Flow-diverter in radiation-induced skull base carotid blowout syndrome: do not write it off!

Comparison of Treatment Modalities in Postirradiation Carotid Blowout Syndrome: A Multicenter Retrospective Review

BACKGROUND

Carotid blowout syndrome (CBS) is not uncommon in our locality, where head and neck cancers, especially nasopharyngeal carcinoma, are prevalent. Traditionally, CBS has resulted in high morbidity and mortality. The treatment paradigm has evolved from open surgery to endovascular interventions, and each treatment modality has its merits and drawbacks. In the present study, we investigated the outcomes of different treatment modalities for postirradiation CBS.

METHODS

We performed a 10-year multicenter retrospective review of the outcomes after endovascular trapping, flow diverters, and bypass surgery from 2009 to 2019.

RESULTS

A total of 53 patients with 60 blowouts were included in the present study. Of the 60 blowout cases, 25 were in the flow diverter group, 27 in the endovascular trapping group, and 8 in the bypass group. The mean survival was 32.2 months, with patient age affecting overall survival (P = 0.002). The stroke rate affected the 3- and 6-month functional outcomes (odds ratio, 7.388 and 6.353; P = 0.008 and P = 0.014, respectively). Of the 24 cases in the flow diverter group, 96% had achieved immediate hemostasis, with a rebleeding rate of 20% (P = 0.009). No rebleeding had occurred with endovascular trapping or bypass. The stroke rate in the endovascular trapping, flow diverter, and bypass groups was 25.9%, 20%, and 12.5%, respectively (P = 0.696).

CONCLUSIONS

Our results have shown that endovascular trapping is the first-line treatment of CBS. For patients with contraindications to endovascular trapping, the flow diverter is an alternative. For patients who have undergone flow diversion alone, definitive treatment such as bypass surgery might be indicated for selected patients to minimize the risk of rebleeding. After endovascular trapping, surgical bypass might be considered for selected patients with a higher risk of stroke.

A Newly Designed Seed-Loading Device for Verifying the Safety of 125I Implants to the Canine Carotid Artery

A seed-loading device was designed and modeled using the Monte Carlo method to verify the biological effect of iodine-125 (125I) particles on blood vessels through animal experiments. The dose distribution characteristics of irradiated vessels were established by adjusting the design variables and geometry. The deviation between the actual value and the theoretical value was verified in vitro by the thermoluminescence dosimetry (TLD) method. After verification, the device was used to examine the biological effect of 125I irradiation of canine carotid arteries in two dogs (and one control dog) for 180 days. The hollow cylinder seed-loading device was constructed with an inner diameter of 0.5 cm and a length of 3.3 cm. When six seeds were loaded into a single layer, the source strength ratio of the intermediate layer to the edge layer was 0.7:1. When six layers of seeds were arranged at 0.45-cm intervals, the deviations between the maximum, minimum and mean energy fluence within 2.25 cm of the vessel wall were 2.19% and -4.12%, respectively, and -9% and 4%, respectively, when verified in vitro using TLD. The carotid arteries showed good tolerance to 0.56 kGy (range of 0.51-0.58 kGy) after 180 days of irradiation. In conclusion, this 125I seed-loading device overcomes the random distribution of seeds and lays an accurate radiophysical foundation for subsequent biological experiments. The preliminary results showed that the carotid artery has good tolerance to 0.56 kGy irradiation.

Comprehensive Treatment Strategy for Internal Carotid Artery Blowout Syndrome Caused by Nasopharyngeal Carcinoma

OBJECTIVE

To evaluate a treatment strategy for internal carotid artery blowout syndrome caused by nasopharyngeal carcinoma.

STUDY DESIGN

A retrospective analysis of a case series was performed.

SETTING

Carotid blowout syndrome is a catastrophic complication caused by malignant tumor of the skull base.

METHODS

A retrospective analysis based on 69 patients with internal carotid artery blowout syndrome admitted to our center between April 2018 and January 2020 was performed. The patients were divided into 2 groups: an EBBA (internal carotid artery embolization + bypass based on American Society of Intervention and Therapeutic Neuroradiology/Society of Interventional Radiology [ASITN/SIR]) group and an embolization/stent group. The follow-up time was 6 to 9 months.

RESULTS

In the EBBA group, 41 patients (41/49, 83.7%) survived. Forty patients had a satisfactory quality of life after 3 months. No death occurred within 3 months. Nonoperative death occurred in 8 cases (8/49, 16.3%). The rate of mortality and disability was 18.4% (9/49). In the embolization/stent group, 16 patients (16/20, 80%) survived. Nonoperative death occurred in 4 cases (4/20, 20%), 3 of which occurred within 1 to 3 months. Four cases reported Modified Rankin Scale ≥2 after 3 months. The rate of mortality and disability was 40% (8/20).

CONCLUSION

A comprehensive revascularization strategy for internal carotid artery (ICA) embolization and intracranial and extracranial bypass grafting based on ASITN/SIR score for ICA blowout syndrome patients not only can prolong the patient survival but also greatly improve the survival probability and quality of life as well as reduce their rate of mortality or disability.