The variants of the retro- and hypotympanum: an endoscopic anatomical study

Abstract

The retro- and hypotympanum are hidden areas of the middle ear, only poorly recognized. Nevertheless, this region is of relevant clinical significance, since it is regularly affected by disease such as cholesteatoma. The aim of this study is to explore and describe the anatomical variants of the hypo- and retrotympanum by the means of transcanal endoscopy. We hypothesize a significant variability of this hidden region of the middle ear. Moreover, we believe that the minimal invasive, endoscopic access is suitable since angled scopes may be used to explore the region. To this end a total of 125 middle ears (83 cadaveric dissections, 42 surgical cases) were explored by the means of 3 mm straight and angled scopes. The variants were documented photographically and tabularized. The bony crests ponticulus, subiculum and finiculus were most frequently represented as ridges. The ponticulus showed the highest variability with 38% ridge, 35% bridge and 27% incomplete presentation. The subiculum was bridge-shaped only in 8% of the cases, the finiculus in 17%. The sinus tympani had a normal configuration in 66%. A subcochlear canaliculus was detectable in 50%. The retro- and hypotympanum were classified, respectively, to the present bony crests and sinus in a novel classification type I-IV. In conclusion, we found abundant variability of the bony structures in the retro- and hypotympanum. The endoscopic access is suitable and offers thorough understanding and panoramic views of these hidden areas.

Assessment of Middle Ear Anatomy Teaching Methodologies Using Microscopy versus Endoscopy: A Randomized Comparative Study

“…The anatomy of the middle ear is particularly complex and challenging (Marchioni et al, ). The hidden recesses of the retrotympanum are difficult to explore, and therefore, are poorly understood (Marchioni et al, ; Bonali et al, ; Alicandri‐Ciufelli et al, ). Conditions affecting the middle ear, such as acute otitis media, transmissive hearing loss, chronic inflammation with or without cholesteatoma or ear drum perforations, are frequent among all age groups.…”

Management of Jugular Bulb Injuries during Endoscopic Ear Surgery: Our Experience

“…[6][7][8] The main advantage is the enhanced visibility of the anatomy and pathology due to wide-angled view and the capability to look around the corner which permits to explore hidden recesses, such as the retro-and hypotympanum. 9 Nevertheless, the onehanded technique can be challenging for the surgeon and bleeding is a major concern. For this reason, powered instruments that allow both suction and dissection simultaneously might be used in case of need (i.e., surgery for glomus tympanicum).…”

Facial sinus endoscopic evaluation, radiologic assessment, and classification

“…In the recent literature, the present authors have already studied the endoscopic and radiologic anatomy of the retrotympanum, describing the variations in shape and relationship of the sinus tympani, the pyramidal eminence with the subpyramidal space, and the round window niche …”

“…In the last decade, there has been a growing interest regarding the transcanal endoscopic ear surgery (TEES), a technique that allows for the management of middle ear disease, such as cholesteatoma, with no external incisions, minimal morbidity for patient, short hospital stay, and low complications rate . As mentioned above, the endoscopic view improves visualization of the retrotympanum as well as its recesses, such as the posterior tympanic sinus (PTS), sinus tympani (ST), and sinus subtympanicus . However, an endoscopic description and analysis of the FS and its topographic relationships are still lacking in the literature.…”

“…8 As mentioned above, the endoscopic view improves visualization of the retrotympanum as well as its recesses, such as the posterior tympanic sinus (PTS), sinus tympani (ST), and sinus subtympanicus. 1 However, an endoscopic description and analysis of the FS and its topographic relationships are still lacking in the literature.…”