Micro-CT analysis of the anatomical characteristics of the stapedial annular ligament

The oval window region has recently been identified as a potential route for drug diffusion into the inner ear. Locally applied gadolinium and trimethylphenylammonium (TMPA) have been shown to directly diffuse into the vestibule through the oval window region. Given the potential importance of the oval window region in the diffusion of substances into the inner ear, this work aimed to use micro-CT to obtain a data set of anatomical characteristics of the annular ligament of the stapes in the human temporal bone, a region thus far poorly studied. Twenty-one temporal bones were micro-dissected to preserve the otic capsule and allow perfusion of fixative stains into the inner ear. The specimens were scanned with micro-CT methods to provide 3D reconstructions and measurement. The 3D reconstructions were able to demonstrate an undisturbed stapes footplate and annular ligament from which measurements could be taken. This study found a wide variance in the volumes and thicknesses of the stapedial ligaments. There was a positive correlation between the size of the stapes footplate and the annular ligament.