Endoscopic Anatomy of the Tensor Fold and Anterior Attic

Abstract

Objectives The objectives of the study were to (1) study the anatomical variations of the tensor fold and its anatomic relation with transverse crest, supratubal recess, and anterior epitympanic space and (2) explore the most appropriate endoscopic surgical approach to each type of the tensor fold variants. Study Design Cadaver dissection study. Setting Temporal bone dissection laboratory. Subjects and Methods Twenty-eight human temporal bones (26 preserved and 2 fresh) were dissected through an endoscopic transcanal approach between September 2016 and June 2017. The anatomical variations of the tensor fold, transverse crest, supratubal recess, and anterior epitympanic space were studied before and after removing ossicles. Results Three different tensor fold orientations were observed: vertical (type A, 11/28, 39.3%) with attachment to the transverse crest, oblique (type B, 13/28, 46.4%) with attachment to the anterior tegmen tympani, and horizontal (type C, 4/28, 14.3%) with attachment to the tensor tympani canal. The tensor fold was a complete membrane in 20 of 28 (71.4%) specimens, preventing direct ventilation between the supratubal recess and anterior epitympanic space. We identified 3 surgical endoscopic approaches, which allowed visualization of the tensor fold without removing the ossicles. Conclusions The orientation of the tensor fold is the determining structure that dictates the conformation and limits of the epitympanic space. We propose a classification of the tensor fold based on 3 anatomical variants. We also describe 3 different minimally invasive endoscopic approaches to identify the orientation of the tensor fold while maintaining ossicular chain continuity.

Distribution of different morphological types of anterior epitympanic plate “cog” and Köerner’s septum in CT images of cholesteatomatous and non-cholesteatomatous CSOM: is it really significant?

“…It was a complete plate in 46.5%, pyramidal projection in 32.6%, while it was not visualized in 20.9% of temporal bones. Li et al [10] had found a cog in all their studied patients with ME disease revealing complete and rudimentary types only. The "complete" type was most commonly seen (89%).…”

“…The height of this bony plate was 1.5 to 3.0 mm, and when complete, it is seen to extend from the facial canal wall to the scutum [29]. The cog is considered a dividing landmark between the anterior and the posterior epitympanic compartments, while the Tensor Tympani mucosal fold (TTF) is subdividing the anterior epitympanic compartment into anterior epitympanic recess (AER) and supra-tubal recess (STR) [10]. Commonly, a vertical type of TTF (mucosal fold) is attached to the cog, and if this TTF is complete, the ventilation to anterior epitympanic recess can be blocked.…”

“…Commonly, a vertical type of TTF (mucosal fold) is attached to the cog, and if this TTF is complete, the ventilation to anterior epitympanic recess can be blocked. In that scenario, removal of the cog and TTF can provide a sufficient ventilation route from the Eustachian tube to the epi-tympanum [10,30]. Otherwise, in the abovementioned case, the only ventilation pathway will be the "isthmus" which is a narrow pathway between the epitympnum and mesotympanum.…”

“…To best of our knowledge, few studies mentioned two different types of cog without correlation to chronic infection predisposition [10,28]. Also, few studies investigated the radio-anatomical assessment of the KS and its predisposition to middle ear infection [13,14] A single more recent prior study in oto-laryngology literature proposed a classification of morphological types of "cog" on an oligo-slice CT, which was followed in our study on multi-slice CT (MSCT) [12].…”

“…A coronally oriented bony septum named the anterior attic bony plate or "Cog" partitionates the anterior epitympanic recess-AER from the epi-tympanum proper (attic) [9]. It is considered the medial continuation of the transverse crest, which is projecting from the tegmen tympani [10]. Moreover, this bony structure and related mucosal fold of this space are closely relevant to the anterior ventilation and drainage of the epi-tympanum and mastoid, which therefore can cause inflammation if got obstructed [11,12].…”