The lower border of the zygomatic arch could be a better landmark for the middle fossa dura: Cadaveric dissection study

BackgroundDural injury and CSF otorrhea is a serious complication during mastoidectomy especially in low level dura.ObjectivesAim of the study is to determine a reliable landmark for the middle fossa dura to minimize risk of dural injury and CSF otorrhea during mastoidectomy. By answering the question which is considered as a more fixed landmark for the dura; the supramastoid crest or the lower border of the zygomatic arch?MethodsA cadaveric study was done on 204 temporal bone specimens in the temporal bone lab at the Ain Shams University Specialized Hospital.A correlation between the level of the supramastoid crest and the level of the zygomatic arch was done.A correlation between the level of the dura and the level of the supramastoid crest in the area of mastoid antrum was done.A correlation between the level of the dura and the level of the zygomatic arch was done.ResultsIn 20.6% of specimens, the dura lies at a lower level than the level of the supramastoid crest but in 2.9% of specimens the dura lies at a lower level than the lower border of the zygomatic arch.ConclusionIt is better to consider the lower border of the zygomatic arch as a reliable landmark of the middle fossa dura in the area of the antrum than to consider the supramastoid crest as a landmark for the dura. It is better to consider imaginary line directed posteriorly from the lower border of the zygomatic arch as a superior limb of the Macewen triangle.