Abstract
The introduction of ONYX liquid embolic system (Onyx) has enabled us to adopt a new treatment approach for brain arteriovenous malformation (AVM), by using microsurgical AVM resection following Onyx embolization. The aim of the present report was to evaluate our results after the application of this strategy, with emphasis on technical considerations for microsurgical resection of Onyx-embolized AVM. From January 2010 to June 2014, 11 consecutive patients with AVM were treated by using microsurgical resection in combination with Onyx embolization. The patients' mean age at the beginning of the treatment was 35, and 8 patients presented with hemorrhage. The embolization achieved a volume reduction more than 80% in 6 patients. One patient experienced transient neurological aggravation after the embolization. One patient exhibited partial visual field defect after surgery, resulting in a decreased mRS score of 1. Postoperative angiography showed complete removal of the nidus in 10 patients, and the remaining underwent radiosurgery for the residual nidus.
Regarding the technical aspects of microsurgery for Onyx-embolized AVM, we noted some advantages, including 1) excellent visibility in the operative field, 2) easy creation of the dissection plane between the nidus and white matter, 3) presence of collapsed drainers, which can be resected at the early phase of the surgery. On the other hand, extensively embolized nidus was firm and less elastic, making retraction difficult. In conclusion, it is important to consistently perform Onyx embolization as a presurgical procedure in accordance with the usage standard approved in Japan. Such a perspective will make this new challenging technique safer and more effective to perform.
