Tympanomastoidectomy with Ossicular Chain Reconstruction
A tympanomastoidectomy consists of two components: tympanoplasty and mastoidectomy. Tympanoplasty aims to restore middle ear function by re-establishing an intact and functional tympanic membrane. Mastoidectomy involves removal of the mastoid air cells in order to remove cholesteatoma or tumor, or allow aeration of the middle ear space to reduce inflammation, or allow access for reconstruction of the ossicular chain. The surgical approach is via both the external auditory canal as well the mastoid. The mastoidectomy may leave the posterior canal wall intact (canal wall up, or CWU) or it may remove the posterior canal wall, thereby forming a common cavity between the mastoid cavity and external auditory canal (canal wall down, or CWD). The canal wall up procedure is covered in this chapter. In the event that infection or cholesteatoma has damaged the ossicular chain, ossiculoplasty or reconstruction of the middle ear bones is performed. There are many methods of achieving this, depending on which part of the ossicular chain is lost. Ossiculoplasty may be performed at the time of surgery or during a planned second stage surgery.
Indications for Surgery
- Chronic otitis media with otorrhea refractory to medical management
- Middle ear or temporal bone tumor
- Coalescent mastoiditis/abscess
Contraindications to Surgery
- Medical comorbidities that would preclude surgical or anesthesia risk
- Canal wall up tympanomastoidectomy is relatively contraindicated in patients with sclerotic, contracted mastoid; labyrinthine fistula; and/or erosion of the posterior bony external canal from cholesteatoma. Patients with limited access to health care or at higher anesthesia risk, in whom revision surgery is better avoided may be a better candidate for canal wall down tympanomastoidectomy because CWU surgery often requires a second look operation to ensure that there is no recurrent disease.
- An audiologic evaluation including pure tone audiogram should be performed to document the extent of hearing loss.
- Computed tomography (CT) may be useful for surgical planning, and should be obtained in revision cases. Diffusion-weighted MRI scans can also be used to detect primary, recurrent or residual cholesteatoma.
Surgical Technique (Canal wall up procedure):
- The patient is placed supine on the OR table and general anesthesia is induced via endotracheal intubation.
- The table is rotated 180 degrees and the periauricular region is prepped and draped. Facial nerve monitor leads are placed.
- The binocular operating otomicroscope is brought into position and used to examine the tympanic membrane.
- The external auditory canal and the postauricular sulcus are injected with 1% lidocaine with 1:100,000 epinephrine.
- A postauricular incision is made through the skin and ear is elevated forward.
- A piece of temporalis fascia or superficial temporalis fascia is harvested and preserved for later use in tympanic membrane repair.
- Attention is turned to the external auditory canal. The posterior canal skin is elevated off of its bony attachments. A tympanomeatal flap is elevated and the middle ear space is entered being careful not to cut the chorda tympani, a branch of the facial nerve.
- Attention is turned back to the postauricular area. An incision is made through the fascia and muscle down to bone in a 7 shape from the superior canal down to the mastoid process being careful not to go too inferiorly as to injure the facial nerve.
- The postauricular soft tissues are elevated until the spine of Henle or the ridge of bone that marks the posterior aspect of the external auditory canal is identified.
- A mastoidectomy is performed using a large cutting bur, identifying the mastoid antrum.
- The ossicular chain is palpated. If the ossicles are involved by cholesteatoma, the incudostapedial joint is separated and the incus is removed.
- Cholesteatoma is removed, taking care to identify and preserve the facial nerve. Particular care must be taken to ensure eradication of disease in the sinus tympani and facial recess (immediately deep and superficial to the facial nerve, respectively), as well as superior and anterior to the ossicles in the epitympanum, the region of the middle ear space above the tympanic membrane.
- An incision is made in the tragus and a piece of cartilage is harvested.
- A partial ossicular reconstruction prosthesis (PORP) is placed over the stapes superstructure if it is present. If the stapes superstructure has been eroded by disease, a total ossicular reconstruction prosthesis (TORP) would be used to connect the tympanic membrane to the stapes footplate.
- The prosthesis is overlaid with the tragal cartilage graft and the previously harvested temporalis fascia.
- Any perforation of the tympanic membrane is repaired with fascia, cartilage, or both, typically as a medial underlay graft.
- The tympanomeatal flap is lowered and adequate coverage of the ossiculoplasty confirmed.
- The canal is packed with Gelfoam and a cotton ball.
- The incisions are closed in layers and a mastoid dressing is placed over the surgical site. Care of the patient is returned to the anesthesiologist for extubation and recovery.
- Tympanomastoidectomy is usually performed on an elective, outpatient basis.
- The patient is instructed to keep the mastoid dressing in place for 24-48 hours after surgery.
- The patient is instructed to maintain dry ear precautions with external canal packing in place until evaluation at the follow-up visit.
- Follow-up appointments are scheduled for one week postoperatively for packing removal and one month postoperatively, at which time a postoperative audiogram is performed.
- Postoperative oral antibiotics and topical antibiotic drops are typically used, especially with infected mastoid cavities.
- Conductive or sensorineural hearing loss
- Horizontal semicircular fistula
- Facial nerve injury
- Bleeding from injury to sigmoid sinus or jugular bulb
- Persistent tympanic membrane perforation/graft failure
- Residual or recurrent cholesteatoma
- Prosthesis extrusion
- Dural injury resulting in cerebrospinal fluid leak