Delayed Cyst Formation After Gamma Knife Radiosurgery for Brain Metastases

Ishikawa, Eiichi; Yamamoto, Masaaki; Saito, Atsushi; Kujiraoka, Yuka; Iijima, Tatsuo; Akutsu, Hidenori; Matsumura, Akira

doi:10.1227/01.neu.0000351771.46273.22

Cited by 23 publications

(19 citation statements)

References 17 publications

(28 reference statements)

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“…In comments on our previous publication focusing on delayed cyst formation in patients with BM surviving > 3 years after SRS, Regis stated that the mean GI value in our series was quite poor (approximately 4) and noted that cyst formation might partially account for this result. 4,13 However, we have long wondered whether either CI or GI truly impacts treatment results, despite these indexes being theoretically regarded as correlating with post-SRS outcomes. We reported that, based on 207 patients with vestibular schwannomas who were followed up for at least 10 years after SRS, CI did not correlate with good tumor control and GI had no impact on the degree of hearing preservation.…”

Section: Discussionmentioning

confidence: 99%

Clinical significance of conformity index and gradient index in patients undergoing stereotactic radiosurgery for a single metastatic tumor

Aiyama

Yamamoto

Kawabe

et al. 2018

Journal of Neurosurgery

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OBJECTIVEAlthough the conformity index (CI) and the gradient index (GI), which were proposed by Paddick and colleagues, are both logically considered to correlate with good posttreatment results after stereotactic radiosurgery (SRS), this hypothesis has not been confirmed clinically. The authors’ aim was to reappraise whether high CI values correlate with reduced tumor progression rates, and whether low GI values correlate with reduced complication incidences.METHODSThis was an institutional review board–approved, retrospective cohort study conducted using a prospectively accumulated database including 3271 patients who underwent Gamma Knife SRS for brain metastases (BMs) during the 1998–2016 period. Among the 3271 patients, 925 with a single BM at the time of SRS (335 women and 590 men, mean age 66 [range 24–93] years) were studied. The mean/median CIs were 0.62/0.66 (interquartile range [IQR] 0.53–0.74, range 0.08–0.88) and the mean/median GIs were 3.20/3.09 (IQR 2.83–3.39, range 2.27–11.4).RESULTSSRS-related complications occurred in 38 patients (4.1%), with a median post-SRS interval of 11.5 (IQR 6.0–25.8, maximum 118.0) months. Cumulative incidences of post-SRS complications determined by a competing risk analysis were 2.2%, 3.2%, 3.6%, 3.8%, and 3.9% at the 12th, 24th, 36th, 48th, and 60th post-SRS month, respectively. Multivariable analyses showed that only two clinical factors (i.e., peripheral doses and brain volume receiving ≥ 12 Gy) correlated with complication rates. However, neither CIs nor GIs impacted the incidences of complications. Among the 925 patients, post-SRS MRI was performed at least once in 716 of them, who were thus eligible for local progression evaluation. Among these 716 patients, local progression was confirmed in 96 (13.4%), with a median post-SRS interval of 10.8 (IQR 6.7–19.5, maximum 59.8) months. Cumulative incidences of local progression determined by a competing risk analysis were 7.7%, 12.6%, 14.2%, 14.8%, and 15.3% at the 12th, 24th, 36th, 48th, and 60th post-SRS month, respectively. Multivariable analyses showed neurological symptoms, extracerebral metastases, repeat SRS, and CIs to correlate with incidences of local progression, whereas GIs had no impact on local tumor progression. Particularly, cumulative incidences of local progression were significantly lower in patients with CIs < 0.65 than in those with CIs ≥ 0.65 (adjusted hazard ratio 1.870, 95% confidence interval 1.299–2.843; p = 0.0034).CONCLUSIONSTo the authors’ knowledge, this is the first analysis to focus on the clinical significance of CI and GI based on a large series of patients with BM. Contrary to the majority opinion that dose planning with higher CI and lower GI results in good post-SRS outcomes (i.e., low local progression rates and minimal complications), this study clearly showed that the lower the CIs were, the lower the local progression rates were, and that the GI did not impact complication rates.

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Section: Discussionmentioning

confidence: 99%

Clinical significance of conformity index and gradient index in patients undergoing stereotactic radiosurgery for a single metastatic tumor

Aiyama

Yamamoto

Kawabe

et al. 2018

Journal of Neurosurgery

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“…The number of reports on CCF cases from various types of primary pathology have been increasing, whilst the aetiopathogenesis of CCF remains to be elucidated. 9,10 Repetitive haemorrhage from an abnormal angiomatous lesion located within or underlying the cyst wall was suggested as a plausible mechanism for cyst enlargement in AVM cases. 9 The CCF in the present cases appeared more than 2-7 years after SRT, and are plausibly derived from a part or the entirety of pre-existing parenchymal injury rather than degenerative change of the necrotic tumour.…”

Section: Discussionmentioning

confidence: 99%

“…[1][2][3] Brain radiation necrosis is one of the important untoward sequelae after radiotherapy, including SRT for HNM, especially nasopharyngeal carcinoma (NPC), with imaging findings being characterized by central loss of enhancement surrounded by feathery or reticular enhancement associated with perilesional oedema. [4][5][6][7] Cerebral cyst formation (CCF) is an unusual subset of radiation-induced brain injury and is usually encountered in cases harbouring intracranial disorders embedded in the parenchyma, such as arteriovenous malformation (AVM) 8,9 or brain metastases, 10,11 and rarely extra-axial tumours, such as meningioma 12 and neuroma, 13 treated with stereotactic radiosurgery (SRS). CCF might also occur as a rare consequence of brain injury following definitive radiotherapy for NPC.…”

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confidence: 99%

Cerebral cyst formation following stereotactic ablative irradiation for non-nasopharyngeal head and neck malignancies: imaging findings and relevant dosimetric parameters

Ohtakara

Hoshi²

2014

The British Journal of Radiology

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Objective: To describe the clinical characteristics, imaging findings and relevant dosimetric parameters of cases presenting with cerebral cyst formation (CCF) after single or oligo-fractionated stereotactic radiotherapy (SRT) for non-nasopharyngeal head and neck malignancies (HNMs). Methods: We identified four cases with the follow-up duration of 5.7–9.1 years from SRT. The irradiated sites included the middle ear in one case and the ethmoid sinus in three cases, two of the latter possessed brain invasion. The chronological changes in MR images and the dose–volume histogram of the adjacent brain tissue were evaluated. Results: CCF with or without multiple septi presented with a latency of 29–86 months (median, 45.5 months), which was preceded by either non-specific parenchymal enhancement or typical radiation necrosis. In three cases, CCF adjacent to the frontal base resultantly caused mass effect, and two of these three cases required surgical intervention at 38 and 54 months, respectively, after SRT for alleviation of symptoms. The relation of the irradiated brain volumes to the biological equivalent dose based on the linear-quadratic (LQ) and LQ-cubic models was represented as a threshold. Conclusion: When contemplating SRT for HNM cases, caution should be exercised to the dose–volume relation-ship of the adjacent brain tissue, especially the frontal base, as well as other critical structures, and long-term vigilant follow-up is also mandatory. Advances in knowledge: CCF can occur as an unusual consequence of late brain injury with variable but mostly long latency following SRT for non-nasopharyngeal HNMs adjacent to the brain, even superficial parts that were previously irradiated via conventional radiotherapy.

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“…Late-onset complications after stereotactic irradiation include radiation-induced edema, radiation necrosis, cyst formation, radiation-related tumorigenesis, and radiation-induced cerebrovascular injury. 2,4,8,16,18,25,29,30) We describe a rarely predictable delayed complication which occurred after SRS in a patient with VS.…”

Section: Introductionmentioning

confidence: 93%

Repeated Delayed Onset Cerebellar Radiation Injuries After Linear Accelerator-Based Stereotactic Radiosurgery for Vestibular Schwannoma

Ujifuku

Matsuo

Toyoda

et al. 2012

Neurol. Med. Chir.(Tokyo)

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A 63-year-old woman presented with right hearing disturbance and vertigo. Magnetic resonance (MR) imaging revealed the presence of right vestibular schwannoma (VS). Stereotactic radiosurgery (SRS) was performed with a tumor marginal dose of 14 Gy using two isocenters. She was followed up clinically and neuroradiologically using three-dimensional spoiled gradient-echo MR imaging. She experienced temporal neurological deterioration due to peritumoral edema in her right cerebellar peduncle and pons for a few months beginning 1.5 years after SRS, when she experienced transient right facial dysesthesia and hearing deterioration. Ten years after SRS, the patient presented with sudden onset of vertigo, gait disturbance, diplopia, dysarthria, and nausea. MR imaging demonstrated a new lesion in the right cerebellar peduncle, which was diagnosed as radiation-induced stroke. The patient was followed up conservatively and her symptoms disappeared within a few months. Multiple delayed onset radiation injuries are possible sequelae of SRS for VS.

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Delayed Cyst Formation After Gamma Knife Radiosurgery for Brain Metastases

Abstract: Although DCF is not a widely recognized complication of GKRS for METs, we advocate careful follow-up, with surgical intervention for DCF if necessary, for frequently irradiated and long-surviving patients with METs treated with GKRS.

Cited by 23 publications

References 17 publications

Clinical significance of conformity index and gradient index in patients undergoing stereotactic radiosurgery for a single metastatic tumor

Clinical significance of conformity index and gradient index in patients undergoing stereotactic radiosurgery for a single metastatic tumor

Cerebral cyst formation following stereotactic ablative irradiation for non-nasopharyngeal head and neck malignancies: imaging findings and relevant dosimetric parameters

Repeated Delayed Onset Cerebellar Radiation Injuries After Linear Accelerator-Based Stereotactic Radiosurgery for Vestibular Schwannoma

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