Abstract: Background and purpose: Vertebral and paravertebral metastases are the common complications in cancer patients. Although pain is the primary complaint, osteolytic bone metastasis causing vertebral compression fracture should also be considered. The aim of this study was to assess the safety and effectiveness of combined procedure of cryoablation and vertebroplasty for reduction of pain caused by vertebral and paravertebral metastases in cancer patients. Methods: We retrospectively analyzed the patients with single vertebral and paravertebral metastases who received combined procedure of cryoablation and vertebroplasty from Mar. 2015 to Mar. 2017. They also had moderate-severe pain around the level of vertebral metastasis and needed analgesic, and two of them had no pain remission after radiotherapy. In order to control the pain and treat the paravertebral neoplasm, they received cryoablation therapy followed by vertebroplasty. All the procedures were performed in CT and digital subtraction angiography (DSA) operating room. Pain intensity was evaluated by the visual analog scale (VAS) score administered before and 1, 3 and 6 months after procedure. Any uncomfortable complaint was recorded during or after operation. Results: There were sixteen patients who received cryoablation and vertebroplasty successfully. The mean age of patients was 58.1 years including 10 male patients (10/16), and the mean volume of bone cement was 4.2 mL. The VAS scores showed a reduction in all patients at 1 month postoperation compared with preoperation (paired t test, P<0.05), furtherdecreased at 3 months (paired t test, P<0.05) and kept stable at 6 months (paired t test, P>0.05). Two patients had neurological disorder after operation, and presented with femoral nerve damage symptoms, unilateral lower limb paresthesia and difficulty lifting leg. After treatment, the symptoms were gradually relieved and disappeared in the following weeks. One patient had soft tissue swelling of the right abdominal wall on the fourth day after operation. MRI showed hematoma and right-sided hydrothorax. Both patients did not receive any treatment, and symptoms were relieved later. Conclusion: This study has shown that combined procedure of cryoablation and vertebroplasty is a safe and effective procedure for pain relief in cancer patients with single vertebral and paravertebral metastases even when radiotherapy treatment has failed. In order to avoid damage to the spinal cord, careful needle positioning and accurate fluoroscopic and CT guidance are important.

Key words: Vertebral and paravertebral metastases, Percutaneous cryoablation, Percutaneous vertebroplasty