Comment on: Current concepts in the management of carotid body tumours.

Preoperative embolization has played a major role in the devascularization of carotid body tumours prior to surgery. There are two currently approved methods to achieve this, which is a superselective transarterial endovascular embolization and a direct percutaneous injection of embolic materials . Superselective transarterial endovascular embolization has potential limitations especially in lesions with a complex angioarchitecture, with small feeding vessels and branches arising from internal carotid and vertebral arteries. This will result in an incomplete devascularization of the tumour resulting in increase intraoperative blood loss. A direct percutaneous injection has the potential to overcome all these limitations. Quadros et al first reported a successful near complete preoperative embolization of a cervicodorsal paraganglioma with a direct percutaneous injection of onyx with endovascular delivery of particles in 2007. In a larger series, Ozyer et al had a success in 10 patients, in which 4 patients only had a direct percutaneous injection with glue or onyx and 6 patients had both direct percutaneous injection and endovascular embolization. There were no technical or clinical complications related to the procedures. Wanke et al performed a direct percutaneous embolization with onyx only in 6 paragangliomas and achieved a complete devascularization in all lesions. This direct percutaneous embolization method might be useful in one of Wee and Goh’s patient who didn’t undergo preoperative embolization due to a small feeding vessel. Various embolic materials were used in either the direct percutaneous injection method or endovascular embolization ranging from particles (PVA), glue or onyx . However currently onyx had been increasing being used in most centres. Onyx has the advantage of a slow distribution like a lava flow into the entire tumour either ante and retrograde flow which will embolized all the feeding arteries either from the external or internal carotid arteries4. This will ensure a complete devascularization of the tumour. Wanke et al had achieved this in 6 paragangliomas by using solely onyx combined with a non detachable microballoon to protect the internal carotid artery.