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

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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.


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.


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).


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.

ABBREVIATIONS AVM = arteriovenous malformation; GKRS = Gamma Knife radiosurgery; LINAC = linear accelerator; RIC = radiation-induced change; SRS = stereotactic radiosurgery.

Article Information

Correspondence Jason P. Sheehan, Box 800212, Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia 22908. email:

INCLUDE WHEN CITING Published online May 26, 2017; DOI: 10.3171/2016.12.JNS162478.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.



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    Flow diagram showing the selection process for studies included in analyses of cyst incidence and latency period.

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    Histogram of the number of newly discovered cysts biennially since SRS treatment in 63 patients from 19 studies with individual patient time-to-cyst-discovery data. The mean time to cyst formation is 78 months (6.5 years).



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