Novel Surgical and Radiologic Classification of the Subtympanic Sinus: Implications for Endoscopic Ear Surgery

Abstract

Objective The aim of this study is to describe the endoscopic anatomy of the subtympanic sinus (STS), establish a classification according to its extension regarding the level of the facial nerve (FN), and assess the feasibility of the transcanal endoscopic approach to the STS. Study Design Experimental anatomic research. Setting Temporal bone laboratory. Methods We performed endoscopic dissection of 34 human whole head and ear block specimens. Of those, 29 underwent high-resolution computed tomography. The STS was classified according to its extension regarding the level of the FN: type A, no extension medial to the FN; type B, extension to the medial limit of the FN; type C, extension of the sinus medially and posteriorly from the FN into the mastoid cavity. Results The majority of cases (n = 21, 72%) showed a shallow type A STS. We observed a deep type B configuration in 6 cases (21%) and a type C in 2 cases (7%). The STS was completely exposable with a 0° endoscope in 44% of the specimens. Using a 45° endoscope, we gained complete insight in 79%. However, in 21% of the cases, the posteromedial extension of the STS was too deep to be completely explored by an endoscopic transcanal approach. Conclusion The majority of the STS is shallow and does not extend medially from the FN. This morphologic variant allows complete transcanal endoscopic visualization. In more excavated STS, a complete endoscopic exploration is not achievable, and a retrofacial approach may be adopted to completely access the STS.

Comparison of 3- vs 2-Dimensional Endoscopy Using Eye Tracking and Assessment of Cognitive Load Among Surgeons Performing Endoscopic Ear Surgery

“…ndoscopic ear surgery (EES) is gaining popularity among ear surgeons because it permits minimally invasive and functional surgery. Advantages of the endoscopic technique include (1) panoramic views of middle ear anatomy, 1 especially of the retrotympanum and hypotympanum [2][3][4] ; (2) enhanced magnification of very small anatomic structures, such as, a malformed stapes 5 ; (3) the possibility to use angled endoscopes 6 ; (4) preservation of healthy mastoid and middle ear mucosa 7 ; and (5) possible shorter operating times. 8 However, the endoscopic technique has its inherent challenges: (1) because it is a 1-handed technique, the learning curve is deemed to be slower and management of bleeding may be challenging, 9 (2) the narrow space available in the external auditory canal (EAC) limits the movements of surgical instruments, (3) disease inside the mastoid may not be addressed, and (4) until recently, high-definition camera systems were exclusively 2-dimensional (2D).…”

Quantification and Comparison of Droplet Formation During Endoscopic and Microscopic Ear Surgery: A Cadaveric Model

“…Endoscopic ear surgery has been developed in recent decades and has gradually gained in importance worldwide in the treatment of different middle ear pathologies 14–16 and, more recently, in minimally invasive lateral skull base surgery 17 . Moreover, the endoscopic approach allows the exploration of the middle ear and even hidden regions, generally with no need for any kind of canaloplasty 18–21 . As indicated by the results presented in this study, the endoscopic approach also appears to be minimally invasive in regard to droplet formation despite the use of powered instruments.…”

“… 17 Moreover, the endoscopic approach allows the exploration of the middle ear and even hidden regions, generally with no need for any kind of canaloplasty. 18 - 21 As indicated by the results presented in this study, the endoscopic approach also appears to be minimally invasive in regard to droplet formation despite the use of powered instruments. One reason is the natural corridor to the middle ear offered by the external auditory canal, acting as a protective shield against aerosol generation.…”

Variability of the retrotympanum and its association with mastoid pneumatization in cholesteatoma patients

“…The introduction of the endoscope for middle ear surgery allowed a greater insight into this hidden region, and endoscopic and radiologic classifications of subsites have recently been published. The current groupings classify the pneumatization of the sinus tympani (ST), sinus subtympanicus (STS) and facial recess (FR) in relation to the facial nerve as follows [6][7][8][9]:…”