Study Design. The effect of ligation of the bilateral segmental arteries at the levels of T11, T12, and T13 on blood flow of the T12 vertebra was studied in a dog model. Objectives. To determine the reduction of the vertebral blood flow resulting from interruption of bilateral segmental arteries at one to three vertebral levels. Summary of Background Data. Intraoperative hemorrhage can be sometimes massive in patients with hypervascular spinal tumors, especially in radical resection such as total en bloc spondylectomy. The recent development of new embolization techniques ensures more aggressive, more extensive, and safer preoperative embolization for spinal tumors. Methods. The blood flow of the T12 vertebra of 12 female dogs was measured after ligation of the bilateral segmental arteries at one to three levels, including the T12. Spinal cord evoked potentials were recorded in this procedure. Spinal angiography using a silicon compound was performed on another 10 dogs after clipping and section of the bilateral segmental arteries. Results. The blood flow of the T12 vertebra decreased to 70.13 +/- 6.37% of the control value after ligation of the bilateral segmental arteries of T12, to 46.48 +/- 8.97% after ligation of the bilateral segmental arteries of T12 and either T11 or T13, to 24.11 +/- 8.31% after ligation of T11, T12, and T13, respectively. The angiogram after ligation and section of T12 and the two levels including T12 showed thick and clear contrast medium in the cut distal ends of the T12 segmental arteries. After interruption at three levels ( T11, T12, and T13), however, the cut distal ends of the T12 segmental arteries were seen thin and faint on the angiogram. No significant changes occurred in spinal cord evoked potentials after ligation of the segmental arteries at three levels in all six dogs. Conclusion. Interruption of the bilateral segmental arteries at three levels, one target vertebra and the two adjacent vertebrae, reduced the blood flow of the target vertebra to one fourth of the control value in the lower thoracic spine in dogs. This result suggests that preoperative embolization at three levels, the levels of the tumor vertebra and the adjacent vertebrae above and below it, may reduce intraoperative hemorrhage effectively during total en bloc spondylectomy for hypervascular spinal tumors.
