Preoperative Onyx embolization of hypervascular head, neck, and spinal tumours is safe and effective

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A study published in the Journal of NeuroInterventional Surgery and jointly led by Leonardo Rangel-Castilla and Orlando M Diaz, Department of Neurosurgery and Interventional Neuroradiology, Methodist Neurological Institute, The Methodist Hospital, Weill Cornell College of Medicine, Houston, Texas, USA, has found that the use of the liquid embolic agent Onyx is safe and effective in the embolization of head, neck, and spinal tumours. According to the authors, the use of Onyx previous to their study had not been well researched.

In the retrospective analysis of 100 cases of preoperative head, neck, and spinal tumour embolization with Onyx, none the patients, under general anaesthesia, died or hadmajor complications. Rangel-Castilla et al reported minor complications in three patients where Onyx extravascularisation around the tumour occurred and in a further three patients groin haematoma occurred. Two patients had a myocardial infarction not relating to embolization and one patient had a repeated bicoronal craniotomy and second attempted tumour resection.

In the 48-hour post embolization period, 79 patients underwent surgical resection and a further six patients underwent surgery at later time (up to 188 days). Rangel-Castilla and others reported the estimated intraoperative blood loss (in 77 patients) as 2,000ml in three patients.

The implications for the use of Onyx for head, neck, and spinal tumour embolization are that it “highlights how neurointerventional embolization has become an important tool in the neurosurgical armamentarium.” The authors also reported that Onyx is useful in the control of intractable tumour bleeding, in the occlusion of tumour feeding arteries that are surgically inaccessible, and that it improves intraoperative visualisation.

The authors found that Onyx embolization was effective as it “precipitates gradually in a radial fashion, forming a cast. The slow precipitation property allows a more slow and precise injection, allowing deeper penetration into the tumour capillary bed.” However, Rangel-Castilla and Diaz also noted the disadvantages of Onyx which were that the injection needs a microcatheter compatible with dimethyl sulfoxide and the catheter needs to be exchanged with each artery embolization. They also noted that Onyx can migrate into the venous circulation or leak around the tumour.

Rangel-Castilla and Diaz said: “This study demonstrates the safety and efficacy of central nervous system tumours embolization with a liquid embolic agent. It penetrates deeply into the tumour, cuts the blood supply and kills the tumour. This makes a surgical resection easier, faster with less blood loss.”

To determine the long term efficacy of Onyx for head, neck, spine, and brain tumours for long term use randomised controlled trials are required, the authors concluded.

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