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A. Anterior Middle Ear Exposure:
Anterior Exposure of the middle ear (Anterior Tympanotomy) is done by soft tissue and bone dissection. Soft tissue dissection is carried by either the classical tympanomeatal (TM) flap or by Extended Anterior Tympanotomy approach dissecting the TM flap from the periosteum of the malleus handle. This extends the approach anteriorly to expose the protympanum and eustachian tube orifice. This is followed by (transcanal) bony dissection of the medial rim of the external canal (annulus attachment) to expose the middle ear. It includes: retro-tympanotomy, anterior atticotomy, anterior epi-tympanotomy and hypo-tympanotomy. Retro-tympanotomy: is done by drilling the bony edge of the posterior auditory canal wall to expose the posterior tympanum. The limits of the exposure are the stapedius tendon, pyramidal eminence, round window and hypotympanic cell tract. Hypo-tympanotomy: will give additional exposure inferiorly. Anterior Atticotomy: is done by extending the bony exposure superiorly and forwards by removal of the scutum and exposure of the malleus head articulating with the incus body. Removal of the incus after separation of incudostapedial articulation is necessary to complete the atticotomy. Anterior Epi-tympanotomy: is done by further extension forward to expose the anterior epitympanic recess and eustachian tube orifice. This necessitates removal of the malleus head after cutting the tendon of the tensor tympani. Bony Canaloplasty: (posterior, superior and inferior) may be required if the bony external canal is narrow, or if additional exposure to the middle ear is required. Anterior canaloplasty, after reflection of anterior canal skin upwards, may be required when grafting total perforations. Posterior Exposure of the middle ear:
This is done through mastoidectomy. Complete mastoidectomy is necessary in advanced mastoid disease according to the stage of the disease (M2). Limited mastoidectomy for exposure is done if the pathology is limited (M1). Intact canal wall (ICW) mastoidectomy is usually adequate for most of the cases. Open ( canal wall down ) technique is reserved for certain anatomical variations involving the sigmoid sinus and middle fossa dural plate, and in cases associated with intracranial complications ( C2) or when the disease has destroyed the posterior canal wall. Posterior exposure techniques include: Posterior atticotomy: is done by anterior extension of the mastoid approach to expose the attic from behind.
Posterior Epi-tympanotomy: is done by extending the posterior atticotomy to expose the anterior epitympanic recess and eustachian tube orifice. Posterior Tympanotomy (Facial recess approach): is necessary to expose the facial recess from the mastoid side.