Small Arteriovenous Malformations Research Articles

Use and Misuse of Small Bowel Video Capsule Endoscopy in Clinical Practice

Video capsule endoscopy (VCE) was introduced into the United States in 2000 and has significantly advanced the ability to visualize the small intestinal mucosa by using noninvasive technology. Compared with traditional imaging with small bowel barium imaging, the use of VCE has demonstrated the ability to enhance diagnostic yield in patients with suspected small bowel pathology by approximately 25%‐50% in patients with suspected small bowel disorders. 1‐3 Although the use of VCE has been recommended as the next step in patients with obscure gastrointestinal hemorrhage after a negative upper and/or lower endoscopic examination, 4 its use in other clinical scenarios such as small bowel inflammatory disorders may not be associated with similar diagnostic yields. The major complication associated with the use of VCE remains small bowel retention. Although the risk of this event is virtually nil in patients with obscure bleeding, it can approach 10% in patients with known inflammatory bowel disease (IBD). 5 A critical appraisement of appropriate use of this technology may help physicians and third-party payers to determine which subset of patients with suspected or known small bowel disorders would benefit the most from undergoing a VCE procedure. To critically examine the use of VCE in clinical practice, an evidence-based approach was performed by using the GRADE system, 6,7 and a critical review of the literature on capsule endoscopy was performed by using PubMed, SCOPUS, and the Cochrane Database from 2000‐2012. The quality of evidence could range from high (implying that further research was unlikely to change the authors’ confidence in the estimate of the effect) to moderate (further research would be likely to have an impact on the confidence in the estimate of effect) or low (further research would be expected to have an important impact on the confidence in the estimate of the effect and would be likely to change the estimate). The strength of a recommendation was graded as strong when the desirable effects of an intervention clearly outweigh the undesirable effects and as conditional when there was uncertainty about the tradeoffs. The evidence-based statements generated from this review are shown in Table 1. Studies including more than 20 patients were included for each topic to increase data quality when metaanalyses or randomized controlled trials were not available.

Long-term Results of Radiosurgery for Cerebral Arteriovenous Malformations

Stereotactic radiosurgery (SRS) is known to safely result in a high obliteration rate for small and medium sized arteriovenous malformations (AVM). To evaluate the long-term outcome of patients treated with SRS, with special emphasis given to obliteration and toxicity rates. We performed a review of 43 cerebral AVM patients, treated from 1998 to 2008 with a single SRS dose ranging from 21-25 Gy. Of these, 37 had a minimal follow-up of one year. Medical files were reviewed to assess patient and AVM characteristics, the SRS treatment, therapy prior to SRS, the obliteration rate and toxicities. Whenever necessary, outcome data was supplemented by telephone interviews with the patient or treating physician. AVM size was ≥3cm in diameter in 21% of patients. Five patients (11.6%) underwent surgery prior to SRS and 31 patients (72.1%) received one or more embolizations prior to SRS. Of the patients followed with angiography ≥1 year post-SRS, 89% (33/37) had a complete obliteration of the nidus, after a median time of 24.7 months post-treatment. Embolization prior to SRS was not predictive of outcome. One patient suffered a non-fatal haemorrhage between treatment and obliteration. The rate of symptomatic radiation-induced radiological changes was 8.1%. Our study shows both obliteration and complication rates in the upper limit of those reported in the literature. SRS seems an attractive treatment option for small AVMs. Unlike other reports, the prior use of embolization did not impact negatively on obliteration rates.

A Technical Note

Ruptured cerebral arteriovenous malformations (AVMs) usually require treatment to avoid re-bleeding. Depending on the angioarchitecture and center strategy, the treatment can be surgical, endovascular, radiosurgical or combined methods. The classic endovascular approach is transarterial, but sometimes it is not always applicable. The transvenous approach has been described as an alternative for the endovascular treatment of small AVMs when arterial access or another therapeutic method is not possible. This approach can be considered when the nidus is small and if there is a single draining vein. We present a technical note on a transvenous approach for the treatment of a ruptured AVM in a young patient.

Local Model of Arteriovenous Malformation of the Human Brain

Vascular diseases of the human brain are one of the reasons of deaths and people's incapacitation not only in Russia, but also in the world. The danger of an arteriovenous malformation (AVM) is in premature rupture of pathological vessels of an AVM which may cause haemorrhage. Long-term prognosis without surgical treatment is unfavorable. The reduced impact method of AVM treatment is embolization of a malformation which often results in complete obliteration of an AVM. Pre-surgical mathematical modeling of an arteriovenous malformation can help surgeons with an optimal sequence of the operation. During investigations, the simple mathematical model of arteriovenous malformation is developed and calculated, and stationary and non-stationary processes of its embolization are considered. Various sequences of embolization of a malformation are also considered. Calculations were done with approximate steady flow on the basis of balanced equations derived from conservation laws. Depending on pressure difference, a fistula-type AVM should be embolized at first, and then small racemose AVMs are embolized. Obtained results are in good correspondence with neurosurgical AVM practice.

Large volumeやeloquent regionのAVMに対するサイバーナイフ少数回分割定位放射線治療

Single-fraction stereotactic radiosurgery (SRS) is effective for small volume arteriovenous malformations (AVMs). However, large AVMs, and AVMs in eloquent regions are often not cured with SRS, because we cannot give an adequate dose to the AVMs without causing radiation damage to the surrounding normal brain tissue. We have used hypo-fractionated stereotactic radiotherapy (HFSRT) including SRS with Cyberknife (CK) for these AVMs in eloquent regions or large volume AVMs. The aim of this study is to evaluate the effectiveness of our HFSRT including SRS with CK for these AVMs with possibly a lower complication rate. During the past six years, single-fraction SRS was used as a basic treatment method for AVMs located in non-eloquent regions or for small volume AVMs. We have treated 36 cases (17 males and 19 females) of large AVMs and AVMs in eloquent regions with HFSRT, including SRS using CK. The age ranged from seven to 66 years (average 33 years). A mean marginal dose of 27 Gy (range 16–30 Gy) was prescribed and the average isodose was 76% (range 64-86%) isodose. Most patients were treated with the HFSRT method (three to five fractions) except for six SRS cases. 3-D SPGR MRA was performed with a 3T MR scanner (Signa HDX 3.0T, GE, US). The time-dependent relative decay of the trans-nidal blood flow and sequential volumetric reduction evidenced by 3D SPGR MRA was referred to as “obliteration dynamics.” All patients had periodical follow-up studies at regular intervals. Subtotal obliteration was determined if the residual nidus volume was 5% or less of the initial nidus volume. The mean follow-up period was 37 months (6–53). All patients tolerated the procedures well. After the treatment, a significant obliteration dynamics was observed in all patients over a 12-month follow-up. Subtotal obliteration was obtained in 11 patients out of 18 (61%) who had over 24-month follow-up. In conjunction with the gradual reduction of AVM volume after CK treatment, visual field defects improved, motor functions recovered and easy medical control of symptomatic epilepsy was realized in a significant number of cases. HFSRT with CK was found to be safe and effective. The use of sequential 3D SPGR MRA at 3T enables a noninvasive quantitative assessment of the dynamic obliteration process induced by HFSRT with CK in AVMs. If the long term follow-up sustains these preliminary results, HFSRT with CK could become the first treatment of choice for large AVM and eloquent regions.

Surgical resection of scalp arteriovenous malformation: Case illustration

Arteriovenous malformation (AVM) of the scalp is a rare lesion whose natural history remains to be elucidated. The report describes a case of a patient with a history of minor head trauma who presented with spontaneous bleeding from the scalp due to a relatively small scalp AVM. Several imaging modalities were used to establish the diagnosis, map the vascular malformation, and plan management. The optimal treatment strategy for this type of lesion remains controversial. Based on the size of AVM and the number of feeding arteries, this patient was treated with complete surgical excision alone. The clinical course was good, without postoperative complication or recurrence. Three-dimensional computed tomography angiography (3D-CTA) was useful for diagnosis, management and follow-up of this small extracranial scalp AVM.

Onyx® in endovascular treatment of cerebral arteriovenous malformations – a review

SummaryArteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. In most cases, the disorder may be asymptomatic. The objective of endovascular AVM treatment is set individually for each case upon consultations with a neurosurgeon and a neurologist. The endpoint of the treatment should consist in prevention of AVM bleeding in a management procedure characterized by a significantly lower risk of complications as compared to the natural history of AVM. Endovascular interventions within AVM may include curative exclusion of AVM from circulation, embolization adjuvant to resection or radiation therapy, targeted closure of a previously identified bleeding site as well as palliative embolization. Onyx was first described in the 1990s. It is a non-adhesive and radiolucent compound. Onyx-based closure of the lumen of the targeted vessel is obtained by means of precipitation. The process is enhanced peripherally to the main flux of the injected mixture. This facilitates angiographic monitoring of embolization at any stage. The degree of lumen closure is associated with the location of the vessel. Supratentorial and cortical locations are most advantageous. Dense and plexiform structure of AVM nidus as well as a low number of supplying vessels and a single superficial drainage vein are usually advantageous for Onyx administration. Unfavorable factors include nidus drainage into multiple compartments as well as multiarterial supply of the AVM, particularly from meningeal arteries, en-passant arteries or perforating feeders. Onyx appears to be a safe and efficient material for embolization of cerebral AVMs, also in cases of intracranial bleeding associated with AVM. Curative embolization of small cerebral AVMs is an efficient and safe alternative to neurosurgical and radiosurgical methods. Careful angiographic assessment of individual arteriovenous malformations should be performed before each Onyx administration.

A case of small pulmonary arteriovenous malformation diagnosed after juvenile stroke

A case of small pulmonary arteriovenous malformation diagnosed after juvenile stroke

Thoracic aortic disease in two patients with juvenile polyposis syndrome and SMAD4 mutations

Dilation or aneurysm of the ascending aorta can progress to acute aortic dissection (Thoracic Aortic Aneurysms and Aortic Dissections, TAAD). Mutations in genes encoding TGF-β-related proteins (TGFBR1, TGFBR2, FBN1, and SMAD3) cause syndromic and inherited TAAD. SMAD4 mutations are associated with juvenile polyposis syndrome (JPS) and a combined JPS-hereditary hemorrhagic telangiectasia (HHT) known as JPS-HHT. A family with JPS-HHT was reported to have aortic root dilation and mitral valve abnormalities. We report on two patients with JPS-HHT with SMAD4 mutations associated with thoracic aortic disease. The first patient, an 11-year-old boy without Marfan syndrome features, had JPS and an apparently de novo SMAD4 mutation (c.1340_1367dup28). Echocardiography showed mild dilation of the aortic annulus and aortic root, and mild dilation of the sinotubular junction and ascending aorta. Computed tomography confirmed aortic dilation and showed small pulmonary arteriovenous malformations (PAVM). The second patient, a 34-year-old woman with colonic polyposis, HHT, and features of Marfan syndrome, had a SMAD4 mutation (c.1245_1248delCAGA). Echocardiography showed mild aortic root dilation. She also had PAVM and hepatic focal nodular hyperplasia. Her family history was significant for polyposis, HHT, thoracic aortic aneurysm, and dissection and skeletal features of Marfan syndrome in her father. These two cases confirm the association of thoracic aortic disease with JPS-HHT resulting from SMAD4 mutations. We propose that the thoracic aorta should be screened in patients with SMAD4 mutations to prevent untimely death from dissection. This report also confirms that SMAD4 mutations predispose to TAAD.

Intra-Arterial Intraoperative Computed Tomography Angiography Guided Navigation

Precise intraoperative surgical localization of small distal aneurysms, arteriovenous malformations (AVMs), and cranial base dural arteriovenous fistulae may be challenging. Current neuronavigational techniques are based on imaging techniques with limited sensitivity to detect vascular lesions that are small. We introduce the technique of intraoperative computed tomography angiography (iCTA) with an intra-arterial injection for surgical navigation. To determine whether iCTA integrated with a navigation platform is accurate and useful for precise localization of small vascular lesions that are challenging to treat. This study included 8 patients: 2 with aneurysms, 3 with small cortical AVMs, and 3 with cranial base dural arteriovenous fistulae. iCTA with intra-arterial contrast injection was performed in all patients for precise localization of the small vascular lesion to facilitate craniotomy planning and microsurgical approach. All operative reports, inpatient and outpatient records, and radiographic studies available were reviewed retrospectively. : The iCTA was used to target 2 aneurysms, 3 small subcortical AVMs, and 3 dural arteriovenous fistulae. This technique was most helpful to localize the 3 AVMs and the distal M4 aneurysm precisely. Craniotomy planning was accurate in all instances; no complications related to the technique were noted, and all patients had uneventful postoperative recoveries. iCTA is an effective and accurate novel technique that can enhance the safety of surgical treatment for small intra-axial vascular pathology. AVM, arteriovenous malformationCTA, computed tomography angiographyDAVF, dural arteriovenous fistulaDSA, digital subtraction angiographyiCTA, intraoperative computed tomography angiographyMCA, middle cerebral arteryMSCT, multislice computed tomographyMRA, magnetic resonance angiography.

Natural history of cerebral arteriovenous malformations: a meta-analysis

The purpose of this report was to provide overall arteriovenous malformation (AVM) hemorrhage rates and, with enhanced statistical power, to elucidate significant risk factors for hemorrhage. The authors performed a meta-analysis via the PubMed database through January 2012 using the terms "AVM," "arteriovenous malformation," "natural history," "bleed," and "hemorrhage." Additional studies were identified through reference searches in each reviewed article. English language studies providing annual hemorrhage rates for AVMs were included. Data extraction, performed independently by the authors, included demographic data, hemorrhage rates, and hazard ratios for hemorrhage risk factors. The analysis was performed using a random effects model. Nine natural history studies with 3923 patients and 18,423 patient-years of follow-up were identified for analysis. The overall annual hemorrhage rate was 3.0% (95% CI 2.7%-3.4%). The rate of hemorrhage was 2.2% (95% CI 1.7%-2.7%) for unruptured AVMs and 4.5% (95% CI 3.7%-5.5%) for ruptured AVMs. Prior hemorrhage (HR 3.2, 95% CI 2.1-4.3), deep AVM location (HR 2.4, 95% CI 1.4-3.4), exclusively deep venous drainage (HR 2.4, 95% CI 1.1-3.8), and associated aneurysms (HR 1.8, 95% CI 1.6-2.0) were statistically significant risk factors for hemorrhage. Any deep venous drainage (HR 1.3, 95% CI 0.9-1.75) and female sex (HR 1.4, 95% CI 0.6-2.1) demonstrated a trend toward an increased risk of hemorrhage that was not statistically significant. Small AVM size and older patient age were not significant risk factors for hemorrhage. Arteriovenous malformations with prior hemorrhage, deep location, exclusively deep venous drainage, and associated aneurysms have greater annual hemorrhage rates than their counterparts, influencing surgical decision making and the selection of radiosurgery for these lesions.

Successful treatment with thalidomide of a patient with congenital factor V deficiency and factor V inhibitor with recurrent gastrointestinal bleeding from small bowel arteriovenous malformations

Successful treatment with thalidomide of a patient with congenital factor V deficiency and factor V inhibitor with recurrent gastrointestinal bleeding from small bowel arteriovenous malformations

Allosensitization in Cardiac Transplantation

Allosensitization in Cardiac Transplantation

Double Arterial Catheterization Technique for Embolization of Brain Arteriovenous Malformations With Onyx

Arteriovenous malformation (AVM) treatment is multidisciplinary, and the patient may undergo embolization, neurosurgery, or radiosurgery combined. Great improvement in endovascular techniques was provided by the introduction of Onyx with different kinds of approach. To evaluate the efficacy and the safety of Onyx embolization of brain AVMs with the double arterial catheterization technique (DACT). This was a retrospective study. From January 2006 until June 2011, 61 AVMs eligible for the DACT were treated. Forty-one of the 61 AVMs were treated with single arterial catheterization technique and 20 of 61 with DACT; patient age and Spetzler-Martin AVM grade were similar in the 2 groups. In the DACT group, we obtained complete occlusion of the nidus in all small AVMs, whereas in the single arterial catheterization technique group, we obtained complete occlusion in only 1 of the 36% of the cases. Among the medium-size AVMs, there were no significant differences in the 2 groups, but we performed fewer procedures per patient when we used the DACT (1.4 vs 2.2). In the DACT group, we observed fewer hemorrhagic complications (3.4% vs 12.5% per procedure) and lower morbidity (5% vs 7% per patient) and mortality (0% vs 2.4%) rates. The DACT in multifeeder AVMs may lead to a higher occlusion rate of the nidus for small AVMs and reduce the number of procedures, ensuring a higher standard of safety because of the possibility of managing the progression of Onyx into venous drainage.

De novo multiple dural arteriovenous fistulas and arteriovenous malformation after embolization of cerebral arteriovenous fistula: case report

A cerebral arteriovenous fistula is a rare neurovascular abnormality. It is very scarce when presenting with other cerebral arteriovenous malformations after embolization. We reported a case primarily presenting with cerebral arteriovenous fistula. When the fistula was embolized completely, de novo multiple dural arteriovenous fistulas and a small arteriovenous malformation occurred due to the hemodynamic change after the embolization. Embolization of parts of the fistulas for the second time led to an untreatable malformation which became curable. At the third time, the remaining fistula was cured. The mechanism of the dural arteriovenous fistula and treatment strategy were discussed. Venous hypertension is the main factor causing a dural arteriovenous fistula. Embolization of the fistulas step by step is recommended.

O-015 Angiographic features help predict outcome after γ knife radiosurgery for the treatment of pediatric arteriovenous malformations

BackgroundGamma Knife radiosurgery (GKRS) is an option in the treatment of pediatric arteriovenous malformations (AVMs), especially for AVMs in eloquent locations or patients with good functional status. Prior studies have...

Resection of an anterior spinal cord AVM through a far-lateral approach.

A small arteriovenous malformation near the craniocervical junction with contributions from the anterior spinal artery was discovered in a young developmentally-delayed woman after she presented with altered mental status and evidence of subarachnoid hemorrhage. The malformation could not be completely treated with endovascular therapy, so it was resected through a far-lateral approach. This stereoscopic video demonstrates how to gain the exposure needed to address a lesion in this area. The video can be found here: http://youtu.be/ByjPGm_eXLc .

Management of Arteriovenous Malformations by Stereotactic Radiosurgery: A Single Center Experience

The aim of this monoinstitutional study is to evaluate the efficiency of stereotactic radiosurgery (SRS) in the management of arteriovenous malformations (AVM). Between June 1998 and July 2011, 51 patients with AVM were treated with linear accelerator-based SRS at our department. All patients were preevaluated for AVM size, location, neurological status, previous history of hemorrhage and Spetzler-Martin grading. Treated patients then underwent follow-up to evaluate obliteration and clinical status. Median followup time was 32 months (range; 20-93 months). Spetzler-Martin grade I-II and AVM sizes below 3 cm were associated with increased obliteration rate (p=0.01). The annual hemorrhage risk was 1.9%. No patients experienced deterioration of neurological status at follow-up. LINAC-based SRS is a safe and effective treatment modality in the management of cerebral AVMs. SRS comprises an effective alternative to surgery for the treatment of particularly small AVMs inaccessible with surgery.

Long-term Outcomes After Staged-Volume Stereotactic Radiosurgery for Large Arteriovenous Malformations

Stereotactic radiosurgery is an effective treatment modality for small arteriovenous malformations (AVMs) of the brain. For larger AVMs, the treatment dose is often lowered to reduce potential complications, but this decreases the likelihood of cure. One strategy is to divide large AVMs into smaller anatomic volumes and treat each volume separately. To prospectively assess the long-term efficacy and complications associated with staged-volume radiosurgical treatment of large, symptomatic AVMs. Eighteen patients with AVMs larger than 15 mL underwent prospective staged-volume radiosurgery over a 13-year period. The median AVM volume was 22.9 mL (range, 15.7-50 mL). Separate anatomic volumes were irradiated at 3- to 9-month intervals (median volume, 10.9 mL; range, 5.3-13.4 mL; median marginal dose, 15 Gy; range, 15-17 Gy). The AVM was divided into 2 volumes in 10 patients, 3 volumes in 5 patients, and 4 volumes in 3 patients. Seven patients underwent retreatment for residual disease. Actuarial rates of complete angiographic occlusion were 29% and 89% at 5 and 10 years. Five patients (27.8%) had a hemorrhage after radiosurgery. Kaplan-Meier analysis of cumulative hemorrhage rates after treatment were 12%, 18%, 31%, and 31% at 2, 3, 5, and 10 years, respectively. One patient died after a hemorrhage (5.6%). Staged-volume radiosurgery for AVMs larger than 15 mL is a viable treatment strategy. The long-term occlusion rate is high, whereas the radiation-related complication rate is low. Hemorrhage during the lag period remains the greatest source of morbidity and mortality.

Surgical and radiosurgical results of the treatment of cerebral arteriovenous malformations

Microsurgical resection of a cerebral arteriovenous malformation (AVM) allows for an immediate therapeutic cure. Stereotactic radiosurgery (SRS) is a reasonable alternative for inoperable or high-risk lesions requiring treatment. Few series evaluate overall results that include data from both modalities as they more often focus on their treatment method of choice. In this study, we evaluated our AVM database of 129 patients seen over the past eight years at our institution: 73 were treated with microsurgery (57%) while 37 (29%) were treated with SRS. We reviewed angiographic obliteration rates, complication rates, and outcome data, excluding seven patients treated with SRS as they did not have at least two years of angiographic follow-up. Patients undergoing microsurgery had smaller AVM (mean 2.2cm compared to 3.5cm for SRS), a smaller proportion of eloquent AVM (53% compared to 83% for SRS), a greater proportion of AVM with superficial drainage only (75% compared to 40% for SRS), and more grade 1 and 2 AVM (78% compared to 17% for SRS). The overall obliteration rate was 80%: 92% for microsurgery and 50% for SRS. The latter increased to 92% for AVM <3cm, but the obliteration rate was 18% for those AVM >3cm. Transient complications, including post-SRS hemorrhage, were seen in 11% of patients overall (8% after microsurgery, 17% after SRS). At follow-up, 53% of patients had improved, 37% remained the same, 7% had become worse and 3% had died. As a result of post-SRS hemorrhage, a greater proportion of patients was worse or had died after SRS (20%) compared to those who had been treated with microsurgery (5%).