Preoperative Embolization of Brain Tumors Using a Provocative Test: Evaluating the Safety and Efficacy of Embolization of Test-Positive Vessels

Purpose: The embolization of vessels potentially involved in the vasa nervorum during brain tumor embolization is often a non-aggressive procedure. In this study, we aimed to investigate the safety and efficacy of embolization of vessels with positive provocative test results.

Methods: Embosphere (Merit Medical Systems, South Jordan, Utah, USA) was the embolization material of choice. A provocative test was performed using 30 mg of 1% lidocaine, with a positive result if neurological symptoms appeared. A size of 500-700 µm was used for positive results and 300-500 µm for negative results. Embolization was performed five to seven days before resection, and contrast-enhanced MRI was performed three to five days after embolization to assess the embolic status.

Results: Provocative tests were performed on 61 vessels from 55 patients. A total of 36 vessels (59.0%) were positive, and 25 vessels were negative. The petrosal branch of the middle meningeal artery and the neuro-meningeal branch of the ascending pharyngeal artery showed particularly high positivity rates (91.7% and 76.5%, respectively). Three patients (8.3%) out of the 36 who underwent embolization of the positive vessels had neurological symptoms after embolization; two had symptoms similar to those observed in the provocative test, and one had different symptoms. All symptoms were mild and transient. The postoperative contrast-enhanced MRI showed that the enhancing effect was attenuated in 18 of the 30 patients (60%) with provocative test-positive vessels.

Conclusion: Embolization of provocative test-positive vessels can be performed safely and effectively with a larger Embosphere (500-700 μm).