Bone Metastases
Preoperative transarterial embolization of hypervascular bone metastases, most commonly renal metastases, is a very useful and helps reduce preoperative blood loss and surgical morbidity. As a technique this was first described by Feldman et al and there have been a number of subsequent studies with favorable results . Barton et al reported 500-1500 ml intraoperative estimated blood loss (EBL) in embolized patients as compared to 2000-18500 ml if no embolization was performed . Further, even partial devascularization of the lesion is beneficial in reducing estimated blood loss although complete devascularization is ideal.
Tumor vessels can originate directly from a main artery or from distal 2nd or 3rd order branches. Embolization of the former carries a higher risk of embolising down the main artery and the latter comes with cannulation problems with smaller calibre arterial branches. Successful cannulation of the smaller branches gives the freedom of aggressive embolization whilst proximal tumor branches require extra care.
The technique involves vascular access via a suitable artery depending on the tumor location. Initual angiography should include detailed demonstration of all the feeding branches. The tumor arteries should be cannulated and catheter positioned beyond any major arterial branches. Embolization is usually performed using polyvinyl alcohol (PVA) particles. The particle size should be appropriate to the size of the arterial branches embolised. Other agents including gelatine sponge and coils have been used.
Transarterial embolization of bone tumors is usually safe with a few potential complications. Post embolization syndrome is not unusual and should be considered for planning both the embolization and the surgical procedure. A number of these bone lesions involve the appendicular skeleton and hence embolization down the femoral or brachial arteries can result in ischemic symptoms. Similarly skin necrosis and nerve palsies have been reported.
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