Neurological manifestations of hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease): report of 2 cases and review of the literature

Untangling sporadic brain arteriovenous malformations: towards targeting the KRAS/MAPK pathway

Brain arteriovenous malformations (AVMs) are vascular lesions characterized by abnormal connections between parenchymal arteries and veins, bypassing a capillary bed, and forming a nidus. Brain AVMs are consequential as they are prone to rupture and associated with significant morbidity. They can broadly be subdivided into hereditary vs. sporadic lesions with sporadic brain AVMs representing the majority of all brain AVMs. However, little had been known about the pathogenesis of sporadic brain AVMs until the landmark discovery in 2018 that the majority of sporadic brain AVMs carry somatic activating mutations of the oncogene, Kirsten rat sarcoma viral oncogene homologue (KRAS), in their endothelial cells. Here, we review the history of brain AVMs, their treatments, and recent advances in uncovering the pathogenesis of sporadic brain AVMs. We specifically focus on the latest studies suggesting that pharmacologically targeting the KRAS/MEK pathway may be a potentially efficacious treatment for sporadic brain AVMs.

Pathogenic Variant Frequencies in Hereditary Haemorrhagic Telangiectasia Support Clinical Evidence of Protection from Myocardial Infarction

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait, due to a single heterozygous loss-of-function variant, usually in ACVRL1 (encoding activin receptor-like kinase 1 [ALK1]), ENG (encoding endoglin [CD105]), or SMAD4. In a consecutive single-centre series of 37 positive clinical genetic tests performed in 2021-2023, a skewed distribution pattern was noted, with 30 of 32 variants reported only once, but ACVRL1 c.1231C>T (p.Arg411Trp) identified as the disease-causal gene in five different HHT families. In the same centre's non-overlapping 1992-2020 series where 110/134 (82.1%) HHT-causal variants were reported only once, ACVRL1 c.1231C>T (p.Arg411Trp) was identified in nine further families. In a 14-country, four-continent HHT Mutation Database where 181/250 (72.4%) HHT-causal variants were reported only once, ACVRL1 c.1231C>T (p.Arg411Trp) was reported by 12 different laboratories, the adjacent ACVRL1 c.1232G>A (p.Arg411Gln) by 14, and ACVRL1 c.1120C>T (p.Arg374Trp) by 18. Unlike the majority of HHT-causal ACVRL1 variants, these encode ALK1 protein that reaches the endothelial cell surface but fails to signal. Six variants of this type were present in the three series and were reported 6.8-25.5 (mean 8.9) times more frequently than the other ACVRL1 missense variants (all p-values < 0.0039). Noting lower rates of myocardial infarction reported in HHT, we explore potential mechanisms, including a selective paradigm relevant to ALK1's role in the initiating event of atherosclerosis, where a plausible dominant negative effect of these specific variants can be proposed. In conclusion, there is an ~9-fold excess of kinase-inactive, cell surface-expressed ACVRL1/ALK1 pathogenic missense variants in HHT. The findings support further examination of differential clinical and cellular phenotypes by HHT causal gene molecular subtypes.

Prevalence of Intracranial Aneurysms in Hereditary Hemorrhagic Telangiectasia: Report from a Single Reference Center

BACKGROUND AND PURPOSE

Neurologic manifestations in hereditary hemorrhagic telangiectasia include an increased incidence of brain abscesses and ischemic strokes due to paradoxic embolization in addition to a wide spectrum of symptoms and complications due to typical brain vascular malformations. Intracranial aneurysms are not part of this brain vascular malformation spectrum. The aim of this study was to determine their prevalence in patients with hereditary hemorrhagic telangiectasia.

MATERIALS AND METHODS

This was a single-center, retrospective study. Adult patients from the institutional Hereditary Hemorrhagic Telangiectasia registry with a definitive diagnosis of hereditary hemorrhagic telangiectasia and an available report or angiographic imaging study were included and reviewed to determine the intracranial aneurysm prevalence. In addition, the morphologic characteristics of intracranial aneurysms and possible associated risk factors were collected.

RESULTS

Two hundred twenty-eight patients were analyzed. Thirty-seven aneurysms in 33 patients (14.5%; 95% CI, 9.9%-19%) were found. The median diameter of intracranial aneurysms was 3.2 mm (interquartile range, 2.6-4.4 mm). No association between intracranial aneurysm and sex, age, or genetic background was noted. There were no subarachnoid hemorrhagic events due to intracranial aneurysm rupture.

CONCLUSIONS

Due to the high prevalence of intracranial aneurysms in adult patients with hereditary hemorrhagic telangiectasia, further studies regarding bleeding risks and monitoring should be addressed.

Shedding the Light on the Natural History of Intracranial Aneurysms: An Updated Overview

The exact molecular pathways underlying the multifactorial natural history of intracranial aneurysms (IAs) are still largely unknown, to the point that their understanding represents an imperative challenge in neurovascular research. Wall shear stress (WSS) promotes the genesis of IAs through an endothelial dysfunction causing an inflammatory cascade, vessel remodeling, phenotypic switching of the smooth muscle cells, and myointimal hyperplasia. Aneurysm growth is supported by endothelial oxidative stress and inflammatory mediators, whereas low and high WSS determine the rupture in sidewall and endwall IAs, respectively. Angioarchitecture, age older than 60 years, female gender, hypertension, cigarette smoking, alcohol abuse, and hypercholesterolemia also contribute to growth and rupture. The improvements of aneurysm wall imaging techniques and the implementation of target therapies targeted against inflammatory cascade may contribute to significantly modify the natural history of IAs. This narrative review strives to summarize the recent advances in the comprehension of the mechanisms underlying the genesis, growth, and rupture of IAs.

CT-Negative Subarachnoid Hemorrhage Caused by Telangiectasia: A Case Report

INTRODUCTION

At present, the mechanism of telangiectasia is unknown, but some evidence suggests that it may be related to genetic abnormalities. Telangiectasia may lead to bleeding of multiple sites. CT-negative subarachnoid hemorrhage is rare, which is mostly related to hemorrhage with a little amount of bleeding. CT-negative subarachnoid hemorrhage due to telangiectasia has not been reported.

CASE REPORT

In this case report, the patient experienced severe headache with nausea, vomiting, and blurred vision for 12 days, and had a history of hypertension. Physical examination revealed a clear state of mind, normal speech, normal limb muscle strength, 2 transverse fingers of neck stiffness, and negative bilateral Babinski signs. Brain CT, MRI, MRA, and MRV showed no obvious abnormalities. SWI suggested the possibility of capillary dilation. The cerebrospinal fluid was pale yellow in appearance after lumbar puncture.

DIAGNOSIS

The patient was diagnosed with subarachnoid hemorrhage(SAH) and capillary dilatation.

INTERVENTIONS

Therapeutic management of blood pressure and brain edema was started.

CONCLUSION

Lumbar puncture should be performed when subarachnoid hemorrhage is clinically suspected and CT is negative. While searching for the cause of subarachnoid hemorrhage, the presence of telangiectasia should be ascertained.

Thalamic abscess in a patient with hereditary hemorrhagic telangiectasia successfully treated with an empiric antibiotic regime: case report and review of the literature

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disease associated with neurological complications, including cerebral abscesses (CA). They tend to be unique, supratentorial and lobar. While the surgical intervention is a rule of thumb when treating and diagnosing the etiology of these lesions, this is not always possible due to dangerous or inaccessible locations. We report the case of a patient solely treated with empiric antibiotics without stereotaxic intervention and satisfactory results.

CASE PRESENTATION

We present the case of a 21-year-old patient with a right thalamic abscess due to HHT and pulmonary arteriovenous malformations, previously embolized, treated solely with antibiotics. At first, we contemplated the possibility of a stereotaxic biopsy, but the high-risk location and the fact that our patient received a previous full course of antibiotic treatment (in another center), made us discard this intervention because of the low diagnostic yield. We started an empiric antibiotic regime. We followed up very closely the clinical and radiological evaluation the next weeks, adjusting our antibiotic treatment when necessary. The results were favorable from both the radiological and clinical aspects and 6 months after the diagnosis the images show its almost complete disappearance.

CONCLUSION

Carefully tailored antibiotic-only regime and vigilance of its adverse effects and close radiological following is a good treatment approach when surgery is not an option.

Anesthetic considerations for cesarean delivery in a parturient with hereditary hemorrhagic telangiectasia: a case report

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is a rare autosomal dominant disorder characterized by mucocutaneous telangiectasia and arteriovenous malformations (AVMs). There are some anesthetic considerations for cesarean delivery in a parturient with HHT.

CASE PRESENTATION

A 27-year-old parturient with pulmonary hemorrhage was admitted to our tertiary perinatal center. She was first diagnosed with HHT and a cesarean delivery using spinal anesthesia at 37 weeks of gestation was initially planned. However, magnetic resonance imaging (MRI) at 32 weeks of gestation revealed spinal AVM ranging from the thoracic to the lumbar levels. Thus, elective cesarean delivery under general anesthesia was planned. The parturient had an uneventful perioperative course.

CONCLUSIONS

HHT should be considered as a differential diagnosis when parturients develop pulmonary hemorrhage. In a cesarean delivery of parturients with HHT, spinal MRI during pregnancy can help in deciding the anesthetic procedure to be used.

KRAS/BRAF mutations in brain arteriovenous malformations: A systematic review and meta-analysis

INTRODUCTION

Somatic KRAS mutations have been identified in the majority of brain arteriovenous malformations (AVM) specimens. The aim of our study was to evaluate the prevalence of Kirsten rat sarcoma (KRAS)/murine sarcoma viral oncogene homolog B1 (BRAF) mutations in brain AVM.

METHODS

A systematic literature review was performed in November 2019. We reviewed MEDLINE/PubMed, Cochrane Library, and ClinicalTrials.gov for citation or ongoing trials from January 2010 to March 2020.

RESULTS

6 studies were identified as meeting the inclusion criteria of this review. The total frequency of KRAS mutations in 1726 patients with AVM was 55%. The prevalence of BRAF mutation was 7.5%. The prevalence of AVMs with grade 2 was the most (39%). Frontal and parietal lobes were the commonest sites of AVMs (21%). the most prevalent presentation of patients with AVM was hemorrhage (62%).

CONCLUSION

Our findings support a high prevalence of somatic activating mutations in KRAS and less commonly, BRAF in the overwhelming majority of brain AVMs. Practically and importantly, this pathway homogeneity in CNS arteriovenous malformations also supports the development of targeted therapies with RAS/RAF pathway inhibitors. However, more studies are needed to confirm this hypothesis.

Hemorrhagic Cerebrovascular Pathology in the Pediatric Population

Hemorrhagic cerebrovascular disease in the pediatric population can have devastating and long-term effects. Progress in the fields of genetics, neuroimaging, pharmacology, and surgical techniques has led to improved diagnosis and management of pediatric cerebrovascular diseases. In this review we discuss the current etiologies and medical and surgical treatments of hemorrhagic cerebrovascular pathology affecting infants and children. A special emphasis is placed on neuroendovascular treatment options. Increased knowledge about this unique pathology and the medical and therapeutic options will empower practitioners to more quickly and accurately identify and accurately treat hemorrhagic diseases in the pediatric population.

[Microsurgical resection of multiple unruptured cerebral AVMs. Case report and literature review]

Multiple brain arteriovenous malformations (AVMs) are extremely rare. We report a 26-year-old patient with paroxysmal symptoms. This was the first case in our center over 10 years (0.15% of all patients with brain AVM in this period). Microsurgical resection of AVM of the left temporal lobe was carried out at the first stage (Spetzler-Martin grade I). A month later, resection of AVM of the left parietal lobe (Spetzler-Martin grade III) after preliminary endovascular embolization was carried out. Early postoperative visual and mental disorders occurred after the second surgery and completely regressed within 1 month. Control angiography after the second operation confirmed total resection of both AVMs. Thus, staged microsurgical resection of two cerebral AVMs combined with preliminary endovascular embolization of more complex AVM was effective and ensured favorable clinical result. We analyzed the features of our clinical case and compared our findings with literature data.

Lactulose to the Rescue: A Case of Toxic Hepatic Encephalopathy Caused by Portosystemic Shunting and Epistaxis in a Patient with Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an uncommon autosomal dominant disorder characterized by telangiectasias and arteriovenous malformations. Multiple organ systems are involved including the skin, lungs, gastrointestinal tract, and brain. Hepatic encephalopathy is an extremely rare complication of HHT and early diagnosis and treatment can be life-saving. We present a rare case of hepatic encephalopathy caused by HHT-induced portosystemic shunting treated with lactulose.

Patients with in-situ metallic coils and Amplatzer vascular plugs used to treat pulmonary arteriovenous malformations since 1984 can safely undergo magnetic resonance imaging

Objective:

To examine the MRI safety of metallic coils and Amplatzer vascular plugs. Currently, concern regarding MR safety of devices used to treat pulmonary arteriovenous malformations (PAVMs) causes delays in performing emergency MRI in patients presenting with acute neurological symptoms.

Methods:

A retrospective audit was performed on all patients who underwent PAVM embolization at Hammersmith Hospital, London UK between 1984 and 2017. Outcomes of all MRI studies performed at our institution were recorded. In addition, known outcomes of all known MRI studies performed on patients treated with the earliest steel coils (1984–1995) were recorded.

Results:

At our institution, 20 patients underwent 1.5 T MRI after the insertion of 100 steel coils (15.5 – 28.6, median 22 years later), 140 coils designated MR-conditional (0.42 – 12.7, median 9.3 years later), and 54 MRI-conditional Amplatzer vascular plugs (0.17 – 8.0, median 0.75 years later), many in combination. The majority of scans were for cerebral indications, but other body regions scanned included spinal, thoracic, and pelvic regions. No adverse events were reported. Similarly, there were no adverse events in any MR scan known to have been performed in other institutions in seven further patients treated with the earliest steel coils (1984–1995). Again, the majority of scans were for cerebral indications.

Conclusion:

The findings demonstrate MR safety at 1.5 T of all PAVM embolization devices inserted in a main UK centre since inception in 1984.

Advances in knowledge:

MRI of patients who have had PAVMs treated by embolization can be implemented without contacting specialist pulmonary arteriovenous malformation treatment centres for approval.

Uptake and radiological findings of screening cerebral magnetic resonance scans in patients with hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) results in arteriovenous malformations (AVMs), most commonly in the lungs, liver and brain. Discussion of cerebral vascular malformations is an important element of patient management. The current study objectives were to examine uptake and results of screening cerebral magnetic resonance (MR) scans, excluding symptomatic patients requiring neurological investigations. The remaining non-symptomatic individuals received formal pretest counselling that differed according to family history. For the 603 patients with no neurological symptoms of concern, screening scan uptake was higher after publication of the ARUBA trial. Patients with a family history of cerebral haemorrhage were 4 to 14-fold more likely to have a screening scan than patients with no such family history. For patients without neurological symptoms suggesting cerebral AVMs, none of the 59 screening scans performed at our institution demonstrated a cerebral AVM. Four scans (6.8%) demonstrated small aneurysms. The most common abnormality was cerebral infarction (20/59, 33.9%), predominantly identified in patients with pulmonary AVMs. Of 29 pulmonary AVM patients with no previous history of clinical stroke, 16 (55.2%) had between one and five silent infarcts. For HHT patients with pulmonary AVMs, the most frequently affected sites were the cerebellum (40%) and thalamus (14.3%), and the age-adjusted odds ratio for an infarct was 21.6 (95% confidence intervals 3.7, 126), p = 0.001. We concluded that for cerebral screening programmes in HHT, the findings support informed patient choice incorporating understanding that cerebral AVMs are rare in non-symptomatic HHT patients, but that screening scans commonly detect silent cerebral infarction due to pulmonary AVMs.

A Pial Arteriovenous Fistula in Infancy as the Presenting Manifestation of Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Pial arteriovenous fistulas (PAVFs) are rare, accounting for 1.6%-4.7% of all intracranial vascular malformations. Often diagnosed in childhood, about 30% are associated with hereditary hemorrhagic telangiectasia. A case of PAVF diagnosed soon after birth and given cerebrovascular therapy 4 months after birth is reported.

CASE DESCRIPTION

The patient presented with heart failure immediately after birth. Ultrasonography of the head showed abnormal blood flow in the brain. On digital subtraction angiography performed 4 months after birth, a PAVF with a dural feeder shunt and a giant varix at the posterior temporal part was confirmed. After transarterial embolization (TAE), shunt blood flow disappeared. New shunt flow from the right posterior cerebral artery into the varix was confirmed by magnetic resonance imaging 3 months after the operation. A second TAE procedure using a liquid embolic material was performed and confirmed the complete disappearance of the shunt.

CONCLUSIONS

This report describes a case of infant PAVF with heart failure, a giant varix, hydrocephalus, and intraventricular hemorrhage treated by TAE using platinum coils and liquid embolic material.

Thyroplasty in unilateral vocal fold paresis with coexisting hereditary hemorrhagic telenagiectasia: A case report

RATIONALE

The coincidence of an idiopathic unilateral vocal fold paresis and hereditary hemorrhagic telenagiectasia (HHT) is extremely rare and has not been described in the available literature yet.

PATIENTS CONCERNS

A 55-year-old female was admitted to hospital due to acute onset of hoarseness, voice fatigue, and effort dyspnea. In the past, the patient was diagnosed with HHT and on admission presented characteristic vascular lesions in the oral cavity. She reported also experiencing a moderate epistaxis at least once per month.

DIAGNOSES

The otolaryngological examination (fiberolaryngoscopy, phoniatric examination) revealed unchanged mobility and morphology of the right vocal fold and paresis of the left vocal fold in intermediate position. Computed tomography and magnetic resonance imaging of head, neck, and chest were inconclusive and showed no pathologic findings.

INTERVENTIONS

The unilateral paresis was treated for 12 months as idiopathic, with extensive rehabilitation. However, no improvement was observed. As a patient suffering from HHT is a challenge for anesthesiologists in terms of general anesthesia, the decision to perform type I thyroplasty (medialization) in local anesthesia was made.

OUTCOMES

There were no complications intraoperatively or in postoperative period. The implemented treatment was successful, as the voice quality improved both in perceptual evaluation (GRBAS scale) and acoustic analysis (F0, jitter, shimmer, NHR).

LESSONS

A routine surgical treatment in patients with HHT is a challenge. However, in this case, it was uneventful and successful, thus it can be recommended in other patients with similar background.

Surgical Treatment vs Nonsurgical Treatment for Brain Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia: A Retrospective Multicenter Consortium Study

BACKGROUND

Cerebral arteriovenous malformations (AVMs) are common in patients with hereditary hemorrhagic telangiectasia (HHT). However, due to the rarity of HHT and little published evidence of outcomes from management of brain AVMs in this disease, current international HHT guidelines recommend an individualized approach. Specifically, the outcomes for surgical vs nonsurgical management of these lesions have not been reported to date.

OBJECTIVE

To report long-term outcomes of surgical resection of brain AVMs in HHT patients compared to outcomes in nonsurgically treated patients.

METHODS

From the database of the Brain Vascular Malformation Consortium HHT project, 19 patients with 20 resected AVMs (group 1) and 22 patients with 33 AVMs who received nonsurgical treatment (group 2) were studied. The groups were retrospectively reviewed for changes in functional status (modified Rankin Scale score) during the follow-up period.

RESULTS

During the follow-up period, 9% of patients in group 1 suffered from worsening of functional status, whereas this figure was 16% for group 2 (P > .05). Functional outcomes were not statistically different between the 2 groups at the latest follow-up (P > .05).

CONCLUSION

HHT patients treated surgically for brain AVMs appear to have long-term functional outcomes comparable to nonsurgical (including observational) therapy with fewer unfavorable outcomes. It is therefore reasonable to consider surgical resection as a management option in the multidisciplinary team's individualized treatment strategy for HHT patients with brain AVMs.

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.

Severe Hepatic and Pulmonary Involvement in Rendu-Osler-Weber Syndrome

We report the case of a young woman with hereditary hemorrhagic telangiectasia (HHT) with severe liver involvement and pulmonary shunting. The medical imaging in this patient illustrates the severe shunting that can occur in these patients who often are asymptomatic. By showing this case, we want to highlight the role of liver transplantation in HHT with hepatic involvement.

Spinal arteriovenous fistulae in patients with hereditary hemorrhagic telangiectasia: A case report and systematic review of the literature

BACKGROUND

Although rare, spinal arteriovenous malformations (AVMs) are thought to be more prevalent in the hereditary Hereditary Hemorrhagic Telangiectasia (HHT) population.

METHODS

We report a case of a spinal AVM in a 37-year-old female with HHT treated with endovascular embolization. In addition, we report findings from a systematic review of the literature on the clinical characteristics, angioarchitecture, and clinical outcomes of HHT patients with spinal AVMs.

RESULTS

The patient is a 37 year-old female with definite HHT who presented with a one-year history of progressive gait difficulty. The spinal fistula was incidentally detected on chest computed tomography (CT). Spinal angiography demonstrated a large perimedullary arteriovenous fistula was supplied by a posterolateral spinal artery. The fistula was treated with detachable coils. The patient made a complete neurological recovery. Our systematic review yielded 25 additional cases of spinal AVMs in HHT patients. All fistulae were perimedullary (100.0%). Treatments were described in 24 of the 26 lesions. Endovascular-only treatment was performed in 16 cases (66.6%) and surgical-only treatment was performed in five cases (20.8%). Complete or near-complete occlusion rates were 86.7% (13/15) for endovascular treated cases, 100.0% (4/4) for surgery and 66.6% (2/3) for combined treatments. Overall, 80.0% of patients (16/20) reported improvement in function following treatment, 100.0% (5/5) in the surgery group and 84.6% (11/13) reported improvement in the endovascular group.

CONCLUSIONS

Spinal fistulae in HHT patients are usually type IV perimedullary fistulae. Both endovascular and surgical treatments appeared to be effective in treating these lesions. However, it is clear that endovascular therapy has become the preferred treatment modality.

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.

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.

Brain abscess as an initial presentation in a patient of hereditary haemorrhagic telangiectasia caused by a novel ENG mutation

Hereditary haemorrhagic telangiectasia (HHT) is a rare inherited autosomal-dominant vascular dysplasia involving multiple organs. Brain abscess is an uncommon and potential fatal complication. We report a case of HHT caused by a novel ENG mutation who initially presented as brain abscess. The patient, with a family history of epistaxis, presented with fever, headache and right-sided haemiparesis. Upon examination, brain MRI showed a contrast-enhanced abscess on the left fronto-parietal region. Open brain drainage was performed and pus culture yielded Actinomyces meyeri. The chest image revealed multiple pulmonary arterio-venous fistulas. HHT was diagnosed according to Curacao criteria. Genetic analysis revealed a novel duplication on exon 6 of ENG gene, which segregates with symptomatic subjects in her family. Clinicians should be cautiously aware of HHT as a differential diagnosis if patients presented with an unknown entry source of intracerebral infections.

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.

Hereditary hemorrhagic telangiectasia: two distinct ENG deletions in one family

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by aberrant vascular development. Mutations in endoglin (ENG) or activin A receptor type II-like 1 (ACVRL1) account for around 90% of HHT patients, 10% of those are large deletions or duplications. We report here the first observation of two distinct, large ENG deletions segregating in one pedigree. An ENG exon 4-7 deletion was observed in a patient with HHT. This deletion was identified in several affected family members. However, some affected family members had an ENG exon 3 deletion instead. These deletions were detected by multiplex ligation-dependent probe amplification and confirmed by mRNA sequencing and an oligo-CGH array. Linkage analysis revealed that one individual with the exon 3 deletion inherited the same chromosome from his mother who has the exon 4-7 deletion. This finding has important clinical implications because it shows that targeted family-specific mutation analysis for exon deletions could have led to the misdiagnosis of some affected family members.

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.

[Brain abscess as the first clinical manifestation of isolated pulmonary arteriovenous malformation without Rendu-Osler disease]

INTRODUCTION

Brain abscesses occur in 5 to 13 % of patients with pulmonary arteriovenous malformation (PAVM), more often present in Rendu-Osler-Weber disease or hereditary hemorrhagic telangiectasia (HHT).

CASE REPORT

A 51-year-old man with a history of transient Parinaud syndrome at 37 years complained of headache for 2 months before acute onset of a left cerebellar syndrome without fever. CT-scan and MRI of the head revealed a heterogeneous left cerebellar lesion. A brain abscess was drained and all signs resolved. CT-scan of the chest revealed a left lingual PAVM; occlusion was incomplete after coil embolization. He had no feature of HHT and no mutation in ENG and ACVRL1 genes. A second embolization was performed 5 months later, but the malformation was not occluded at 6 months.

DISCUSSION

We report the seventh case of PAVM complicated by a cerebellar abscess. The right to left shunt in PAVM results in hypoxemia, secondary polycythemia and paradoxical embolization of infective organisms bypassing the pulmonary filter.

CONCLUSION

Combining different MRI techniques (in particular diffusion and proton MR spectroscopy) provides invaluable data for the diagnosis of brain abscess. Careful search for PAVM must be undertaken, particularly in adults with cryptogenic abscess, to avoid further abscess formation or stroke.

Pulmonary arteriovenous fistulas in hereditary hemorrhagic telangiectasia

We reviewed all available chest X-rays of 95 patients with hereditary hemorrhagic telangiectasia (HHT). The diagnosis of pulmonary arteriovenous fistula (PF) had previously been made in 13 patients, nine of whom had been operated on. Another three cases were found in the review. The 16 patients with HHT and PF came from eight families, one of which contributed seven patients. Median observation time between the first and the latest chest X-ray examination was 11 years (range 1/2-35). Growth of the PF was seen in four patients and spontaneous regression in one. Four of the 16 patients with PF had symptoms consistent with cerebral embolism, while only two of the 79 patients without PF had such symptoms. This study is part of an epidemiological investigation of HHT--to our knowledge not carried out before. The calculated period prevalence of simultaneous HHT and PF in the decade 1964-74 in the county of Fyn (429 207 inhabitants) was 2.6 per 100 000.

Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease) complicated by pulmonary arteriovenous fistula and brain abscess

A man who developed two brain abscesses was later found to have hereditary hemorrhagic telangiectasia with a pulmonary arteriovenous fistula. Brain abscess is a known complication of pulmonary arteriovenous fistulas. About 15% of patients with hereditary hemorrhagic telangiectasia develop such a fistula during their lives. Surgical resection of pulmonary arteriovenous fistulas is recommended because of the risk of severe neurological sequelae.

Transillumination of the fingers for vascular anomalies: a novel method for evaluating hereditary hemorrhagic telangiectasia

PURPOSE

We describe a novel approach for detecting vascular abnormalities deep in the digits by means of a handheld illuminator.

METHODS

Ten patients with hereditary hemorrhagic telangiectasia were compared with 10 controls for telangiectases in the fingers using a handheld otoscope.

RESULTS

This noninvasive transillumination method revealed telangiectases in 9 of 10 patients with hereditary hemorrhagic telangiectasia and none in controls.

CONCLUSIONS

Transillumination of fingers with an otoscope identifies telangiectases in patients with hereditary hemorrhagic telangiectasia. Further studies are needed to determine the prevalence of telangiectases in the finger and whether this finding is present in other vascular diseases.

Hereditary haemorrhagic telangiectasia: a clinical and scientific review

The autosomal-dominant trait hereditary haemorrhagic telangiectasia (HHT) affects 1 in 5-8000 people. Genes mutated in HHT (most commonly for endoglin or activin receptor-like kinase (ALK1)) encode proteins that modulate transforming growth factor (TGF)-beta superfamily signalling in vascular endothelial cells; mutations lead to the development of fragile telangiectatic vessels and arteriovenous malformations. In this article, we review the underlying molecular, cellular and circulatory pathobiology; explore HHT clinical and genetic diagnostic strategies; present detailed considerations regarding screening for asymptomatic visceral involvement; and provide overviews of management strategies.

Hereditary haemorrhagic telangiectasia: a clinical and scientific review

The autosomal-dominant trait hereditary haemorrhagic telangiectasia (HHT) affects 1 in 5-8000 people. Genes mutated in HHT (most commonly for endoglin or activin receptor-like kinase (ALK1)) encode proteins that modulate transforming growth factor (TGF)-beta superfamily signalling in vascular endothelial cells; mutations lead to the development of fragile telangiectatic vessels and arteriovenous malformations. In this article, we review the underlying molecular, cellular and circulatory pathobiology; explore HHT clinical and genetic diagnostic strategies; present detailed considerations regarding screening for asymptomatic visceral involvement; and provide overviews of management strategies.

Transoesophageal echocardiographic diagnosis of pulmonary arteriovenous malformation in a patient with ischaemic stroke

We report a case of an ischaemic stroke secondary to an isolated pulmonary arteriovenous malformation. In this case, transoesophageal echocardiogram played a pivotal role in shunt identification, exclusion of atrial septal defect, and definitive diagnosis and localization of the pulmonary arteriovenous malformations. Pulmonary arteriovenous malformations should be excluded in all patients with cryptogenic stroke.

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.