Early regrowth of juvenile cerebral arteriovenous malformations: report of 3 cases and immunohistochemical analysis

Recurrence of brain arteriovenous malformations in pediatric patients: a long-term follow-up study

BACKGROUND

Previously thought to be congenital, AVMs have shown evidence of de-novo formation and continued growth, thus shifting thoughts on their pathophysiology. Pediatric AVM patients have been reported to be more prone to develop AVM recurrence after a seemingly complete cure. Therefore, we assessed the risk of AVM treated in childhood to recur in adulthood after a long-term follow-up in our own cohort.

METHODS

Control DS-angiography was arranged during 2021-2022 as part of a new protocol for all AVM patients who were under 21 years of age at the time of their treatment and in whom the treatment had occurred at least five years earlier. Angiography was offered only to patients under 50 years of age at the time of the new protocol. The complete eradication of AVM after the primary treatment had been originally confirmed with DSA in every patient.

RESULTS

A total of 42 patients participated in the late DSA control, and 41 of them were included in this analysis after excluding the patient diagnosed with HHT. The median age at the time of admission for AVM treatment was 14.6 (IQR 12-19, range 7-21 years) years. The median age at the time of the late follow-up DSA was 33.8 years (IQR 29.8-38.6, range 19.4-47.9 years). Two recurrent sporadic AVMs and one recurrent AVM in a patient with hereditary hemorrhagic telangiectasia (HHT) were detected. The recurrence rate was 4.9% for sporadic AVMs and 7.1% if HHT-AVM was included. All the recurrent AVMs had originally bled and been treated microsurgically. The patients with sporadic AVM recurrence had been smoking their whole adult lives.

CONCLUSIONS

Pediatric and adolescent patients are prone to develop recurrent AVMs, even after complete AVM obliteration verified by angiography. Therefore, imaging follow-up is recommended.

Delayed recurrence of pediatric arteriovenous malformations after radiologically confirmed obliteration

OBJECTIVE

Arteriovenous malformations (AVMs) are a major cause of intracerebral hemorrhage in children, resulting in significant morbidity and mortality. Moreover, the rate of AVM recurrence in children is significantly higher than in adults. The aim of this study was to define the risk of delayed pediatric AVM (pAVM) recurrence following confirmed radiological obliteration. Further understanding of this risk could inform the role of long-term radiological surveillance.

METHODS

The authors conducted a retrospective review of ruptured and unruptured pAVM cases treated at a single tertiary care referral center between 1994 and 2019. Demographics, clinical characteristics, treatment modalities, and AVM recurrence were analyzed.

RESULTS

A total of 102 pediatric patients with intracranial AVMs, including 52 (51%) ruptured cases, were identified. The mean patient age at presentation was 11.2 ± 4.4 years, and 51 (50%) patients were female. The mean nidus size was 2.66 ± 1.44 cm. The most common Spetzler-Martin grades were III (32%) and II (31%). Stereotactic radiosurgery was performed in 69.6% of patients. AVM obliteration was radiologically confirmed in 68 (72.3%) of 94 patients with follow-up imaging, on angiography in 50 (73.5%) patients and on magnetic resonance imaging in 18 (26.5%). AVM recurrence was identified in 1 (2.3%) of 43 patients with long-term surveillance imaging over a mean follow-up of 54.7 ± 38.9 months (range 2-153 months). This recurrence was identified in a boy who had presented with a ruptured AVM and had been surgically treated at 5 years of age. The AVM recurred 54 months after confirmed obliteration on surveillance digital subtraction angiography. Two other cases of presumed AVM recurrence following resection in young children were excluded from recurrence analysis because of incomplete sets of imaging available for review.

CONCLUSIONS

AVM recurrence following confirmed obliteration on imaging is a rare phenomenon, though it occurs more frequently in the pediatric population. Regular long-term follow-up with dedicated surveillance angiography is recommended even after obliteration following resection.

Hemorrhage and Recurrence of Obliterated Brain Arteriovenous Malformations Treated With Stereotactic Radiosurgery

BACKGROUND

Although complete nidal obliteration of brain arteriovenous malformations (AVM) is generally presumed to represent durable cure, postobliteration hemorrhage, and AVM recurrence have become increasingly recognized phenomena. The goal of the study was to define hemorrhage and nidal recurrence risks of obliterated AVMs treated with stereotactic radiosurgery (SRS).

METHODS

This is a retrospective cohort study from the International Radiosurgery Research Foundation comprising AVM patients treated between 1987 and 2020. Patients with AVM obliteration on digital subtraction angiography (DSA) were included. Outcomes were (1) hemorrhage and (2) AVM recurrence. Follow-up duration began at the time of AVM obliteration and was censored at subsequent hemorrhage, AVM recurrence, additional AVM treatment, or loss to follow-up. Annualized risk and survival analyses were performed. A sensitivity analysis comprising patients with AVM obliteration on magnetic resonance imaging or DSA was also performed for postobliteration hemorrhage.

RESULTS

The study cohort comprised 1632 SRS-treated patients with AVM obliteration on DSA. Pediatric patients comprised 15% of the cohort, and 42% of AVMs were previously ruptured. The mean imaging follow-up after AVM obliteration was 22 months. Among 1607 patients with DSA-confirmed AVM obliteration, 16 hemorrhages (1.0%) occurred over 2223 patient-years of follow-up (0.72%/y). Of the 1543 patients with DSA-confirmed AVM obliteration, 5 AVM recurrences (0.32%) occurred over 2071 patient-years of follow-up (0.24%/y). Of the 16 patients with postobliteration hemorrhage, AVM recurrence was identified in 2 (12.5%). In the sensitivity analysis comprising 1939 patients with post-SRS AVM obliteration on magnetic resonance imaging or DSA, 16 hemorrhages (0.83%) occurred over 2560 patient-years of follow-up (0.63%/y).

CONCLUSIONS

Intracranial hemorrhage and recurrent arteriovenous shunting after complete nidal obliteration are rare in AVM patients treated with SRS, and each phenomenon harbors an annual risk of <1%. Although routine postobliteration DSA cannot be recommended to SRS-treated AVM patients, long-term neuroimaging may be advisable in these patients.

Pediatric brain arteriovenous malformation recurrence: a cohort study, systematic review and meta-analysis

BACKGROUND

Recurrence following obliteration of brain arteriovenous malformations (AVMs) is common in children surgically treated, but recurrences following endovascular (EVT) and radiosurgical approaches are scantily reported.

OBJECTIVE

To analyze the rates and risk factors for AVM recurrence after obliteration in a single-center cohort of children with ruptured AVMs treated with multimodal approaches, and to carry out a comprehensive review and meta-analysis of current data.

METHODS

Children with ruptured AVMs between 2000 and 2019 enrolled in a prospective registry were retrospectively screened and included after angiographically determined obliteration to differentiate children with/without recurrence. A complementary systematic review and meta-analysis of studies investigating AVM recurrence in children between 2000 and 2020 was aggregated to explore the overall recurrence rates across treatment modalities by analyzing surgery versus other treatments.

RESULTS

Seventy children with obliterated AVMs were included. AVM recurrences (n=10) were more commonly treated with EVT as final treatment (60% in the recurrence vs 13.3% in the no-recurrence group, p=0.018). Infratentorial locations were associated with earlier and more frequent recurrences (adjusted relative risk=4.62, 95% CI 1.08 to 19.04; p=0.04).In the aggregate analysis, the pooled rate of AVM recurrence was 10.9% (95% CI 8.7% to 13.5%). Younger age at presentation was associated with more frequent recurrences (RR per year increase, 0.97, 95% CI 0.93 to 0.99; p=0.046).

CONCLUSION

Location of infratentorial AVMs and younger age at presentation may be associated with earlier and more frequent recurrences. The higher rates of recurrence in patients with AVMs obliterated with EVT questions its role in an intent-to-cure approach and reinforces its position as an adjunct to surgery and/or radiosurgery.

Cerebral Arteriovenous Malformation Recurrence After Complete Surgical Excision in an Adult: Case Report and Review of the Literature

Angiographically confirmed complete surgical excision of brain arteriovenous malformations (bAVMs) is conventionally considered curative. Recurrence in adults is rarely encountered; only 18 cases have been reported in the English literature over the past 30 years. The potential for recurrence and consequent need for routine long-term follow-up are important considerations in the management of these lesions. We report a case of a 23-year-old female with a recurrent bAVM discovered incidentally on routine imaging three years after complete surgical excision. We review the existing literature and discuss the options for surveillance and management.

Chinese Cerebrovascular Neurosurgery Society and Chinese Interventional & Hybrid Operation Society, of Chinese Stroke Association Clinical Practice Guidelines for Management of Brain Arteriovenous Malformations in Eloquent Areas

Aim: The aim of this guideline is to present current and comprehensive recommendations for the management of brain arteriovenous malformations (bAVMs) located in eloquent areas. Methods: An extended literature search on MEDLINE was performed between Jan 1970 and May 2020. Eloquence-related literature was further screened and interpreted in different subcategories of this guideline. The writing group discussed narrative text and recommendations through group meetings and online video conferences. Recommendations followed the Applying Classification of Recommendations and Level of Evidence proposed by the American Heart Association/American Stroke Association. Prerelease review of the draft guideline was performed by four expert peer reviewers and by the members of Chinese Stroke Association. Results: In total, 809 out of 2,493 publications were identified to be related to eloquent structure or neurological functions of bAVMs. Three-hundred and forty-one publications were comprehensively interpreted and cited by this guideline. Evidence-based guidelines were presented for the clinical evaluation and treatment of bAVMs with eloquence involved. Topics focused on neuroanatomy of activated eloquent structure, functional neuroimaging, neurological assessment, indication, and recommendations of different therapeutic managements. Fifty-nine recommendations were summarized, including 20 in Class I, 30 in Class IIa, 9 in Class IIb, and 2 in Class III. Conclusions: The management of eloquent bAVMs remains challenging. With the evolutionary understanding of eloquent areas, the guideline highlights the assessment of eloquent bAVMs, and a strategy for decision-making in the management of eloquent bAVMs.

Basic research and surgical techniques for brain arteriovenous malformations

Arteriovenous malformations (AVMs) are hemorrhagic vascular diseases in which arteries and veins are directly connected with no capillary bed between the two. We herein introduce the results of basic research of this disease and surgical techniques based on our data and experiences. The results obtained from our research show that cell death- and inflammation-related molecules changed or became activated compared with control specimens. These findings indicate that chronic inflammation occurs in and around the nidus of AVMs. Various molecules are involved in the mechanisms of cell death and angiogenesis during this process. Confirmation of blood flow in the nidus is very important to avoid hemorrhagic complications during surgical removal of the nidus. The risk of hemorrhage increases when the blood flow in the nidus is not reduced. We reported the advantages of serial indocyanine green videoangiography, which is used to assess the blood flow during AVM nidus removal. Since publication of the ARUBA trial and Scottish Audit, treatments with high morbidity have not been allowed. It is especially important for neurosurgeons to treat low Spetzler-Martin grade AVMs with low morbidity. J. Med. Invest. 67 : 222-228, August, 2020.

Evidence for endothelial-to-mesenchymal transition in human brain arteriovenous malformations

BACKGROUND

Brain arteriovenous malformations (AVMs) are rare, potentially devastating cerebrovascular lesions that can occur in both children and adults. AVMs are largely sporadic and the basic disease biology remains unclear, limiting advances in both detection and treatment. This study aimed to investigate human brain AVMs for endothelial-to-mesenchymal transition (EndMT), a process recently implicated in cerebral cavernous malformations (CCMs).

METHODS

We used 29 paraffin-embedded and 13 fresh/frozen human brain AVM samples to profile expression of panels of EndMT-associated proteins and RNAs. CCMs, a cerebrovascular disease also characterized by abnormal vasculature, were used as a primary comparison, given that EndMT specifically contributes to CCM disease biology. AVM-derived cell lines were isolated from three fresh, surgical AVM samples and characterized by protein expression.

RESULTS

We observed high collagen deposition, high PAI-1 expression, and expression of EndMT-associated transcription factors such as KLF4, SNAI1, and SNAI2 and mesenchymal-associated markers such as VIM, ACTA2, and S100A4. SMAD-dependent TGF-β signaling was not strongly activated in AVMs and this pathway may be only partially involved in mediating EndMT. Using serum-free culture conditions, we isolated myofibroblast-like cell populations from AVMs that expressed a unique range of proteins associated with mature cell types and with EndMT. Conditioned medium from these cells led to increased proliferation of HUVECs and SMCs.

CONCLUSIONS

Collectively, our results suggest a role for EndMT in AVM disease. This may lead to new avenues for disease models to further our understanding of disease mechanisms, and to the development of improved diagnostics and therapeutics.

Ectopic Recurrence of Arteriovenous Malformation After Radiosurgery: Case Report and Insight Regarding Pathogenesis

BACKGROUND

While prior studies reporting de novo arteriovenous malformations after birth are not uncommon, reports of ectopic recurrence of arteriovenous malformation after radiotherapy are scarce.

CASE DESCRIPTION

An 8-year-old girl with a ruptured cerebellar arteriovenous malformation was treated with stereotactic radiosurgery. The nidus was completely obliterated 17 months after stereotactic radiosurgery; however, 20 years later she had a rupture of a recurrent nidus that occurred adjacent to the original nidus, accompanied by a radiation-induced cyst. Surgical resection was performed, and subsequent pathologic examination revealed 2 different compartments: a typical nidus and a postirradiated degenerated nidus with an encapsulated hematoma. Immunohistochemical stains showed increased expression of Ki-67 and decreased expression of endoglin in endothelial cells in the recurrent nidus.

CONCLUSIONS

Depletion in endoglin may lead to the formation of vessel malformations in the presence of angiogenic stimuli. This case serves as a strong reminder of the importance of long-term follow-up after stereotactic radiosurgery, especially for pediatric cases.

KRAS G12D or G12V Mutation in Human Brain Arteriovenous Malformations

BACKGROUND

Brain arteriovenous malformations (BAVMs) are vascular malformations composed of tangles of abnormally developed vasculature without capillaries. Abnormal shunting of arteries and veins is formed, resulting in high-pressure vascular channels, which potentially lead to rupture. BAVMs are generally considered a congenital disorder. But clinical evidence regarding involution, regrowth, and de novo formation argue against the static condition of this disease. Recently, the presence of the somatic activating KRAS mutations in more than half of BAVM cases was reported, suggesting the role of KRAS function in the pathogenesis.

METHODS

KRAS mutation in codon35 (G→A, G12D; G→T, G12V) was examined by a digital polymerase chain reaction analysis using genome purified from paraffin-embedded slides of human BAVMs. We also examined protein expression of KRAS G12D in lesions to corroborate results from digital polymerase chain reaction analysis.

RESULTS

We detected codon35 G→A mutation in 15 (39.5%) among 38 samples and codon35 G→T mutation in 10 (27.0%) among 37 samples we could assess mutations. There were no samples positive for both codon35 G→A and G→T mutation. The ratio of codon35 G→A mutation ranged from 0.60% to 12.28% and that of G→T was from 1.20% to 8.99%. We next examined protein expression of KRAS G12D in BAVM lesions in immunohistochemistry. A KRAS G12D mutant was detected mainly in endothelial cells of dilated vessels in lesions.

CONCLUSIONS

KRAS mutations in codon35 were detected in about two thirds of specimens examined. KRAS function may actively contribute to the pathobiology of BAVM and can become a therapeutic target.

Role of follow-up imaging after resection of brain arteriovenous malformations in pediatric patients: a systematic review of the literature

OBJECTIVE Pediatric patients are at risk for the recurrence of brain arteriovenous malformation (AVM) after resection. While there is general consensus on the importance of follow-up after surgical removal of an AVM, there is a lack of consistency in the duration of that follow-up. The object of this systematic review was to examine the role of follow-up imaging in detecting AVM recurrence early and preventing AVM rupture. METHODS This systematic review was performed using articles obtained through a search of the literature contained in the MeSH database, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS Search results revealed 1052 articles, 13 of which described 31 cases of AVM recurrence meeting the criteria for inclusion in this study. Detection of AVM occurred significantly earlier (mean ± SD, 3.56 ± 3.67 years) in patients with follow-up imaging than in those without (mean 8.86 ± 5.61 years; p = 0.0169). While 13.34% of patients who underwent follow-up imaging presented with rupture of a recurrent AVM, 57.14% of those without follow-up imaging presented with a ruptured recurrence (p = 0.0377). CONCLUSIONS Follow-up imaging has an integral role after AVM resection and is sometimes not performed for a sufficient period, leading to delayed detection of recurrence and an increased likelihood of a ruptured recurrent AVM.

Postoperative imaging for detection of recurrent arteriovenous malformations in children

OBJECT The optimal method for detecting recurrent arteriovenous malformations (AVMs) in children is unknown. An inherent preference exists for MR angiography (MRA) surveillance rather than arteriography. The validity of this strategy is uncertain. METHODS A retrospective chart review was performed on pediatric patients treated for cerebral AVMs at a single institution from 1998 to 2012. Patients with complete obliteration of the AVM nidus after treatment and more than 12 months of follow-up were included in the analysis. Data collection focused on recurrence rates, associated risk factors, and surveillance methods. RESULTS A total of 45 patients with a mean age of 11.7 years (range 0.5-18 years) were treated for AVMs via surgical, endovascular, radiosurgical, or combined approaches. Total AVM obliteration on posttreatment digital subtraction angiography (DSA) was confirmed in 27 patients, of whom the 20 with more than 12 months of follow-up were included in subsequent analysis. The mean follow-up duration in this cohort was 5.75 years (median 5.53 years, range 1.11-10.64 years). Recurrence occurred in 3 of 20 patients (15%). Two recurrences were detected by surveillance DSA and 1 at the time of rehemorrhage. No recurrences were detected by MRA. Median time to recurrence was 33.6 months (range 19-71 months). Two patients (10%) underwent follow-up DSA, 5 (25%) had DSA and MRI/MRA, 9 (45%) had MRI/MRA only, 1 (5%) had CT angiography only, and 3 (15%) had no imaging within the first 3 years of follow-up. After 5 years posttreatment, 2 patients (10%) were followed with MRI/MRA only, 2 (10%) with DSA only, and 10 (50%) with continued DSA and MRI/MRA. CONCLUSIONS AVM recurrence in children occurred at a median of 33.6 months, when MRA was more commonly used for surveillance, but failed to detect any recurrences. A recurrence rate of 15% may be an underestimate given the reliance on surveillance MRA over angiography. A new surveillance strategy is proposed, taking into account exposure to diagnostic radiation and the potential for catastrophic rehemorrhage.

Immunohistochemical Analysis of Sox17 Associated Pathway in Brain Arteriovenous Malformations

BACKGROUND

Sox17 has emerged as an important factor in vascular remodeling because of the potential linkage with Wnt/β-catenin, Notch, and the inflammatory pathway. Brain arteriovenous malformation (BAVM), as an angiogenic and inflammatory disorder, might possess an aberrant regulation of the Sox17 associated pathway. We sought to investigate the expression of the Sox17 associated pathway in BAVMs.

METHODS

Using immunohistochemical methods, 16 paraffin specimens of BAVM nidus were analyzed. Specimens were obtained from patients during surgical procedures.

RESULTS

Expression of Sox17, Hey1, and β-catenin was observed in all specimens. Large veins possessed a distinct pattern of expression; thick-walled veins had a stronger intensity, whereas thin-walled veins had a weaker intensity, of Sox17, Hey1, and β-catenin (P < 0.001). Thick-walled veins also had a higher expression of Sox17, Hey1, and β-catenin compared with large arteries (P < 0.05). Hey1 and β-catenin expression was also higher in thick-walled veins compared with brain microvessels (P < 0.01). In addition, the difference in expression of the Sox17 associated pathway (Hey1 and β-catenin) was observed in medium and small arteries compared with large arteries in BAVM nidus and brain microvessels (P < 0.01).

CONCLUSIONS

The Sox17 associated pathway was activated in the BAVM nidus. Our results indicate that arterial identity is gained in thick-walled veins; this might reflect the process of arterialization of the veins as a result of hemodynamic stress. In addition, high expression of the Sox17 associated pathway in medium and small arteries indicates that BAVM vessels are intrinsically active.

Increased expression of angiogenic factors in cultured human brain arteriovenous malformation endothelial cells

To compare the mRNA level of angiogenic factor vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP)-2, and MMP-9 in cultured human brain arteriovenous malformation (AVM) endothelial cells (ECs) and normal brain endothelial cells (BECs). Tissue explants both from deformed vessels of AVM and normal microvessel were put into culture for endothelial cells. After the monolayer adherent ECs reached confluence, they were tested with endothelial specific marker CD34 and von Willebrand factor (vWF) by immunochemical assay. mRNA levels of VEGF-A, MMP-2, and MMP-9 in AVM endothelial cells (AVMECs) and BECs were measured by PCR. Immunostaining confirmed that more than 95 % of the cultured cells were CD34 (Fig. 1b) and/or vWF positive. Expression levels of VEGF-A and MMP-2 mRNAs were significantly higher in AVMECs than in BECs. The MMP-9 level was also increased in AVMECs, but the difference was not statistically significant. Vascular tissue explants adherent method is a better approach for isolation and culture of AVMECs. Cultured AVMECs expressed higher angiogenic factors (VEGF, MMP-2) than the controlled BECs, implicating angiogenesis plays an important role in the pathogenesis of AVM.

Unique double recurrence of cerebral arteriovenous malformation

Surgically treated patients with arteriovenous malformations (AVMs) are considered cured when the postoperative angiogram proves complete resection. However, despite no residual nidus or early draining vein on postoperative angiogram, rare instances of AVM recurrence have been reported in adults. In this paper, the authors present a case of a 24-year-old woman with asymptomatic double recurrence of her cerebral AVM after angiographically proven complete resection. To the authors' knowledge, this patient represents the first case with double de novo asymptomatic recurrence of Spetzler-Martin grade I AVM. Also, she represents the first case with unique AVM criteria in each recurrence.

Differential gene expression in relation to the clinical characteristics of human brain arteriovenous malformations

Arteriovenous malformations (AVMs) of the central nervous system are considered as congenital disorders. They are composed of abnormally developed dilated arteries and veins and are characterized microscopically by the absence of a capillary network. We previously reported DNA fragmentation and increased expression of apoptosis-related factors in AVM lesions. In this article, we used microarray analysis to examine differential gene expression in relation to clinical manifestations in 11 AVM samples from Japanese patients. We categorized the genes with altered expression into four groups: death-related, neuron-related, inflammation-related, and other. The death-related differentially expressed genes were MMP9, LIF, SOD2, BCL2A1, MMP12, and HSPA6. The neuron-related genes were NPY, S100A9, NeuroD2, S100Abeta, CAMK2A, SYNPR, CHRM2, and CAMKV. The inflammation-related genes were PTX3, IL8, IL6, CXCL10, GBP1, CHRM3, CXCL1, IL1R2, CCL18, and CCL13. In addition, we compared gene expression in those with or without clinical characteristics including deep drainer, embolization, and high-flow nidus. We identified a small number of genes. Using these microarray data we are able to generate and test new hypotheses to explore AVM pathophysiology. Microarray analysis is a useful technique to study clinical specimens from patients with brain vascular malformations.

Recurrence of a paediatric arteriovenous malformation 9 years postcomplete excision: case report and review of literature

Cerebral arteriovenous malformations (AVMs) are a common congenital vascular anomaly, which often present in both children and adults. Surgery is considered curative once postoperative angiography confirms the absence of vessels. We describe a 6-year-old girl, who had a Spetzler-Martin Grade II AVM resected successfully, in which a recurrent AVM was detected on routine follow-up over 9 years post excision. The aetiopathogenesis of this rare occurrence with a review of literature is discussed. Long-term postoperative follow-up in the form of MRI/MR angiogram is recommended for all fully resected AVMs in the paediatric age group, anticipating the possibility of future recurrence.

Influence of the combination of patient age and deep venous drainage on brain arteriovenous malformation recurrence after surgery

OBJECT

Case reports suggest that young age is a critical factor in determining recurrence of brain arteriovenous malformations (AVMs) after surgery. However, other factors that may contribute to the increased risk of recurrence have not been considered. In this study, the authors' goal was to ascertain the risk and risk factors of recurrence after resection of AVMs of the brain.

METHODS

A consecutive case series (prospectively collected data) of 600 cases of resection of brain AVMs was retrospectively analyzed. Radiological evidence of recurrence or nonrecurrence, as well as clinical evidence of recurrence, could be established in 427 of these cases that underwent follow-up for more than 350 days after initial surgery. These cases were analyzed using Kaplan-Meier curves and Cox regression with respect to age and the presence of deep venous drainage.

RESULTS

Nine recurrent AVMs were found in 8 patients. By analysis of the Kaplan-Meier curves, the 10-year recurrence rate was 14% for those with deep venous drainage, compared with 4% for those without deep venous drainage. Stratifying by age, in the 0- to 20-year age group, the 10-year recurrence rates were 63% and 13% for those with and without deep venous drainage, respectively. In the 20- to 39-year age group, the rates were 5% and 0% respectively, and in the 40-year and older age group they were 0% and 3%, respectively. The hazard ratio for deep venous drainage, adjusted for age, was 5.97 (95% CI 1.20-29.69, p = 0.029).

CONCLUSIONS

The risk of recurrence after AVM resection is significant for young patients with deep venous drainage.

Follow-up imaging to detect recurrence of surgically treated pediatric arteriovenous malformations

OBJECT

The true postoperative incidence of arteriovenous malformation (AVM) recurrence in the pediatric population remains largely unreported. Some literature suggests that delayed imaging studies should be obtained at 6 months to 1 year after negative findings on a postoperative angiogram. The aim of this study was to describe the timing of AVM recurrences after resection and the neuroimaging modalities on which the recurrences were detected.

METHODS

This study was performed in a retrospective cohort of all pediatric patients treated surgically for AVM resection by a single neurosurgeon between 2005 and 2010. Patients were followed after resection with MR angiography (MRA) or conventional angiography, when possible, at various time points. A visual scale for compactness of the initial AVM nidus was used, and the score was correlated with probability of recurrence after surgery.

RESULTS

A total of 28 patients (13 female, 15 male) underwent an AVM resection. In 18 patients (64.3%) an intraoperative angiogram was obtained. In 4 cases the intraoperative angiogram revealed residual AVM, and repeat resections were performed immediately. Recurrent AVMs were found in 4 children (14.3%) at 50, 51, 56, and 60 weeks after the initial resection. Recurrence risk was 0.08 per person-year. No patient with normal results on an angiogram obtained at 1 year developed a recurrence on either a 5-year angiogram or one obtained at 18 years of age. All patients with recurrence had a compactness score of 1 (diffuse AVM); a lower compactness score was associated with recurrence (p = 0.0003).

CONCLUSIONS

All recurrences in this cohort occurred less than 15 months from the initial resection. The authors recommend intraoperative angiography to help ensure complete resection at the time of the surgery. Follow-up vascular imaging is crucial for detecting recurrent AVMs, and conventional angiography is preferred because MRA can miss smaller AVMs. One-year follow-up imaging detected these recurrences, and no one who had negative results on an angiogram obtained at 1 year had a late recurrence. However, not all of the patients have been followed for 5 years or until 18 years of age, so longer follow-up is required for these patients. A lower compactness score predicted recurrent AVM in this cohort.

Arteriovenous malformation in the adult mouse brain resembling the human disease

OBJECTIVE

Brain arteriovenous malformations (bAVMs) are an important cause of hemorrhagic stroke. The underlying mechanisms are not clear. No animal model for adult bAVM is available for mechanistic exploration. Patients with hereditary hemorrhagic telangiectasia type 2 (HHT2) with activin receptor-like kinase 1 (ALK1; ACVRL1) mutations have a higher incidence of bAVM than the general population. We tested the hypothesis that vascular endothelial growth factor (VEGF) stimulation with regional homozygous deletion of Alk1 induces severe dysplasia in the adult mouse brain, akin to human bAVM.

METHODS

Alk1(2f/2f) (exons 4-6 flanked by loxP sites) and wild-type (WT) mice (8-10 weeks old) were injected with adenoviral vector expressing Cre recombinase (Ad-Cre; 2 × 10(7) plaque forming units [PFU]) and adeno-associated viral vectors expressing VEGF (AAV-VEGF; 2 × 10(9) genome copies) into the basal ganglia. At 8 weeks, blood vessels were analyzed.

RESULTS

Gross vascular irregularities were seen in Alk1(2f/2f) mouse brain injected with Ad-Cre and AAV-VEGF. The vessels were markedly enlarged with abnormal patterning resembling aspects of the human bAVM phenotype, displayed altered expression of the arterial and venous markers (EphB4 and Jagged-1), and showed evidence of arteriovenous shunting. Vascular irregularities were not seen in similarly treated WT mice.

INTERPRETATION

Our data indicate that postnatal, adult formation of the human disease, bAVM, is possible, and that both genetic mutation and angiogenic stimulation are necessary for lesion development. Our work not only provides a testable adult mouse bAVM model for the first time, but also suggests that specific medical therapy can be developed to slow bAVM growth and potentially stabilize the rupture-prone abnormal vasculature.