Tympanoplasty Techniques

The two most common tympanoplasty techniques used by the surgeons of the Ear Institute of Chicago, LLC are the underlay and the overlay techniques. The technique chosen is based on several factors. These factors include the size and location of the perforation, if the ear drum had been operated on previously and surgeon preference. In general, the underlay technique is used most often, while the overlay technique is often reserved for total tympanic membrane perforations and revision procedures. Temporalis fascia is the graft material used most commonly for either technique. The graft acts as a scaffold to support regenerating tissue on the undersurface (medial) and epithelial layer on the top surface (lateral) aspect of the drum.

Underlay Tympanoplasty

While viewing the ear under a surgical microscope, an apron-shaped flap of skin in the back portion of the outer (external) ear canal is created. Next, a curved incision is made immediately behind the crease of the outer ear. A thin layer of tissue known as fascia that surrounds a muscle above the ear is obtained for later use as a graft material. The outer ear is folded forward and the external ear canal is entered by lifting the apron-shaped flap created earlier. This approach provides an excellent view of the entire tympanic membrane.

Next, the scar tissue around the edges of the tympanic membrane perforation is removed to encourage growth of the tympanic membrane over the graft material. The remaining tympanic membrane is lifted up and the middle ear bones (ossicles) are inspected. If the ossicles are normal, then the tympanic membrane repair proceeds as planned. If the ossicles are damaged or do not move properly, then repair of the ear bones is performed in a procedure known as ossicular chain reconstruction or ossiculoplasty. The tympanic membrane is repaired after the ossicles have been reconstructed.

The middle ear is filled with an absorbable sponge-like material known as gelfoam. This packing will hold the graft against the tympanic membrane. The graft is then placed on top of the packing material and the existing tympanic membrane is placed on top of the graft. In this way, the graft is placed under the tympanic membrane; hence the term “underlay” technique. The apron-like skin flap is returned to its original position and the incision behind the ear is closed with absorbable sutures. Lastly, the ear canal is packed with gelfoam and antibiotic ointment.

Overlay Tympanoplasty

While viewing the ear under a surgical microscope, an apron-shaped flap of skin in the back portion of the outer (external) ear canal is created. Next, a curved incision is made immediately behind the crease of the outer ear. A thin layer of tissue known as fascia that surrounds a muscle above the ear is obtained for later use as a graft material. The outer ear is folded forward and the external ear canal is entered by lifting the apron-shaped flap created earlier (These are the same initial steps performed in underlay tympanoplasty described above).

The skin of the front (anterior) portion of the outer ear canal is removed and set aside to be replaced at the end of the procedure. The bone of the anterior ear canal is thinned with a surgical drill in order to provide complete exposure of the anterior portion of the tympanic membrane. All remnants of the existing tympanic membrane are removed in order to prevent the development of epithelial pearls (trapped skin tissue under the graft), one of the possible complications of this procedure. Middle ear contents are inspected and ossicular reconstruction is performed if necessary.