Tympanoplasty (Contd)

By

Dr. T. Balasubramanian M.S. D.L.O.

Selection of approach:

Transcanal approach: is mostly used for repairing large acute traumatic perforations. The external canal should be fairly wide, and the rims of the perforation should be clearly visible.

Figure showing large traumatic perforation

End aural approach: Perforations involving the posterior portion of ear drum can be adequately visualized by endaural approach.

Image showing posterior perforation

Postaural approach: Is reserved for those perforations whose margins could not be entirely visualised through intact external canal.

Figure showing large central perforation

Grafting techniques:

Two types of grafting techniques are available i.e. overlay and underlay.

Overlay: The term overlay means that the graft has been placed over the bony tympanic sulcus, or over a bony ledge carved newly for this purpose when sulcus is absent. The overlaid fascia is supported by the presence of new / old annulus and is held in position by a remnant of tympanic membrane if still present.

Underlay: The term underlay indicates the position of the graft under the tympanic membrane and surrounding bone.

Combination of anterior underlay and posterior overlay: For this type of grafting procedure to succeed, there should be an anterior remnant of the tympanic membrane (atleast of the fibrous annulus). Anteriorly the graft is placed under the anterior remnant of the tympanic membrane and under the lateral wall of protympanum. Posteriorly, it is placed over the posterior tympanic sulcus and under the remnant of the tympanic membrane. With the exception of perforations limited to the anteroinferior quadrant, the graft lies under the malleus handle.

Total overlay: This technique is useful when there is no remnant of the tympanic membrane is present. A new bony sulcus is drilled to support the fascia at the lateral opening of the tympanic cavity. The graft rests over the sulcus and underneath the malleus handle. The edges of the graft are covered along the canal wall by meatal skin.

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