Tympanoplasty - Medial graft

Considerations

• • https://www.ncbi.nlm.nih.gov/pubmed/19403180

  • These Sydney Endoscopic Ear Surgery Research Group videos show transcanal dissection of the middle ear space anatomy:

    • https://www.youtube.com/watch?v=VSB0wWG6BgQ

Preparation

• • Local anesthetic: lidocaine with epinephrine.

  • Operating microscope: set to working distance of 250 mm, low magnification, and with the assistant eye piece towards the head of the bed.  

  • Facial nerve monitor: sometimes used.  

  • Shaver: if temporalis fascia is going to be used, shave a small strip of hair just posterosuperior to the root of the helix.

Procedure

• 1. Examine the external auditory canal and tympanic membrane with the microscope.

     • A large anterior canal hump can preclude visualization and make a transcanal tympanoplasty very difficult. 

     • If so, an endoscopic assisted approach, drilling down the anterior hump, or a postauricular approach may be needed.  

     • Examine the middle ear mucosa for evidence of keratin, inflammation, or ossicular erosion.  

  2. Inject the external auditory canal meatus at four points (posterior, inferior, superior, anterior) with local anesthetic (lidocaine with epinephrine).

     • Start at the posterior aspect first, end with the anterior aspect last, so that blood does not drip down from the anterior canal wall and interfere with visualization.

     • Do not inject too medially into the canal; the skin is fragile here and easily forms blebs or hematomas.  

     • Do not inject too quickly; this too can lead to bleb or hematoma.

  3. Inject the posterior aspect of the tragal cartilage or the planned site for harvesting the temporalis fascia.  

  4. Prep and drape the patient (attendings have different preferences).  

     • Dr. Macy (Redwood City)

       • Blot the iodine with a blue towel, which is then discarded.

       • Place the 1030 eye drape over the ear.  Be sure to keep open the potential area for temporalis fascia harvest.

       • Place the split drape.  

       • Assist the surgical tech in draping the microscope.  

  5. Freshen the edges of the tympanic membrane perforation with a Rosen needle and cup forceps.

• • 1. This can be done several ways.  The Rosen needle is used to incise around the margin of the perforation circumferentially, and the up-biting cup forceps is then used to pull off this now partially detached strip of tympanic membrane that is the perforation margin.

    2. This expectedly enlarges the perforation size.

• 6. Raise the tympanomeatal flap.

     • This can be done several ways.  

     • Most commonly, lateral incisions at 6 o'clock and 12 o'clock are made with a sickle or beaver blade, beginning several millimeters from the annulus.  These are then connected with a circumannular incision made with a large round canal knife, which is around 6 mm from the annulus edge.  The flap is then raised with the round canal knife in one hand and a 3 suction or smaller in your left hand to clear away the blood.  Minimize suctioning the flap. When the annulus is encountered, the Rosen needle is used to lift it and pierce the middle ear mucosa inferiorly.  

     • Macy (Redwood City):  Lateral incisions at 6 o'clock and 12 o'clock are not done.  The circumannular incision is made (as above) with the large round canal knife, curving closer to the annulus superior and inferiorly where the lateral incisions would have been made.  The flap is elevated with the round canal knife in one hand and the 3 suction in the other.  If the flap tents or becomes restricted superiorly or inferiorly, then curved Belluci scissors are used to release the tenting fibrous bands.  The Rosen needle is used to elevate the annulus out of the bony sulcus inferiorly and expose the middle ear mucosa, which is then pierced with the Rosen needle to enter the middle ear space.  The Gimmick (also known as the House) elevator is used to raise the flap inferiorly in a quick manner.  The Rosen needle is used to raise it superiorly and cautiously.  Identify the chorda tympani nerve.  Dissect on it with the Rosen needle; this will show you bands on either side of it that can be released with sideways pressure with the Rosen.  

  7. Examine the ossicular chain and middle ear space for abnormalities such as keratin deposition.  For the latter, be sure to inspect the undersurface of the tymapnomeatal flap as well. 

  8. Harvest the graft.

     • Temporalis fascia: The incision is behind and above the root of the helix, in the hairline.  This area is infiltrated with the local anesthetic prior to raising the tympanomeatal flap.  Make the skin incision with the 15 blade.  Go down sharply in layers to the level of the temporalis fascia.  Some attendings prefer to harvest the superficial tempoparietal fascia (ie the "false" fascia), others the deep temporal fascia.  The latter is thicker, more durable, and easier to handle when insetting.  Once the desire fascia is encountered, harvest a 1 cm x 1 cm piece with curved tenotomy scissors.  Pass the graft off to be pressed and dried.  Close the incision in layers, with a 4-0 Polysorb for deeper tissue approximation and a running 5-0 Fast for the skin.  

     • Cartilage (tragal): The incision is on the posterior aspect of the tragus.  The tip of the tragus (that which gives it its external appearance) should be left undisturbed.  Removing this will cause a cosmetic deformity.  Make the incision sharply with the 15 blae to the level of the perichondrium.  Dissect at this level with the tenotomy scissor to expose the size of the graft to be harvested.  Using the 15 blade, partially incise the tragal cartilage.  Complete the incision into the cartilage with the round canal knife.  This will then put you on the contralateral side of the tragal cartilage.  Dissect with the canal knife in the subperichondrial plane (like in septoplasty) on this contralateral side.  Using curved scissors, sharply excise the tragal cartilage graft.  One side will have perichondrium on it, the other side will not.  

  9. Estimate the perforation (defect) size with the canal knife.  

  10. Trim the graft to this estimated side.

      • For cartilage grafts, leave a healthy overhang of perichondrium off the cartilage.  

  11. Prepare the tympanic membrane and middle ear space to receive the graft.

      • Lift the tympanic membrane up for maximal exposure.

      • Make sure the middle ear space is clean and dry. 

  12. Inset the graft.  

      • Temporalis fascia: Place the graft under the tympanic membrane to cover the perforation.  There should be overlap with the scutum.  Place small pieces of unwet, pressed Gelfoam anteriorly under the graft.  As these pieces of Gelfoam become wet they will swell and then lift up and support the graft in place.  After placing these Gelfoam pieces anteriorly, place them in the rest of the middle ear space to support the graft and tympanic membrane. Lay the tympanic membrane back down.  Make sure that it is completely unfurled.  Failure to do so increases the risk for a canal cholesteatoma. Place Floxin-soaked Gelfoam onto the graft. 

      • Cartilage (tragal): Inset in a similar manner as above.  The perichondrial side faces the canal, and there should be perichondrium draping onto the scutum/canal.  

  13. Place an antibiotic coated cotton ball into the meatus.

  14. Place antibiotic ointment onto the skin incision used for the temporalis fascia harvest (if done).

Sample operative report

Post-op

• • Macy (Redwood City)

    • Keep the ear dry.

    • Avoid blowing your nose, sneezing, straining, coughing, etc.  

    • Take the cotton ball out of the meatus on POD 1.

    • Start using Floxin drops into the ear when the cotton ball is out.  Continue until instructed otherwise.

Pearls & Pitfalls

High-Yield

Links

• • https://www.youtube.com/watch?v=VVqxq-mWXI8

  • https://www.youtube.com/watch?v=VSB0wWG6BgQ (Sydney Endoscopic Ear Surgery Research Group)

• eMedicine - Tympanoplasty

• OPEN ACCESS ATLAS OF OTOLARYNGOLOGY, HEAD & NECK OPERATIVE SURGERY - MYRINGOPLASTY & TYMPANOPLASTY

• UTMB - Tympanoplasty