Stereotactic radiosurgery for sylvian fissure arteriovenous malformations with emphasis on hemorrhage risks and seizure outcomes

Sylvian fissure arteriovenous malformations: case series and systematic review of the literature

BACKGROUND

Sylvian fissure arteriovenous malformations are rare but important vascular lesions, whose importance lies in both haemorrhage and seizure risk. Although surgery has been recommended as a treatment, the overall estimation of success has not been reported to render outcomes easier to understand in comparison to other treatment modalities.

OBJECTIVES

This systematic review of the literature and two cases aims to illustrate the results of surgery as a contemporary treatment option and present a novel anatomical classification system for Sylvian fissure arteriovenous malformations.

MATERIALS AND METHODS

A systematic review was performed by searching MEDLINE (PubMed), EMBASE and Cochrane electronic bibliographic databases from conception to 2018. The following keywords were used: 'Sylvian fissure' AND 'AVM' OR 'arteriovenous malformation' OR 'intracranial arteriovenous malformation' OR 'cerebral arteriovenous malformation' OR 'brain arteriovenous malformation'. The search strategy was not limited by study design but only included keywords in the English language. In addition, two local institution Sylvian fissure arteriovenous malformations are presented and incorporated.

RESULTS

A total of nine full-text articles were included in the analysis. The results of reported cases and the literature review emphasise the role of surgery in the treatment of Sylvian fissure arteriovenous malformations, with an acceptable result in carefully selected patients. We propose a classification system which may inform the choice of surgical approach for these lesions.

CONCLUSIONS

Surgery remains the cornerstone of Sylvian fissure arteriovenous malformation treatment, which may apply to high-grade lesions in this special anatomical location.

Gamma Knife Radiosurgery Followed by Flow-Reductive Embolization for Ruptured Arteriovenous Malformation

Background: Aggressive treatment to achieve complete obliteration of brain arteriovenous malformation (AVM) is necessary in patients with a recent history of hemorrhage. The major drawback of Gamma knife radiosurgery (GKRS) alone for AVM is risk of bleeding during the latent period until the AVM occludes. At our center, patients who present with ruptured AVMs are frequently offered GKRS followed by embolization. The goal of this study was to compare outcomes of embolization for patients who have previously undergone GKRS for ruptured AVMs. Methods: A database including 150 GKRS for ruptured AVMs between November 2008 and October 2017 was reviewed. The embolized group was selected by including AVMs with post-GKRS embolization. The non-embolized group was defined as AVMs treated by GKRS alone. Outcomes including obliteration rate, incidence of repeat hemorrhage, and delayed cyst formation were compared between two groups. The predictive factors related to AVM obliteration and complications were analyzed. Results: The study consisted of 81 patients in the non-embolized group and 17 patients in the embolized group. Statistically significant differences were detected between the two groups with respect to age, Pollock-Flickinger score, Spetzler-Martin (SM) grade, eloquence of adjacent brain, and presence of aneurysms. The embolized group included more AVMs with larger median nidus volume. The predictive factors for the obliteration of ruptured AVMs were nidus volume, SM grade, Virginia Radiosurgery AVM Scale (VRAS), and Pollock-Flickinger score and for the subsequent hemorrhage were marginal dose, nidus volume, SM grade, VRAS, and Pollock-Flickinger score. The obliteration rates and complication rates after GKRS between groups were not significantly different. However, this study demonstrated statistically significant difference in the cumulative incidence of obliteration in AVMs with SM grade III and IV (p = 0.037). Conclusion: Although the current study demonstrated similar results in patients who underwent GKRS with and without embolization, the embolized group included more AVMs with larger nidus volume, higher SM grade, Pollock-Flickinger score, and aneurysm, which have a lower chance of obliteration and a higher probability of repeat hemorrhage. GKRS followed by embolization appears to be a beneficial approach for the treatment of ruptured AVMs that are at risk for obliteration failure and repeat hemorrhage during the latency period after single-session GKRS alone. Further studies involving a larger number of cases and continuous follow-up are necessary to confirm our conclusions.

Seizure control after radiosurgery for cerebral arteriovenous malformations: a 25-year experience

OBJECTIVE

Seizures are the second-most common presenting symptom in patients with lobar arteriovenous malformations (AVMs). However, few studies have assessed the long-term effect of stereotactic radiosurgery (SRS) on seizure control. The authors of this study assess the outcome of SRS for these patients to identify prognostic factors associated with seizure control.

METHODS

Patients with AVM who presented with a history of seizure and underwent SRS at the authors' institution between 1987 and 2012 were retrospectively assessed. The total cohort included 155 patients with a mean follow-up of 86 months (range 6-295 months). Primary outcomes assessed were seizure frequency, antiepileptic drug regimen, and seizure freedom for 6 months prior to last follow-up.

RESULTS

Seizure-free status was achieved in 108 patients (70%), with an additional 23 patients (15%) reporting improved seizure frequency as compared to their pre-SRS status. The median time to seizure-free status was estimated to be 12 months (95% CI 0-27 months) as evaluated via Kaplan-Meier survival analysis. The mean seizure frequency prior to SRS was 14.2 (95% CI 5.4-23.1) episodes per year. Although not all patients tried, the proportion of patients successfully weaned off all antiepileptic drugs was 18% (28/155 patients). On multivariate logistic regression, focal impaired awareness seizure type (also known as complex partial seizures) and superficial venous drainage were significantly associated with a decreased odds ratio for seizure-free status at last follow-up (OR 0.37 [95% CI 0.15-0.92] for focal impaired awareness seizures; OR 0.36 [95% CI 0.16-0.81] for superficial venous drainage). The effects of superficial venous drainage on seizure outcome were nonsignificant when excluding patients with < 2 years of follow-up. AVM obliteration did not correlate with long-term seizure freedom (p = 0.202, chi-square test).

CONCLUSIONS

This study suggests that SRS improves long-term seizure control and increases the likelihood of being medication free, independently of AVM obliteration. Patients with focal impaired awareness seizures were less likely to obtain long-term seizure relief.

Cyst formation after stereotactic radiosurgery for brain arteriovenous malformations: a systematic review

OBJECTIVE Cyst formation can occasionally occur after stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVMs). Given the limited data regarding post-SRS cyst formation in patients with AVM, the time course, natural history, and management of this delayed complication are poorly defined. The aim of this systematic review was to determine the incidence, time course, and optimal management of cyst formation after SRS for AVMs. METHODS A literature review was performed using PubMed to identify studies reporting cyst formation in AVM patients treated with SRS. Baseline and outcomes data, including the incidence and management of post-SRS cysts, were extracted from each study that reported follow-up duration. The mean time to cyst formation was calculated from the subset of studies that reported individual patient data. RESULTS Based on pooled data from 22 studies comprising the incidence analysis, the overall rate of post-SRS cyst formation was 3.0% (78/2619 patients). Among the 26 post-SRS cyst patients with available AVM obliteration data, nidal obliteration was achieved in 20 (76.9%). Of the 64 cyst patients with available symptomatology and management data, 21 (32.8%) were symptomatic; 21 cysts (32.8%) were treated with surgical intervention, whereas the remaining 43 (67.2%) were managed conservatively. Based on a subset of 19 studies reporting individual time-to-cyst-formation data from 63 patients, the mean latency period to post-SRS cyst formation was 78 months (6.5 years). CONCLUSIONS Cyst formation is an uncommon complication after SRS for AVMs, with a relatively long latency period. The majority of post-SRS cysts are asymptomatic and can be managed conservatively, although enlarging or symptomatic cysts may require surgical intervention. Long-term follow-up of AVM patients is crucial to the appropriate diagnosis and management of post-SRS cysts.

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.

Estimating the Risks of Adverse Radiation Effects After Gamma Knife Radiosurgery for Arteriovenous Malformations

Background and Purpose—

We evaluated risk factors associated with the development of adverse radiation effects (ARE) after stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVMs).

Methods—

We evaluated 755 patients with AVM who underwent a single Gamma Knife SRS procedure with at least a 2-year minimum follow-up. Eighty-seven patients (12%) underwent previous resection and 128 (17%) had previous embolization. The median target volume was 3.6 mL (range, 0.1–26.3 mL). The median margin dose was 20 Gy (range, 13–27 Gy).

Results—

Fifty-five patients (7%) developed symptomatic ARE at a median follow-up of 75 months. The cumulative rates of symptomatic ARE were 3.2%, 5.8%, 6.7%, and 7.5% at 1, 2, 3, and 5 years, respectively. Factors associated with a higher rate of developing symptomatic ARE included larger AVM volume, higher margin dose, larger 12-Gy volume, higher Spetzler–Martin grade, and higher radiosurgery-based score. The rates of developing symptomatic ARE were higher in the brain stem (22%) or thalamus (16%), compared with AVMs located in other brain locations (4%–8%). Nineteen patients (3%) sustained irreversible new neurological deficits related to ARE, and 1 patient died. The rates of irreversible symptomatic ARE were 0.8%, 1.9%, 2.1%, and 2.8% at 1, 2, 3, and 5 years, respectively. The 5-year cumulative rates of irreversible symptomatic ARE were 9.1% in thalamus, 12.1% in brain stem, and 1.4% in other locations.

Conclusions—

The knowledge of ARE risk rates after AVM radiosurgery can assist informed consent for patients with AVM, their families, and healthcare providers.

Medical vs. invasive therapy in AVM-related epilepsy: Systematic review and meta-analysis

OBJECTIVE

To compare invasive arteriovenous malformation (AVM) therapy to conservative management using only antiepileptic drugs (AEDs) for achieving seizure freedom in patients with AVM-related epilepsy.

METHODS

We searched Medline, Embase, and Cochrane Central up to June 2015 using epilepsy and AVM Medical Subject Headings and keywords. We included original research involving controlled observational cohort studies or randomized controlled trials (RCTs) comparing seizure outcomes between invasive AVM treatments vs. AED management alone, and uncontrolled case series of invasive AVM therapy for seizures that contained ≥20 patients. The estimates of seizure freedom were pooled using meta-analysis for the controlled trials, while the estimates for the case series were evaluated using descriptive statistics.

RESULTS

Of 2,166 identified abstracts, 98 were reviewed in full text, of which 31 were included in the final dataset. We identified 2 controlled observational studies (n = 106 patients) and 29 uncontrolled case series. We identified 1 RCT but it did not report seizure outcomes. The pooled risk ratio for seizure freedom in controlled studies (0.99; 95% confidence interval [CI] 0.69, 1.43) did not indicate superiority to either approach. Seizure freedom in case series varied from 19% (95% CI 11, 30%) to 95% (95% CI 76, 99%) at last follow-up.

CONCLUSIONS

There is insufficient evidence available to determine if invasive AVM management is superior to AED only for controlling seizures. An RCT of interventional vs. medical management using standardized epilepsy-specific presurgical protocols is warranted.