PMC10442812_01
(A) Tonal audiometry showing a bilateral sensorineural hearing loss, more pronounced on the left side. (B, C) Left SSCD in axial (B) and coronal plane (C) and CFD (blue arrow) (C). (D) Post-operative 3D MRI showing a correctly plugged superior canal. (E-G) Post-operative HRCT control showing CFD and another location of SCCD near the surgical approach (yellow arrow).
fneur-14-1209567-g0003.jpg
PMC10442812_06_fneur-14-1209567-g0003.jpg
F3
In patients 1 and 2, no typical conductive hearing loss was found (Figures 2A, 3A), as may be expected in symptomatic SSCD. Patient 1 presented a profound postsurgical neurosensorial hearing loss, despite what would appear to be a well-performed left SSC plugging on the postoperative MRI (Figure 3D). After analysis of the postoperative radiological images, the existence of a second dehiscence (or near dehiscence) between the left LSC and the FN in its second segment (LSC/FN) was suspected (Figure 3C - blue arrow and G - yellow arrow). A third OCD was also observed on the same LE, which was probably iatrogenic and mainly contributed to the symptom's reappearance (Figures 3E, F).
PMC10442812_02
(A) Tonal and vocal audiometry showing a bilateral sensorineural hearing loss. (B, C) Right SSCD in axial (B) and coronal plane (C). (D) Post-operative audiometry showing a major deterioration of intelligibility. (E, F) Right OCD involving vestibular aqueduct and intern jugular vein in axial (E) and coronal plane (F). (G) Right OCD between LSC and FN (yellow arrows in B, C, E-G indicating various OCD).
fneur-14-1209567-g0004.jpg
PMC10442812_06_fneur-14-1209567-g0004.jpg
F4
Although postoperative pure-tone hearing loss did not occur in patient 2, speech audiometry dramatically decreased after SSCD plugging (Figure 4D). As in Case 1, when the radiological records were reexamined after the surgery, an additional OCD was diagnosed on the operated ear (Figures 4E-G).
PMC10442812_03
(A) Tonal and vocal audiometry showing a bilateral sensorineural hearing loss, with conductive component on the right side. (B, C) Right SSCD in axial (B) and control plane (C). (D) Post-operative audiometry. (E, F) Right CFD in axial (E), coronal (F) and sagittal plane (G). (H) Post-operative 3D MRI showing a complete obliteration of SSCC.
fneur-14-1209567-g0005.jpg
PMC10442812_06_fneur-14-1209567-g0005.jpg
F5
An ipsilateral CFD II (Figures 5E-G) was diagnosed after surgery, while a 3D labyrinthine MRI confirmed a well-performed SSCD plugging (Figure 5H). Type III additional OCD (LSC/FN) was rather "near" dehiscence (Figures 5K, L). Therefore, it is difficult in this case to attribute the appearance of clinical signs of hydrops to a reduction in the volume of the endolymphatic system that would be minimal with this surgical technique.
PMC10442812_04
(A) Tonal and vocal audiometry showing a mild conductive hearing loss on the left side. (B, C) Left SDC in axial (B) and coronal plane (C). (D, E) Right SDC in axial (D) Poschl plane (E). (F, G) Dehiscence between right IVJ and vestibular aqueduct in axial (F) and coronal plane (G). (H) Post-operative tonal and vocal audiometry. (I) Coronal plane in negative contrast showing near-cochleofacial dehiscence, near-dehiscence between LSC and FN II and SSCD. (J) Near-cochleofacial dehiscence. (K, L) Near-cochleofacial between the right LSC and FN II in coronal (K) and sagittal plane (L). (M) Post-operative 3D MRI showing an effective capping of SCC.
fneur-14-1209567-g0006.jpg
PMC10442812_04_fneur-14-1209567-g0006.jpg
F6
Audiometry confirmed a left low-frequency conductive hearing loss (Figure 6A). The HRCT confirmed a left SSCD (Figures 6B-D). AC in both ears (Figure 6H). A postoperative vestibular assessment revealed normalization of the cVEMPs, thereby presenting in favor of a technically successful surgery. Reexamination of the HRCT showed an additional near-dehiscence Type III (between the right LSC and the tympanic segment of the FN in the LE) (Figures 6I, J). A similar localization was also identified on the RE (Figures 6K, L). The MRI showed a well-performed surgical capping technique without any complications (Figure 6M).
PMC10442812_05
(A) Tonal and vocal audiometry showing a mild conductive hearing loss on the left side. (B, C) left SDC in axial (B) and coronal plane (C). (D, E) Right SDC in axial (D) Poschl plane (E). (F, G) Dehiscence between right IVJ and vestibular aqueduct in axial (F) and coronal plane (G). (H) Post-operative tonal and vocal audiometry. (I) Post-operative 3D MRI showing an effective plugging of SCC.
fneur-14-1209567-g0007.jpg
PMC10442812_06_fneur-14-1209567-g0007.jpg
F7
This can also be explained by the appearance of hydrops induced by the SSCD plugging, which was well performed according to the control labyrinthine MRI (Figure 7I).
PMC10442812_06
Distribution of OCD between uni- or bilateral and single or multiple OCD localizations in all 157 patients.
fneur-14-1209567-g0002.jpg
PMC10442812_06_fneur-14-1209567-g0002.jpg
F2
In patients 1 and 2, no typical conductive hearing loss was found (Figures 2A, 3A), as may be expected in symptomatic SSCD.
(A) Tonal audiometry showing a bilateral sensorineural hearing loss, more pronounced on the left side. (B, C) Left SSCD in axial (B) and coronal plane (C) and CFD (blue arrow) (C). (D) Post-operative 3D MRI showing a correctly plugged superior canal. (E-G) Post-operative HRCT control showing CFD and another location of SCCD near the surgical approach (yellow arrow).
fneur-14-1209567-g0003.jpg
PMC10442812_06_fneur-14-1209567-g0003.jpg
F3
In patients 1 and 2, no typical conductive hearing loss was found (Figures 2A, 3A), as may be expected in symptomatic SSCD. Patient 1 presented a profound postsurgical neurosensorial hearing loss, despite what would appear to be a well-performed left SSC plugging on the postoperative MRI (Figure 3D). After analysis of the postoperative radiological images, the existence of a second dehiscence (or near dehiscence) between the left LSC and the FN in its second segment (LSC/FN) was suspected (Figure 3C - blue arrow and G - yellow arrow). A third OCD was also observed on the same LE, which was probably iatrogenic and mainly contributed to the symptom's reappearance (Figures 3E, F).
(A) Tonal and vocal audiometry showing a bilateral sensorineural hearing loss. (B, C) Right SSCD in axial (B) and coronal plane (C). (D) Post-operative audiometry showing a major deterioration of intelligibility. (E, F) Right OCD involving vestibular aqueduct and intern jugular vein in axial (E) and coronal plane (F). (G) Right OCD between LSC and FN (yellow arrows in B, C, E-G indicating various OCD).
fneur-14-1209567-g0004.jpg
PMC10442812_06_fneur-14-1209567-g0004.jpg
F4
Although postoperative pure-tone hearing loss did not occur in patient 2, speech audiometry dramatically decreased after SSCD plugging (Figure 4D). As in Case 1, when the radiological records were reexamined after the surgery, an additional OCD was diagnosed on the operated ear (Figures 4E-G).
(A) Tonal and vocal audiometry showing a bilateral sensorineural hearing loss, with conductive component on the right side. (B, C) Right SSCD in axial (B) and control plane (C). (D) Post-operative audiometry. (E, F) Right CFD in axial (E), coronal (F) and sagittal plane (G). (H) Post-operative 3D MRI showing a complete obliteration of SSCC.
fneur-14-1209567-g0005.jpg
PMC10442812_06_fneur-14-1209567-g0005.jpg
F5
An ipsilateral CFD II (Figures 5E-G) was diagnosed after surgery, while a 3D labyrinthine MRI confirmed a well-performed SSCD plugging (Figure 5H). Type III additional OCD (LSC/FN) was rather "near" dehiscence (Figures 5K, L). Therefore, it is difficult in this case to attribute the appearance of clinical signs of hydrops to a reduction in the volume of the endolymphatic system that would be minimal with this surgical technique.
(A) Tonal and vocal audiometry showing a mild conductive hearing loss on the left side. (B, C) left SDC in axial (B) and coronal plane (C). (D, E) Right SDC in axial (D) Poschl plane (E). (F, G) Dehiscence between right IVJ and vestibular aqueduct in axial (F) and coronal plane (G). (H) Post-operative tonal and vocal audiometry. (I) Post-operative 3D MRI showing an effective plugging of SCC.
fneur-14-1209567-g0007.jpg
PMC10442812_06_fneur-14-1209567-g0007.jpg
F7
This can also be explained by the appearance of hydrops induced by the SSCD plugging, which was well performed according to the control labyrinthine MRI (Figure 7I).
(A) Tonal and vocal audiometry showing a slight bilateral conductive hearing loss. (B-D) Left SSCD in axial (B), coronal (C) and Poschl plane (D). (E, F) Left cochleofacial dehiscence in axial (E), and coronal plane (F). (G) Left SSCD in a control plane.
fneur-14-1209567-g0008.jpg
PMC10442812_06_fneur-14-1209567-g0008.jpg
F8
A tinnitus assessment could not accurately indicate the characteristics of bilateral tinnitus (Figure 8A). HRCT showed SSCD (Type I OCD) on the LE (Figures 8B-D) and a very thin bony covering on the RE, suggesting a "near" SSCD. HRCT images showed a second OCD (a CFD variant) (Figures 8E, F) on the LE. We also noticed that the SSCD on the LE was located on the anterior slope (arrows) and not "typically" placed on the convexity of the bony SSC (Figure 8G). Therefore, any temporal lobe descent into the membranous SSC would be limited by the bony overhang of the semicircular canal (Figure 8C).