Journal of Communication Disorders, Deaf Studies & Hearing Aids
Open Access

3D-CT analysis of FMT location after VSB surgery - Its correlation to hearing performances

International Conference and Expo on Audiology and Hearing Devices

August 17-18, 2015 Birmingham, UK

Katsumi Doi, Takamitsu Kobayashi, Mitsuo Sato, M, Kazuya Saito and Kumi Kohama

Posters-Accepted Abstracts: Commun Disord Deaf Stud Hearing Aids

Abstract :

Educational Objective: At the conclusion of this presentation, the participants should be able to demonstrate that the hearing
performance (BC-V threshold) after VSB surgery tended to be better as the FMT angle to RW became larger (more perpendicular to
the surface of RWM) and suggest that the measurements of the FMT angle to RW/OW during VSB surgery should be promising and
very useful procedure in future to predict much better hearing performances with VSB.
Objectives: In Japan, the clinical trial of VSB (Vibrant Soundbridge®, Med-El) implantation has just been ended, and the data
concerning on the efficacy and the safety of VSB surgery has now been under the judgement by PMDA of the Ministry of Health,
Labour and welfare. The present study was designed to see whether to not 3D-CT analysis of the FMT angle to RW/OW should be
useful to predict the hearing performances with VSB.
Study Design: Retrospective analysis of 3D-CT images reconstructed from 2D-CT images after VSB surgery.
Methods: After VSB implantation, thin-sliced 2D-CT images (0.625 mm slice) with GE Discovery CT750 HD® (GE, USA) were
collected and 3D-CT images were reconstructed by using Zio station® (Amin, Japan). The locations of round window (RW) and oval
window (OW) were identified, and the angle of FMT to RW/OW (FMT angle) was measured. The correlation between FMT angle
and BC-V (bone conduction threshold-vibrogram) threshold was finally evaluated.
Results: The FMT angle was scattered from 36.9 degree to 83.9 degree. The BC-V threshold (averaged at 1-4 kHz) was scattered
from 15 to 31.7 dB (n=11, RWV). The correlation between FMT angle and BC-V threshold did each to the significant level (P=0.049,
Spearman rank correlation), indicating the negative correlation between them (y = -0.2494x + 38.21, R2 = 0.36322).
Conclusions: The hearing performance (BC-V threshold) after VSB surgery tended to be better as the FMT angle to RW became
larger (more perpendicular to the surface of RWM). If the measurements of the FMT angle to RW/OW during VSB surgery could be
possible in future, it might be able to contribute to the achievement of much better hearing performances with VSB.