PMC4340474_01
Preoperative and 1-year postoperative audiograms. Of note, bone conduction thresholds from the 6 month postoperative were used in 1-year postoperative audiogram as these thresholds were not recorded at the one year time point.
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F1
Audiometry revealed bilateral down-sloping sensorineural hearing loss (SNHL) in a noise-induced configuration (Figure 1). His one year postoperative audiogram demonstrated a 10-30dB improvement in the patient's low frequency air conduction thresholds in the operative ear (Figure 1) and a speech discrimination score of greater than 92% with normal tympanometry.
Axial (A and B) and oblique Poschl (C and D) images of the right (A and C) and left (B and D) temporal bone demonstrate bilateral dehiscence of the superior semicircular canal (arrowheads, A and C; arrows B and D) in close proximity to the common crus. Also note the anterior positioning of the groove for the right sigmoid sinus (A, asterisk) compared to the normal left side.
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F2
Temporal bone computed tomography (CT) in the axial and oblique planes revealed dehiscences of both superior (Figures 2A & 2C) and posterior (Figures 2B & 2D) canals on the right side of 2-3 mm.
Axial (A and B) and oblique Poschl (C and D) images of the right (A and C) and left (B and D) temporal bone demonstrate bilateral dehiscence of the posterior semicircular canal (arrows, A and C; dashed arrows B and D) also in close proximity to the common crus.
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F3
A similar pattern was detected on the contralateral side (Figure 3) but with smaller dehiscences (approximately 1mm each).