PMC4722512_01
(a) Intraoperative view showing the posterior inferior cerebellar artery compressing the root exit zones of the glossopharyngeal and vagus nerves. (b) A piece of shredded Teflon is interposed between the root exit zone of IX nerve (arrow) and posterior inferior cerebellar artery. (c) Another piece of Teflon ball is inserted between the root exit zone of X nerve (arrow head) and posterior inferior cerebellar artery. IX: Glossopharyngeal nerve, X: Vagus nerve
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F1
The offending vessel was confirmed to be a loop of the posterior inferior cerebellar artery (PICA) compressing the proximal sites of the glossopharyngeal and vagus nerves, which were also recognized under microscopy [Figure 1a]. PICA [Figure 1b and c]. Postoperatively, the patient was completely free of pain, and no recurrence has been seen after 18 months of follow-up.
PMC4722512_02
(a) Intraoperative view showing the posterior inferior cerebellar artery compressing and clinching the root exit zones of IX and X nerves. (b) The posterior inferior cerebellar artery is retracted and transposed with a sling made of divided dura mater (arrow)
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F2
During the microscopic procedure, the loop of PICA was confirmed to be compressing the glossopharyngeal and vagus nerve fibers exiting the medulla oblongata [Figure 2a]. The tortuous vessel impinging on those nerve roots was dissected carefully and displaced from the nerves by hanging the vessel using the sling technique with dura mater [Figure 2b].
(a) Pharyngeal MEP elicited by transcranial electrical stimulation demonstrating transient reduction <50% of the amplitude of the control baseline and pleomorphic change (red-encircled) when free-running electromyography showed intermittent spike discharge sporadically. (b) Free-running electromyography of the stylopharyngeal muscle monitored continuously reveals intermittent spike discharges (white arrows) during direct procedure around the glossopharyngeal nerve
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F3
Transposition of the offending vessel was finally accomplished within the normal range of IONM [Figure 3].
PMC4722512_03
(a) Intraoperative view shows the caudal loop of posterior inferior cerebellar artery compressing the root exit zones of the IX and X nerves. (b) The offending vessel is dissected and adhered to the dura mater in the jugular tuberculum to maintain separation from the root exit zone (arrow)
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F4
The PICA proximal to the loop was observed to compress the ventral aspect of the glossopharyngeal and vagus nerve roots in the REZ [Figure 4a]. The arachnoid membrane supporting and connecting the surrounding vasculature and nerve roots was dissected gently and the mobilized loop of PICA was moved away from the REZs of the glossopharyngeal and vagus nerves, and affixed to the jugular tubercle using fibrin-coated collagen fleece (Tachosil; Nycomed, Linz, Austria) [Figure 4b].
Pharyngeal and vagal MEPs demonstrate no significant changes between before and after microvascular decompression
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F5
Transcranial MEP did not reveal any evidence of significant reductions in facial, pharyngeal, or vagal MEPs, even while manipulating around the glossopharyngeal and vagus nerves [Figure 5].