Kumara SPP¹*, Jayasena KDNUD², Mahindawansa SI³ and Selvarathnam S⁴

¹Senior Registrar in Otorhinolaryngology, National Hospital, Kandy, Sri Lanka
²Senior Registrar in Otorhinolaryngology, General Hospital, Rathnapura, Sri Lanka
³Registrar in Radiology, National Hospital, Kandy, Sri Lanka
⁴Consultant ENT surgeon, National Hospital, Kandy, Sri Lanka

*Corresponding Author: Kumara SPP, Senior Registrar in Otorhinolaryngology, National Hospital, Kandy, Sri Lanka.

Received: November 24, 2022; Published: December 13, 2022

Abstract

Introduction: Mastoid exploration is carried out in almost all ENT units in Sri Lanka. A Computed Tomography (CT scan) will give detailed anatomical information which assist surgical planning. Unfortunately, in most occasions it is not available due to resource limitations. A low-lying dura, high sigmoid sinus, Korner’septum, lateral semicircular canal are encountered when performing this surgery.

Objective: Establish a data bank of the distance from the inner surface of superior bony canal wall to tegmen, the distance from the outer margin of the posterior bony ear canal to the lateral semicircular canal and the distance to the sigmoid sinus from the posterior bony canal.

Method: A retrospective cohort study was carried out at the ENT unit of the National Hospital, Kandy. All the patients fulfilling the inclusion criteria were selected till the total number reach 50 patients from April 2020 to December 2020.

Results: Fifty mastoid explorations were studied focusing on the anatomical distances from the bony ear canal. The minimum distance from the inner surface of the superior bony canal wall to the middle fossa dural plate (tegmen) was found to be 4 mm. The minimum distance of the sigmoid sinus wall; which was an anteriorly placed sigmoid sinus, from the inner surface of the posterior canal wall was 4 mm. The average distance to the lateral semicircular canal from the outer surface of the bony ear canal was 15.0 mm (16.2-14.2 mm).

Conclusion: The closest distance to the middle fossa dura and the sigmoid sinus was 4.0 mm and the aditus and the lateral semicircular canal encountered more than 14 mm deep from the outer mastoid wall. Therefore choosing a 4.0 mm drill is safe when performing surgery near the middle fossa dura and the unexpected anteriorly placed sigmoid sinus. However, since this study has examined fifty samples; more data and a bigger sample would give a better representation of the population.

Keywords: Mastoid Exploration; Tegmen; Lateral Semicircular Canal; Sigmoid Sinus

References

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6. https://pubs.rsna.org/doi/10.1148/rg.323115117

Citation

Citation: Kumara SPP., et al. “Anatomical Landmarks in Relation to Mastoid Exploration; Distance to Tegmen, Sigmoid Sinus and Semicircular Canal from the Bony Ear Canal".Acta Scientific Otolaryngology 5.1 (2023): 07-11.

Copyright

Copyright: © 2022 Kumara SPP., et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.