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Endaural Approach (Tympanoplasty - Surgical Approach to the Ear Drum and Middle Ear)

last modified on: Mon, 12/18/2023 - 13:14

Return to: Otology - Neurotology

GENERAL CONSIDERATIONS

  1. Indications:
    1. Conductive hearing loss due to perforation or ossicular dysfunction
    2. Chronic or recurrent OM secondary to perforation (preferably want a "dry ear" prior to proceeding)
    3. Attic cholesteatoma or retraction pocket (typically limited to the epitympanum/attic and not extending into antrum). In these cases the endaural approach involves an atticotomy.
  2. Note: similar in general to post-auricular, transcanal, or endoscopic tympanoplasty with indications differing in:
    1. Whether perforation has significantly involved anterior annulus margin or fibrosis that would lead to problems with seating graft on the anterior canal wall from posterior approach
    2. Whether attic is involved with cholesteatoma and adequate visualization would not be feasible
  3. Contraindications:
    1. Labyrinthine fistula
    2. Meningeal involvement
    3. Malignancy
    4. Relative: active otitis, eustachian tube dysfunction (greater risk for failure), smokers, slag injury, better hearing ear
  4. Complications:
    1. Failure to resolve perforation
    2. Recurrent perforation
    3. Facial nerve injury, damage or disarticulation of ossicles
    4. Cholesteatoma (EAC, ME, TM)
    5. Dysgeusia (chorda injury)
    6. Blunting
    7. Lateralization
    8. SNHL
    9. Vertigo
    10. FN injury with paresis/paralysis

PREOPERATIVE PREPARATIONS

  1. Consent - including laterality
  2. Up to date audiometry
  3. General tympanoplasty guidelines:
    1. Wullstein (1956) classification of tympanoplasty: 
      1. Type I - graft to intact ossicular chain 
      2. Type II - Malleus is partially eroded, TM +/- malleus remnant grafted to the incus 
      3. Type III- malleus and incus are eroded, TM is grafted to stapes suprastructure 
      4. Type IV - stapes suprastructure is eroded but foot plate is mobile, TM grafted to foot plate 
      5. Type V - TM is grafted to fenestration in the horizontal SCC
    2. Anatomy
      1. Tympanic membrane is oval in shape
      2. TM is 8 x 10 mm, middle ear cleft about 5 mm deep
      3. 55 degrees to the floor of the meatus
      4. 3 layers - 130 microns thick: outer layer is keratinizing squamous, middle is fibrous, and inner is mucosa
      5. Blood supply: Inner surface - anterior tympanic a.; Outer surface- Deep auricular a.
        1. When performing an endaural approach, the incision comes out the ear canal toward the temporalis muscle. As you cross the lateral EAC bone, there is usually a large vessel that needs to be cauterized. If not performed adequately, profuse bleeding from this area can occur during packing removal. Recognize this and try to cauterize this area when making the incision.

NURSING CONSIDERATIONS

  1. Room Setup
    1. Hang consent, H&P and most recent audiogram on wall.
  2. Instrumentation and Equipment
    1. Lempert endaural speculum
    2. Modified Richard's self-retaining retractors x 2
  3. Medications (specific to nursing)
    1. 0.5% lido w/ epi (1:200,000) for preauricular incision for children
    2.  2% lido with 1:20,000 epi in adults
  4. Prep and Drape - in adults, can be done under local anesthesia similar to Stapedotomy/stapedectomy protocol or general anesthesia 
    1. Position patient so that ear to be operated on is close to the edge of the bed
    2. Gel donut for head
    3. Three straps for foam to strap the patient down to the table.
    4. 180 degrees from anesthesia.
    5. Position the blood pressure cuff on the non-operative side.
    6. Test balance microscope.
    7. Test roll patient
    8. Square off with towels on inferior, superior and lateral aspects then drape towel from Mayo stand to medial face
    9. Place 1030 or "medium" aperture drape from lateral face to Mayo stand
    10. Split drape
  5. Drains and Dressings
    1. No drains
    2. Gauze for "packing" EAC

ANESTHESIA CONSIDERATIONS

  1. Consider facial nerve monitoring. Inform anesthesia not to paralyze.
  2. Sometimes performed under local/MAC

OPERATIVE PROCEDURE

  1. The patient will be endotracheally intubated by anesthesia with the tube placed out of the contralateral oral commissure. NIMS electrodes are possibly used for this procedure ie. if under GA.
  2. Place a speculum in the ear canal. Clear debris from the ear canal and inspect the perforation.
  3. Rim the perforation using a Rosen needle and/or Drum Scraper can be done in cases with a mature, fibrous edge of the perforation.
    1. To do so, poke the Rosen needle into the TM at the edge of the perforation and elevate a small rim of TM using a back and forth sweeping motion – do this completely around the perforation if possible. Use a small cup forcep to bite any edge of the perforation not made raw by the poking and sweeping of the Rosen needle. Rough up the under surface of the TM around the perforation using the Drum Scraper. (Note: can do before prep or later before raising the tympanomeatal flap)
      1. This effectively disrupts the edges where the outer squamous layer has made contact with the inner mucosal layer to allow for integration of the graft.
  4. In the pediatric population, inject the canal with 1:50,000 epinephrine. For adults, inject with 1:20,000 epinephrine. If done under local anesthesia, include 2% lidocaine in injections.
    1. Place the ear speculum in the canal and causing the canal skin to pooch at the bony cartilagenous junction. Inject the canal skin subcutaneously at the 12 o’clock, 3 o'clock, 6 o’clock and 9 o’clock positions just proximal to the bony cartilagenous junction. Inject slowly and watch for a blanch of the canal skin, stop the injection and move to another spot if a bleb is raised. A key to a successful surgery is adequate injection.
  5. Inject 0.5% lidocaine w/ 1:200,000 epinephrine into pre-auricular area and incisura. For adults, use 1% lidocaine w/ 1:100,000 epinephrine into pre-auricular area and incisura
  6. Prep the patient, square out the field with green towels stapled to themselves (helpful to place horizontal drape at lateral canthus of the ipsilateral eye and vertical drape along infratemporal line) and then place a ten ten drape over the face and towels, if done under local anesthesia.
  7. The incision extends from the 12 o'clock position from the bony cartilagenous junction through the incisura and gently curves upwards and slightly backwards over the temporal area.
  8. The tissues are dissected down to the temporalis layer.
  9. Finger dissect the tissue overlying the temporalis and its fascia.
  10. Incise the fascia inferiorly using an 15 blade scalpel and then dissect superiorly both anteriorly and posteriorly using scissors to widely undermine and separate the fascia from the muscle. (Army-Navy's are good to help retract the tissue superiorly to facilitate harvest). Place the graft in the fascia press x 5 min and then open the press to air. Alternatively, the graft can be widely spread on a cartilage block with removal of any attached muscle tissue and left to dry.
  11. Canal incisions are made with the 6400 beaver blade typically at the bony cartilagenous junction, but certainly lateral to the anterior bony hump. The cut should incorporate the full extent of the perforation.
  12. Canal skin is elevated down to the level of the annulus. This is often done blindly over the anterior hump. It is easiest to enter the middle ear in the pars flaccida and ensure you are under the annulus to then raise it out of its ring. Often the drum needs to be fully detached from the malleus. This can be done in a subperiosteal plane.
  13. A canalplasty is then drilled starting laterally and superiorly with saucerization. Care is taken not to violate air cells.
  14. The canalplasty continues along the anterior canal to remove the bony hump. This can be done by first drilling a trough above the level of the jaw joint and then removing the bony hump. Often a small piece of suture foil is placed on the flap to prevent from being torn by the drill. Care is taken not to drill on the malleus if there is an intact ossicular chain.
  15. The canalplasty continues all the way to the level of the annulus with the goal of converting the acute tympanomeatal angle into a more obtuse angle. This helps prevent blunting. 
  16. If there is an attic retraction or cholesteatoma, this can be exposed by drilling an atticotomy at this point.
  17. Palpate the ossicles (ensure mobility), and shape the graft to fit the perforation. A notch may be made in the graft if the perforation goes around the malleus. Slide in the graft and position it circumferentially under the perforation. The anterior edge is positioned 1-2 mm up the anterior canal wall. The "tail" of the graft extends superiorly.
  18. If an attictomy has been made, a piece of tragal or conchal cartilage is used to reconstruct the scutum to prevent recurrent retraction.
  19. Ensure proper position of the graft by folding your flap and TM back into their native position and looking at the TM perforation through the hole. Often releasing incisions need to be made in the superior flap canal skin.
  20. If needed, gelfoam can be placed into the ME space to support the graft. The graft will fail if it's not against the edges of the perforation all the way around (special attention should be paid to anterior superior portion).
  21. Turn back the TM flap, examine the placement through the releasing incision in the canal skin, gently place Gelfoam on top of the graft (EAC side) to ensure placement. Fill the medial EAC with Gelfoam.
  22. The lateral EAC is packed open with bacitracin soaked 1/4 inch Iodoform strip gauze. 
  23. Close the incision (4-0 vicryl, 5-0 fast-absorbing gut or vicryl rapid).
  24. Mastoid dressing is placed.

POST OPERATIVE CARE

  1. Pain medication 

  2. Consider postop antibiotics while pack in place

  3. Mastoid dressing can be removed that evening.

  4. Strip gauze packing is removed after one week.

  5. Floxin otic 4 drops BID to start immediately after packing removed at one week appointment

  6. Follow up at one month to remove any residual gelfoam and assess healing. 

  7. Occasionally a small polyp will form in the lateral, superior EAC and this can be removed and cauterized at this stage.

  8. Audiogram 2-3 months

DICTATION TEMPLATE

After informed consent was reviewed, the patient was brought back to the operating room by Anesthesia and placed in a supine position. He was intubated and the table was turned 180 degrees. The operating microscope was brought in, and the left ear canal, following a timeout procedure, verifying the correct site and procedure, was cleaned of cerumen. A 30% anterior inferior perforation was visualized. The perforation included the annulus anteriorly. The decision was reached to perform an endaural approach with canal plasty and temporalis fascia graft. The perforation was prepared at the inferior aspect only, given that the perforation abutted the malleus posteriorly and was completely to the annulus anteriorly. A Rosen needle was used to postage stamp the inferior border and a cup forceps was used to remove this prepared edge. Canal injections using 1:50,000 epinephrine were performed at the 12, 3, 6, and 9 o'clock positions with 0.8 mL total injected. The face and ear were then prepped and draped in a sterile fashion including placement of NIMS facial nerve integrity monitoring probes at the orbicularis oris and oculi. These probes were verified to be in good functioning order. Once again, the operating microscope was brought in, and the initial canal cut using a round knife at approximately 5 mm lateral to the anterior tympanic annulus was performed just over the anterior hump from approximately the 6 o'clock to the 12 o'clock position. A further canal cut was performed using a Beaver blade intersecting the initial cut, however, running straight lateral towards the incisura of the auricle just posterior to the tragal cartilage. A 15-blade was then used to continue this incision out of the ear and on to the preauricular area through the incisura of that ear. A Lempert endaural speculum was placed to provide traction and contertraction in the EAC while the incision was carried down to the bone overlying the zygomatic root. The temporalis fascia graft was then harvested at the portion of the temporalis fascia just superior to the zygomatic arch through our initial preauricular incision. A Stevens scissors was used to dissect down to the level of the temporalis fascia and a 1.5 x 2 cm fascia graft was harvested. This was handed off for placement into the fascia graft press for 5 minutes. With a Freer elevator, the canal tissue elevation was performed in a subperiosteal plane and kept retracted with modified Richard's self-retaining retractors. With these self-retaining retractors in place, an excellent view of the anterior canal and the zygomatic root was obtained. The Freer elevator was used to further elevate the canal flap skin farther medially until we reached our initial canal cut that was parallel to the tympanic membrane. The EAC skin was elevated using a Rosen round knife and a McCabe flap knife to the level of the annulus. The middle ear was entered superiorly in the pars flaccida and the anterior and posterior annulus were elevated with a flap knife. The TM remnant was released from the manubrium. A small foil shield was fashioned from a suture pack and used to protect the flap and TM. A canalplasty was drilled using a 4 mm cutting burr and 4, 3 and 2 mm diamond burrs. The lateral EAC was saucerized superiorly and the anterior hump and portions of the more lateral canal were drilled, providing excellent view of the tympanic membrane. The external auditory canal was then irrigated with normal saline.  The temporalis fascia graft was then brought back in the field and placed following a central cut in the graft to allow manipulation around the handle of the malleus. The graft was maneuvered into place posterior to the handle of the malleus, as well as anterior to the handle of the malleus with a portion effectively underlying the umbo. The graft extended to the bony anterior canal wall. The initial perforation was completely remedied in this fashion. The tympanomeatal flap was then sectioned at approximately the 11 o'clock position, and both segments laid down over top of the graft. The graft and TM were again elevated  Gelfoam soaked in ofloxacin was placed into the middle ear space to provide medial support for the graft. The graft and TM were returned to their natural position and floxin-soaked Gelfoam was  placed in the external auditory canal on top of the graft and flap. A few interrupted deep stitches were placed in the preauricular tissues around the incisura of the auricle using a 4-0 Vicryl. The remainder of the skin incision was closed using 5-0 fast absorbing gut in running locking fashion. The external auditory canal was then lightly packed using bacitracin-soaked quarter inch strip Gauze.  A mastoid dressing was applied. The patient was turned back to Anesthesia in stable condition, having tolerated the procedure well.

REFERENCES

Endaural tympanoplasty without flap. A report on 34 cases. The Journal of Laryngology & Otology / Volume 85 / Issue 06 / June 1971, pp 541 565

Man SC, Nunez DA. Tympanoplasty--conchal cavum approach. J Otolaryngol Head Neck Surg. 2016 Jan 6;45:1. doi: 10.1186/s40463-015-0113-3. PMID: 26739478; PMCID: PMC4702389. 

Min J, Kim SH. Comparison of transcanal endoscopic tympanoplasty with sterile acellular dermal allograft to conventional endaural microscopic tympanoplasty with tragal perichondrium. Am J Otolaryngol. 2018 Mar-Apr;39(2):167-170. doi: 10.1016/j.amjoto.2017.11.014. Epub 2017 Dec 7. PMID: 29290312. 

da Costa SS, Alves de Souza LC, Ribeiro de Toledo Piza M. The flexible endaural tympanoplasty: pathology-guided, pathogenesis-oriented surgery for the middle ear. Otolaryngol Clin North Am. 1999 Jun;32(3):413-41. doi: 10.1016/s0030-6665(05)70143-2. PMID: 10393777. 

Szymanski A, Toth J, Ogorevc M, et al. Anatomy, Head and Neck, Ear Tympanic Membrane. [Updated 2023 May 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448117/ 

McManus LJ, Dawes PJ, Stringer MD. The orientation of the tympanic membrane. Clin Anat. 2012 Mar;25(2):260-2. doi: 10.1002/ca.22014. Epub 2011 Dec 2. PMID: 22139762.