Pediatric arteriovenous malformation: University of Toronto experience using stereotactic radiosurgery

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 >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).

The rationale and development of a CyberKnife© registry for pediatric patients with CNS lesions

BACKGROUND

CyberKnife© Radiosurgery (CKRS) is a recognized treatment concept for CNS lesions in adults due to its high precision and efficacy beside a high patient comfort. However, scientific evidence for this treatment modality in pediatric patients is scarce. A dedicated registry was designed to document CyberKnife© procedures in children, aiming to test the hypothesis that it is safe and efficient for the treatment of CNS lesions.

METHODS

The CyberKnife© registry is designed as a retrospective and prospective multicenter observational study (German Clinical Trials Register ( https://www.drks.de ), DRKS-ID 00016973). Patient recruitment will be ongoing throughout a 5-year period and includes collection of demographic, treatment, clinical, and imaging data. Follow-up results will be monitored for 10 years. All data will be registered in a centralized electronic database at the Charité-Universitätsmedizin. The primary endpoint is stable disease for benign and vascular lesions at 5 years of follow-up and local tumor control for malign lesions at 1- and 2-year follow-up. Secondary endpoints are radiation toxicity, side effects, and neurocognitive development.

CONCLUSION

The CyberKnife© registry intends to generate scientific evidence for all treatment- and outcome-related aspects in pediatric patients with treated CNS lesions. The registry may define safety and efficacy of CKRS in children and serve as a basis for future clinical trials, inter-methodological comparisons and changes of treatment algorithms.

[Arteriovenous malformations of the brain in children: treatment results for 376 patients]

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Cerebral arteriovenous malformations (AVM) are increasingly detected in children.

Objective

To estimate the risk of hemorrhage in children with AVM before and after treatment and evaluate the outcomes of various methods of AVM management in children.

Material and methods

This study included 376 patients with various cerebral AVM under the age of 18 years. There were 273 patients with intracranial hemorrhage (72.6%).

Results

Recurrent hemorrhages within the first month were registered in 1.1% of patients with angiomatous AVM prior to treatment and in 15.4% of patients with fistulous AVM. Microsurgical resection of AVM was performed in 135 (35.9%) patients. Total resection was achieved in 97.8% of cases. There were no mortality after microsurgical procedures. Endovascular treatment was applied in 79 (21%) patients. Total embolization was achieved in 29.1% of patients. One patient (1.3%) died after endovascular procedure. Radiosurgery was performed in 140 (37.2%) patients with total obliteration after a single fraction in 64.4% of patients. Favorable long-term outcomes (GOS grades V-IV) were achieved in 89.6% of patients with available follow-up data (n=182). Recurrent hemorrhages were registered in 6% of patients (3.3% after radiosurgery, 2.7% after endovascular treatment). One patient with recurrent hemorrhage died after radiosurgery.

Conclusion

Early relapses of hemorrhage are not characteristic for children with cerebral AVM. Therefore, there are no indications for urgent surgery except for cases of intracerebral hematoma. In children, microsurgical treatment is preferred for angiomatous AVM, endovascular treatment - for fistulous AVM. Radiosurgery also ensures favorable outcomes. However, it is unreasonable to postpone AVM radiosurgical treatment in children with increased risk of recurrent hemorrhage considering relatively long period of post-radiation obliteration of AVM.

Leksell Gamma Knife for pediatric and adolescent cerebral arteriovenous malformations: results of 100 cases followed up for at least 36 months

OBJECT

The goal of this study was to evaluate advantages, risks, and failures of Gamma Knife radiosurgery (GKRS) in a large series of pediatric and adolescent patients with cerebral arteriovenous malformations (cAVMs) who were followed up for at least 36 months.

METHODS

Since February 1993, 100 pediatric and adolescent patients (≤ 18 years of age) with cAVMs have undergone GKRS at the authors' institution and were followed up for at least 36 months. Forty-six patients were boys and 54 were girls; the mean age was 12.8 years (range 3-18 years). Hemorrhage, either alone or combined with seizure, was the clinical onset in 70% of cases. The mean pre-GK cAVM volume was 2.8 ml; 92% of cAVMs were Spetzler-Martin (S-M) Grades I-III. Most lesions (94%) were in eloquent or deep-seated brain regions, according to S-M classification. The parameters for mean and range in treatment planning were prescription isodose 53.8% (40%-90%); prescription dose (PD) 20.2 Gy (9.0-26.4 Gy); maximal dose (MD) 37.8 Gy (18-50 Gy); and number of shots 4.7 (1-17). On the day of GKRS, stereotactic CT or stereotactic MRI and digital subtraction angiography were used.

RESULTS

Obliteration rate (OR) was angiographically documented in 75 of 84 cases (89.3%) after single-session GKRS, with actuarial ORs at 3 and 5 years of 68.0% and 88.1%, respectively. A repeat treatment was performed in 7 patients (6 with obliteration), and 16 patients with cAVMs underwent staged treatment (9 of them were angiographically cured). Thus, the overall OR was 90%, with actuarial ORs at 3, 5, and 8 years of 59.0%, 76.0%, and 85.0%, respectively. Permanent symptomatic GK-related complications were observed in 11% of cases, with surgical removal of enlarged mass seen on post-RS imaging needed in 5 cases. Hemorrhage during the latency period occurred in 9% of patients, but surgical evacuation of the hematoma was required in only 1 patient. One patient died due to rebleeding of a brainstem cAVM. Radiosurgery outcomes varied according to cAVM sizes and doses: volumes ≤ 10 ml and PDs > 16 Gy were significantly associated with higher ORs and lower rates of permanent complication and bleeding during the latency period.

CONCLUSIONS

The data from this study reinforce the conclusion that GKRS is a safe and effective treatment for pediatric and adolescent cAVMs, yielding a high OR with minimal permanent severe morbidity and no mortality. The very low frequency of severe hemorrhages during the latency period further encourages a widespread application of RS in such patients. Univariate analysis found that modified RS-based cAVM score, nidus volume, PD, integral dose, S-M grade, and preplanned treatment (the last 2 parameters were also confirmed on multivariate analysis) significantly influenced OR. Lower S-M grades and single-session planned treatments correlated with shorter treatment obliteration interval on univariate analysis. This statistical analysis suggests that a staged radiosurgical treatment should be planned when nidus volume > 10 ml and/or when the recommended PD is ≤ 16 Gy.

Gamma Knife Radiosurgery for Pediatric Arteriovenous Malformations: A Canadian Experience

BACKGROUND

Gamma Knife (GK) radiosurgery for pediatric arteriovenous malformations (AVM) of the brain presents a non-invasive treatment option. We report our institutional experience with GK for pediatric AVMs.

METHODS

We performed a retrospective review of all pediatric patients treated with GK for cerebral AVMs at our institution from November 2003 up to and including September 2014. Patient demographics, AVM characteristics, treatment parameters and AVM responses were recorded.

RESULTS

Nineteen patients were treated, with 4 lost to follow-up. The mean age was 14.2 years (range. 7-18 years), with 10 being males (52.6%). The mean AVM diameter and volume were 2.68 cm and 3.10 cm3 respectively. The mean Spetzler-Martin (SM) and Pollock grades of the treated AVMs were 2.4 and 0.99 respectively. The mean follow-up was 62 months. All AVMs treated demonstrated a response on follow-up imaging. Nine of 15 (60.0%) patients displayed obliteration of their AVMs. Nine of 11 patients with a minimum of 3 years follow-up (81.8%) displayed obliteration, with SM and Pollock grades correlating to the chance of obliteration in this group. Two patients developed post-GK edema requiring short course dexamethasone therapy. No other major complications occurred. No permanent complications occurred.

CONCLUSIONS

GK radiosurgery for pediatric AVMs offers a safe and effective treatment option, with low permanent complication rates during early follow-up.

Gamma Knife for Cerebral Arteriovenous Malformations at a Single Centre

Background:

We report the results of a consecutive series of patients treated with Gamma Knife (GK) Surgery for cerebral arteriovenous malformations (AVMs).

Methods:

We retrospectively reviewed 69 patients treated with GK for cerebral AVMs between November 2003 and April 2009, recording clinical data, treatment parameters, and AVM obliteration rates in order to assess our effectiveness with GK in treating these lesions.

Results:

Ten patients were lost to follow-up. Presentations included: seizure (24), hemorrhage (18), persistent headache (12), progressing neurological signs (10), and incidental (9). In 24 patients (34.8%) treatment planning consisted of digital subtraction angiography (DSA), magnetic resonance imaging (MRI), and computed tomogram (CT) angiography (CTA). Currently we rely predominantly on CTA and/or MRI scanning only. Fourty-one patients have been followed for a minimum of 3 years; average age 40.9yr., 58.5% males. Average dose at the 50% isodose line was 20.3 Gy (range 16 to 26.4 Gy). Obliteration was observed in 87.8% by MRI, CT, or DSA. Not all obliteration was confirmed by DSA. Complications occurred in 12 of 59 (20.3%) patients, and in 11 of 41 (26.8%) with 3 year follow-up. Major (temporary) complications for the 59 included symptomatic cerebral edema (7), seizure (2), and hemorrhage (1). Major permanent complications occurred in one patient suffering a cranial nerve V deafferentation, and in two patients suffering a hemorrhage.

Conclusion:

GKS for cerebral AVM's offers an effective and safe method of treatment, with low permanent complication rate.

Stereotactic radiosurgery at a low marginal dose for the treatment of pediatric arteriovenous malformations: obliteration, complications, and functional outcomes

OBJECT.: Stereotactic radiosurgery (SRS) is an established treatment modality for brain arteriovenous malformations (AVMs) in children, but the optimal treatment parameters and associated treatment-related complications are not fully understood. The authors present their single-institution experience of using SRS, at a relatively low marginal dose, to treat AVMs in children for nearly 20 years; they report angiographic outcomes, posttreatment hemorrhage rates, adverse treatment-related events, and functional outcomes.

METHODS

The authors conducted a retrospective review of 2 cohorts of children (18 years of age or younger) with AVMs treated from 1991 to 1998 and from 2000 to 2010.

RESULTS

A total of 80 patients with follow-up data after SRS were identified. Mean age at SRS was 12.7 years, and 56% of patients had hemorrhage at the time of presentation. Median target volume was 3.1 cm(3) (range 0.09-62.3 cm(3)), and median prescription marginal dose used was 17.5 Gy (range 12-20 Gy). Angiograms acquired 3 years after treatment were available for 47% of patients; AVM obliteration was achieved in 52% of patients who received a dose of 18-20 Gy and in 16% who received less than 18 Gy. At 5 years after SRS, the cumulative incidence of hemorrhage was 25% (95% CI 16%-37%). No permanent neurological deficits occurred in patients who did not experience posttreatment hemorrhage. Overall, good functional outcomes (modified Rankin Scale Scores 0-2) were observed for 78% of patients; for 66% of patients, functional status improved or remained the same as before treatment.

CONCLUSIONS

A low marginal dose minimizes SRS-related neurological deficits but leads to low rates of obliteration and high rates of hemorrhage. To maximize AVM obliteration and minimize posttreatment hemorrhage, the authors recommend a prescription marginal dose of 18 Gy or more. In addition, SRS-related symptoms such as headache and seizures should be considered when discussing risks and benefits of SRS for treating AVMs in children.

Dynamic radiosurgery at the Toronto - Bayview Regional Cancer Centre, 1988-2007

Dynamic radiosurgery was first developed in Montreal and was subsequently adopted at the Toronto-Bayview Regional Cancer Centre in 1988. At that time radiosurgery was in its infancy in Canada. The opportunity of offering highly conformal radiation treatments for intracranial targets presented numerous technical challenges notably in the area of quality assurance. This review chronicles the development of radiosurgery at the Toronto-Bayview Regional Cancer Centre and summarises the successes and failures of the program over the following two decades.

Stereotactic radiosurgery of cranial arteriovenous malformations and dural arteriovenous fistulas

Cranial arteriovenous malformations (AVM) and cranial dural arteriovenous fistulas (AVF) carry a significant risk of morbidity and mortality when they hemorrhage. Current treatment options include surgery, embolization, radiosurgery, or a combination of these treatments. Radiosurgery is thought to reduce the risk hemorrhage in AVMs and AVFs by obliterating of the nidus of abnormal vasculature over the course of 2 to 3 years. Success in treating AVMs is variable depending on the volume of the lesion, the radiation dose, and the pattern of vascular supply and drainage. This article discusses the considerations for selecting radiosurgery as a treatment modality in patients who present with AVMs and AVFs.

Ruptured brain arteriovenous malformations in children: correlation of clinical outcome with admission parameters

AIMS

To gain a better understanding of how clinical outcome in children with ruptured brain arteriovenous malformations (bAVMs) correlates with clinical and imaging parameters on admission.

METHODS

The authors retrospectively reviewed patients with bAVMs, aged 18 or below, managed at their hospital between January 1992 and December 2008. Clinical outcome was assessed using the modified Rankin Scale (mRS). Patients with ruptured bAVMs were analyzed; their clinical parameters and computerized tomography findings on admission were recorded. Clinical outcome was then evaluated against admission scores using the Glasgow Coma Scale (GCS), the World Federation of Neurosurgical Societies Grading System of Subarachnoid Hemorrhage (WFNS-SAH), the Spetzler-Martin grade, the intracerebral hemorrhage score and 2 other independent parameters, namely pupillary response and significant focal neurological injuries. Spearman's correlation coefficient, linear regression analysis and multivariate logistic regression analysis were used for data analysis.

RESULTS

40 pediatric patients with bAVMs were found and 32 of them presented with hemorrhage (80%). In the 32 children with ruptured bAVMS, follow-up ranged between 7 and 204 months (median 100.5 months). The complete excision/obliteration rate as confirmed by digital subtraction angiography was 73.3%. The mRS scores at the last follow-up were: grades 0-II in 87.5%; grades IV-V in 6.25%, and grade VI in 6.25%. The Spetzler-Martin grade, the intracerebral hemorrhage score, the WFNS-SAH grade, the GCS scores, and a combined scoring scale consisting of the GCS, pupillary response and significant focal neurological injuries correlated significantly with clinical outcome 6 months after hemorrhage. However, on the scatter diagrams, it appeared that only the combined scoring scale might be valid for clinical practice. Multivariate logistic regression analysis showed that the combined scoring scale was a statistically significant independent predictor of clinical outcome 6 months after hemorrhage.

CONCLUSION

In this series of pediatric patients with ruptured bAVMs, although various grading scales correlated significantly with clinical outcome 6 months after hemorrhage, only the combined scoring scale might have the potential to be applied to predict clinical outcome in these children.