PMC5385458_01
Preoperative audiogram of the patient.
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F1
She still had normal hearing, with a Pure Tone Average tone threshold (averaged over 1,000, 2,000, and 4,000 Hz) of 10 dB on the right side and 5 dB on the left side (Figure 1).
Auditory brainstem response audiometry (ABR) artifacts during drilling. The left panel shows the surgical drilling, and the right panel shows the synchronized ABR signal. It illustrates that surgical drilling induces ABR artifacts, making it impossible to draw any precise conclusions about the ABR signal during drilling.
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F2
In order to be able to precisely measure the response, surgical drilling was paused during ABR measurements, since major artifacts occurred when drilling was performed (Figure 2).
Illustration of electrode placement and fenestrations in the semicircular canals. The LSCC and PSCC were fenestrated at points away from their ampullae. The electrode was first inserted into the LSCC, up to the cupula (1). After removal of the electrode out of this canal, it was inserted into the PSCC, up to the cupula (2). Abbreviations: SSCC, superior semicircular canal; LSCC, lateral semicircular canal; PSCC, posterior semicircular canal.
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F3
The electrode was inserted until a resistance was met, and from insertion depth it was deduced that the tip of the electrode was adjacent to the ampulla (Figure 3).