PMC9218268_01
(A) Oto-endoscope showed perforation in the left tympanic membrane with formation of granulation tissue and cholesteatoma. (B) There was no response to air and bone conductions in the left ear. PTA, pure tone audiometry. (C,D) The VEMPs could not be elicited in the left ear. VEMP, vestibular evoked myogenic potentials; oVEMP: ocular VEMP; cVEMP: cervical VEMP. (E) The HIMP revealed reduced VOR gains of the lateral, superior, and posterior semicircular canals in the left ear. HIMP, head-impulse paradigm; VOR, vestibulo-ocular reflex.
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TM with formation of granulation tissue and cholesteatoma (Figure 1A). Tympanometry examination showed a "B" type flat curve, indicating there was perforation in the tympanic membrane or blockage of the auditory canal (Supplementary Figure 1, Supplementary Video 1). The PTA illustrated there were no response to air and bone conductions in the left ear, but normal hearing in the right ear (Figure 1B). The patient showed absence of both oVEMP and cVEMP on the left side in bone-conducted vibration mode, with 500 Hz tone-burst stimulation delivered at 131 dB FL (Figures 1C,D). The HIMP displayed reduced vestibulo-ocular reflex (VOR) gains of the lateral, superior, and posterior semicircular canals during head impulses to the left side (Figure 1E). The CT scans of the temporal bone detected fistulae in both the basal turn of the cochlea and the horizontal semicircular canal (Figures 2A,B).
(A,B) Computed tomographic images of the temporal bone showed fistulae (yellow arrows) in both the basal turn of the cochlea and the horizontal semicircular canal. (C) Fistulae in both the basal turn of the cochlea and the horizontal semicircular canal were evident during the operation. Co, cochlea; ET, epitympanum; F, fistula; FN (m), mastoid segment of facial nerve; LSC, lateral semicircular canal; MFP, middle fossa plate.
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The VEMPs results elicited by air-conducted sound (ACS-VEMPs) and galvanic vestibular stimulation (GVS-VEMPs) are shown in Supplementary Figure 2. The HIMP displayed reduced vestibulo-ocular reflex (VOR) gains of the lateral, superior, and posterior semicircular canals during head impulses to the left side (Figure 1E). The CT scans of the temporal bone detected fistulae in both the basal turn of the cochlea and the horizontal semicircular canal (Figures 2A,B). The surgical procedure was complicated by the intraoperative finding of fistulae in both the basal turn of the cochlea and the horizontal semicircular canal during surgery (Figure 2C).
H&E staining of biopsy specimen showed cholesterol clefts [(A), yellow arrow] and inflammatory granulation tissue formation [(B), yellow arrows] around fistulae. Scale bar, 50mum (x 20).
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Our MRI showed the vestibule and the cochlea were presented as nearly isointense on T1-weighted imaging (Supplementary Figures 3A,B). After contrast administration, the portion of lesion was slightly enhanced (Supplementary Figures 3C,D). H&E staining of the biopsy specimen showed cholesterol clefts and inflammatory granulation tissue formation around the fistulae (Figure 3).