What is a mastoidectomy

A mastoidectomy is surgery to remove cells in the hollow, air-filled spaces in the skull behind the ear within the mastoid bone. These cells are called mastoid air cells. Mastoidectomy surgery used to be a common way to treat an infection in mastoid air cells. In most cases, mastoiditis was caused by an ear infection that spread to the bone in the skull. Mastoidectomy successfully gets rid of the infection in the mastoid bone in most people.

Mastoidectomy may be used to treat:

• Cholesteatoma. An individual with a cholesteatoma is at significant risk for intracranial and other complications if they refuse surgical intervention in this disorder.
• Complications of an ear infection (otitis media). Chronic otitis media, with or without cholesteatoma, is one of the more common indications for performing a mastoidectomy. Patients with chronic otitis media often present with otorrhea and progressive hearing loss. Mastoidectomy permits access to remove cholesteatoma matrix or diseased air cells. In addition, mastoidectomy often provides access to the temporal bone which are more challenging to visualize through the external auditory canal (ie, supratubal recess, epitympanum, facial recess, perilabyrinthine air cells, retrofacial air cells).
• Infections of the mastoid bone that do not get better with antibiotics. Complications of otitis media, including intratemporal or intracranial suppuration and lateral venous sinus thrombosis, often necessitate a mastoidectomy ¹.
• To place a cochlear implant. Mastoidectomy is one of the key steps in placing a cochlear implant to rehabilitate acquired or congenital sensorineural hearing loss. A mastoidectomy allows the surgeon access to the middle ear through the facial recess. The implant electrode array is placed through the facial recess into a cochleostomy, which is drilled inferior and slightly anterior to the round window.
• A mastoidectomy is often an initial step in removal of lateral skull base neoplasms, including vestibular schwannomas, meningiomas, temporal bone paragangliomas (glomus tumors), and epidermoids.

Mastoidectomy alternatives:

• Canal wall up or down mastoidectomy procedures.

You will receive general anesthesia, so you will be asleep and pain free. The surgeon will make a cut behind the ear. A bone drill will be used to gain access to the middle ear cavity that is behind the mastoid bone in the skull. The infected parts of the mastoid bone or ear tissue will be removed and the cut is stitched and covered with a bandage. The surgeon may put a drain behind the ear to prevent fluid from collecting around the incision. The operation will take 2 to 3 hours.

Figure 1. Mastoidectomy scar

Mastoidectomy surgery

Before the mastoidectomy procedure

A preoperative temporal bone CT scan provides useful information with respect to the location of the tegmen, sigmoid, sinus, facial nerve, and inner ear. CT scans are particularly useful if the normal anatomy of the temporal bone has been significantly distorted by disease or previous surgery. Identification of dehiscences in the tegmen or the sigmoid sinus may reduce the risk of a cerebrospinal fluid leak, encephalocele, copious bleeding, a rarely an air embolus. Fistulas into the otic capsule are readily visible on CT scans, which may alter the surgical planning and allow for improved preoperative counseling ².

You may need to stop taking any medicines that make it hard for your blood to clot 2 weeks before your surgery, including aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), and some herbal supplements. Your health care provider may ask you not to eat or drink after midnight the night before the procedure.

Mastoidectomy procedure

Mastoidectomy procedures are typically performed under general anesthesia. The use of long-acting paralytics is not recommended because this does not allow the surgeon to assess the function of the facial nerve, either through a hand-held stimulator or a nerve integrity monitor.

A post-auricular incision is made down to the level of the superficial layer of the deep temporalis fascia. A simple mastoidectomy consists of opening the mastoid cortex and identifying the aditus ad antrum.

A complete or canal wall up mastoidectomy necessitates removal of all of the mastoid air cells along the tegmen, sigmoid sinus, presigmoid dural plate, and posterior wall of the external auditory canal. The posterior wall of the external auditory canal is preserved.

A canal wall down mastoidectomy includes a complete mastoidectomy in addition to removal of the posterior and superior osseous external auditory canal. The tympanic membrane is reconstructed to separate the mucosal lined middle ear space from the mastoid cavity and ear canal.

A modified radical mastoidectomy is identical to a canal wall down mastoidectomy except the middle ear space and native tympanic membrane are not manipulated. This procedure is useful when there is no extension of cholesteatoma in the middle ear space or medial to the malleus head or incus body. This procedure is often indicated in patients with a cholesteatoma in their only or better hearing ear.

A radical mastoidectomy is a canal wall down mastoidectomy in which the tympanic membrane and ossicles are not reconstructed, thus exteriorizing the middle ear and the mastoid. The eustachian tube is often obliterated with soft tissue to reduce the risk of a chronic otorrhea. A skin graft can be placed in the middle ear to reduce the risk of mucosalization and otorrhea ³.

After the mastoidectomy procedure

You will have stiches behind your ear. You may also have a large dressing over the operated ear. A mastoid dressing consisting of gauze wrapped around the head or a neoprene flexible dressing is placed over the operative site to collect drainage from the ear and to decrease the risk of a wound hematoma. These dressing are typically removed 24 hours after surgery. Patients are typically instructed to keep the operative ear dry by covering it with a cup or placing a petroleum jelly covered cotton ball over the external ear canal while bathing.

You may need to stay in the hospital overnight. Your provider will give you pain medicines and antibiotics to prevent infection.

Postoperative care typically entails a visit to remove packing in the ear canal 1-2 weeks after surgery. Patients can start topical antibiotic drops the following day after surgery or several days before the initial postoperative visit. The topical antibiotic drops serve a dual purpose of decreasing the risk of a postsurgical infection and to keep the packing moist to ease removal at their initial postoperative visit.

Patients undergoing a canal wall down procedure may have sponge packs, strip gauze, or resorbable packing in the mastoid cavity and/or meatus. This packing is often removed in the first 2 weeks after surgery. Canal wall down cavities can take weeks to months to completely heal. Intermittent debridements of the canal wall down cavity is required periodically (3-12 months), even after the cavity has completely healed.

Long-term monitoring

Patients with cholesteatoma need to be followed long term, as recurrence can occur in up to 50% of patients in whom the canal wall was preserved and up to 10% of patients in whom a canal wall down procedure was performed. Recurrent tympanic membrane retraction can usually be identified with otomicroscopy in clinic. Residual disease in the middle ear can sometimes be visualized in cases in which the tympanic membrane is translucent. Residual disease in the mastoid, epitympanum, hypotympanum, sinus tympani, facial recess, and protympanum are not typically visible on clinical examination.

Non-ECHO planar diffusion weighted magnetic resonance imaging (MRI) may in some cases detect pearl-like recurrences down to 2 mm in size. Sheetlike cholesteatoma recurrences are very difficult to detect with CT scanning or MRI until significant debris is present ⁴. In patients undergoing canal wall up procedures, a second-look procedure 6-12 months after the initial surgery allows for assessment and removal of residual disease, and, in some cases, staged ossicular chain reconstruction if this was not undertaken at the initial procedure.

Patients with poor eustachian tube function or obstruction of the aditus ad antrum often develop a depression in the postauricular area. This depression has no significant long-term implications. Some surgeons advocate obliterating the mastoid with soft tissue flaps, bone dust, or covering the defect with titanium mesh to prevent skin depression into the mastoid ⁵.

Mastoidectomy complications

Complications of general anesthesia including heart attack, stroke, and death.

Risks of mastoidectomy surgery may include:

• Bleeding
• Changes in taste from sacrifice of chorda tympani nerve
• Dizziness
• Hearing loss or deafness/sensorineural hearing loss
• Worse hearing (conductive loss) immediately after surgery is common due to ossicular discontinuity
• Infection that persists or keeps returning, including loss of reconstructed bony canal wall or exposure of bone in canal wall
• Noises in the ear (tinnitus)
• Facial paralysis – reported 0.6-3.6%
• Vertigo – 5-10% of cholesteatomas form lateral semicircular canal fistula
• Recurrence of cholesteatoma – 1.5%
• Need for further surgeries, including a planned surgery for re-evaluation of the ear and possible reconstruction of ossicles (bones that transmit sound from the eardrum to inner ear).

Facial nerve injury

Facial nerve paralysis is the most dreaded complication of mastoidectomy. The incidence of this complication is fortunately exceeding low (~0.1%). Revision surgery, operator experience, extensive disease, osseous dehiscence of the nerve all increase the risk of an iatrogenic facial nerve injury. A transient facial weakness can be seen in the immediate postoperative period from local anesthetic, which enters the middle ear space adjacent to the facial nerve. This typically resolves within a period of 2-4 hours. Postoperative facial nerve paralysis that does not resolve after a few hours should be taken back to the operating room for exploration. A partial-thickness injury can be decompressed or observed, while a full-thickness injury should be repaired with a primary anastomosis or interposition graft. Drilling in the direction of the nerve with a diamond burr using copious irrigation significantly reduces the risk of a facial nerve injury ⁶.

Hearing loss

A temporary conductive hearing loss is very common after mastoidectomy, as blood, serous fluid, and packing frequently fill the middle ear space. In the setting of chronic otitis media with cholesteatoma, the ossicles are frequently eroded or absent, which results in a preoperative significant conductive hearing loss. Depending on the extent of the cholesteatoma and surgeon preference, an ossicular chain reconstruction with autologous materials or implants can allow for improvement in conductive hearing loss. A significant sensorineural hearing loss is rarely encountered in patients undergoing surgical intervention for chronic otitis media. Sensorineural hearing loss may arise from the high-speed drill contacting an intact ossicular chain, labyrinthine fistula, or noise exposure from the drill ⁷.

Vertigo

Vertigo and/or dizziness is frequently seen in patients undergoing otologic surgery. A number of factors contribute to these symptoms including the type and duration of anesthesia, cool irrigation adjacent to the labyrinth, and possible manipulation of the ossicles. Permanent vestibular symptoms are quite rare after mastoidectomy. An iatrogenic injury to the labyrinth is fortunately quite rare (0.1%). A labyrinthine fistula, especially involving the lateral semicircular canal, typically results in severe room-spinning vertigo that typically lasts up to 72 hours.

Labyrinthine injury carries an additional risk of sensorineural hearing loss. If a fistula is identified, intraoperatively suctioning over the area should be avoided and the opening should be covered with fascia immediately. Packing the fistula with bone wax or other materials may increase the risk of hearing loss or vertigo, especially in the setting of inflammation or infection ⁸.

Change in taste

The chorda tympani nerve travels through the middle ear space from its origin along the mastoid portion of the facial nerve. This nerve may need to be sacrificed if it is encased in cholesteatoma or inflammatory tissue. This nerve is typically removed in patients undergoing revision surgery or a canal wall down procedure. Patients typically notice an altered sensation of taste, typically described as a metallic or sour taste on the affected side. This sensation may be persistent but often resolves over a period of months.

Mastoid cutaneous fistula

Mastoid cutaneous fistulas are rarely encountered after mastoidectomy. This may be seen in patients who have undergone multiple postauricular incisions or have poor wound healing. This defect can be closed with local advancement or rotational flaps ⁹.

Dural injury

Dural exposure without injury can be observed without repair. A suspected dural injury from drilling or a microinstrument should be carefully inspected even if a cerebrospinal fluid leak is not identified. A partial or nearly full-thickness dural injury should be repaired with either fascia, cartilage, autologous bone, or bone cement depending on the extent and size of the injury. If bone cement is used, it should be covered with fascia after it has dried. Failure to repair this may result in an encephalocele. A cerebrospinal fluid leak involving the middle fossa plate typically abates if the dura is closed primarily or is covered with a graft. Posterior fossa dural plate injuries can be more challenging to close and may require mastoid obliteration with fat or bone cement. Caution is advised using nonautologous materials in an infected field. A cerebrospinal fluid leak often necessitates admission, elevation of the head of the bed, and, in refractory cases, placement of a lumbar drain ¹⁰.

Vascular injury

The sigmoid sinus is one of the initial landmarks used to mastoid surgery. This large vessel can be injured with a drill or microinstruments. Injury typically results in copious venous bleeding. Since the sigmoid sinus is a low-flow system, gentle pressure with a moist cottonoid with Gelfoam or Surgicel over the injured area frequently results in the cessation of bleeding. Care must be taken not to displace packing into the sinus lumen with resultant embolization ¹¹. An arterial injury to the petrous carotid artery should be taken to interventional neuroradiology immediately. Gentle continuous pressure is required over the vessel until the bleeding is controlled. Temporary or permanent occlusion may be necessary if the vessel injury cannot be repaired primarily ¹².

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