Cerebral AVMs are important causes of intracerebral hemorrhage in young adults. For previously unruptured brain AVMs, the rate of developing hemorrhage was approximately 1% per year, but increases by five folds once ruptured [15, 19, 20]. Our single-center retrospective study showed 48 patients (68.6%) presenting ruptured AVMs. The treatment for AVMs aimed to minimize the risk of blood vessel rupture and resect lesions. Currently, treatment approaches mainly include microsurgical resection, endovascular embolization, and stereotactic radiosurgery [1, 2, 26].
Microsurgical resection is still a primary or “gold-standard” method for the authoritative management of low-grade AVMs . Its main advantages lie in the high rate of complete elimination, the immediate elimination of bleeding risk, and its long-term stability, thus reducing morbidity and mortality . Johannes et al reported that a consecutive series of 288 cases underwent microsurgical resection. And microsurgical resection of a cerebral AVM has a high cure rate . Although microsurgery is currently the mainstream surgical method for the treatment of AVMs, it also has its shortcomings, such as large trauma, long recovery time, and the risk of related neurological defects. Endovascular embolization is often used to improve the safety of microsurgery. The main objectives of preoperative embolization include occlusion of the supplying arteries, reduction of blood flow or malformation of vascular mass volume to allow safer surgical excision, and management of those high-risk angiography features, including aneurysm located on supplying arteries and malformation . Intraoperative angiography has also been used to guide AVM surgical treatment. The main purpose of DSA during the operation was to verify whether the deformed vascular mass was completely removed, while the main purpose of fluorescein or indocyanine green angiography during the operation was to show AVM vascular architecture. Therefore, the use of these surgical auxiliary means may improve patients’ selection, reduce surgical complications, and promote patients’ recovery, although these advantages are difficult to be definitively determined in clinical studies.
Endovascular embolization has been generally recognized as a safe and effective means for the AVMs . It is generally accepted that endovascular embolization is also an effective adjunctive treatment in a variety of clinical situations to facilitate complete surgical excision and reduce the risk of intra-operative bleeding [8, 33]. In some cases, the healing effect of AVMs is achieved by embolization alone, which is helpful in the application of the healing embolization strategy . This is corroborated in the study by Adam et al . They drew the conclusion that only 15% of patients achieved safely complete angiographic obliteration of the bAVM with embolization alone. However, our outcomes of complete bAVM obliteration are far superior to their study. They speculate that proximal occlusion of feeding arteries may be associated with recurrence. Another indication for endovascular therapy is as a substitute for microsurgery or stereotactic radiosurgery . In this study, endovascular embolization helps to reduce AVMs volume or occlusion of high-risk characteristics, such as ruptured aneurysms in or around the deformed vascular cluster, and final treatment of remaining AVMs. Finally, embolization has been used as palliative care to reduce vascular irregular blood flow to malformed vascular masses, thereby improving the underlying symptoms associated with blood theft.
Recently, multimodality treatment, especially hybrid surgery, has been paid more and more attention as an effective treatment of intracranial AVM [8, 9]. Preoperative partial embolization of the malformation can assist surgical positioning, reduce blood flow to the malformation, and reduce intraoperative bleeding risk and surgical difficulty . Intraoperative angiography can detect the residual malformation immediately for one-stop resection, greatly reducing the residual rate of postoperative malformation and the risk of postoperative rebleeding [16, 17, 21, 31]. Despite the lack of large sample evidence, multiple single-center randomized controlled studies have reported that the application of a hybrid operating room provides more satisfactory therapeutic effects compared with traditional surgery. However, for grade III or above, especially for complex bAVM lesions located in functional areas, simultaneous intraoperative angiography or embolization combined microsurgical resection under a hybrid operating room can achieve a better therapeutic effect and long-term prognosis, as well as a good functional protective effect.
Few reports were addressing the surgical efficacy between several above treatments. Procedure-related complications were higher in the hybrid group in comparison with the embolization alone group in our study, but the results showed no significant difference between the hybrid operation and embolization alone groups in any of the favorable clinical outcomes. These results are consistent with our results. Wang et al. found that better long-term outcomes in 92.5% of unruptured AVM patients compared with ruptured AVMs in long-term follow-up . These results support our finding that the immediate neurological deficits are usually transient and that many patients recover over time. Immediate post-operative radiological findings demonstrated complete obliteration in 99.4% of patients in the hybrid surgery group, whereas 38.3% in the embolization alone group. Wen et al. also found that the hybrid operation presented distinct advantages in cure rates, especially for complex AVMs . In our series, the cured rate of the embolization alone group was lower than that in other studies on the safety of embolization with large case series. Among the embolization alone group, disorders were located in functional areas in a large percentage of patients. This selection bias for embolization might be the cause of a lower cure rate in the embolization alone group. In our study, the removal of AVM in several patients was supposed to be completed safely through the hybrid operation in our cases, though with high-grade AVM lesions, which was similar to Wen’s results . Furthermore, the mortality rate in the hybrid group was much lower than that in the embolization alone group, although this difference was not found to be statistically significant. Wang et al. reported lower operation-related morbidity in their series of low-grade AVMs. They attributed the low morbidity to several reasons . The most important target is embolizing the feeding arteries to reduce intraoperative bleeding rather than the AVM nidus. We also believed that it was important to follow this strategy, particularly for high SM grade and complex AVMs.
Admittedly, our research also has some defects. First, the main limitation of our study is a retrospective analysis, single-center, non-randomized study design, and sample size of patients with cerebral arteriovenous malformation small, which may result in patient selection and registration of bias. Secondly, the clinical results are carefully evaluated through medical record review, but they are prone to deviation without blind evaluation and document errors. Finally, some patients were lost to follow-up, although the low rate did not influence final results.