Original ArticleLinac-based Stereotactic Radiosurgery for Brain Arteriovenous Malformations
Introduction
Arteriovenous malformations (AVMs) of the brain can be the cause of epileptic seizures, neurological dysfunctions and intracranial haemorrhage. The annual bleeding risk from AVMs is estimated to be between 2 and 4% and the life risk of haemorrhage is usually calculated using the Brown formula: risk (%) = 105 – age [1], [2]. It is obvious that the cumulative risk of a life-threatening haemorrhage is substantial, especially in young patients and, thus, most AVMs require treatment that can eliminate or significantly minimise the risk of bleeding. The most effective treatment is microneurosurgery — total removal of the lesion guarantees cure. Stereotactic radiosurgery is a widely recognised method of treatment for AVMs of the brain that are not suitable for surgery. The reported percentage of obliteration is usually about 80–90% in selected cases of lesions smaller than 3 cm [3], [4], [5], [6]. The results of stereotactic irradiation of larger AVMs are less encouraging and usually range between 43 and 70% [7], [8], [9], [10]. Moreover, the influence of combined treatment involving endovascular procedures and stereotactic radiosurgery on treatment outcome is not fully elucidated. Available reports often contain conflicting data indicating either beneficial or deleterious effects of endovascular treatment on radiosurgery outcome [11], [12], [13]. Still more data are needed to establish reliable indications for embolisation before radiosurgery.
Most papers dealing with stereotactic irradiation of brain AVMs report the results of gamma-knife radiosurgery. Linac-based radiosurgery for brain AVMs is less extensively described and still new data are needed to confirm the influence of selected clinical and treatment parameters on treatment outcome. The aim of the study was to evaluate the obliteration and rebleeding rates as well as the adverse effects of linac-based stereotactic radiosurgery for brain AVMs of relatively large mean volume (11.7 cm3). We also attempted to identify clinical and treatment-related factors influencing obliteration rates after linac-based stereotactic radiosurgery.
Section snippets
Patients
The analysis was based on a group of 62 consecutive patients aged 8–76 years old (mean age 39.5 years), irradiated with a linac-based stereotactic technique for brain AVMs between October 2001 and December 2005. The proportion of males and females was almost equal — 32 and 30, respectively. Twenty-nine patients were referred to our institution without prior treatment, just after the diagnosis, whereas 33 patients were previously treated. Five patients were treated surgically. The surgical
Results
AVMs were obliterated in 22 of 62 patients, which resulted in a crude obliteration rate of 35.5%. Actuarial obliteration rates after 1, 2 and 3 years of follow-up were 17, 36 and 40%, respectively. In 17 of 22 (77.3%) patients, obliteration was diagnosed during the first 2 years of follow-up (Figure 2). Nevertheless, five of 22 obliterations (22.7%) occurred after 2 years and three (13.6%) after 3 years of observation. The mean time to obliteration was 18.7 months (range 3–53 months). Among 13
Discussion
Actuarial obliteration rates of 17, 36 and 40% after 1, 2 and 3 years of follow-up, respectively, are somewhat lower than usually reported in the literature and can be attributed to the relatively large mean volume of treated lesions, as well as to the moderate radiation doses applied. They are, however, comparable with obliteration rates reported by Zabel-du Bois et al. [16]. They reported a 50% actuarial 3 year obliteration rate in a group of 65 patients with a median time to obliteration of
Conclusions
The large heterogeneity of the group, moderate doses of radiation used in some patients and the method of assessment of AVM obliteration are the disadvantages of the study that could influence our results. However, the current analysis shows that linac-based stereotactic radiosurgery proved to be a safe method of treatment for cerebral AVMs and within the range of applied doses no serious adverse effects were observed, even in the case of large AVMs of volumes exceeding 14 cm3. Adequate, at
References (40)
- et al.
An analysis of the dose-response for arteriovenous malformation radiosurgery and other factors affecting obliteration
Radiother Oncol
(2002) - et al.
Gamma knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part II: Differences in obliteration rates, treatment–obliteration intervals, and prognostic factors
Int J Radiat Oncol Biol Phys
(2006) - et al.
Efficacy and morbidity of arc-therapy radiosurgery for cerebral arteriovenous malformations: a comparison with the natural history
Int J Radiat Oncol Biol Phys
(2004) - et al.
Stereotactic irradiation for intracranial arteriovenous malformation using stereotactic radiosurgery or hypofractionated stereotactic radiotherapy
Int J Radiat Oncol Biol Phys
(2004) - et al.
Single-fraction stereotactic radiotherapy: a dose-response analysis of arteriovenous malformation obliteration
Int J Radiat Oncol Biol Phys
(1998) - et al.
Pediatric cerebral arteriovenous malformations: the role of stereotactic linac-based radiosurgery
Int J Radiat Oncol Biol Phys
(2006) - et al.
Linac radiosurgery for cerebral arteriovenous malformations: results in 169 patients
Int J Radiat Oncol Biol Phys
(2000) - et al.
Stereotactic linac-based radiosurgery in the treatment of cerebral arteriovenous malformations located deep, involving corpus callosum, motor cortex or brainstem
Int J Radiat Oncol Biol Phys
(2006) - et al.
Linac-based radiosurgery or hypofractionated stereotactic radiotherapy in the treatment of large cerebral arteriovenous malformations
Int J Radiat Oncol Biol Phys
(2006) - et al.
Long-term results of radiosurgery for arteriovenous malformation: neuroradiodiagnostic imaging and histological studies of angiographically confirmed nidus obliteration
Surg Neurol
(1992)