Radiofrequency thermal ablation of intraosseous metastases with nerve protection
History of metastatic liposarcoma. Presented with two lytic metastases, one in left iliac bone and other in left ischial tuberosity.
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Radiofrequency thermal ablation was performed on two metastatic lesions, one in the left iluac bone and the other in the left ischial tuberosity. Note injection of carbon dioxide to the soft tissue surrounding the sciatic nerve to protect it from thermal damage.
Artifact caused by right hip prosthesis.
Minimally invasive percutaneous radiofrequency thermal ablation (RFTA) is applied extensively in the management of various benign and malignant bone tumours. It is used for curative treatment for benign lesions or as palliative treatment for malignant tumours.
In this case, it was decided to perform local treatment by RFTA, though it posed a technical challenge in the approach to the ischial lesion due to its close proximity to the sciatic nerve, meaning that any deviation in localisation, electrode introduction, or ablation zone planning, could lead to severe neurological damage.
The procedure itself was as follows:
- accurate localisation of the entry points under CT guidance
- two vertebroplasty needles were introduced into the bones, one in each lesion
- a spinal needle was placed close to the sciatic nerve
- CO2 was injected through spinal needle to form an isolating layer surrounding the sciatic nerve, to displace it laterally and protect it from any thermal injury
- a monopolar electrode with a 1 cm active tip was introduced sequentially in each needle
- the ablation process was started in this protocol: 6 minutes of dry ablation at 85 degrees centigrade was performed in each location (12 minutes in total) with track ablation at the end of the procedure, to prevent needle track seeding