Microsurgery is presumed the most preferred treatment for low-grade AVMs. However, some of these AVMs may have an alternative option, such as radiosurgery, to minimize treatment risk. Through comparison with the surgical sub-cohort, we aim to identify possible sub-cohorts of patients that are optimal for radiosurgery.
Retrospective chart review of 763 patients with AVMs seen in our institution between 1990-2015 was collected. Patients with grade 1/2 AVMs that were treated by surgery or radiosurgery were included. Those with missing data, loss-to-follow-up or with hereditary hemorrhagic telangiectasia(HHT) were excluded. Patient baseline data were collected and compared between radiosurgery and surgery cohorts. Outcome was assessed by obliteration status and functional outcome using modified Rankin Scale(mRS).
Of the 254 low-grade AVMs found, 186(73.2%) were included after application of exclusion criteria. Mean age was 37.5+/-17.4 years with 47.8% male. Ninety-four patients underwent radiosurgery and 92 received microsurgery. Spetzler-Martin grades were: grade 1(25.8%) and grade 2(74.2%). The average size was 2.1cm without difference between two treatment groups(p=0.552). More grade 2 patients were managed by radiosurgery(p=0.006), and more ruptured AVMs(n=80, 43.0%) tend to be surgically managed(n=46, 50%; p=0.057). Obliteration was 95.7% by surgery and 41.5% by radiosurgery(p<0.001), and follow-up mRS displays no difference(p=0.892). Obliteration was achieved in all two brainstem lesions for radiosurgery, while none was attempted for surgery(p=0.032). Similarly, 80% of the paramedian lesions were obliterated by radiosurgery, while none underwent surgery(p=0.022). Of patients with improved/unchanged mRS, 52.6% of those who underwent radiosurgery had lesions in eloquent areas, compared to only 35.8% in surgery(p=0.033).
There may be a subset of low-grade AVMs that are more suitable for radiosurgery than surgery. We identified paramedian lesions and eloquent location as potential subgroups to consider for radiosurgery. More studies should be conducted in this cohort to confirm our findings and subsequently refine an algorithm for best management strategy.
In this study, we explored treatment risk profile for low grade AVMs. Despite an established entity, these AVMs still demonstrate considerable heterogeneity that warrants further refining of treatment algorithm to achieve best outcomes. Our findings suggest that there might be a subset of patients more suitable for radiosurgery than surgery in this cohort, and paramedian lesions and eloquency may be indicators to consider alternative therapy to surgery. If confirmed by further studies, a small subset of patients in this cohort will be benefitted from reasonable obliteration rate without additional operative risk from radiosurgery.
By the conclusion of this session, participants should be able to: 1) Raise awareness that some low-grade AVMs may be more suitable for radiosurgery 2) Understand that paramedian lesions, eloquent location (especially brainstem) may be potential indicators to consider radiosurgery