Article Type

Original Study


objectives:1- Describe a classification for the si-nus tympani (ST) different typesbased on their otoendoscopicand surgical anatomy in relationto their development theories.2- Evaluate possible approaches toeach of its types.3- Eliminate the discrepancy betweenthe various methods usedtodescribe it in literature.Methods:Fifty-five temporal bones weredissected, and the anatomical detailswere studied utilizing an operatingmicroscope and otoendoscopes ofdifferent angles. In addition, the STanatomy and relations were studiedin two hundred temporal bones CTscans. Results:Four distinct types of ST could beobserved. Type 1, the most commontype, it was pneumatized and consistedof an orifice and cavity. Type2,the well pneumatized type, thecavitywas deep enough posteriorlytoexceed the level of the mastoidsegmentof the facial nerve in any direction.Type 3, the common posteriortympanic sinus, in which ST communicatedwith the upper posteriortympanicsinus proper or with a retro-ponticulusup-ward extension.Type4, the non- pneumatized type,wasshallow with no true orifice andcavity.Type 1 and 4 were mainly approachedvia the trans-canal route.Type 2 and 3 required a combinedtrans-canal and trans-mastoidapproaches.Endoscopic trans-canal approach alone was satisfactory fortypes 1and 4 but to less extent type3.Conclusions:ST shape and extension both de-pend mainly on the extent of itspneumatization, which in turn influencesits relations to the surroundingstructuresin the retro-tympanic area.Extensivelyor unusually pneumatizedtypes need special or combinedapproaches.

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This work is licensed under a Creative Commons Attribution 4.0 International License.