PMC6495004_01
(A) Timeline of the patient's medical history and of diagnostic interventions. (B,C) Repeated pure-tone audiometric recordings for the left ear (B) and right ear (C) between age 27 and 50 years. Curves indicate air conduction thresholds. Arrows and brackets indicate bone conduction (BC) thresholds, as measured at age 27.
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A synopsis of relevant events in the patient's medical history is given in Figure 1A. PTA showed that the left ear had mixed, predominantly sensorineural, downward-sloping hearing loss (HL) up to 100 dB HL at 6 kHz (Figure 1B), while the right ear had moderate to severe presbyacusis (Figure 1C). In the 4 years following the onset of MD symptoms, hearing function in the left ear fluctuated in the low and middle frequencies and progressively declined to a level of 50-80 dB HL (Figure 1B).
High-resolution CT (HRCT) imaging and gadolinium-enhanced MRI (Gd-MRI) of the inner ears was performed after the onset of Meniere's symptoms (HRCT, at age 44; Gd-MRI, at age 48). (A,B) Sagittal HRCT projections and 3D segmentations of the left (A) and right (B) labyrinth. (VA, vestibular aqueduct (blue in 3D segmentation); sSCC, superior semicircular canal; Ve, vestibule; red dotted line in (A), bony obliterated VA. (C,D) Axial Gd-MRI (3D inversion recovery sequence) and 3D segmentations of the left (C) and right (D) labyrinth. Signal voids in the cochlear turns (green arrowheads) and the saccule (green asterisk) indicate endolymphatic hydrops; blue arrow, signal originating from the extraosseous endolymphatic sac. 3D segmentations were performed using the 3D Slicer software [version 4.6.2, ]. (E-H) Fusion of axial HRCT (E) and Gd-MRI [F; false color-coded image in (G)] images of the left temporal bone in the corresponding axial plane (H). Arrowheads (E-H): T2 signal localized posterior to the operculum, corresponding to the localization of the distal (extraosseous) endolymphatic sac (D). (Co, cochlea; PSCC, posterior semicircular canal; VA, vestibular aqueduct; Ve, vestibule). Scale bars: 5 mm. The false color-coding image overlay was generated using Adobe Photoshop CC2017 (version 18.1.0, San Jose, CA, USA).
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On HRCT imaging, the left VA appeared to be almost completely obliterated by bone along its course between the isthmus and the operculum (Figure 2A). In contrast, the right VA exhibited a patent lumen throughout its entire course (Figure 2B). IR sequence), a segment of total T2 signal loss was observed in the partially obliterated left VA (Figure 2C) but not in the right VA (Figure 2D). In the left VA, a delineated T2 signal was seen distal (posterior) to the segment with total signal loss (Figure 2C, blue arrows). T2 signal distal (posterior) to the operculum (Figures 2E-H). Therefore, the signal most likely originated from the eES, as proposed previously.