PMC6333014_01
Magnetic resonance imaging (MRI) and intraoperative findings of hemifacial spasm (HFS) caused by distal offender (the meatal loop of AICA, case 1).
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HFS, there was no discernible vascular structure in the REZ of left facial nerve (Figure 1(a)). However, a meatal loop of AICA abutting to the cisternal portion of the facial nerve was found. Upon exposure of the REZ of the facial nerve, there was no offending vessel in the REZ as expected (Figure 1(b)). AICA (Figure 1(b)). Teflon felt was interposed between the facial nerve and the meatal loop of the AICA with extreme care not to stretch the internal auditory artery and the distal facial nerve (Figure 1(c)). After interposition of Teflon felt, LSR immediately disappeared and BEAP was stable also (Figure 1(d)).
PMC6333014_02
Magnetic resonance imaging (MRI) and intraoperative findings of the right-sided hemifacial spasm (HFS) caused by distal offender (the postmeatal segment of AICA, case 2).
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In the MRI, although the PICA passed around the REZ of the facial nerve, it did not compress the REZ (Figure 2(a)). As expected, the PICA had no association with the REZ or attached segment of the facial nerve (Figure 2(b)). It was carefully separated from the facial nerve and 2 thin leaflets of Teflon were interposed between the postmeatal AICA and the facial nerve (Figure 2(c)). Disappearance of LSR was confirmed within 2 minutes (Figure 2(d)).