Background: Cerebrospinal fluid (CSF) rhinorrhea following temporal bone surgery involves drainage from the eustachian tube (ET) into the nasopharynx, causing significant patient morbidity. Variable anatomy of the ET accounts for failures of currently used ET obliteration techniques.
Objective: To describe the surgical anatomy of the ET and examine possible techniques for ET closure through middle fossa (MF) and transmastoid (TM) approaches.
Methods: We described the surgical anatomy of the ET from the MF and TM approaches in five adult cadaveric heads, establishing morphometric and surgical anatomy parameters establishing targets for definite ET obliteration.
Results: The osseous ET measured an average 19.53mm (±1.56mm), with a mean diameter of 2.24mm (±0.29mm). The shortest distance between the greater superficial petrosal nerve (GSPN) and the ET junction was 6.61mm (±0.61mm). Shortest distances between the ET junction and the foramen spinosum and posterior border of the foramen ovale were 1.09mm (±0.24mm) and 2.03mm (±0.30mm), respectively. Closure of the cartilaginous ET may be performed by folding it in upon itself, securing it by packing, suturing or surgical clip ligation.
Conclusion: Definite obliteration of the cartilaginous ET appears feasible and the most definite approach to eliminate egress of CSF to the nasopharynx. This technique may be used as an adjunct to skull base procedures where ET closure is planned.
Liu J, Pinheiro-Neto CD, Fernandez-Miranda JC, et al. Eustachian tube and internal carotid artery in skull base surgery: An anatomical study. Laryngoscope. 2014;124(12):2655-2664. doi:10.1002/lary.24808
Komune N, Matsuo S, Miki K, et al. Surgical Anatomy of the Eustachian Tube for Endoscopic Transnasal Skull Base Surgery: A Cadaveric and Radiologic Study. World Neurosurg. 2018;112:e172-e181. doi:10.1016/j.wneu.2018.01.0032.