Bleeding after Radiosurgery for Cerebral Arteriovenous Malformations

Long-term outcomes of microsurgery and stereotactic radiosurgery as the first-line treatment for arteriovenous malformations: a propensity score-matched analysis using nationwide multicenter prospective registry data

BACKGROUND

This study aimed to compare the risk and benefit profile of microsurgery (MS) and stereotactic radiosurgery (SRS) as the first-line treatment for unruptured and ruptured arteriovenous malformations (AVMs).

MATERIALS AND METHODS

The authors included AVMs underwent MS or SRS as the first-line treatment from a nationwide prospective multicenter registry in mainland China. The authors used propensity score-matched methods to balance baseline characteristics between the MS and SRS groups. The primary outcomes were long-term hemorrhagic stroke or death, and the secondary outcomes were long-term obliteration and neurological outcomes. Subgroup analyses and sensitivity analyses with different study designs were performed to confirm the stability of our findings.

RESULTS

Of the 4286 consecutive AVMs in the registry from August 2011 to December 2021; 1604 patients were eligible. After matching, 244 unruptured and 442 ruptured AVMs remained for the final analysis. The mean follow-up duration was 7.0 years in the unruptured group and 6.1 years in the ruptured group. In the comparison of primary outcomes, SRS was associated with a higher risk of hemorrhagic stroke or death both in the unruptured and ruptured AVMs (unruptured: hazard ratio 4.06, 95% CI: 1.15-14.41; ruptured: hazard ratio 4.19, 95% CI: 1.58-11.15). In terms of the secondary outcomes, SRS was also observed to have a significant disadvantage in long-term obliteration [unruptured: odds ratio (OR) 0.01, 95% CI: 0.00-0.04; ruptured: OR 0.09, 95% CI: 0.05-0.15]. However, it should be noted that SRS may have advantages in preventing neurofunctional decline (unruptured: OR 0.56, 95% CI: 0.27-1.14; ruptured: OR 0.41, 95% CI: 0.23-0.76). The results of subgroup analyses and sensitivity analyses were consistent in trend but with slightly varied powers.

CONCLUSIONS

This clinical practice-based real-world study comprehensively compared MS and SRS for AVMs with long-term outcomes. MS is more effective in preventing future hemorrhage or death and achieving obliteration, while the risk of neurofunctional decline should not be ignored.

Chronic Encapsulated Expanding Hematomas After Stereotactic Radiosurgery for Intracranial Arteriovenous Malformations: An International Multicenter Case Series

BACKGROUND

Stereotactic radiosurgery (SRS) offers a minimally invasive treatment modality for appropriately selected intracranial arteriovenous malformations (AVMs). Recent reports have described the development of rare, delayed chronic encapsulated expanding hematomas (CEEHs) at the site of an angiographically confirmed obliterated AVM.

OBJECTIVE

To elucidate the incidence, characteristics, and management of CEEH in patients with AVM after SRS.

METHODS

The records of all patients who underwent SRS for an intracranial AVM at 4 institutions participating in the International Radiosurgery Research Foundation between 1987 and 2021 were retrospectively reviewed. Data regarding characteristics of the AVM, SRS treatment parameters, CEEH presentation, management, and outcomes were collected and analyzed.

RESULTS

Among 5430 patients, 15 developed a CEEH at a crude incidence of 0.28%. Nine patients were female, and the mean age was 43 ± 14.6 years. Nine patients underwent surgical evacuation, while 6 were managed conservatively. The median CEEH development latency was 106 months after SRS. The patients were followed for a median of 32 months, and 9 patients improved clinically, while 6 patients remained stable. No intraoperative complications were reported after CEEH resection, although 1 patient recovered from postoperative meningitis requiring intravenous antibiotics.

CONCLUSION

CEEH is a rare, late complication of AVM SRS with an incidence of 0.28% and a median latency of 106 months. In the presence of a delayed and symptomatic expanding hematoma in the bed of an angiographically obliterated AVM, surgical resection resulted in clinical improvement in most patients. Conservative management is possible in asymptomatic patients with stable, small-sized hematomas in deeply seated locations.

Risk for Hemorrhage the First 2 Years After Gamma Knife Surgery for Arteriovenous Malformations: An Update

BACKGROUND

Knowledge about the natural course of brain arteriovenous malformations (AVMs) have increased during the past 20 years, as has the number of AVMs treated, especially larger ones. It is thus timely to again analyze the risk for hemorrhage after Gamma Knife Surgery (GKS).

OBJECTIVE

To confirm or contradict conclusions drawn 20 years ago regarding factors that affect the risk for post-GKS hemorrhage.

METHODS

The outcome after GKS was studied in 5037 AVM patients followed for up to 2 years. The relation between post-treatment hemorrhage rate and a number of patient, AVM, and treatment parameters was analyzed. The results were also compared with the results from our earlier study.

RESULTS

The annual post-treatment hemorrhage rate was 2.4% the first 2 years after GKS. Large size, low treatment dose, and old age were independent risk factors for AVM hemorrhage. After having compensated for the factors above, peripheral AVM location and female sex, at least during their child bearing ages, were factors associated with a lower post-GKS hemorrhage rate.

CONCLUSION

Large AVMs (>5 cm 3 ) treated with low doses (≤16 Gy) had higher and small AVMs treated with high doses a lower risk for hemorrhage as compared with untreated AVMs. This was detectable within the first 6 months after GKS. No difference in hemorrhage rate could be detected for the other AVMs. Based on our findings, it is advisable to prescribe >16 Gy to larger AVMs, assuming that the risk for radiation-induced complications can be kept at an acceptable level.

Chronic encapsulated expanding hematomas after stereotactic radiosurgery for intracranial arteriovenous malformations

OBJECTIVE

Cerebral arteriovenous malformations (AVMs) are rare cerebral vascular lesions that are associated with high morbidity and mortality from hemorrhage; however, stereotactic radiosurgery (SRS) is a well-validated treatment modality. Few reports have delineated a subgroup of patients who develop delayed chronic encapsulated expanding hematomas (CEEHs) despite angiographic evidence of AVM obliteration following radiosurgery. In this report, the authors performed a retrospective review of more than 1000 radiosurgically treated intracranial AVM cases to delineate the incidence and management of this rare entity.

METHODS

Between 1988 and 2019, 1010 patients with intracranial AVM underwent Gamma Knife SRS at the University of Pittsburgh Medical Center. In addition to a review of a prospective institutional database, the authors performed a retrospective chart review of the departmental AVM database to specifically identify patients with CEEH. Pertinent clinical and radiological characteristics as well as patient outcomes were recorded and analyzed.

RESULTS

Nine hundred fifty patients with intracranial AVM (94%) had sufficient clinical follow-up for analysis. Of these, 6 patients with CEEH underwent delayed resection (incidence rate of 0.0045 event per person-year). These patients included 4 males and 2 females with a mean age of 45.3 ± 13.8 years at the time of initial SRS. Four patients had smaller AVM volumes (4.9-10 cm3), and 3 of them were treated with a single SRS procedure. Two patients had larger-volume AVMs (55 and 56 cm3), and both underwent multimodal management that included staged SRS and embolization. Time to initial recognition of the CEEH after initial SRS ranged between 66 and 243 months. The time between CEEH recognition and resection ranged from 2 to 9 months. Resection was required because of progressive neurological symptoms that correlated with imaging evidence of gradual hematoma expansion. All 6 patients had angiographically confirmed obliteration of their AVM. Pathology revealed a mixed chronicity hematoma with areas of fibrosed blood vessels and rare areas of neovascularization with immature blood vessels but no evidence of a persistent AVM. All 6 patients reported persistent clinical improvement after hematoma resection.

CONCLUSIONS

CEEH after SRS for AVM is a rare complication with an incidence rate of 0.0045 event per person-year over the authors' 30-year experience. When clinical symptoms progress and imaging reveals progressive enlargement over time, complete resection of a CEEH results in significant clinical recovery. Knowledge of this rare entity facilitates timely detection and eventual surgical intervention to achieve optimal outcomes.

Clinical outcome following cerebral AVM hemorrhage

BACKGROUND

A significant difference exists between the published results reporting the clinical outcome following brain arteriovenous malformation (AVM) ruptures. Information about the outcome following hemorrhage in an AVM population treated with radiosurgery could provide additional information to assess the risk of mortality and morbidity following an AVM hemorrhage.

METHODS

Clinical outcome was studied in 383 patients, the largest patient population yet studied, who suffered from a symptomatic hemorrhage after Gamma Knife® surgery (GKS) but before confirmed AVM obliteration. The impact of different patient, AVM, and treatment parameters on the clinical outcome was analyzed. The aim was to generate outcome predictions by comparing our data to and combining them with earlier published results.

RESULTS

No relation was found between clinical outcome and treatment parameters, indicating that the results are applicable also on untreated AVMs. Twenty-one percent of the patients died, 45% developed or experienced worsening of neurological sequelae, and 35% recovered completely after the hemorrhage. Old age was a predictor of poor outcome. Sex, AVM location, AVM volume, and history of prior hemorrhage did not influence the outcome. The mortality rate was comparable to earlier published prospective data, but higher than that found in retrospective studies.

CONCLUSIONS

The mortality rates in earlier published retrospective series as well as in studies focusing on clinical outcome following AVM hemorrhage significantly underestimate the risk for a mortal outcome following an AVM hemorrhage. Based on our findings, an AVM rupture has around 20% likelihood to result in mortality, 45% likelihood to result in a minor or major deficit, and 35% likelihood of complete recovery. The findings are probably applicable also for AVM ruptures in general. The cumulative mortality and morbidity rates 25 years after diagnosis were estimated to be around 40% in a patient with a patent AVM.

Pediatric intracranial arteriovenous malformations: a single-center experience

OBJECTIVE

Intracranial arteriovenous malformations (AVMs) are a common cause of intracranial hemorrhage in children. Exploring outcomes of treatment and factors that predict recurrence may help guide the management of pediatric AVMs. In this study, the authors review a single-center experience with pediatric AVMs, aiming to identify factors contributing to recurrence and areas for improvement in treatment.

METHODS

A single-center retrospective review of patients ages 0–18 years with AVMs in the period from 2005 to 2018 was conducted. Demographic, clinical, and radiographic data were collected and examined to compare the clinical and functional outcomes of patients managed with and those managed without open microsurgical resection.

RESULTS

One hundred five patients were diagnosed and treated during the study period. Fifty (47.6%) had been treated surgically and 35 (33.3%) nonsurgically, and 20 (19%) had been treated primarily at an outside institution and thus were excluded from further analysis. Of the 50 treated surgically, 92% had complete obliteration on postoperative imaging, with the remaining patients having residual AVM and undergoing re-resection or SRS, ultimately resulting in a 96% radiographic cure rate. The surgically treated patients were followed up for an average of 3.34 years. Eighty-two percent had a modified Rankin Scale (mRS) score of 0–2. There was a recurrence rate of 12%, with the time to recurrence averaging 327.86 days (range 85–596 days). Of the 35 patients managed without open surgery, 77% underwent serial imaging surveillance, 20% underwent endovascular embolization, and 3% underwent stereotactic radiosurgery. Radiographic cure was seen in 6% of those treated nonsurgically, and all had undergone endovascular treatment alone. The nonsurgically treated patients were followed up for an average of 2.14 years. Eighty percent had an mRS score of 0–2.

CONCLUSIONS

The data revealed that patients with lower-grade AVMs treated surgically and those with higher-grade AVMs managed without surgery have good functional and clinical outcomes. A high rate of recurrence was noted, and the possible contributing factors were explored. The authors encourage further study into mechanisms to reduce AVM recurrence in pediatric patients and look forward to advances in the medical management of lesions that are considered unresectable.

Short Term Effectiveness of Gamma Knife Radiosurgery in the Management of Brain Arteriovenous Malformation

AIM:

To evaluate the short-term effectiveness of Gamma knife radiosurgery as a modality of treatment of brain arteriovenous malformation.

METHODS:

Sixty-three patients with arteriovenous brain malformations underwent Gamma knife radiosurgery included in this prospective study between April 2017 and September 2018 with clinical and radiological with MRI follow up was done at three months and six months post-Gamma knife radiosurgery. By the end of the 12th-month post-Gamma knife radiosurgery, the patients were re-evaluated using digital subtraction angiography co-registered with M.R.I. During the 12 months follow up, CT scan or MRI was done at any time if any one of the patients' condition deteriorated or developed signs and symptoms of complications. The mean volume of the arteriovenous malformations treated was 26.0 ± 5 cm³ (range 12.5–39.5 cm³) in The Neurosciences Hospital, Baghdad/Iraq.

RESULTS:

By the end of the 12th month of follow up, the overall obliteration of the arteriovenous malformations was seen in six patients only (9.5%), while shrinkage was noticed in 57 patients (90.5%). Improvement or clinical stability was found in 24 out of 39 patients (61.5%) presented with epilepsy as a chief complaint before Gamma knife radiosurgery and 21 out of 24 patients (87.0%) complained of a headache before Gamma knife radiosurgery. Post-Gamma knife radiosurgery bleeding was found in only three patients (5.0%).

CONCLUSION:

Even with the short term follow up, Gamma knife radiosurgery has an excellent clinical outcome in most patients with arteriovenous brain malformations. The clinical symptoms like headache and seizure were either diminished or controlled with the same medical treatment dose before Gamma knife radiosurgery. Long term clinical and radiological follow up is recommended.

Morphologic Change of Flow-Related Aneurysms in Brain Arteriovenous Malformations after Stereotactic Radiosurgery

BACKGROUND AND PURPOSE

The natural history of flow-related aneurysms after obliteration of brain arteriovenous malformations is poorly understood. The purpose of this study was to evaluate the angioarchitecture and morphologic change in flow-related aneurysms after gamma knife surgery of brain arteriovenous malformations.

MATERIALS AND METHODS

During a 12-year period, 823 patients with brain arteriovenous malformations underwent gamma knife surgery at our institution with complete peritherapeutic angiographic evaluation. From this population, a series of 72 patients (8.8%) with 111 flow-related aneurysms were enrolled (1.5 aneurysms per patient). There were 43 men and 29 women; ages ranged from 18 to 72 years (mean, 43 years). The morphologic change of flow-related aneurysms was longitudinally evaluated before and after obliteration of brain arteriovenous malformations. After gamma knife surgery, angiographic follow-up varied from 26 to 130 months (mean, 58 months).

RESULTS

All flow-related aneurysms were small (mean, 4.1 mm; range, 2-9 mm). There were 72 proximal flow-related aneurysms (mean size, 4.3 mm) and 39 distal flow-related aneurysms (mean size, 3.7 mm). Spontaneous thrombosis occurred more frequently in distal flow-related aneurysms than in proximal flow-related aneurysms (P < .001). Smaller flow-related aneurysms (<5 mm) tended to spontaneously occlude after obliteration of brain arteriovenous malformations (P = .036). Two patients had ruptures of proximal flow-related aneurysms at 27- and 54-month follow-ups, respectively.

CONCLUSIONS

Spontaneous thrombosis occurred more frequently in distal flow-related aneurysms due to occlusion or normalization of distal feeders. Smaller flow-related aneurysms also tended to spontaneously thrombose after obliteration of brain arteriovenous malformations. The rate of flow-related aneurysm rupture in our series was similar to that of natural intradural aneurysms.

Transvenous embolization of arteriovenous malformations

Embolization of arteriovenous malformations is characteristically used as part of a multimodal treatment approach, pre-operatively to facilitate microsurgical resection or as a preradiosurgical adjunct. The concept of AVM cure via embolization alone has gained popularity in recent years. Embolization of AVMs has been most commonly performed transarterially, with the transvenous route traditionally eschewed given concern over precipitating premature venous occlusion and consequent hemorrhage. However, the transvenous approach in treating AVMs offers several distinct advantages compared to the transarterial route and can be used in instances when the latter is not feasible, with several series having proven its efficacy and safety. Conceptually, AVM embolization performed via the transvenous route achieves complete obliteration by directly and facilely targeting the nidus. Nidal embolisate penetration is facilitated by control of arterial inflow via systemic or local hypotension. Innovation in endovascular strategies has led to significantly improved obliteration rates. The experience with transvenous AVM embolization is reviewed and discussed.

Modern radiosurgical and endovascular classification schemes for brain arteriovenous malformations

Stereotactic radiosurgery (SRS) and endovascular techniques are commonly used for treating brain arteriovenous malformations (bAVMs). They are usually used as ancillary techniques to microsurgery but may also be used as solitary treatment options. Careful patient selection requires a clear estimate of the treatment efficacy and complication rates for the individual patient. As such, classification schemes are an essential part of patient selection paradigm for each treatment modality. While the Spetzler-Martin grading system and its subsequent modifications are commonly used for microsurgical outcome prediction for bAVMs, the same system(s) may not be easily applicable to SRS and endovascular therapy. Several radiosurgical- and endovascular-based grading scales have been proposed for bAVMs. However, a comprehensive review of these systems including a discussion on their relative advantages and disadvantages is missing. This paper is dedicated to modern classification schemes designed for SRS and endovascular techniques.

Critical review of brain AVM surgery, surgical results and natural history in 2017

BACKGROUND

An understanding of the present standing of surgery, surgical results and the role in altering the future morbidity and mortality of untreated brain arteriovenous malformations (bAVMs) is appropriate considering the myriad alternative management pathways (including radiosurgery, embolization or some combination of treatments), varying risks and selection biases that have contributed to confusion regarding management. The purpose of this review is to clarify the link between the incidence of adverse outcomes that are reported from a management pathway of either surgery or no intervention with the projected risks of surgery or no intervention.

METHODS

A critical review of the literature was performed on the outcomes of surgery and non-intervention for bAVM. An analysis of the biases and how these may have influenced the outcomes was included to attempt to identify reasonable estimates of risks.

RESULTS

In the absence of treatment, the cumulative risk of future hemorrhage is approximately 16% and 29% at 10 and 20 years after diagnosis of bAVM without hemorrhage and 35% and 45% at 10 and 20 years when presenting with hemorrhage (annualized, this risk would be approximately 1.8% for unruptured bAVMs and 4.7% for 8 years for bAVMs presenting with hemorrhage followed by the unruptured bAVM rate). The cumulative outcome of these hemorrhages depends upon whether the patient remains untreated and is allowed to have a further hemorrhage or is treated at this time. Overall, approximately 42% will develop a new permanent neurological deficit or death from a hemorrhagic event. The presence of an associated proximal intracranial aneurysm (APIA) and restriction of venous outflow may increase the risk for subsequent hemorrhage. Other risks for increased risk of hemorrhage (age, pregnancy, female) were examined, and their purported association with hemorrhage is difficult to support. Both the Spetzler-Martin grading system (and its compaction into the Spetzler-Ponce tiers) and Lawton-Young supplementary grading system are excellent in predicting the risk of surgery. The 8-year risk of unfavorable outcome from surgery (complication leading to a permanent new neurological deficit with a modified Rankin Scale score of greater than one, residual bAVM or recurrence) is dependent on bAVM size, the presence of deep venous drainage (DVD) and location in critical brain (eloquent location). For patients with bAVMs who have neither a DVD nor eloquent location, the 8-year risk for an unfavorable outcome increases with size (increasing from 1 cm to 6 cm) from 1% to 9%. For patients with bAVM who have either a DVD or eloquent location (but not both), the 8-year risk for an unfavorable outcome increases with the size (increasing from 1 cm to 6 cm) from 4% to 35%. For patients with bAVM who have both a DVD and eloquent location, the 8-year risk for unfavorable outcome increases with size (increasing from 1 cm to 3 cm) from 12% to 38%.

CONCLUSION

Patients with a Spetzler-Ponce A bAVM expecting a good quality of life for the next 8 years are likely to do better with surgery in expert centers than remaining untreated. Ongoing research is urgently required on the outcome of management pathways for bAVM.

Radiosurgery in treatment of cerebral arteriovenous malformation: Mid-term results of 388 cases from a single center

Background and Objectives:

The purpose of this study is to evaluate the outcome and risks of radiosurgery for patients with arteriovenous malformations (AVM) of the brain all treated in a single center in the 3^rd world with all its limitations.

Materials and Methods:

We performed a retrospective analysis of 388 patients with AVM treated with radiosurgery during an 8-year period. Factors associated with increased chance of AVM obliteration or hemorrhages during the follow-up period were analyzed.

Results:

Among 388 cases included in our series, 74 were Spetzler-Martin (SM) grade IV or V. Forty-four patients (11.3%) experienced post-radiosurgery hemorrhage in their follow-up period. The number of feeders (one/multiple) and deep location of the AVM did not alter the chance of bleeding (P < 0.05). Higher SM grading of the AVM was associated with increased chance of hemorrhage and decreased obliteration rate (P > 0.05) in the mid-term follow up.

Conclusions:

Our case series showed that radiosurgery can be considered a viable alternative in the treatment of even large AVMs which might not be considered good candidates for surgery or endovascular treatment. Further data including large size lesions are warranted to further support our findings.

Linear Accelerator Stereotactic Radiosurgery of Central Nervous System Arteriovenous Malformations: A 15-Year Analysis of Outcome-Related Factors in a Single Tertiary Center

BACKGROUND

Linear accelerator stereotactic radiosurgery is one of the modalities available for the treatment of central nervous system arteriovenous malformations (AVMs). The aim of this study was to describe our 15-year experience with this technique in a single tertiary center and the analysis of outcome-related factors.

METHODS

From 1998 to 2013, 195 patients were treated with linear accelerator-based radiosurgery; we conducted a retrospective study collecting patient- and AVM-related variables. Treatment outcomes were obliteration, posttreatment hemorrhage, symptomatic radiation-induced changes, and 3-year neurologic status. We also analyzed prognostic factors of each outcome and predictability analysis of 5 scales: Spetzler-Martin grade, Lawton-Young supplementary and Lawton combined scores, radiosurgery-based AVM score, Virginia Radiosurgery AVM Scale, and Heidelberg score.

RESULTS

Overall obliteration rate was 81%. Nidus diameter and venous drainage were predictive of obliteration (P < 0.05), ruptured status and previous embolization were not related to rate of obliteration, and low-grade AVMs had higher obliteration rates. Posttreatment hemorrhage incidence was 8.72%; nidus diameter was the only predictor (P = 0.05). Symptomatic radiation-induced changes occurred in 11.79% of patients and were significantly associated with unruptured status (P < 0.05). Treatment success as a composite measure was obtained in 70.77% of patients. Receiver operating characteristic curves were presented for each scoring system and outcome measure; best area under the curve was 0.687 for Lawton combined score in the obliteration outcome.

CONCLUSIONS

In the long-term, linear accelerator-based radiosurgery is a useful, valid, effective, and safe modality for treatment of brain AVMs.

Arterial spin labeling magnetic resonance imaging: toward noninvasive diagnosis and follow-up of pediatric brain arteriovenous malformations

OBJECT Arterial spin labeling (ASL)-MRI is becoming a routinely used sequence for ischemic strokes, as it quantifies cerebral blood flow (CBF) without the need for contrast injection. As brain arteriovenous malformations (AVMs) are highflow vascular abnormalities, increased CBF can be identified inside the nidus or draining veins. The authors aimed to analyze the relevance of ASL-MRI in the diagnosis and follow-up of children with brain AVM. METHODS The authors performed a retrospective analysis of 21 patients who had undergone digital subtraction angiography (DSA) and pseudo-continuous ASL-MRI for the diagnosis or follow-up of brain AVM after radiosurgery or embolization. They compared the AVM nidus location between ASL-MRI and 3D contrast-enhanced T1 MRI, as well as the CBF values obtained in the nidus (CBFnidus) and the normal cortex (CBFcortex) before and after treatment. RESULTS The ASL-MRI correctly demonstrated the nidus location in all cases. Nidal perfusion (mean CBFnidus 137.7 ml/100 mg/min) was significantly higher than perfusion in the contralateral normal cortex (mean CBFcortex 58.6 ml/100 mg/min; p < 0.0001, Mann-Whitney test). Among 3 patients followed up after embolization, a reduction in both AVM size and CBF values was noted. Among 5 patients followed up after radiosurgery, a reduction in the nidus size was observed, whereas CBFnidus remained higher than CBFcortex. CONCLUSIONS In this study, ASL-MRI revealed nidus location and patency after treatment thanks to its ability to demonstrate focal increased CBF values. Absolute quantification of CBF values could be relevant in the follow-up of pediatric brain AVM after partial treatment, although this must be confirmed in larger prospective trials.

Draining Vein Shielding in Intracranial Arteriovenous Malformations During Gamma-Knife

BACKGROUND:

Following gamma knife (GK) therapy for intracranial arteriovenous malformations (AVMs), obliteration of the nidus occurs over several years. During this period, complications like rebleeding have been attributed to early draining vein occlusion.

OBJECTIVE:

To evaluate if shielding the draining vein(s) during GK therapy prevents early draining vein obliteration and complications following GK therapy.

METHODS:

This was a nonrandomized case-control study over 5 years (January 2009-February 2014) and included patients with intracranial AVM who underwent GK therapy at our center. All patients who underwent draining vein shielding by the senior author (D.A.) were included in the test group, and patients who did not undergo draining vein shielding were put in the control group. Patients were followed up for at least 6 months (and every 6 months thereafter) clinically as well as radiologically with computed tomography head scans/magnetic resonance imaging brain scans to check for postradiosurgery imaging (PRI) changes.

RESULTS:

One hundred eighty-five patients were included in this study, of which 96 were in the control group and 89 were in the test group. Both groups were well matched in demographics, comorbidities, adjuvant treatment, angioarchitecture, and radiation dosing. Because of shielding, the test group patients received significantly less radiation to the draining vein than the control group (P = .001). On follow-up, a significantly lower number of patients in the test group had new neurological deficits (P = .001), intracranial hemorrhage (P = .03), and PRI changes (P = .002).

CONCLUSION:

Shielding of the draining vein is a potent new strategy in minimizing PRI and hemorrhage as well as clinical deterioration following GK therapy for intracranial AVMs.

Stereotactic radiosurgery of intracranial arteriovenous malformations

Stereotactic radiosurgery for intracranial arteriovenous malformations (AVMs) has been performed since the 1970s. When an AVM is treated with radiosurgery, radiation injury to the vascular endothelium induces the proliferation of smooth muscle cells and the elaboration of extracellular collagen, which leads to progressive stenosis and obliteration of the AVM nidus. Obliteration after AVM radiosurgery ranges from 60% to 80%, and relates to the size of the AVM and the prescribed radiation dose. The major drawback of radiosurgical AVM treatment is the risk of bleeding during the latent period (typically 2 years) between treatment and AVM thrombosis.

Vascular complications of stereotactic radiosurgery for arteriovenous malformations

OBJECTIVE

Although vasculopathy and de novo aneurysm formation are known complications of traditional radiation therapy, their occurrence following AVM SRS is rare and thus infrequently addressed in the literature. We sought to evaluate these phenomena through a review of our institutional experience.

METHODS

Our review afforded 32 patients treated with LINAC-based SRS over an eight year period. We noted obliteration rates, complication rates and long-term outcomes, with particular attention paid to follow-up angiographic studies.

RESULTS

After a mean follow-up of 4.3 years, the overall obliteration rate was 50%, increasing to 87% for AVMs less than 3cm. Eight patients had nine hemorrhages following SRS (25%). One occurred in the context of a de novo arterial pseudoaneurysm and another in the context of a new venous varix. Two patients with post-SRS hemorrhage had intranidal aneurysms that were not as apparent on initial angiography. Two patients that did not suffer from latency period hemorrhage developed dysplastic changes of feeding arteries, and one patient suffered from early venous thrombosis with resultant permanent hemiparesis from infarction. After a mean follow-up of 4.3 years, 8 patients were clinically improved (25%), 19 were the same (59%), and 5 were worse (16%), including 2 that died as a result of latency period hemorrhage.

CONCLUSION

While radiosurgery of AVMs is safe and successful in the vast majority of cases, vasculopathic complications including de novo aneurysm and varix development, early venous occlusion and stenotic vasculopathy, while infrequent, can occur. Closer long-term angiographic surveillance of these patients may thus be warranted.

Radiosurgery for arteriovenous malformations

Stereotactic radiosurgery is the term coined by Lars Leksell to describe the application of a single, high dose of radiation to a stereotactically defined target volume. In the 1970s, reports began to appear documenting the successful obliteration of arteriovenous malformations (AVMs) with radiosurgery. When an AVM is treated with radiosurgery, a pathologic process appears to be induced that is similar to the response-to-injury model of atherosclerosis. Radiation injury to the vascular endothelium is believed to induce the proliferation of smooth-muscle cells and the elaboration of extracellular collagen, which leads to progressive stenosis and obliteration of the AVM nidus thereby eliminating the risk of hemorrhage. The advantages of radiosurgery - compared to microsurgical and endovascular treatments - are that it is noninvasive, has minimal risk of acute complications, and is performed as an outpatient procedure requiring no recovery time for the patient. The primary disadvantage of radiosurgery is that cure is not immediate. While thrombosis of the lesion is achieved in the majority of cases, it commonly does not occur until two or three years after treatment. During the interval between radiosurgical treatment and AVM thrombosis, the risk of hemorrhage remains. Another potential disadvantage of radiosurgery is possible long term adverse effects of radiation. Finally, radiosurgery has been shown to be less effective for lesions over 10 cc in volume. For these reasons, selection of the optimal treatment for an AVM is a complex decision requiring the input of experts in endovascular, open surgical, and radiosurgical treatment. In the pages below, we will review the world's literature on radiosurgery for AVMs. Topics reviewed will include the following: radiosurgical technique, radiosurgery results (gamma knife radiosurgery, particle beam radiosurgery, linear accelerator radiosurgery), hemorrhage after radiosurgery, radiation induced complications, repeat radiosurgery, and radiosurgery for other types of vascular malformation.

Management of incidentally discovered intracranial vascular abnormalities

With the widespread use of brain imaging studies, neurosurgeons have seen a marked increase in the number of incidental intracranial lesions, including vascular abnormalities. Specifically, the detection of incidentally discovered aneurysms, arteriovenous malformations, cavernous angiomas, developmental venous anomalies, and capillary telangiectasias has increased. The best management strategy for most of these lesions is controversial. Treatment options include observation, open surgery, endovascular procedures, and radiosurgery. Multiple factors should be taken into account when discussing treatment indications, including the natural history of the disease and the risk of the treatment. In this article, the authors focus on the natural history of these lesions and the risk of the treatment, and they give recommendations regarding the most appropriate management strategy based on the current evidence in the literature and their experience with intracranial vascular abnormalities.

Linac stereotactic radiosurgery for the treatment of small arteriovenous malformations: lower doses can be equally effective

OBJECTIVE

The purpose of this study was to examine the efficacy and toxicity of treating small arteriovenous malformations (AVMs) (≤3 cm in diameter) with a median marginal applied dose of 14 Gy.

METHODS

Two hundred and thirteen patients diagnosed with AVMs were treated between January 1991 and December 2005. Seventy-three percent of the patients had hemorrhaged prior to treatment, 13% had had previous surgery and 19.2% had had previous embolization. The median follow-up duration was 48.1 months.

RESULTS

The Kaplan-Meier analysis estimated that the 36-month obliteration rate was 65.5% for patients undergoing their first stereotactic radiosurgery (SRS) and 68.3% for those undergoing repeated SRS. The Kaplan-Meier analysis estimated the 60-month AVMs obliteration rate for the entire cohort to be 82.4%. The median time to AVM obliteration was 40 ± 2.8 months. We found a statistically significant relationship between the time of obliteration and the following factors: site of the AVMs (sites other than brainstem), a higher prescribed dose and a positive history of previous hemorrhage. Thirteen patients (7.6%) experienced toxicities.

CONCLUSIONS

SRS was an effective and safe treatment for AVMs ≤3 cm in diameter, with acceptable toxicity.

Characteristics of arteriovenous malformations associated with cerebral aneurysms

OBJECTIVE

To analyze the characteristics of brain arteriovenous malformations (AVMs) associated with cerebral aneurysms.

METHODS

A total of 302 consecutive, retrospectively reviewed patients from the Beijing Tiantan Hospital were analyzed in this study. The presence of cerebral aneurysm was confirmed by pretherapeutic selective and superselective angiography. Clinical presentation was categorized as intracranial hemorrhage or nonhemorrhagic presentation. Univariate and multivariate statistical models were applied to test the effect of age, sex, AVM size and location, and venous drainage pattern.

RESULTS

Of the 302 patients, 74 (24.5%) had AVMs associated with cerebral aneurysms. AVMs coexisting with aneurysms were significantly associated with hemorrhage at initial presentation (2.27; 95% confidence interval 1.31-3.95; P = 0.003). Infratentorial AVM location was significantly associated with AVMs coexisting with aneurysms (2.31; 95% confidence interval 1.02-5.24; P = 0.040). Deep or superficial venous drainage, female sex, or AVM size were not significantly associated with AVMs coexisting with aneurysms. The regression model showed significant effect was found for initial presentation with hemorrhage (P = 0.003), age (P = 0.003), and infratentorial AVM location (P = 0.040).

CONCLUSIONS

Our findings suggest that AVMs associated with cerebral aneurysms are frequently associated with initial hemorrhage presentation and infratentorial AVM location.

A 10-year experience of radiosurgical treatment for cerebral arteriovenous malformations: a perspective from a series with large malformations. Clinical article

OBJECT

The purpose of this study was to describe a 10-year experience in the use of radiosurgery (RS) for patients with arteriovenous malformations (AVMs) in Puerto Rico.

METHODS

This retrospective analysis was performed for all patients with AVMs treated with RS by the senior author (R.H.B.) in Puerto Rico. Between February 1999 and December 2009, a total of 83 patients underwent the procedure. All charts were reviewed for recollection of demographic data, and AVM and treatment characteristics. Clinical and radiographic follow-up information was collected retrospectively.

RESULTS

Eighty-three patients were treated and 86 RS procedures for AVMs were performed during a 10-year period. Eight patients were lost to follow-up. The remaining 75 patients included 36 males and 39 females, whose median age was 34.5 years. Hemorrhage was the initial presentation in 40% of patients. Fifty-seven AVMs (73%) were treated previously with endovascular neurosurgery, without success. The median volume of the malformation was 17.7 ml. Nearly 65% of the malformations were considered large (≥ 10 ml) in volume. Forty patients had AVMs with largest diameter ≥ 3.5 cm. The overall obliteration rate was 56.4%, and the median time for obliteration was 29 months. The AVMs ≥ 3.5 cm in diameter had a greater latency period than those < 3.5 cm (31 months vs 46 months, respectively; p = 0.01). In addition, AVM obliteration was inversely associated with its volume, especially in large lesions (p = 0.037). In bivariate analysis, patients achieving obliteration had lower Spetzler-Martin scores compared with patients in whom obliteration was not achieved (p = 0.009). Postradiosurgery hemorrhages were seen in 9 cases. Eleven patients underwent surgery after RS. Major neurological deficits developed in 9 patients, whereas 17 had only minor deficits. The occurrence of neurological deficits was significantly associated with lesions with volume ≥ 10 ml.

CONCLUSIONS

Radiosurgery is a reasonable treatment option for AVMs in the majority of cases, in spite of the large, difficult-to-treat malformations.

How to deal with incompletely treated AVMs: experience of 67 cases and review of the literature

INTRODUCTION

Despite the availability of multimodal treatment options, some arteriovenous malformations remain difficult to treat, either for intrinsic reasons at initial presentation or for reasons evolving during the course of treatment. Frequently, such cases can be easily resolved with further therapy, but some become a continuously growing treatment dilemma while exhausting dwindling therapeutic options.

PATIENTS AND METHODS

A retrospective analysis was performed to identify patients with cerebral AVM who were treated unsuccessfully. Treatment was termed "not successful" if (1) postoperative angiography showed a residual AVM or missing flow reduction after palliative embolization, (2) therapy was associated with a substantial deterioration of existing neurological deficits or death, or (3) rebleeding from residual AVM occurred after therapy. Special interest was focused on the angiographic appearance of residual AVMs, their characteristic features, and their follow-up regarding second and third therapies.

RESULTS

According to these criteria we identified 46 internal patients from our own series of 474 patients and 21 external patients who were referred from other institutions or sought a second opinion after incomplete treatment elsewhere. Out of those 67 cases, 50 patients (74.6%) were diagnosed with a residual AVM. Eleven patients (16.4%) experienced a deterioration of their clinical condition under therapy. Six patients did not show a flow reduction after palliative embolization. Twenty-five of the 67 patients were readmitted because of an ICH, either originating from an AVM residual or under palliative embolization. Thus, an increased risk of re-hemorrhage was found for palliative embolization (n = 16) in partially treated lesions (n = 10) and in patients with AVM grade IV and V located in eloquent regions (n = 22). In dealing with residual AVMs, microsurgical resection alone or in combination was found to be the most efficient therapeutic option, being successful in 58.9% of cases.

CONCLUSION

An estimated 10% of AVM treatments may fail because of inadequate selection of either patients or management. Besides, for thorough decision-making, angiographic follow-up in all AVM patients is mandatory to allow an early identification of patients with an incompletely treated AVM requiring a second attempt. Major attention should be focused especially on high-risk subgroups with complex AVMs, partially treated AVMs, or those treated by only a palliative regimen.

Speech Reorganization after an AVM Bleed Cured by Embolization. A Case Report and Review of the Literature

SUMMARY

Intracerebral arteriovenous malformations (AVMs) are defined as the direct communication of arteries to abnormal veins without interposing capillaries. Although AVMs can have various clinical presentations due to their dynamic nature, the most common presenting sign is intracerebral hemorrhage. Whenever an AVM is discovered, the therapeutic choice is often not obvious and it is influenced not only by the hemodynamic features of the AVM, but also by considerations of the extent of intervention-related morbidity and mortality. A patient with a left frontal AVM is described. He bled three years after gamma knife radiosurgery and developed aphasia. The complete obliteration of the AVM was later achieved by embolization. Functional compensatory brain reorganization and plasticity is discussed, since our patient presented with a fast recovery from aphasia and unexpected contralateral redistribution of the speech function and with preference for his second spoken language.

THE PROTECTIVE STATUS OF SUBTOTAL OBLITERATION OF ARTERIOVENOUS MALFORMATIONS AFTER RADIOSURGERY

OBJECTIVE

Arteriovenous malformations (AVMs) treated by radiosurgery with complete obliteration of the nidus but a persisting early draining vein on follow-up angiography can be termed subtotally obliterated. However, these are persistent circulating AVMs. The significance of these lesions, their hemorrhage rate, and their management are analyzed.

METHODS

In a series of 862 consecutive patients with AVMs treated by radiosurgery, 121 patients (14%) achieved subtotal obliteration (STO). The angiographic evolution and rate of obliteration were studied. The pretreatment angiographic features, dosimetric parameters, and postradiosurgery hemorrhage rate were compared with those in the rest of the treated population. Finally, the options for follow-up and treatment were analyzed.

RESULTS

Of 121 subtotally obliterated AVMs, the bleeding rate was 0%; 53% of patients achieved complete obliteration. This occurred in 71% of those who had STO at 1 year. In the cases in which STO was detected at 2, 3, and 4 years, total obliteration eventually occurred in 43%, 28.5%, and 0%, respectively. Comparative analysis with AVMs in which a part of the nidus persisted showed a significant difference in the bleeding rate. Except for volume, no significant statistical difference in angiographic and dosimetric parameters was found between the STO group and the rest of the studied population with residual nidus. Six cases received further treatment, resulting in 2 cures and 2 treatment-related complications.

CONCLUSION

Subtotally obliterated AVMs are different from other partially obliterated AVMs, with a 0% bleeding rate. Their complete obliteration is a function of delay of appearance on follow-up angiography. Invasive follow-up and further treatment of these AVMs do not seem warranted.

Thrombosis and hemorrhage in the acute period following Gamma Knife surgery for arteriovenous malformation

Bleeding of an arteriovenous malformation (AVM) following stereotactic radiosurgery (SRS) is a known risk during the latency interval, but hemorrhage in the 30-day period following radiosurgery rarely has been reported in the literature. The authors present the case of a 57-year-old man who underwent Gamma Knife surgery for a large AVM, and they provide radiographic documentation of a thrombus in the primary draining vein immediately preceding an AVM hemorrhage within 9 days after radiosurgery. They postulate that the pathophysiology of an AVM hemorrhage in the acute period following SRS is related to an association among tissue irradiation, acute inflammatory response, and vessel thrombosis.

The authors also review the literature on risk factors for hemorrhage due to untreated and radiosurgically treated AVMs. Recent evidence on the role of inflammation in the pathogenesis of AVMs and the pathophysiology of AVM rupture is presented. Inflammatory markers have been demonstrated in brain AVM tissue, and the association between inflammation and AVM hemorrhage has been established. There is an acute inflammatory response following tissue irradiation, resulting in structural and functional vascular changes that can lead to vessel thrombosis. Early hemorrhage following radiosurgical treatment of AVMs may be related to the acute inflammatory response and associated vascular changes that occur in irradiated tissue. In the first stage of a planned 2-stage Gamma Knife treatment for a large AVM in the featured case, the superior posteromedial portion of the primary draining vein was included in the treatment field. The authors present the planning images and subsequent CT scans demonstrating a new venous thrombus in the primary draining vein. An acute inflammatory response following radiosurgery with resultant acute venous thrombus formation and venous obstruction is proposed as one mechanism of an AVM hemorrhage in this patient. Radiographic evidence of the time course of thrombosis and hemorrhage supports the hypothesis that acute venous obstruction is a cause of intracranial hemorrhage.

Treatment of arteriovenous malformations using Gamma Knife surgery: the experience at the University of Washington from 2000 to 2005

Object

The purpose of this study was to examine the efficacy and toxicity of treating arteriovenous malformations (AVMs) with the model 3C Gamma Knife at the University of Washington Medical Center.

Methods

Ninety-five evaluable patients with 99 treatable AVMs were treated at the University of Washington Medical Center from April 2000 through June 2005. The median patient age at the time of treatment was 40 years (range 6–68 years). The male to female patient ratio was 0.98:1. The median AVM volume treated was 3.8 cm3 (range 0.12–32 cm3). Forty-four percent of the patients had hemorrhaged prior to treatment. The median peripheral Gamma Knife surgery dose was 20 Gy with a median of 12 isocenters treated. The median follow-up duration was 38 months (range 3–91 months). Eighty-one percent of the patients had no previous stereotactic radiosurgery (SRS), whereas the remaining 19% had previously been treated with linear accelerator–based SRS.

Results

The Kaplan–Meier estimated 6-year AVM obliteration rate for the entire cohort was 71.4%. The Kaplan–Meier estimated 6-year obliteration rate was 72% for patients having no prior SRS and 54.5% for those undergoing repeat SRS. The median time to AVM obliteration was 47 months, with 90% of the obliterations occurring between 24 and 58 months. Eight patients (7.4%) experienced late toxicities. There were 2 fatal bleeds and 13 (13.8%) nonfatal bleeds after Gamma Knife surgery.

Conclusions

Gamma Knife surgery is an effective treatment for AVMs, resulting in an excellent obliteration rate with acceptable toxicity.

Microsurgery or Radiosurgery for Cerebral Arteriovenous Malformations? A Study of Two Paired Series

OBJECTIVE

To detect parameters that may augment the therapeutic strategy in patients with a cerebral arteriovenous malformation (AVM) that is considered equally suitable for treatment by neurosurgery or radiosurgery, we compared the efficacy and risks of these two methods in a paired series with similar patient and AVM characteristics.

PATIENTS AND METHODS

Two series of patients with AVM were studied, including a series of 39 patients treated using microsurgery (MS) and another series of 39 patients treated via radiosurgery (RS). These series were paired for age and sex, initial symptoms, size, location and Spetzler-Martin grade, and presence of embolization preceding treatment. We compared the posttreatment outcome in the two groups with respect to obliteration rate, neurological status, mortality rate, and recurrent bleeding. Statistical analysis was performed using paired Student's t test.

RESULTS

The Glasgow Outcome Scale values and Modified Rankin Scores measured at discharge and 12 to 24 months were significantly better in the RS series than in the MS series. The obliteration rate tended to be higher in the MS series (91% versus 81%; P = 0.10, not significant), whereas the rate of neurological deficit was higher in the MS series than in the RS series(P &lt; 0.001). The mortality rate was not significantly different in the two series, but the rate of recurrent bleeding was higher in the RS group (10% versus 0%; P = 0.04).

CONCLUSIONS

Although the rate of cure was similar for patients treated with MS and RS, neurological morbidity was higher after MS and recurrent bleeding was more frequent after RS.

Treatment of arteriovenous malformations of the brain

The treatment of ruptured and unruptured brain arteriovenous malformations (AVMs) is driven by the need to prevent incident or recurrent intracranial hemorrhages. Improving feasibility of the rapidly developing endovascular, neurosurgical, and radiotherapeutic procedures leads to invasive treatment of an increasing number of neurologically intact patients with accidentally diagnosed AVMs. Recent data confirm that the natural history risk of unruptured AVMs is significantly lower than the risk of those presenting with rupture, and the treatment risk of invasive management of unruptured AVMs seems higher than their natural history risk. The treatment decision algorithm for these patients remains unsettled, as no randomized clinical trial data exist on the benefit of invasive AVM treatment for patients with bled or with unbled AVMs. The recently launched study A Randomized Trial of Unruptured Brain AVMs (ARUBA) will be the first trial randomizing patients with nonhemorrhaged AVMs to invasive versus conservative management.

Neurovascular radiosurgery

SUMMARY

This article focuses on the treatment of neurovascular diseases, in particular brain arteriovenous malformations (BAVMs), with radiosurgery. The target group for this review is physicians who manage patients with neurovascular diseases, but are not actively engaged in radiosurgery. Radiosurgery for BAVMs is an established treatment with clearly defined risks and benefits. The efficacy of radiosurgery for dural arteriovenous shunts (DAVSs) is probably similar but the treatment has not yet gained the same acceptance. Radiosurgical treatment of cavernomas (cavernous hemangiomas) remains controversial. Well founded predictive models for BAVM radiosurgery show: * The probability of obliteration depends on the dose of radiation given to the periphery of the BAVM. * The risk of adverse radiation effects depends on the total dose of radiation, i.e. the amount of energy imparted into the tissue. The risk is greater in centrally located lesions. The risk of damage to brainstem nucleii and cranial nerves must be added to the risk predicted from current outcome models. * The risk of hemorrhage during the time span before obliteration depends on the BAVM volume, the dose of radiation to the periphery of the lesion and the age of the patient. Central location is a probably also a risk factor.

Treatment of arteriovenous malformations with linear accelerator–based radiosurgery compared with Gamma Knife surgery

Object

The authors sought to compare the outcomes of patients with arteriovenous malformations (AVMs) treated by Gamma Knife surgery (GKS) with those of patients treated by linear accelerator–based (LINAC) radiosurgery.

Methods

One hundred and eighty-seven patients with AVMs were treated at our institution between 1992 and 2003. Ninety-one patients were treated with GKS and 96 patients were treated with LINAC radiosurgery. Patient and treatment characteristics in the two groups included the following. In the LINAC group, the median age was 33 years (range 9–66 years); the median dose was 16 Gy (70% isodose line); the median treated AVM volume was 5.5 cm3; and 46% of patients in this group were treated after hemorrhage. In the GKS group, the median age was 38 years (range 6–63 years); the median dose was 20 Gy (50% isodose line); the median treated AVM volume was 4.3 cm3; and 44% of patients in this group were treated after hemorrhage. Obliteration of AVMs was determined by performing computed tomography (CT) angiography and/or magnetic resonance (MR) angiography and angiography. Patient follow-up evaluation included obtaining an MR angiogram/MR image or CT angiogram at 6 months, at 1 year, and then annually thereafter. Angiography was performed to confirm obliteration when MR angiography and/or CT angiography no longer revealed evidence of an AVM.

The 5-year estimated AVM obliteration rate was 66% in the entire patient group; the LINAC group was 60%; the GKS group was 72%; this difference was not statistically significant (p = 0.97). Twelve patients who underwent treatment with LINAC radiosurgery underwent retreatment with GKS and one was retreated with LINAC radiosurgery. The obliteration rate was 82%. Six patients treated with GKS were retreated with GKS, but the follow-up time is of short duration. Chronic toxicity occurred in 8% of both the GKS and the LINAC groups (p = 0.61). Posttreatment hemorrhage during the time of risk before AVM obliteration was 13% in the GKS group and 6.2% in the LINAC group (p = 0.05).

Conclusions

Treatment of patients with AVMs by using LINAC radiosurgery and GKS treatment produces high obliteration rates with acceptable long-term radiation toxicity in the patients treated.

Responses of arteriovenous malformations to radiosurgery: ultrastructural changes

OBJECTIVE

To examine the ultrastructural changes in arteriovenous malformations (AVMs) after radiosurgery and to explore the possible mechanisms of posttreatment obliteration and hemorrhage.

METHODS

Twenty-two specimens, among them three irradiated AVMs (size, 3-6 cm), 15 nonirradiated AVMs, and four normal controls were processed for ultrastructural study immediately after removal. Transmission electron microscopy was used to compare the vasculature of irradiated AVMs with nonirradiated AVMs and normal controls.

RESULTS

Thirty-three months postradiosurgery, partial vaso-occlusion (36-74% lumen) occurred by coagulation of cytoplasmic debris and proteinaceous material leaking from the endothelium. Forty-eight months postradiosurgery, heterogeneous thrombus formation (86-96% lumen) with fibrinoid and proteinaceous materials was observed. Sixty-four months postradiosurgery, complete luminal closure (90-100% lumen) by a fibrin thrombus was seen in vessels with diameters up to 5.5 mm including feeding arteries and draining veins. In occluded vessels, there was extensive degeneration of endothelial cells, subendothelial fibroblasts, and myofibroblasts. Neoproliferation and endothelialization of smooth muscle cells with Weibel-Palade bodies was observed in arteries.

CONCLUSION

Radiosurgery causes irreversible cellular damage of the vascular wall. Partial vaso-occlusion that increases blood flow in remaining vessels and degenerative changes on the blood-brain barrier may contribute to hemorrhage at early stage postradiosurgery. Radiosurgery stimulates neoproliferating and endothelializing smooth muscle cells in vessel walls, which might lead to narrowing of the vessel lumina. Complete vaso-occlusion achieved 64 months postradiosurgery suggested a minimum follow-up duration of 5 years to determine final outcome of radiosurgery. Histological end point of vaso-occlusion of AVMs takes longer time than neuroimaging endpoint of complete obliteration.

History of surgery for cerebrovascular disease in children. Part III. Arteriovenous malformations

✓ Arteriovenous malformations (AVMs) are the most common cause of intracerebral hemorrhage in children. In this paper the authors trace the historical evolution of the recognition, diagnosis, and treatment of pediatric intracerebral AVMs, and they summarize the contemporary approach and current controversies surrounding treatment of these lesions. Important distinctions between adult and pediatric AVMs are emphasized.

Invasive treatment of unruptured brain arteriovenous malformations is experimental therapy

PURPOSE OF REVIEW

Brain arteriovenous malformations (AVMs) are currently being treated in a variety of ways, including medical management, endovascular procedures, neurosurgery and radiotherapy. The widespread diffusion of these various treatment approaches is partially driven by the existence of variations in the perception about the risks of rupture, and how devastating such events would be.

RECENT FINDINGS

Data from the most recent studies suggest the majority of AVM patients are diagnosed without signs of hemorrhage, further, that the natural history risk for the unruptured cohort is far more benign than for those presenting with rupture. In cases where hemorrhage occurs, the clinical syndrome is significantly less disabling than in patients with non-AVM related hemorrhage. For unruptured AVMs, current morbidity data suggest a higher risk for invasive management than for the natural history of untreated patients.

SUMMARY

No randomized clinical trial data exist on the benefit of invasive AVM treatment, and the most contentious issue at present is whether intervention should be considered for AVMs that have not bled. In a scientific sense, invasive treatment for unruptured brain AVMs may be considered experimental therapy awaiting the results from 'A Randomized Trial of Unruptured Brain AVMs' (ARUBA), which is currently underway.

Surgical Applications To Arteriovenous Malformations Involving The Brainstem

Objective:

To evaluate possible applications of microsurgical extirpation to arteriovenous malformations (AVMs) involving the brainstem.

Methods:

We retrospectively reviewed clinical records of 25 patients with AVMs involving brainstems who were admitted to our institute from 1984 to 2004. We defined a brainstem AVM as an AVM in which some part was located within the brainstem. The main location of the nidus was classified into ventral midbrain (n = 3), dorsal midbrain (n = 10), pons (n = 5), cerebellopontine angle (n = 6), and medulla oblongata (n = 1). Bleeding risks from the AVMs were calculated, and applied treatment modalities, respectability, and clinical outcomes were analyzed.

Results:

The annual bleeding and rebleeding risks of brainstem AVMs were 15.1 and 14.2%, respectively. Total resection was successfully performed in 0 out of 3, 6 out of 10,2 out of 5,6 out of 6, and 0 out of 1 in each of the groups, respectively. Stereotactic radiosurgery was applied as a main treatment modality in three patients (two ventral midbrain AVMs and one pontine AVM), and after microsurgery in one patient with a medulla oblongata AVM. Microsurgery-related permanent neurological complications were observed in five patients (one postoperative bleeding, one hemiparesis, three hearing deterioration, one abducens nerve palsy). During a follow-up period of 8 years (range, 8 mo-15 yr), one patient with an untreated pontine AVM died owing to hemorrhage and one patient with a subtotally resected dorsal midbrain AVM died owing to an unknown etiology 4 years later.

Conclusion:

Surgical resection can be applied with considerable, but acceptable, morbidity and mortality in some groups of brainstem AVMs with hemorrhagic presentation, particularly dorsal midbrain and cerebellopontine angle types, in which most parts of the nidus located sub- or extrapially.

Gamma knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part I: Differences in epidemiologic, morphologic, and clinical characteristics, permanent complications, and bleeding in the latency period

PURPOSE

To compare the epidemiologic, morphologic, and clinical characteristics of 92 children/adolescents (Group A) and 362 adults (Group B) with cerebral arteriovenous malformations (cAVMs) considered suitable for radiosurgery; to correlate radiosurgery-related permanent complication and post-radiosurgery bleeding rates in the 75 children/adolescents and 297 adults available for follow-up.

METHODS AND MATERIALS

Radiosurgery was performed with a model C 201-source Co60 Leksell Gamma Unit (Elekta Instruments, Stockholm, Sweden). Fisher exact two-tailed, Wilcoxon rank-sum, and two-sample binomial exact tests were used for statistical analysis.

RESULTS

There were significant differences between the two populations in sex (p = 0.015), clinical presentation (p = 0.001), and location (p = 0.008). The permanent complication rate was lower in younger (1.3%) than in older patients (5.4%), although the difference was not significant (p = 0.213). The postradiosurgery bleeding rate was lower in Group A (1.3%) than in Group B (2.7%) (p = 0.694), with global actuarial bleeding rates of 0.56% per year and 1.15% per year, respectively.

CONCLUSIONS

The different characteristics of child/adolescent and adult cAVMs suggest that they should be considered two distinct vascular disorders. The similar rates of radiosurgery-related complications and latency period bleeding in the two populations show that gamma knife radiosurgery does not expose young patients to a higher risk of sequelae than that for older patients.

La radiothérapie des affections bénignes : quelles indications huit ans plus tard ?

The authors present an update version of the indications for radiotherapy in the management of benign diseases. This is based on available randomized trials and recent international meetings. Validated indications remain the prevention of resected heterotopic bone ossifications, keloïds scars and pterygium and also treatment of arteriovenous malformations; the place of radiotherapy for malignant exophtalmia is more and more restricted. Randomized trials have demonstrated the efficacy of endobrachytherapy in the prevention of restenosis after angioplasty but the use of embedded stent has replaced this indication. Macular degeneration is no more an indication of radiotherapy. Quality requirements for radiotherapy are identical for benign or malignant indications.

Management of brain arteriovenous malformations

PURPOSE OF REVIEW

This review highlights recent data regarding factors associated with brain arteriovenous malformation hemorrhage and different treatment options.

RECENT FINDINGS

More risk factors were identified in association with intracranial hemorrhage, including age at initial diagnosis of arteriovenous malformation, co-existing extranidal aneurysms and genetic factors. Patients with unruptured arteriovenous malformations were found to be more susceptible to worsening in neurological function after microsurgery compared with those presenting with hemorrhagic arteriovenous malformation. Radiosurgery has achieved satisfactory obliteration of deep arteriovenous malformations, but with increased actuarial hemorrhage rates from the first to the fifth year. Although the Intraoperative Hypothermia for Aneurysm Surgery Trial failed to show a significant neurological improvement, the superior efficiency of endovascular cooling has offered optimism in cerebral protection during neurovascular surgeries by shortening the time to achieve hypothermia and rewarming. A multi-center trial (ARUBA) has been proposed to test the hypothesis that, for unruptured brain arteriovenous malformations, there is no difference between interventional and conservative management. Recent studies have also shown the promise of using tetracyclines to decrease the rate of spontaneous arteriovenous malformation rupture.

SUMMARY

The recent identification of clinical and genetic factors associated with brain arteriovenous malformation hemorrhage, as well as studies on treatment outcomes, will help risk stratification in management choices. Future studies are needed to identify arteriovenous malformation patients at the greatest risk of spontaneous hemorrhage and to develop specific medical therapies.