Carotid body tumors (CBTs) are relatively rare neoplasms (incidence rate one in 30 000) that usually grow slowly, and most are benign (1). Surgical resection of CBTs is currently the gold standard for the treatment of disease, but the operation can frequently be tricky because of the adjacent neurovascular structures that may be involved in the tumors, especially in the case of advanced Shamblin classification (1, 2). Excessive blood loss and cranial nerve damage may be the most worrying complications during the operation; excessive intraoperative bleeding may increase the chances of cranial nerve injury and thus complicate the operation (3, 4). Preoperative embolization prior to surgical excision of CBTs has been reported to reduce blood loss and thus provide better operational visualization, facilitate tumor excision and decrease morbidity related to perioperative complications (5, 6). However, the embolization of the feeding arteries of CBTs can also cause some unwanted complications, such as ectopic embolization or stroke (3, 4).

Preembolization of CBTs can be carried out by delivering agents such as particulates or coils into the feeding arteries of the tumors via a microcatheter. The preoperative embolization technique has been proven to be effective in the devascularization of CBTs before surgical resection in previous studies (7–10). Several materials have been successfully applied in the preoperative embolization of CBTs, such as gelatin microspheres, nonspherical polyvinyl alcohol particles, coils, Onyx and gelfoam (8–10). However, discrepancies in the safety and efficacy of these materials have rarely been reported in the literature. The aim of this study was to retrospectively compare different embolization agents, such as particulates or coils, in the preoperative embolization of CBTs at our institution.

Carotid body tumors are rare tumors that belong to the paraganglioma system, the incidence is approximately 1:30 000 and accounts for 65% of paraganglioma of the head and neck (1, 11). Although most CBTs are benign, the possible malignant potential (the metastasis rate is about 5%) necessitates early and thorough surgical resection. However, a large amount of blood loss and other severe complications may occur in surgical excision, especially in Shamblin type II and III CBTs (12–14). Preoperative embolization of the tumor-feeding artery has been reported to aid in the successful surgical removal of tumors. Operative blood loss, resection time of the tumor, and hospitalization time can be decreased by preoperative angiography and tumor embolization (14–17). However, some other researchers found that preoperative embolization could not improve the outcomes of surgical resection of CBTs (15–17). In a previous study, the author found that preoperative embolization was beneficial to the surgical outcomes of CBTs, and no increased stroke rates or postoperative complications were observed (7). In this study, we confirmed that pre-embolization was a useful adjunct procedure for the surgical resection of CBTs, and the particulate and coil embolization material displayed a similar effect on the devascularization of CBT tumors.

Few studies, however, have been performed to explore the differences of those embolization agents in the surgical operations of CBTs. Multiple materials can be used for preoperative embolization, such as gelatin microspheres, nonspherical polyvinyl alcohol particles, coils, Onyx and gelfoam (10, 18–21). Some researchers even implanted covered stents into the external or internal carotid artery for preoperative embolization and proved the efficacy (8, 9). Although these materials can be adequate for devascularization of CBTs, complete embolization of the feeding artery is usually difficult to achieve. In addition, operative complications may occur during the devascularization of CBTs (2, 19), and our results were consistent with these studies.

In our study, we used polyvinyl alcohol (or gelatin microsphere) particles and coils for preoperative embolization of CBTs. We found that operative blood loss in the particulate group was not significantly different from that in the coil group. We presumed that particulates might disperse through the vasculature of CBT while coils could only block the main trunk of the feeding artery, but actually the embolization efficacy of those materials turned out to be almost the same. Furthermore, in a recent research without embolization (22), the mean intraoperative blood loss (750-800 ml) and operative time (140-150 min) were significantly high than our results (Table 2). The particulates were theoretically more liable to introduce ectopic embolization when compared to coils. Although no statistically significant differences were observed in these 2 groups, the cases suffering ectopic embolization only occurred in the particulate group. These data might indicate that coil embolization shows a better safety trend; however, this still needs further verification. However, what we need to emphasize is that there is no difference in the total effectiveness and adverse events index between the two technologies. Moreover, embolization combined with surgical resection does not increase the incidence of postoperative complications and stroke, and which was an adjunctive procedure to beneficial for CBT surgical outcomes (14); however, we also need to acknowledge that the surgical resection without embolization has achieved good surgical outcomes in experienced centers (22).

Furthermore, radiation damage and protection are some of the main concerns during endovascular therapy; however, there are no studies about the radiation dosage and potential injury of the pre-embolization of CBTs. In the present study, we found that the pre-embolization time was obviously longer in the particulate group than in the coil group, as well as the higher dosage of radiation (the fluo time and cumulative air kerma) during embolization in the particulate group. These data indicate that coil embolization may have a faster operation and better radiation safety, which has potential benefits for both patients and doctors. Normally, we have to spend extra time preparing particulate suspensions while the coils just save trouble, and the coil embolization operation is simpler; thus, it may save procedure time and reduce the radiation dosage. Moreover, medical expenditure was higher in the particulate group than in the coil group, and thus, the choice of coils for preoperative embolization might alleviate the financial burden of CBT patients.

In conclusion, our study concludes that preoperative embolization with coils could be relatively safe, have a lower radiation dosage and be cost-effective for the surgical treatment of CBTs.

The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author.

The studies involving human participants were reviewed and approved by the First Affiliated Hospital of Xi’an Jiaotong University Institutional Review Board. The patients/participants provided their written informed consent to participate in this study.

Study design, XH, LW, YC, and LY. Data collection and data analysis, XH, LW, YC, JL, YL, and LY. Writing, XH, LW, YC, and LY. Revision and review manuscript, XH, LW, YC, JL, YL, and LY. All authors contributed to the article and approved the submitted version.

This work was supported by the Natural Science Foundation of China (NO.8197 0365).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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