Timing of Embolization, Radiosurgery, and Resection of Arteriovenous Malformations in Pediatric Patients: A Retrospective, Descriptive Study

OBJECTIVE

Cerebral arteriovenous malformations (AVMs) are a challenging pathology in pediatric patients, carrying a high risk of morbidity and mortality. Treatment modalities include resection, endovascular embolization, and stereotactic radiosurgery. There is currently no consensus favoring one modality over another. Timing of multimodal therapy with embolization/stereotactic radiosurgery and resection is not well explored in the literature. We present a series of pediatric patients with AVMs, with special attention directed to the timing of treatment.

METHODS

Electronic medical records of all pediatric patients (<18 years old at treatment) with AVMs treated at our institution were retrospectively reviewed after institutional review board approval. Demographic information, AVM characteristics, treatment variables, and outcomes were recorded.

RESULTS

In our cohort of 27 patients, 21 (77.8%) presented with a ruptured AVM. Of these patients, 6 (28.6%) had a Glasgow Coma Scale score of 3-10 and underwent treatment within 24 hours of presentation, and 10 (47.6%) with a Glasgow Coma Scale score of 12-15 were treated between 24 and 120 hours after presentation. The remaining 5 patients (23.8%) were treated 3 weeks to 14 months after AVM rupture. Regardless of rupture status, 96% of our cohort had a modified Rankin Scale score of 1-2 at most recent follow-up.

CONCLUSIONS

We present our institution's experience with pediatric AVMs, focusing on the timing of treatment. Based on our experience, early treatment of AVMs seems to be safe and effective regardless of rupture status.

Three-Pillar Expansive Craniotomy in Children with Acute Ruptured Supratentorial Brain Arteriovenous Malformations

OBJECTIVE

Acute rupture and hemorrhage of pediatric brain arteriovenous malformations (AVMs) may lead to cerebral herniation or intractable intracranial hypertension, necessitating emerging surgical interventions to alleviate intracranial pressure. However, there is still controversy regarding the timing of treatment for ruptured AVMs. This study aimed to assess the feasibility of utilizing three-pillar expansive craniotomy (3PEC) at different times during the treatment of pediatric ruptured supratentorial AVMs.

METHODS

A retrospective analysis was conducted on all consecutive cases of acute rupture in supratentorial AVM children who underwent 3PEC at a single institution from 2020 to 2022. General information, clinical characteristics, radiological data, and prognosis were reviewed and analyzed.

RESULTS

Thirteen children were included in the analysis. The intracranial pressure of all patients decreased to below 15 mmHg within 10 days. The expansion volume of the cranial cavity of the patients increased by 18.3 cm3 (95% confidence interval, 10.2-26.3; P < 0.001) compared to the hematoma volume. None of the patients required decompressive craniectomy due to intractable intracranial hypertension caused by cerebral swelling. The median waiting period for patients with delayed AVMs treatment was 8 days, during which no rebleeding occurred.

CONCLUSIONS

Emergency intervention with 3PEC in children experiencing acutely ruptured supratentorial AVMs appears to be feasible. For children requiring delayed management of the AVMs, 3PEC may diminish the risk of rebleeding during the waiting period and shorten the waiting period.

Vascular stability of brain arteriovenous malformations after partial embolization

INTRODUCTION

Brain arteriovenous malformation (bAVM) might have a higher risk of rupture after partial embolization, and previous studies have shown that some metrics of vascular stability are related to bAVM rupture risk.

OBJECTIVE

To analyze vascular stability of bAVM in patients after partial embolization.

METHODS

Twenty-four patients who underwent partial embolization were classified into the short-term, medium-term, and long-term groups, according to the time interval between partial embolization and surgery. The control group consisted of 9 bAVM patients who underwent surgery alone. Hemodynamic changes after partial embolization were measured by angiogram. The inflammatory infiltrates and cell-cell junctions were evaluated by MMP-9 and VE-cadherin. At the protein level, the proliferative and apoptotic events of bAVMs were analyzed by immunohistochemical staining of VEGFA, eNOS, and caspase-3. Finally, neovascularity and apoptotic cells were assessed by CD31 staining and TUNEL staining.

RESULTS

Immediately after partial embolization, the blood flow velocity of most bAVMs increased. The quantity of MMP-9 in the medium-term group was the highest, and VE-cadherin in the medium-term group was the lowest. The expression levels of VEGFA, eNOS, and neovascularity were highest in the medium-term group. Similarly, the expression level of caspase-3 and the number of apoptotic cells were highest in the medium-term group.

CONCLUSION

The biomarkers for bAVM vascular stability were most abnormal between 1 and 28 days after partial embolization.

Embolization as stand-alone strategy for pediatric low-grade brain arteriovenous malformations

OBJECTIVES

We evaluated the safety and efficacy of endovascular embolization as first-line stand-alone strategy for the treatment of low-grade brain arteriovenous malformations (bAVMs) (Spetzler Martin [SM] grade I and II) in pediatric patients. In addition, we assessed the predictors of procedure-related complications and radiographic complete obliteration in a single session.

MATERIAL AND METHODS

We conducted a single center retrospective cohort study of all pediatric (≤18 years) patients who underwent embolization as a stand-alone strategy for low-grade bAVMs between 2010 and 2022. Safety was measured by procedure-related complications and mortality. Efficacy was defined as complete angiographic obliteration after the last embolization session.

RESULTS

Sixty-eight patients (41 females; median age 14 years) underwent a total of 102 embolization sessions. There were 24 (35%) SM grade I lesions and 44 (65%) grade II. Six procedure-related complications (5.8% of procedures) were observed and no deaths were reported. All the complications were intraoperative nidus ruptures. A single draining vein was the only significant predictor of procedure-related complications (OR=0.10; 95% CI 0.01 - 0.72; p=0.048). Complete angiographic obliteration was achieved in 44 patients (65%). In 35 patients (51%) the bAVM was completely occluded in one session. The bAVM nidal size was a predictor of complete obliteration in one session (OR=0.44; 95% CI, 0.21-0.80; p=0.017).

CONCLUSION

Endovascular treatment as a stand-alone strategy for pediatric low-grade bAVMs is an adequate first-line approach in high volume centers with endovascular expertise. Nidal size evaluation is relevant in order to optimize patient selection for embolization as a stand-alone treatment modality.

Curative embolization of ruptured pediatric cerebral arteriovenous malformations

INTRODUCTION

Embolization with the intention to cure has not been well studied in ruptured arteriovenous malformations (AVMs). Furthermore, the role of primary curative embolization of pediatric AVMs is uncertain. Hence, we aimed to characterize the safety and efficacy of curative embolization of ruptured pediatric AVMs and assess predictors of obliteration and complications.

METHODS

A retrospective analysis of all pediatric (≤18 years) patients who underwent curative embolization of ruptured AVMs was conducted in two institutions between 2010 and 2022. The efficacy (complete angiographic obliteration after the last embolization session), recurrence (radiological recurrence of the lesion after confirmed obliteration in follow-up imaging), and safety (procedure-related complications and mortality) of the procedure were evaluated.

RESULTS

Sixty-eight patients (38 females; mean age 12.4 ± 3.4 years) underwent a total of 109 embolization sessions. Median follow-up time was 18 months after embolization (ranged from 2 to 47 months). Complete angiographic obliteration was achieved in 42 patients (62%). In 30 patients (44%) the AVM was occluded with a single embolization session. Recurrence of a totally embolized lesion occurred in 9 patients (13%). Thirteen complications (11.9% of procedures) were observed, and no deaths were reported. A nidus size > 2 cm was the only independent predictor of complete obliteration (OR = 0.16; 95% CI 0.03 - 0.77; p = 0.030).

CONCLUSION

Embolization of pediatric ruptured AVMs with curative intent can achieve acceptable obliteration rates. However, recurrence after complete obliteration and procedure-related complications of curative embolization of these lesions cannot be ignored. Ruptured AVMs ≤ 2 cm are adequate to achieve complete obliteration with curative endovascular management.

Closing the Gap in Pediatric Hemorrhagic Stroke: A Systematic Review

Pediatric hemorrhagic stroke (HS) accounts for a large proportion of childhood strokes, 1 of the top 10 causes of pediatric deaths. Morbidity and mortality lead to significant socio-economic and psychosocial burdens. To understand published data on recognizing and managing children with HS, we conducted a systematic review of the literature presented here. We searched PubMed, Embase, CINAHL and the Cochrane Library databases limited to English language and included 174 studies, most conducted in the USA (52%). Terminology used interchangeably for HS included intraparenchymal/intracranial hemorrhage, spontaneous ICH, and cerebrovascular accident (CVA). Key assessments informing prognosis and management included clinical scoring (Glasgow coma scale), and neuroimaging. HS etiologies reported were systemic coagulopathy (genetic, acquired pathologic, or iatrogenic), or focal cerebrovascular lesions (brain arteriovenous malformations, cavernous malformations, aneurysms, or tumor vascularity). Several scales were used to measure outcome: Glasgow outcome score (GOS), Kings outcome score for head injury (KOSCHI), modified Rankin scale (mRS) and pediatric stroke outcome measure (PSOM). Most studies described treatments of at-risk lesions. Few studies described neurocritical care management including raised ICP, seizures, vasospasm, or blood pressure. Predictors of poor outcome included ethnicity, comorbidity, location of bleed, and hematoma &gt;2% of total brain volume. Motor and cognitive outcomes followed independent patterns. Few studies reported on cognitive outcomes, rehabilitation, and transition of care models. Interdisciplinary approach to managing HS is urgently needed, informed by larger cohort studies targeting key clinical question (eg development of a field-guide for the clinician managing patients with HS that is reproducible internationally).

Concurrent decompression and resection versus decompression with delayed resection of acutely ruptured brain arteriovenous malformations

OBJECTIVE

Brain arteriovenous malformations (bAVMs) most commonly present with rupture and intraparenchymal hemorrhage. In rare cases, the hemorrhage is large enough to cause clinical herniation or intractable intracranial hypertension. Patients in these cases require emergent surgical decompression as a life-saving measure. The surgeon must decide whether to perform concurrent or delayed resection of the bAVM. Theoretical benefits to concurrent resection include a favorable operative corridor created by the hematoma, avoiding a second surgery, and more rapid recovery and rehabilitation. The objective of this study was to compare the clinical and surgical outcomes of patients who had undergone concurrent emergent decompression and bAVM resection with those of patients who had undergone delayed bAVM resection.

METHODS

The authors conducted a 15-year retrospective review of consecutive patients who had undergone microsurgical resection of a ruptured bAVM at their institution. Patients presenting in clinical herniation or with intractable intracranial hypertension were included and grouped according to the timing of bAVM resection: concurrent with decompression (hyperacute group) or separate resection surgery after decompression (delayed group). Demographic and clinical characteristics were recorded. Groups were compared in terms of the primary outcomes of hospital and intensive care unit (ICU) lengths of stay (LOSs). Secondary outcomes included complete obliteration (CO), Glasgow Coma Scale score, and modified Rankin Scale score at discharge and at the most recent follow-up.

RESULTS

A total of 35/269 reviewed patients met study inclusion criteria; 18 underwent concurrent decompression and resection (hyperacute group) and 17 patients underwent emergent decompression only with later resection of the bAVM (delayed group). Hyperacute and delayed groups differed only in the proportion that underwent preresection endovascular embolization (16.7% vs 76.5%, respectively; p < 0.05). There was no significant difference between the hyperacute and delayed groups in hospital LOS (26.1 vs 33.2 days, respectively; p = 0.93) or ICU LOS (10.6 vs 16.1 days, respectively; p = 0.69). Rates of CO were also comparable (78% vs 88%, respectively; p > 0.99). Medical complications were similar in the two groups (33% hyperacute vs 41% delayed, p > 0.99). Short-term clinical outcomes were better for the delayed group based on mRS score at discharge (4.2 vs 3.2, p < 0.05); however, long-term outcomes were similar between the groups.

CONCLUSIONS

Ruptured bAVM rarely presents in clinical herniation requiring surgical decompression and hematoma evacuation. Concurrent surgical decompression and resection of a ruptured bAVM can be performed on low-grade lesions without compromising LOS or long-term functional outcome; however, the surgeon may encounter a more challenging surgical environment.

Curative Embolization for Pediatric Spetzler-Martin Grade III Cerebral Arteriovenous Malformations

OBJECTIVE

Spetzler-Martin (SM) grade III arteriovenous malformations (AVMs) represent a gray zone due to their high variability in location, size, and angioarchitecture. In addition, there is a lack of information on curative embolization in the pediatric population, especially in this subgroup of lesions. Here we present our experience treating grade III AVMs by curative embolization in pediatric patients.

METHODS

Clinical and angiographic data from pediatric patients with grade III SM AVMs were retrospectively collected between 2011 and 2020 in a referral institution. We grouped the AVMs into subtypes according to size (S), venous drainage (V), and eloquence (E) and obtained subtypes: IIIA (S1V1E1), IIIB (S2V1E0), IIIC (S2V0E1), and IIID (S3V0E0).

RESULTS

A total of 61 embolization sessions were performed in 35 pediatric patients. There were 25 females (64%), and the mean age was 12.2 years (range 5-18). Complete angiographic occlusion was achieved in 16 patients (47%). In 13 patients (37%), the AVM was occluded with a single embolization session and most (12/13) had small lesions (IIIA subtype). Among the 19 patients with incomplete occlusion, most (58%) had large lesions (IIIB, IIIC, and IIID). Large AVMs (IIIB, IIIC, and IIID) underwent 36 sessions; however, only 3 patients (21%) achieved complete occlusion in 11 sessions. Eight intraoperative complications (13% procedures) occurred mainly in ruptured AVMs (7/8) and eloquent zones (7/8).

CONCLUSIONS

Curative embolization for SM grade III AVMs in children carries a high complication rate, especially in small, ruptured, and eloquent lesions. In addition, acceptable immediate complete angiographic occlusion rates were achieved, especially in small AVMs.

Paediatric Cerebral Arteriovenous Malformation: Outcomes from a Singapore Children's Hospital

OBJECTIVES

Paediatric brain arteriovenous malformation (bAVM) is a rare and distinct clinical entity. There is a growing body of literature that support the success of multimodality approaches for this difficult condition. The authors aim to firstly, describe our institutional experience with a consecutive series of patients and next, corroborate our results with current literature.

MATERIAL AND METHODS

This is a single institution, retrospective study conducted over a 20-year period. Patients less than 19 years old with bAVM were included. Variables of interest included patient demographics, clinical presentation, neuroimaging features, bAVM characteristics and treatment modality. Functional outcomes were measured with modified Rankin scale (mRS).

RESULTS

There were 58 paediatric bAVMs, presenting at a mean age of 8.7 ± 4.2 years, and followed up for a mean duration of 7.7 years. Thirty-six patients (62.1%) underwent microsurgical resection, 10 patients had stereotactic radiosurgery (17.2%) and 2 patients had endovascular treatment (3.4%). 50 patients (86.2%) had a favourable outcome at 1-year follow up. Microsurgical resection and SRS had similar obliteration rates (resection 83.3%; SRS 80.0%) and recurrence (resection 10.0%; SRS 12.5%). There were 6 cases of bAVM recurrence (12.8%). This subgroup was noted to be less than 7.5 years old at presentation (OR 15.0, 95% CI 1.56 - 144), and less likely to present with bAVM rupture (OR 0.11, 95% CI 0.01 - 0.96).

CONCLUSION

This study describes our experience in managing paediatric bAVM, whereby monomodal therapy can still be effective. Of note, we also demonstrate the role of extended surveillance to detect recurrence.

Radiosurgery as a microsurgical adjunct: outcomes after microsurgical resection of intracranial arteriovenous malformations previously treated with stereotactic radiosurgery

OBJECTIVE

Microsurgical resection of arteriovenous malformations (AVMs) can be aided by staged treatment consisting of stereotactic radiosurgery followed by resection in a delayed fashion. This approach is particularly useful for high Spetzler-Martin (SM) grade lesions because radiosurgery can reduce flow through the AVM, downgrade the SM rating, and induce histopathological changes that additively render the AVM more manageable for resection. The authors present their 28-year experience in managing AVMs with adjunctive radiosurgery followed by resection.

METHODS

The authors retrospectively reviewed records of patients treated for cerebral AVMs at their institution between January 1990 and August 2019. All patients who underwent stereotactic radiosurgery (with or without embolization), followed by resection, were included in the study. Of 1245 patients, 95 met the eligibility criteria. Univariate and multivariate regression analyses were performed to assess relationships between key variables and clinical outcomes.

RESULTS

The majority of lesions treated (53.9%) were high grade (SM grade IV-V), 31.5% were intermediate (SM grade III), and 16.6% were low grade (SM grade I-II). Hemorrhage was the initial presenting sign in half of all patients (49.5%). Complete resection was achieved among 84% of patients, whereas 16% had partial resection, the majority of whom received additional radiosurgery. Modified Rankin Scale (mRS) scores of 0-2 were achieved in 79.8% of patients, and 20.2% had poor (mRS scores 3-6) outcomes. Improved (44.8%) or stable (19%) mRS scores were observed among 63.8% of patients, whereas 36.2% had a decline in mRS scores. This includes 22 patients (23.4%) with AVM hemorrhage and 6 deaths (6.7%) outside the perioperative period but prior to AVM obliteration.

CONCLUSIONS

Stereotactic radiosurgery is a useful adjunct in the presurgical management of cerebral AVMs. Multimodal therapy allowed for high rates of AVM obliteration and acceptable morbidity rates, despite the predominance of high-grade lesions in this series of patients.

Acute surgical management of children with ruptured brain arteriovenous malformation

OBJECTIVE

Rupture of brain arteriovenous malformation (AVM) is the main etiology of intracerebral hemorrhage (ICH) in children. Ensuing intracranial hypertension is among the modifiable prognosis factors and sometimes requires emergency hemorrhage evacuation (HE). The authors aimed to analyze variables associated with HE in children with ruptured AVM.

METHODS

This study was a single-center retrospective analysis of children treated for ruptured AVM. The authors evaluated the occurrence of HE, its association with other acute surgical procedures (e.g., nidal excision, decompressive hemicraniectomy), and clinical outcome. Variables associated with each intervention were analyzed using univariable and multivariable models. Clinical outcome was assessed at 18 months using the ordinal King's Outcome Scale for Childhood Head Injury.

RESULTS

A total of 104 patients were treated for 112 episodes of ruptured AVM between 2002 and 2018. In the 51 children (45.5% of cases) who underwent HE, 37 procedures were performed early (i.e., within 24 hours after initial cerebral imaging) and 14 late. Determinants of HE were a lower initial Glasgow Coma Scale score (adjusted odds ratio [aOR] 0.83, 95% CI 0.71-0.97 per point increase); higher ICH/brain volume ratio (aOR 18.6, 95% CI 13-26.5 per percent increase); superficial AVM location; and the presence of a brain herniation (aOR 3.7, 95% CI 1.3-10.4). Concurrent nidal surgery was acutely performed in 69% of Spetzler-Martin grade I-II ruptured AVMs and in 25% of Spetzler-Martin grade III lesions. Factors associated with nidal surgery were superficial AVMs, late HE, and absent alteration of consciousness at presentation. Only 8 cases required additional surgery due to intracranial hypertension. At 18 months, overall mortality was less than 4%, 58% of patients had a favorable outcome regardless of surgical intervention, and 87% were functioning independently.

CONCLUSIONS

HE is a lifesaving procedure performed in approximately half of the children who suffer AVM rupture. The good overall outcome justifies intensive initial management.

Arteriovenous malformation surgery in children: the Rady Children's Hospital experience (2002-2019)

PURPOSE

Compared to adult AVMs, there is a paucity of data on the microsurgical treatment of pediatric AVMs. We report our institutional experience with pediatric AVMs treated by microsurgical resection with or without endovascular embolization and radiation therapy.

METHODS

We retrospectively reviewed all patients ≤ 18 years of age with cerebral AVMs that underwent microsurgical resection at Rady Children's Hospital 2002-2019.

RESULTS

Eighty-nine patients met inclusion criteria. The mean age was 10.3 ± 5.0 years, and 56% of patients were male. In total, 72 (81%) patients presented with rupture. Patients with unruptured AVMs presented with headache (n = 5, 29.4%), seizure (n = 9, 52.9%), or incidental finding (n = 3, 17.7%). The mean presenting mRS was 2.8 ± 1.8. AVM location was lobar in 78%, cerebellar/brainstem in 15%, and deep supratentorial in 8%. Spetzler-Martin grade was I in 28%, II in 45%, III in 20%, IV in 6%, and V in 1%. Preoperative embolization was utilized in 38% of patients and more frequently in unruptured than ruptured AVMs (62% vs. 32%, p = 0.022). Radiographic obliteration was achieved in 76/89 (85.4%) patients. Complications occurred in 7 (8%) patients. Annualized rates of delayed rebleeding and recurrence were 1.2% and 0.9%, respectively. The mean follow-up was 2.8 ± 3.1 years. A good neurological outcome (mRS score ≤ 2) was obtained in 80.9% of patients at last follow-up and was improved relative to presentation for 75% of patients.

CONCLUSIONS

Our case series demonstrates high rates of radiographic obliteration and relatively low incidence of neurologic complications of treatment or AVM recurrence.

Bringing high-grade arteriovenous malformations under control: clinical outcomes following multimodality treatment in children

OBJECTIVE

Brain arteriovenous malformations (AVMs) consist of dysplastic blood vessels with direct arteriovenous shunts that can hemorrhage spontaneously. In children, a higher lifetime hemorrhage risk must be balanced with treatment-related morbidity. The authors describe a collaborative, multimodal strategy resulting in effective and safe treatment of pediatric AVMs.

METHODS

A retrospective analysis of a prospectively maintained database was performed in children with treated and nontreated pediatric AVMs at the University of California, San Francisco, from 1998 to 2017. Inclusion criteria were age ≤ 18 years at time of diagnosis and an AVM confirmed by a catheter angiogram.

RESULTS

The authors evaluated 189 pediatric patients with AVMs over the study period, including 119 ruptured (63%) and 70 unruptured (37%) AVMs. The mean age at diagnosis was 11.6 ± 4.3 years. With respect to Spetzler-Martin (SM) grade, there were 38 (20.1%) grade I, 40 (21.2%) grade II, 62 (32.8%) grade III, 40 (21.2%) grade IV, and 9 (4.8%) grade V lesions. Six patients were managed conservatively, and 183 patients underwent treatment, including 120 resections, 82 stereotactic radiosurgery (SRS), and 37 endovascular embolizations. Forty-four of 49 (89.8%) high-grade AVMs (SM grade IV or V) were treated. Multiple treatment modalities were used in 29.5% of low-grade and 27.3% of high-grade AVMs. Complete angiographic obliteration was obtained in 73.4% of low-grade lesions (SM grade I-III) and in 45.2% of high-grade lesions. A periprocedural stroke occurred in a single patient (0.5%), and there was 1 treatment-related death. The mean clinical follow-up for the cohort was 4.1 ± 4.6 years, and 96.6% and 84.3% of patients neurologically improved or remained unchanged in the ruptured and unruptured AVM groups following treatment, respectively. There were 16 bleeding events following initiation of AVM treatment (annual rate: 0.02 events per person-year).

CONCLUSIONS

Coordinated multidisciplinary evaluation and individualized planning can result in safe and effective treatment of children with AVMs. In particular, it is possible to treat the majority of high-grade AVMs with an acceptable safety profile. Judicious use of multimodality therapy should be limited to appropriately selected patients after thorough team-based discussions to avoid additive morbidity. Future multicenter studies are required to better design predictive models to aid with patient selection for multimodal pediatric care, especially with high-grade AVMs.

Long-term functional outcome after intervention for pediatric intracranial arteriovenous malformations: A systematic review and meta-analysis

Intervention (surgery, embolization, and radiosurgery) is critical in maximizing outcomes of pediatric arteriovenous malformations (pAVMs). Although short-term functional outcomes following intervention have been stablished to be favorable, long-term outcomes have yet to be thoroughly consolidated. Searches of 7 electronic databases from inception to April 2019 were conducted following PRISMA guidelines. Articles were screened against pre-specified criteria. Favorable functional were modified Rankin Scale (mRS) scores ranging from 0 to 2, and the incidences were extracted and pooled by random-effects meta-analysis of proportions. Fourteen pertinent studies were identified describing outcomes of 699 pAVM patients, with median 75 % presenting with hemorrhage. Surgery, embolization and radiosurgery use were reported by 12 (86 %), 14 (100 %) and 10 (71 %) studies respectively. By median study follow-up time of 4.1 years, a favorable functional outcome was estimated to occur in 87 % (95 % CI, 82-91 %) of subjects respectively. Hemorrhagic versus non-hemorrhagic presentations did not statistically differ in incidence of this long-term outcome, 78 % (95 % CI, 67-87 %) and 91 % (95 % CI, 80-98 %) respectively. This study demonstrates that favorable long-term functional outlook of pAVM subjects after intervention can persist for many years after initial intervention. The certainty of achieving this outcome is moderate, irrespective of hemorrhagic presentation or intervention modality. Long-term functional deficit risk should not be the sole factor in deciding if intervention should be pursued.

Expert Consensus on the Management of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are complex, heterogeneous, and uncommon intracranial lesions. They can be treated by one or a combination of the following treatment modalities, namely embolization, radiosurgery, or microsurgical resection. In Spetzler-Martin Grade 4 and 5 arteriovenous malformations (AVMs), conservative management may be the best option. A group of experts in the management of AVMs of different disciplines gathered in January 2019 in Hanoi to compile the “Expert Consensus on the Management of Brain Arteriovenous Malformations”.

Neurovascular Lesions in Pediatric Epilepsy

INTRODUCTION

Neurovascular lesions are rare and understudied in the pediatric population. Their initial presentation can range from seizures to focal neurologic deficits, as well as headaches. The goal of this study was to examine the clinical presentation and natural history of neurovascular lesions in children with epilepsy.

METHODS

We reviewed all pediatric epilepsy patients with neurovascular lesions diagnosed between 2006 and 2018 at the University of Alberta and the Stollery Children's Hospital, Edmonton, Canada. Initial clinical presentation and brain imaging, as well as long-term epilepsy and postsurgical outcome, were assessed.

RESULTS

Of the 14 patients, 10 patients had an initial presentation of focal seizures with impaired awareness, whereas 2 patients presented with headache, 1 presented with visual field defects as well as chronic headaches, and 1 with decreased level of consciousness. Seven patients had cavernous angiomas, 6 had arteriovenous malformation, and 1 patient had an arteriovenous fistula. Notably, all patients with cavernous angiomas and 4 of 6 patients with arteriovenous malformations presented with seizures. Among 9 of the 14 who underwent neurovascular corrective surgery, all 9 patients required long-term antiepileptic treatment of at least 1 antiepileptic drug for seizure control after the operation.

CONCLUSION

In this novel case series, we describe focal seizures as the initial presentation of pediatric neurovascular lesions. This clinical presentation appears to be independent of the type of neurovascular lesion. Furthermore, unlike our pediatric surgical patients with epilepsy due to other causes, seizure freedom following neurovascular surgery is limited, and patients require long-term antiepileptic treatment.

Long-term outcomes in pediatric unruptured brain arteriovenous malformation treated by nonconservative management: a single center analysis

PURPOSE

The best management of pediatric unruptured brain arteriovenous malformations (ubAVM) should be further elucidated.

METHODS

Pediatric patients who presented to our facility with ubAVM and were treated nonconservatively were retrospectively analyzed regarding demographics, presenting symptoms, AVM characteristics, treatment modality, and outcome.

RESULTS

Thirteen patients were included. There were 9 male and 4 female patients with an average age (± SD) of 7.8 ± 4.6 years. The most common presenting symptom was seizure. The mean Spetzler Martin (SM) grade was 3.2. Seven patients were treated by surgical excision, 8 by embolization, 6 by radiosurgery, and during the mean follow-up period of 8.9 years (2.6-14.4 years), there were no hemorrhage. Complete ubAVM obliteration was achieved in all 7 patients (100%) who underwent surgical excision. AVM was obliterated in 5 out of 9 patients whose SM grade was 3 or 4. Modified Rankin scale was good (mRS 0-2) in all 13 patients.

CONCLUSIONS

Since the lifetime hemorrhage rate of pediatric ubAVM is high, it may be better to proceed with nonconservative treatment, especially when surgical excision is amenable. Nonconservative treatment could be an appropriate treatment with acceptable neurological outcome even in those with moderate to high-grade AVMs in selected cases.

The Extent of Neurologic Improvement and Social Life in Young Patients with Ruptured and Unruptured Brain AVM: A Long-Term Follow-Up

BACKGROUND

Intracerebral hemorrhage, seizures, neurologic deficits, and cognitive impairments due to brain AVM in childhood are incriminating for brain and executive function with sequelae for further social life. Long-term follow-up data on brain AVM in young patients are rare, making it difficult to compare and evaluate treatment risks and outcomes.

METHODS

We studied young patients with brain AVM who were referred to our institution between 2005 and 2012 and for whom follow-up data were available. We stratified the patients into those with ruptured AVM (rAVM) and unruptured AVM (uAVM) and compared treated and nontreated patients. Differences in outcome and social participation were assessed.

RESULTS

A total of 29 young patients with brain AVM, median age 16 years, were included in our study with complete follow-up data of over 5 years (mean, 6 years). In 18 (62.1%) patients rAVM and in 11 (37.9%) patients uAVM were found. Twenty (69%) patients received treatment (rAVM 70% vs. uAVM 30%). Among treatment methods, microsurgery was most frequently used (rAVM 33.3% vs. uAVM 36.4%). In rAVM, 16 of 18 (88.9%) patients returned to work or school, and in uAVM, 11 (100%) patients did so. Concerning cognitive problems, no statistically significant difference was found in the 2 groups comparing treated and nontreated patients (P > 0.05). A favorable outcome was achieved in 13 (72.2%) patients with rAVM and in 11 (100%) patients with uAVM.

CONCLUSION

Favorable outcome was achieved in the majority of patients. The rate of neurologic improvement and participation in social life was very high in the 2 groups.

The factors associated with hemorrhagic presentation in children with untreated brain arteriovenous malformation: a meta-analysis

OBJECTIVE Rupture of arteriovenous malformations (AVMs) would result in high mortality and prevalence of disability in pediatric patients. Decisions regarding the treatment of AVMs need to weigh the risk of rupture over the course of their natural history against the possibility of creating a lesion during treatment. Multiple factors have been proposed to predict hemorrhagic presentation of pediatric patients with AVMs. The aim of this meta-analysis was to evaluate the predictors of hemorrhagic presentation in pediatric patients with AVMs. METHODS The authors searched the PubMed and EMBASE databases. Studies reporting the predictors of hemorrhagic presentation in children with untreated brain AVMs were included. The predictive ability of identified predictors was assessed by odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS A higher risk of hemorrhagic presentation was found in AVMs with smaller size (< 3 cm, OR 2.97, 95% CI 1.94–4.54, p < 0.00001), deep venous drainage (OR 2.28, 95% CI 1.55–3.36, p < 0.0001), a single draining vein (OR 2.23, 95% CI 1.27–3.92, p = 0.005), a single feeder (OR 3.72, 95% CI 1.31–10.62, p = 0.01), a deep location (OR 1.82, 95% CI 1.22–2.72, p = 0.004), an infratentorial location (OR 2.25, 95% CI 1.19–4.26, p = 0.01), and diffuse morphology (OR 8.94, 95% CI 3.01–26.55, p < 0.0001). In addition, the AVMs with draining vein ectasia (OR 0.35, 95% CI 0.13–0.97, p = 0.04) and high Spetzler-Martin (SM) grade (OR 0.53, 95% CI 0.36–0.78, p = 0.001) had a lower risk of hemorrhagic presentation in pediatric patients. CONCLUSIONS Smaller AVMs, deep venous drainage, a single draining vein, a single feeder, deep/infratentorial location, diffuse morphology, and high SM grade were identified as positive predictors for hemorrhagic presentation. Particularly, patients with diffuse AVMs have a higher risk of hemorrhagic presentation than other factors and may need active treatments. However, factors such as age, sex, draining vein stenosis, and associated aneurysms were not associated with hemorrhagic presentation. ABBREVIATIONS AVM = arteriovenous malformation; CI = confidence interval; NOS = Newcastle-Ottawa Scale; OR = odds ratio; SM = Spetzler-Martin.

Safety and outcome of combined endovascular and surgical management of low grade cerebral arteriovenous malformations in children compared to surgery alone

PURPOSE

To evaluate the outcomes of combined preoperative embolization and microsurgical resection in comparison with microsurgical resection alone as the current standard of care for low-grade cerebral arteriovenous malformations (AVM) in the pediatric population.

MATERIALS & METHODS

We performed a single-center retrospective study of pediatric patients presenting with Spetzler-Martin (SM) grade I and II cerebral AVMs at a high-volume tertiary pediatric hospital between January 2005 and September 2016. Low grade AVM patients were divided into two groups: pre-operative embolization with subsequent microsurgical resection or microsurgical resection alone. Patient demographics, clinical and imaging presentations, AVM morphological characteristics, post-operative complications, and mid to long-term clinical outcomes were studied. Post-embolization and post-surgical outcomes were assessed prior to and after treatment, at 3 months and at final follow-up using the modified Rankin Scale (mRS) to compare both final independent (mRS 0-2) and favorable (no change or improved mRS) clinical outcomes for comparison between study groups. Statistical associations of patient demographics, AVM characteristics/SM grading, and treatment modality group with post-operative complications were performed using univariate logistic regression analysis.

RESULTS

Thirty-four patients with low grade cerebral AVMs met the study inclusion criteria (mean age 10.6 ± 3.4 years; range 3-16 years, 22M:12 F). Twenty patients (59%) presented with ruptured AVMs. Twenty-five patients (73.5%) underwent combined treatment with embolization and microsurgical resection, while 9/34 (26.5%) underwent microsurgical resection alone. A total of 35 embolization procedures performed in 25 patients (Mode, 1; Range, 1-7) were associated with two minor post-embolization and 7 subsequent post-surgical (28%) complications, resulting in clinical deterioration in a single patient. Microsurgical resection alone was associated with 3 post-surgical complications (33%), resulting in permanent neurological disability in a single patient. There was no significance association of post-operative complications with either treatment modality group, combined treatment versus surgical resection alone [OR:1.13; 95% CI:0.23-5.62; p-value 0.88]. SM Grade II and eloquent locations were found to be significantly associated with post-surgical complications of low grade pediatric cerebral AVMs [OR 13.2 and OR 8 respectively, p-value 0.004 and 0.005). On mean follow-up time of 35.7 months, final clinical outcome was favorable in the majority of both treatment arms with no dependent (mRS>2) patients in the combined endovascular and surgical cohort. Two patients in the surgical cohort failed to achieve independent functional status, primarily due to a pre-operative morbid status (p-value 0.015). However, there was no significant difference in favorable outcomes between the treatment groups [p-value 0.14].

CONCLUSION

Our study suggests equivalent safety and favorable clinical outcomes related to combined endovascular embolization and microsurgical resection of low grade pediatric cerebral AVMs in comparison to microsurgical resection alone. On long term clinical follow-up, the vast majority of patients achieved an independent and favorable functional status irrespective of pre-operative embolization.

Functional and educational outcomes after treatment for intracranial arteriovenous malformations in children

BACKGROUND

Arteriovenous malformations (AVMs) in the pediatric population are rare, yet they form the most frequent cause of hemorrhagic stroke in children. Compared to adults, children have been suggested to have beneficial neurological outcomes. However, few studies have focused on other variables than neurological outcomes. This study aims to assess the long-term functional and educational outcomes of children after multimodality approach of treatment for intracranial AVMs.

METHODS

All children treated in our center between 1998 and 2016 for intracranial AVMs were reviewed. Patient characteristics, as well as AVM specifics, were collected. Functional outcomes were compared using the modified Rankin scale (mRs). Educational levels, using the International Standard Classification of Education (ISCED), were compared to the age-matched general population of the Netherlands.

RESULTS

In total, 25 children were included at mean age of 10 years (range 2-16 years). Nineteen patients (76%) presented with intracranial bleeding. Mean follow-up was 11.5 ± 5.3 years (range 4.1-24.4). Four (16%) of patients were treated with embolization, three (12%) with microsurgery, and 18 patients (72%) received a combination of different treatment modalities. Altogether, 21 (84%) were embolized, 14 (56%) were treated with microsurgery, and eight (32%) received stereotactic radiosurgery. One child had a worse mRs at discharge compared to admission; all others improved (n = 11) or were stable (n = 13). At follow-up, all patients scored a stable or improved mRs compared to discharge, with 23 children (92%) scoring mRs 0 or 1. These 23 children followed regular education during follow-up without specialized or adapted schooling. No significant differences in educational level with the age-matched general population were found.

CONCLUSION

This retrospective review shows positive long-term results of both functional and educational outcomes after multidisciplinary treatment of pediatric brain AVMs.

High-resolution 3D volumetric contrast-enhanced MR angiography with a blood pool agent (ferumoxytol) for diagnostic evaluation of pediatric brain arteriovenous malformations

OBJECTIVE Patients with brain arteriovenous malformations (AVMs) often require repeat imaging with MRI or MR angiography (MRA), CT angiography (CTA), and digital subtraction angiography (DSA). The ideal imaging modality provides excellent vascular visualization without incurring added risks, such as radiation exposure. The purpose of this study is to evaluate the performance of ferumoxytol-enhanced MRA using a high-resolution 3D volumetric sequence (fe-SPGR) for visualizing and grading pediatric brain AVMs in comparison with CTA and DSA, which is the current imaging gold standard. METHODS In this retrospective cohort study, 21 patients with AVMs evaluated by fe-SPGR, CTA, and DSA between April 2014 and August 2017 were included. Two experienced raters graded AVMs using Spetzler-Martin criteria on all imaging studies. Lesion conspicuity (LC) and diagnostic confidence (DC) were assessed using a 5-point Likert scale, and interrater agreement was determined. The Kruskal-Wallis test was performed to assess the raters' grades and scores of LC and DC, with subsequent post hoc pairwise comparisons to assess for statistically significant differences between pairs of groups at p < 0.05. RESULTS Assigned Spetzler-Martin grades for AVMs on DSA, fe-SPGR, and CTA were not significantly different (p = 0.991). LC and DC scores were higher with fe-SPGR than with CTA (p < 0.05). A significant difference in LC scores was found between CTA and fe-SPGR (p < 0.001) and CTA and DSA (p < 0.001) but not between fe-SPGR and DSA (p = 0.146). A significant difference in DC scores was found among DSA, fe-SPGR, and CTA (p < 0.001) and between all pairs of the groups (p < 0.05). Interrater agreement was good to very good for all image groups (κ = 0.77-1.0, p < 0.001). CONCLUSIONS Fe-SPGR performed robustly in the diagnostic evaluation of brain AVMs, with improved visual depiction of AVMs compared with CTA and comparable Spetzler-Martin grading relative to CTA and DSA.

Onyx embolization prior to stereotactic radiosurgery for brain arteriovenous malformations: a single-center treatment algorithm

BACKGROUND

Embolization before stereotactic radiosurgery (SRS) for brain arteriovenous malformations (BAVMs) is controversial.

OBJECTIVE

To compare clinical and radiographic outcomes in patients undergoing pre-SRS embolization with ethylene copolymer (Onyx) with outcomes in patients undergoing SRS alone.

METHODS

Seventy consecutive patients with BAVMs who underwent SRS were retrospectively reviewed. Univariate and multivariate analyses were performed to assess the factors associated with radiographic obliteration and complication.

RESULTS

Forty-one (59%) patients presented without BAVM rupture and 29 (41%) patients presented with rupture. Pre-SRS embolization was used in 20 patients (28.6%; 7 unruptured and 13 ruptured). Twenty-five of 70 (36%) patients sustained a complication from treatment, including 6 (9%) patients with a post-SRS latency period hemorrhage. Ten (14%) patients had persistent neurological deficits after treatment. Functional outcome (as modified Rankin Scale), complication rate, and radiographic obliteration at last follow-up were not significantly different between embolized and non-embolized groups in both unruptured and ruptured BAVMs. For unruptured BAVMs, 3- and 5-year rates of radiographic obliteration were 23% and 73% for non-embolized patients and 20% and 60% for embolized patients, respectively. For ruptured BAVMs, 3- and 5-year rates of radiographic obliteration were 45% and 72% for non-embolized patients and 53% and 82% for embolized patients, respectively.

CONCLUSION

Pre-SRS embolization with Onyx was not associated with worse clinical or radiographic outcomes than SRS treatment without embolization. Pre-SRS embolization has a low complication rate and can safely be used to target high-risk BAVM features in carefully selected patients destined for SRS.

International multicenter cohort study of pediatric brain arteriovenous malformations. Part 2: Outcomes after stereotactic radiosurgery

OBJECTIVE Pediatric patients (age < 18 years) harboring brain arteriovenous malformations (AVMs) are burdened with a considerably higher cumulative lifetime risk of hemorrhage than adults. Additionally, the pediatric population was excluded from recent prospective comparisons of intervention versus conservative management for unruptured AVMs. The aims of this multicenter, retrospective cohort study are to analyze the outcomes after stereotactic radiosurgery for unruptured and ruptured pediatric AVMs. METHODS We analyzed and pooled AVM radiosurgery data from 7 participating in the International Gamma Knife Research Foundation. Patients younger than 18 years of age who had at least 12 months of follow-up were included in the study cohort. Favorable outcome was defined as AVM obliteration, no post-radiosurgical hemorrhage, and no permanently symptomatic radiation-induced changes (RIC). The post-radiosurgery outcomes of unruptured versus ruptured pediatric AVMs were compared, and statistical analyses were performed to identify predictive factors. RESULTS The overall pediatric AVM cohort comprised 357 patients with a mean age of 12.6 years (range 2.8-17.9 years). AVMs were previously treated with embolization, resection, and fractionated external beam radiation therapy in 22%, 6%, and 13% of patients, respectively. The mean nidus volume was 3.5 cm³, 77% of AVMs were located in eloquent brain areas, and the Spetzler-Martin grade was III or higher in 59%. The mean radiosurgical margin dose was 21 Gy (range 5-35 Gy), and the mean follow-up was 92 months (range 12-266 months). AVM obliteration was achieved in 63%. During a cumulative latency period of 2748 years, the annual post-radiosurgery hemorrhage rate was 1.4%. Symptomatic and permanent radiation-induced changes occurred in 8% and 3%, respectively. Favorable outcome was achieved in 59%. In the multivariate logistic regression analysis, the absence of prior AVM embolization (p = 0.001) and higher margin dose (p < 0.001) were found to be independent predictors of a favorable outcome. The rates of favorable outcome for patients treated with a margin dose ≥ 22 Gy vs < 22 Gy were 78% (110/141 patients) and 47% (101/216 patients), respectively. A margin dose ≥ 22 Gy yielded a significantly higher probability of a favorable outcome (p < 0.001). The unruptured and ruptured pediatric AVM cohorts included 112 and 245 patients, respectively. Ruptured AVMs had significantly higher rates of obliteration (68% vs 53%, p = 0.005) and favorable outcome (63% vs 51%, p = 0.033), with a trend toward a higher incidence of post-radiosurgery hemorrhage (10% vs 4%, p = 0.07). The annual post-radiosurgery hemorrhage rates were 0.8% for unruptured and 1.6% for ruptured AVMs. CONCLUSIONS Radiosurgery is a reasonable treatment option for pediatric AVMs. Obliteration and favorable outcomes are achieved in the majority of patients. The annual rate of latency period hemorrhage after radiosurgery for both ruptured and unruptured pediatric AVM patients conveys a significant risk until the nidus is obliterated.

Multimodality management and outcomes of brain arterio-venous malformations (AVMs) in children: personal experience and review of the literature, with specific emphasis on age at first AVM bleed

PURPOSE

The purpose of this paper is to study the presentation and analyse the results of multimodality treatment of brain arterio-venous malformations (AVMs) in children at our centre and review age at first AVM rupture in the literature.

METHODS

Of 52 patients aged <18 years, 47 with brain AVMs (27 males and 20 females) aged 4-17 years (mean 12.2) were retrospectively reviewed. PubMed search revealed five additional studies including 267 patients where the prevalence of age-related AVMs rupture was analysed.

RESULTS

In our study, 37 patients had bled, 9 were symptomatic without haemorrhage and 1 was incidental. Spetzler-Martin score distribution was 5 cases grade I, 18 grade II, 21 grade III and 3 grade IV. Appropriate imaging was performed, either CT/MRI angiogram only (in emergency cases) or catheter angiogram, prior to definitive treatment. There were 40 supratentorial and 7 infratentorial AVMs. Twenty-nine patients had microsurgery alone and 9 patients were treated by radiosurgery only. Three patients were embolised, all followed by radiosurgery, with one requiring surgery too, while 4 patients had combined surgery and radiosurgery. One patient is awaiting radiosurgery while another was not treated. Good outcomes, classified as modified Rankin score (mRS) 0-2 improved significantly after intervention to 89.4% from 38.3% pre-treatment (p value <0.0001). Angiography confirmed 96.6% obliteration after first planned operation. Repeat cerebral angiogram around age 18 was negative in all previously cured patients. Reviewing the literature, 82.0% (95% CI = [77-87]; N = 267) of children diagnosed with brain AVMs (mean age 11.4 ± 0.4) presented with a bleed in the last 22 years. Males significantly outnumbered females (136 vs 84) (p < 0.001). Ninety-five patients underwent surgical intervention alone when compared to other treatment modalities (p < 0.001).

CONCLUSIONS

Microsurgical excision of surgically accessible intracranial AVMs remains the primary treatment option with very good outcomes. A significant number of patients' AVMs ruptured around puberty; therefore, understanding the pathophysiology of AVM instability at this age may aid future therapy.

Arteriovenous malformations: epidemiology, clinical presentation, and diagnostic evaluation

Brain arteriovenous malformations (AVMs) represent an uncommon disease of the central nervous system characterized by an arteriovenous shunt in which one or multiple arterial pedicles feed into a vascular nidus, creating early drainage into a venous outflow channel. These lesions are considered to be congenital and can come to clinical attention in a variety of ways such as seizure, intracranial hemorrhage, chronic headache or progressive neurological deficit. We focus on the epidemiology, clinical presentation and diagnostic evaluation in this chapter.

Toward a comprehensive assessment of functional outcomes in pediatric patients with brain arteriovenous malformations: the Pediatric Quality of Life Inventory

OBJECTIVE Brain arteriovenous malformations (bAVMs) are rare in pediatric patients but represent the most common cause of hemorrhagic stroke in this population. Pediatric patients demonstrate superior outcomes in comparison with adult patients with similar lesions and presentations. Most studies of clinical outcomes of pediatric bAVMs use the modified Rankin Scale (mRS), despite a lack of validation in pediatric patients. METHODS The authors interviewed the parents of 26 pediatric patients who underwent multimodality bAVM treatment and administered the Pediatric Quality of Life Inventory (PedsQL)-a well-validated tool for pediatric outcomes that quantifies performance in a physical, emotional, social, and school domains. They also reviewed clinical information from the patients' medical charts. Statistical analysis was performed using a log-transformed t-test, the Mann-Whitney exact test, the Kruskal-Wallis test, and Spearman correlation. In addition, the literature was reviewed for prior reports of clinical outcome of pediatric cases of bAVM. RESULTS The average PedsQL health-related quality of life score was 71 ± 24, with an average age at diagnosis of 12.5 years and an average follow-up period of 6.8 years. Seventeen patients (65%) presented with hemorrhage and 4 (15%) with seizures. PedsQL scores correlated strongly and at a statistically significant level (p < 0.001) with mRS, Pediatric Overall Performance Category (POPC), Pediatric Cerebral Performance Category (PCPC), and Glasgow Outcome Scale scores. Multivariate modeling validated special education, corrective devices, and cure status as significant predictors of PedsQL scores. Statistically significant risk factors for undergoing placement of a ventriculoperitoneal shunt included lower Glasgow Coma Scale motor scores on admission (p = 0.042), cerebellar location (p = 0.046), and nidus volume (p = 0.017). Neither treatment modality nor location statistically affected clinical outcomes at follow-up. CONCLUSIONS There have been few studies of long-term clinical outcomes of bAVM in pediatric patients, and previously published studies have used conventional metrics that have been validated in the adult population, such as the mRS. Although these metrics can serve as reasonable surrogates, an accurate understanding of overall health-related quality of life is contingent on utilizing validated toolsets, such as the PedsQL.

Pediatric neurointervention: collimation on radiation exposure-associated lifetime excess tumor risk

Background

Intracranial vascular malformations in children are being addressed through a variety of treatment modalities including open surgery, external beam radiation, and image-guided neuroendovascular procedures. These patients often receive multiple treatments and incur serial exposures to ionizing radiation which has been linked to tumor development in population-based data.

Objective

This study quantifies the effect of collimation on exposures from single procedures and over patient lifetimes to estimate excess risk of lifetime tumor development.

Methods

215 patients aged 0–21 years from a single center took part in the study. Radiation exposure from neuroendovascular procedures was tabulated and converted to brain doses using modeled data and extrapolated to risk ratios using results of population-based estimates found in the literature.

Results

Lifetime and per procedure risk was highest in patients with brain arteriovenous malformations, brain arteriovenous fistulas, and vein of Galen malformations, a reflection of our institutional referral patterns. Across all pathologies the per procedure excess relative risk decreased from 13.4 to 2.3 when full collimation was employed. Lifetime excess relative risk decreased from 49.0 to 7.7 for full collimation.

Conclusions

This is the first study to quantify the effect of collimation on lifetime and per procedure risk of tumor development in a pediatric population. In addition to collimation, technical and operator-based aspects of the neurointerventional suite are discussed to further reduce patient exposure without sacrificing image quality.