August 05, 2015
This short video, emphasizes the risks involved with over-embolization of large pedicles in expectation of surgical resection. This is a 46 year-old female who presented with recurrent seizures and a left-sided, parieto-occipital arteriovenous malformation was found. The location of the AVM is apparent as one expects. This AVM is primarily fed from the distal branches of the posterior cerebral artery, aggressive embolization was performed pre-operatively in expectation of microsurgical resection. Most of the larger pedicles were embolized. However, as you can see, the deep white matter feeders are quite evident and enlarged at the end of aggressive embolization of the large pedicles. I personally do believe that the function of the deep white matter feeders, significantly expands upon embolization of the larger cortical and subcortical pedicles. The function of the AVM is arteriovenous shunting. And if the larger pedicles are excluded, the AVM will find a way to improve its shunting capability via recruitment and expansion of white matter feeders. Therefore embolization has to be performed selectively. I usually, sparingly use preoperative embolization for arteriovenous malformations only in cases where large AVM pedicles are not easily accessible, during the early part of the operation. An example includes a tentorial arteriovenous malformation, where the superior cerebral artery feeders, are not easily accessible during the initial stages of dissection, and are located very deep within the operative corridor. However, if the larger pedicles are quite accessible such as in this case, I do believe operative intervention, is the best method of their exclusion. And aggressive preoperative embolization, can lead to expansion of the white matter feeders that are quite challenging to control interoperatively. Let's go ahead and review the operative events, around the care of this patient. A paramedian left parallel to occipital craniotomy, was completed with a patient in the lateral position. You can see the paramedian incision, the location or the sagittal suture. The AVM was skeletonized, however, the deep white matter feeders were quite apparent. These feeders led to significant amount of bleeding. And in this case, I had to follow these white matter feeders at a short distance within the white matter away from the nidus in order to be able to find a more robust wall for this white matter feeders. My strategy for managing the white matter feeders, therefore, involves following them, until their walls are more robust slightly away from the nidus. The white matter feeders carry a very attenuated walls next to the nidus. These walls are not effectively controlled via the use of bipolar coagulation or microclip ligation. Thank you.
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