ラジオ波凝固療法を併用した経皮的椎体形成術により治療を行った転移性脊椎椎体腫瘍の1例

Percutaneous Vertebroplasty Combined with Radiofrequency Ablation for a Patient with a Spinal Metastatic Tumor ： Case Report

Ⅰ．はじめに

　経皮的椎体形成術（percutaneous vertebroplasty, PVP）は，経皮的に金属針を脊椎椎体内に進め骨セメントを椎体内に注入する方法で，椎体病変由来の疼痛を除くことを目的とする．適応疾患としては骨粗鬆症性椎体圧迫骨折が代表的であるが¹⁰⁾，椎体および椎弓根内に溶骨性変化を生じる転移性椎体腫瘍もよい適応である．

　一方，ラジオ波による凝固（焼灼）療法（radiofrequency ablation, RFA）は，ジェネレーターで発生したラジオ波を病変部に刺入した専用の電極から周囲組織に通電させ，病変の凝固壊死を得るものである．以前から不整脈や三叉神経痛，パーキンソン病などの治療に用いられてきたが，最近のシステムでは針の内部冷却やパルス式通電により電極周囲の組織を炭化，蒸散させることなく広範囲に凝固させることが可能となっている．これにより悪性腫瘍に対する治療への応用が年々盛んとなっており，放射線科領域では肝臓や肺，腎，骨等の腫瘍に対して同法による治療が積極的に行われている^4,7)．

　これまでにPVPとRFAを併用した報告例は少なく，今回われわれは除痛と腫瘍増大の抑制を目的として両法を一期的に行った転移性椎体腫瘍の1例を経験したので報告する．

Recent technological development has allowed expanding applications of radiofrequency ablation (RFA) for malignant tumor therapy. We report a case with a spinal metastatic tumor treated with combination of percutaneous vertebroplasty (PVP) that provides pain relief and spinal stabilization and RFA.

　A 68-year-old male who had undergone resection of left ureteric carcinoma was referred to our hospital with lower back pain due to the fifth lumbar (L5) vertebral metastatic tumor. Conventional radiation therapy was discontinued because of pneumonia. One year later,the patient was admitted again with weakness of the right knee and foot and severe pain of the back and the right lower extremity. Radiographs demonstrated a compressive fracture of the L5 vertebra predominantly on the right side. CT and MRI showed a tumor of the L5 body invading the right pedicle,the intervertebral foramen,and the retroperitoneal space. RFA was performed in the ventral part of the L5 body,and then around the right L5/the first sacral intervertebral foramen. Temperature and time for ablation ranged from 74℃ to 95℃ and from 11 min. to 30 min.,respectively. Next,PVP was performed by the right transpedicular approach. Bone cement was injected into the L5 body and the pedicle by an amount of 3.0 ml in total without technical complications. Postoperatively,visual analogue scale demonstrated decreased pain degree from 10 cm to 5.4 cm.

　Combined treatment with RFA and PVP is a feasible and promising procedure for spinal metastatic tumors. Further evaluation is necessary to confirm its long-term efficacy.