January 16, 2015
Microvascular decompression surgery can become challenging, due to variable anatomy. And this video, reviews technical nuances to avoid complications under these circumstances. This is a 62-year-old male who presented with left-sided V2 and V3 trigeminal neuralgia. And on MRI, was found to have a collection of arteries, and veins in the area of the CP angle on the way towards the fifth cranial nerve. A left-sided retromastoid craniotomy was completed. This is the bone just over the transverse sinus, here is the sigmoid sinus, the mastoid bone is over in this region, and this is cranial, and this direction is caudal. As you can see, a small dural opening has been completed upon inspection of the CP angle. I noted a collection of arteries, and veins, almost a network, of arteries, and veins blocking our way toward the fifth cranial nerve. More importantly, you can see that the cranial nerve seven, and eight, is much more cranially located, and there is very minimal space between cranial nerve seven, and eight, and the fifth cranial nerve at the depth of our dissection. This limited space to work through was rather unexpected, and record ample amount of microdissection in the region of these arteries, and veins more superficially with preservation of as many of the veins, as possible. Here is dissection through these arteries, and veins, sharp dissection was used. You can see this is the seven, and eight cranial nerve that is much more cranially located, and in this circumstance, could be mistaken with cranial nerve five. You can see this is the tentorium. Again, petrous bone, and the seven, and eight cranial nerve located much more closer than to the tentorium, than expected. And the fifth cranial nerve located at the depth of our dissection. This is a branch of meningeal artery going to the petrous dura, that can be coagulated, and cut, should not be mistaken with labyrinthine artery, which is located closer to the seventh, and eighth cranial nerves. You can see the fifth cranial nerve at the depth of our dissection. Here is this meningeal branch, that's going to the, petrous dura, and it's been coagulated, and cut. Now, the fifth cranial nerve is more visible. We use papaverine-soaked gelfoam to make sure there is no evidence of vasospasm in any of the vessels close to the seventh, and eighth cranial nerves. Due to the limited space, a branch of superior petrosal vein had to be sacrificed. Our other branches of this vein were kept intact. You can see the large vascular loop, at the medial portion of the root entry zone of the trigeminal nerve that is being mobilized. The piece of papaverine-soaked gelfoam remains over the seventh, and eighth cranial nerves. You can see the vascular loop has been mobilized. I look underneath the nerve more distally, and no vascular compression was present. A piece of shredded Teflon, now is being used in a stepwise fashion to mobilize this large vascular loop, away from the medial aspect of the nerve. Here, you can see, still a portion of the vascular loop could be in contact with the, nerve. And, I continue to use small pieces of Teflon to not only mobilize the artery, but also carry on the dissection furthermore anteriorly, and mobilize the artery away from the anterior segment, the cisternal segment of the nerve. Here is further mobilization or the artery. Inferior, you can appreciate the pieces of Teflon, proving that the entire segment of the vein has been decompressed. At this juncture, a larger piece of Teflon was necessary to mobilize this, relatively large, vascular loop away from the trigeminal nerve. And more superficial vascular loop was noted to be compressing the trigeminal nerve at this juncture. And this is an important point, where a vascular loop was found more at the depth of the dissection. The operator should continue further inspection more superficially, or underneath the nerve to assure a complete decompression is achieved, as multiple, offending vessels could be present in each patient. Here, you can see this more superficial vascular loop is being mobilized, no further compressive vessel is present.
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