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Vascular Compression Along the Nerve During MVD for Hemifacial Spasm

January 16, 2015

Transcript

This video demonstrates another variation in configuration vascular compression found during MVD for hemifacial spasm. This is a 67 year old female who presented with left-sided hemifacial spasms, and was found on high resolution T2 axial MRI of her posterior fossa to have a vascular loop along the axilla of the nerve or around the region of the left facial nerve. She subsequently underwent a left-sided restromastoid craniotomy. You can see the boney opening, the mastoid bone, and the tip is in this region. The dura is open in a curvilinear fashion. You can again see the Pterion turning into becoming the floor of their posterior fossa. And this is a landmark used to go around the cerebellum to find the lower cranial nerves without necessarily placing their seven and eighth cranial nerve under direct vector of retraction to cause hearing loss. Additional CSF is released, and you can see the landmark that I'm trying to show with the tip of the suction. Here you can appreciate the ninth cranial nerve that will be followed along its path to find the root exit zone of the facial nerve. Here you can see a very superficial vascular loop. We continue to use microsurgical techniques to open the olivocochlear membranes over the lower cranial nerves. Here's the vascular loop that I initially found, and I didn't believe this is, potentially, the offending vessel. But actually, ultimately after further inspection, I hope I will be able to convince you that this is actually the offending vessel. Most often the basal conflict is not along the more distal aspect of the artery, but in this case, you can see that the root exit zone of the nerve is very clearly apparent. And this vascular loop was very much in close proximity of this root exit zone of the facial nerve. Again, you can see due to my disbelief here, I continue to look very carefully in the area of the root exit zone of the nerve even more inferiorally around the brainstem to make sure, absolutely, I have not ignored any other compressive vessel. As you can see, I am not able to find another vessel. There is area of the discoloration present along the root exit zone. Again, continuing to convince myself, and hopefully you, that no other vessel has been found. And this is a principle that we have to just look for vessels to make sure we're not ignoring them even if a more superficial vessel is found. Here is me looking all the way along the ninth and 10th cranial nerve exit zone along the brain stem to convince myself that no compressive vessel has been missed. Now that I was unable to find another vessel, I'll go ahead and generously pad the area of the root exits on one of the nerve. And also along the facial nerve to assure that this vessel is not coming into contact with the nerve. Here's, again, the labyrinthine artery under the eighth cranial nerve, going to their internal auditory meatus that has been carefully protected and not too much manipulated. And here is the final product demonstrating generous padding of the artery along its entire length when it comes close to the facial nerve, both along its cisternal segment and the level end at the level of the brainstem. Here's the more de magnified view of the vascular compression and the dural closure. Thank you.

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