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

Abstract

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.

Radiation-induced cystic brain necrosis developing 10 years after linac-based stereotactic radiosurgery for brain metastasis

“…CBN after SRS has been reported mainly as a late complication after GK-based SRS for benign non-neoplastic diseases, like AVMs [ 1 ] (reported incidence: 3%). However, cases related to BMs after SRS have been scarcely reported [ 6 , 7 ].…”

“…In non-cystic BN, conservative therapies, such as hyperbaric oxygen therapy, corticosteroids or bevacizumab, are the standard of care [ 4 , 8 , 9 ], and surgical procedures are seldom required. Conversely, CBN tends to be resistant to these conservative therapies and readily recurs, and no standard therapy has been established yet; surgical resection or continuous cyst drainage using a cystoperitoneal shunt or Ommaya reservoir placement is usually required [ 1 – 3 , 6 , 7 ]. According to previous reports, 32.8–88% of CBNs were symptomatic and 32.8–63% required surgery [ 1 , 6 ].…”

“…Recently, a unique type of radiation-induced brain necrosis (BN), which accompanies cyst formation, has been reported mainly in patients treated with Gamma knife (GK)-based stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVMs) [ 1 – 3 ]. This cystic BN (CBN) has also been previously reported as a late complication of conventional radiation therapy (RT) for head and neck cancers, for example, in nasopharyngeal carcinoma [ 4 , 5 ].…”

“…Non-cystic BN typically develops within a few years after RT and is mostly asymptomatic or controllable with conservative therapy [ 4 ]. In comparison, CBN tends to occur with longer latency and is usually symptomatic and difficult to manage with conservative therapy [ 1 – 3 ]. Although there have been several reports of CBN following SRS, its long-term clinical features are poorly documented, and reports related to SRS for brain metastasis (BM) are extremely limited [ 6 , 7 ].…”

Proceedings of the 2018 next-generation Gamma Knife research meeting

“…28 Late complications can include cyst formation, progressive vasogenic edema, and chronic expanding hematoma development. 16,25,26 Preliminary data from Lee and colleagues (Lee CC et al, unpublished data) have shown that the risks of adverse radiation effects are reduced if radiation exposure of intervening normal brain is minimized, especially in diffuse forms of AVMs. These authors have therefore developed, using fuzzy c-means clustering techniques, a method of separating CSF, brain tissue, and AVM vasculature on high-resolution T2-weighted images, producing color-coded maps of the AVM showing these 3 components separately in order to help guide GKSRS planning.…”