A 3-D analysis of the protympanum in human temporal bones with chronic ear disease

Abstract

Eustachian tube dysfunction is believed to be an important factor to cholesteatoma development and recurrence of disease after surgical treatment. Although many studies have described prognostic factors, evaluation methods, or surgical techniques for Eustachian tube dysfunction, they relied on the soft tissues of its structure; little is known about its bony structure – the protympanum – which connects the Eustachian tube to the tympanic cavity, and can also be affected by several inflammatory conditions, both from the middle ear or from the nasopharynx. We studied temporal bones from patients with cholesteatoma, chronic otitis media (with and without retraction pockets), purulent otitis media, and non-diseased ears, looking for differences between the volume of the protympanum, the diameter of the Eustachian tube isthmus, and the distance between the anterior tympanic annulus and the promontory. Light microscopy and 3-D reconstruction software were used for the measurements. We observed a decrease of volume in the lumen of the four middle ear diseased ears compared to the control group. We observed a significant decrease in the volume of the protympanic space in the cholesteatoma group compared to the chronic otitis media group. We also observed a decrease in the bony space (protympanum space) in cholesteatoma, chronic otitis media with retraction pockets, and purulent otitis media compared to the control group. We found a correlation in middle ear diseases and a decrease in the middle ear space. Our findings may suggest that a smaller bony volume in the protympanic area may trigger middle ear dysventilation problems.

In vivo endoscopic study of the variations of anatomical structures in the hidden spaces of the middle ear during endoscopic ear surgery

“…Moreover, the round window region and subcochlear canaliculus have great clinical importance in many approaches like cochlear implant surgery, trans tympanic drug delivery to the inner ear, and approaches to the petrous apex [15,16]. The protympanum is another less well-studied partition of the middle ear despite having many landmarks for different procedures and applications [8,18]. Therefore, we conducted this study on 250 cases to describe the variations of the different anatomical landmarks of the middle ear, especially the retro, hypo, and protympanic spaces.…”

Functional aspects of the Eustachian tube by means of 3D-modeling

“…Imaging procedures without dissecting procedures increasingly provide insight into the anatomy and physiology of the tube [ 22 – 24 ]. Tomographic multiplanar imaging is especially the subject of static and dynamic functional studies both from bony parts of the ear [ 25 ] and of the ET [ 11 , 25 – 29 ]. In addition, optical coherence tomography might present new possibilities for three dimensional imaging [ 30 ].…”