, CM, and pulmonary AVMs were assessed.

RESULTS

Eighty-nine patients were included. Thirteen (14.6%) had definite HHT, 11 (12.4%) suspected HHT, and 4 (4.5%) definite CM-AVM. Having ≥2 episodes of epistaxis/year and ≥ 2 sites with telangiectasias were each associated with definite HHT (P < .001). Having ≥ 2 CM was associated with definite CM-AVM (P < .001). Pulmonary AVM was associated with increased odds of having definite HHT (OR = 6.3, 95% CI: 1.2-33.4). Multiple lesions (OR = 24.5, 95% CI: 4.5-134.8) and arteriovenous fistulas (OR = 6.2, 95% CI: 1.9-20.3) each increased the likelihood of having definite HHT or CM-AVM. Genetic testing was positive in 31% of patients tested.

CONCLUSIONS

We recommend that children with neurovascular shunt lesions be offered genetic testing and undergo further evaluation for HHT and CM-AVM. Awareness and early diagnosis of these conditions is a critical step toward improving long-term outcomes and preventing disease-associated complications.

[Hereditary hemorrhagic telangiectasia]

Hereditary hemorrhagic telangiectasia, also known as Rendu-Osler - Weber disease, is a rare, autosomal dominant vascular disease, with prevalence of 1/5,000. The condition is characterized by muco-cutaneous telangiectasias, which are responsible for a hemorrhagic syndrome of variable severity, as well as arteriovenous malformations (AVMs) appearing in the lungs, the liver, and the nervous system. They can be the source of shunts, which may be associated with high morbidity (neurological ischemic stroke, brain abscess, high-output heart failure, biliary ischemia…). It is therefore crucial to establish a clinical diagnosis using the Curaçao criteria or molecular diagnosis based on genetic analysis of the ENG, ACVRL1, SMAD4 and GDF2 genes. In most cases, multidisciplinary management allows patients to have normal life expectancy. Advances in interventional radiology and better understanding of the pathophysiology of angiogenesis have resulted in improved therapeutic management. Anti-angiogenic treatments, such as bevacizumab (BVZ, an anti-VEGF antibody), have proven to be effective in cases involving bleeding complications and severe liver damage with cardiac repercussions. Other anti-angiogenic agents are currently being investigated, including tyrosine kinase inhibitors.

Neurovascular Manifestations in Pediatric Patients With Hereditary Haemorrhagic Telangiectasia

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a multiorgan vascular dysplasia with limited data regarding its neurovascular manifestations and genotype-phenotype correlation in children. The objective of this study was to describe the neurovascular findings in a large cohort of children with HHT and correlate between phenotype and genotype.

METHODS

This retrospective study was conducted on 221 children (<18 years) with a definite or possible diagnosis of HHT based on Curacao criteria, or with positive genetics for the mutated genes of ENG, ACVRL-1, and SMAD-4, who also underwent brain MRI and/or conventional angiography. Demographic and clinical information, imaging findings, and follow up information were gathered.

RESULTS

Two hundred twenty-one children with HHT (70.6% genetically confirmed, and 99.5% positive family history) were included, with a median age of 7 years (interquartile range: 3 to 11 years) and 58.8% male predominance. Neurovascular lesions were found in 64 of 221 (28.9%), with 3.1% prevalence of intracranial hemorrhage. The most commonly observed vascular malformations were developmental venous anomalies (48.5%) and brain arteriovenous malformations (AVMs) (31.2%), followed by capillary malformations (14.1%). Multiple AVMs were seen in 10.0% of the cohort. We found no instances of de novo AVM (1281.8 patient-years).A significantly higher proportion of patients with ENG mutations (19.7%) had brain AVM than those with ACVRL-1 (4.9%) and SMAD-4 (0%) mutations (P < 0.01). There was no significant difference in the hemorrhagic risk of shunting lesions associated with ENG (35.3%) or ACVRL-1 (33.3%) positivity (P = 0.9).

CONCLUSIONS

We describe the neurovascular imaging and genetic findings from a large pediatric cohort of HHT, to enhance clinical awareness and guide management of patients with HHT.

Pediatric Spinal Cord Diseases

Spinal cord diseases in pediatric patients are highly variable in terms of presentation, pathology, and prognosis. Not only do they differ with respect to each other but so too with their adult equivalents. Some of the most common diseases are autoimmune (ie, multiple sclerosis, acute disseminated encephalomyelitis, and acute transverse myelitis), congenital (ie, dysraphism with spina bifida, split cord malformation, and tethered cord syndrome), tumor (ie, juvenile pilocytic astrocytoma, ependymoma, and hem-angioblastoma), and vascular (ie, cavernous malformations, arteriovenous malformations, and dural arteriovenous fistulas) in nature. These each require their own niche treatment paradigm and prognosis. Furthermore, presentation of different spinal cord diseases in children can be difficult to discern without epidemiologic and imaging data. Interpretation of these data is crucial to facilitating a timely and accurate diagnosis. Correspondingly, the aim of this review was to highlight the most pertinent features of the most common spinal cord diseases in the pediatric population.

Systemic and CNS manifestations of inherited cerebrovascular malformations

Cerebrovascular malformations occur in both sporadic and inherited patterns. This paper reviews imaging and clinical features of cerebrovascular malformations with a genetic basis. Genetic diseases such as familial cerebral cavernous malformations and hereditary hemorrhagic telangiectasia often have manifestations in bone, skin, eyes, and visceral organs, which should be recognized. Genetic and molecular mechanisms underlying the inherited disorders are becoming better understood, and treatments are likely to follow. An interaction between the intestinal microbiome and formation of cerebral cavernous malformations has emerged, with possible treatment implications. Two-hit mechanisms are involved in these disorders, and additional triggering mechanisms are part of the development of malformations. Hereditary hemorrhagic telangiectasia encompasses a variety of vascular malformations, with widely varying risks, and a more recently recognized association with cortical malformations. Somatic mutations are implicated in the genesis of some sporadic malformations, which means that discoveries related to inherited disorders may aid treatment of sporadic cases. This paper summarizes the current state of knowledge of these conditions, salient features regarding mechanisms of development, and treatment prospects.