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Nervus Intermedius Transection for Geniculate Neuralgia

January 17, 2015


I perform exploratory posterior fossa operation for typical geniculate neuralgia. The procedure that I have come to believe in, relies upon inspection of the root entry zone of the trigeminal nerve, inspection of the seventh and eighth cranial nerves, at the level of the brain stem as well as transection of nervous intermedius, and lastly microvascular decompression of the ninth and 10th cranial nerves. Unfortunately, diagnosis of nervous intermedius neuralgia or geniculate neuralgia can be very difficult. However, neuralgic components have to be present there such as typical cutaneous triggers within the ear canal for the diagnosis to be made and the neurosurgical intervention warranted. This is the case of a 46 year old male who presented with typical left-sided geniculate neuralgia on high resolution MRI. You can see evidence of potential vascular conflict at the level of the seventh and eighth cranial nerves. However, this conflict is not very impressive. Due to his classic features as was neuralgic character of his pain. I offered him a left-sided posterior fossa retromastoid operation. You can see the transfer sinus leading to the sigmoid sinus. This is a typical exposure that I perform for MVD for trigeminal neuralgia. They caught two noises sliding over the rubber dam to reach the cerebral pontine angles just above the seven and eighth cranial nerves and parallel to the fifth cranial nerve. All the arachnoid membranes are carefully opened, enuring that all the perforators and vascular structures are preserved. First, I'll start by inspecting the root entry zone of the trigeminal nerve. You can see at the tip of my error that there is a vein around the nerve. However, is no obvious evidence of neurovascular conflict here. So I'll go ahead and divert attention to seventh and eighth cranial nerve and first inspect the superior shoulder of the nerve. And you can see there is evidence of a vein there. However, this did not convince me that there is any evidence of neurovascular compression. I'll go ahead next then try to inspect between the seven and eighth cranial nerves and you can see they are nervous intermediate fast skulls. Usually there's two or three fast skulls but in this case here is one large on and a few small ones. So I'll go ahead and hold the nerve in place with suction and go ahead and cut the nerve. After the nerve has been transected, I find a vascular loop that could potentially cause some conflict there. And go ahead and decompress the artery. All the way along the seventh and eighth cranial nerve, as well as the lower cranial nerves. You can see the labyrinthine artery here that should be carefully protected. I go ahead and more aggressively look between the seventh and eighth cranial nerve. And I cannot see any other fast poles for the nervous intermediates. The next step will be to proceed with generous Teflon implantation between the vascular loop and the brainstem at the level of the seventh and eighth and the lower cranial nerves. A piece of Teflon is placed. This is augmented with additional pieces. You can see another piece of Teflon along the superior aspect of the seventh and eighth cranial nerve to assure me that there is no possibility of the vein causing any vascular compression there. Additional pieces of Teflon are placed along the larger vascular loop inferiorly. And here's essentially the final product as shown that the lower cranial nerves are generously decompressed. This patient subsequently benefited with complete relief of his trigenically neuralgia for but four years, which would be his last follow-up to date. Thank you.

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