Mastoidectomy

Abstract

Mastoidectomy involves the removal of bone and air cells contained within the mastoid portion of the temporal bone. Common indications for this procedure include acute mastoiditis, chronic mastoiditis, cholesteatoma, and the presence of tympanic retraction pockets. Mastoidectomy may also be performed as part of other otologic procedures (e.g. cochlear implantation, lateral skull base tumors, labyrinthectomy, etc.) in order to gain access to the middle ear cavity, petrous apex, and cerebellopontine angle. The procedure involves dissecting within the confines of the mastoid cavity, which include the tegmen superiorly, the sigmoid sinus posteriorly, the bony ear canal anteriorly, and the labyrinth medially. Mastoidectomy is traditionally classified as: simple (cortical/Schwartze), radical, and modified radical/Bondy’s mastoidectomy. The procedure can also be classified based on the preservation of the posterior canal wall: canal wall up (CWU) or canal wall down (CWD). 

Keywords 

Mastoid; otolaryngology; otology; microscopic otolaryngology; mastoiditis.

Case Overview

Background

Mastoidectomy is the surgical removal of mastoid air cells. The mastoid process is accessed via a postauricular incision. Afterwards cautery is used to dissect down to the temporoparietal fascia. The anterior and posterior flaps are raised, providing the option to incorporate a fascial graft if deemed necessary. The mastoid cortex is opened with a drill to expose the inner air cells. Once the antrum is opened, any granulation tissue can be removed and the epitympanum/middle ear space can be accessed. The cavity is then enlarged by opening all air cells to create a single large cavity. Typically, the concept of “saucerization” is paramount, with the most lateral/superficial aspect being the widest portion of the dissection. This allows better visualization and access to deeper structures. The remainder of the procedure depends on the technique utilized. In simple (cortical) mastoidectomy, the mastoid cavity is accessed and cleaned with preservation of the ear canal. Radical mastoidectomy involves removal of the posterior canal wall and the removal of the tympanic membrane and middle ear structures. The modified-radical approach preserves parts of the tympanic membrane and ossicles and may be used in more limited disease or if hearing preservation is critical (only-hearing ear). 

When mastoidectomy is performed as a primary procedure, the goal of the surgery is to increase the rate of drainage and infection clearance.¹ For instance, in cases of acute mastoiditis, mastoidectomy might be indicated when antibiotics alone are not adequate to clear the infection, particularly when intracranial complications are present (meningitis, epidural abscess, sigmoid sinus thrombosis).² The procedure may also be helpful in patients with chronic middle ear infections.³ In these patients, mastoidectomy enhances drainage and reduces the risks of recurrences and complications. When cholesteatoma is present and is adherent to the facial nerve or a labyrinthine fistula, radical and modified mastoidectomy aid in exposure and creating a safe ear that can be monitored in the clinic. Mastoidectomy also provides exposure to middle ear structures for any needed reconstructions.⁴ Patients with middle ear tumors with extension into the mastoid process may also require a mastoidectomy.

Mastoidectomy can also be performed to gain access to the middle ear as an initial step of other otologic surgeries. Cochlear implant (CI) surgery, endolymphatic sac decompression, and the translabyrinthine approach to skull base tumors all start with mastoidectomy.⁵ Other approaches for CI that don’t involve mastoidectomy, such as the endomeatal approach have been developed. However, these approaches are not widely accepted/practiced and are usually reserved for patients with certain conditions.^6, 7 It has been proposed that mastoidectomy approaches for CI may have some benefits in terms of minimizing chronic otitis media occurrence and offering increased space to allow for electrode expansion during child growth.⁵

Focused History of the Patient

A mastoidectomy evaluation requires a thorough review of the patient’s otologic history, disease progression, and timeline, as well as the patient’s expectations from surgery. A thorough history taking for a mastoidectomy procedure should question frequency and duration of middle ear infections for recurrent and chronic infections, respectively, history of tympanic membrane perforations, otologic surgical history, presence of persistent middle ear disease, or postauricular periosteal infection that is unresponsive to medical treatment, and presence of hearing loss or other symptomatic middle ear diseases. 

Physical Exam

A focused physical exam should include a complete evaluation of the ear canal and tympanic membrane bilaterally, an assessment of the postauricular area, cranial nerve evaluation with a description of facial nerve status, and audiometry testing. 

Imaging

In some cases, a temporal bone CT scan may be obtained during preoperative assessment. Imaging may help reveal any abnormal anatomical variations as well as areas of bony dehiscence. Cone-beam CT is an option for preoperative imaging as an alternative to conventional, high-resolution CT and this might provide valuable information for the surgical approach for example a high sinus/low hanging dura, and pneumatization of the temporal bone.

MRI assumes a nuanced role in mastoidectomy, providing detailed soft tissue characterization and enhancing diagnostic precision beyond the capabilities of CT. This modality excels in elucidating subtle anatomical structures, such as the sigmoid sinus and facial nerve, cholesteatoma and brain tissue, contributing to comprehensive preoperative assessment and preventing unnecessary revision mastoidectomies.⁸

Natural History

Natural history varies by the underlying condition. Untreated chronic middle ear infections can cause serious complications from infection spreading to surrounding tissues. Untreated mastoiditis can cause intracranial complications such as meningitis, brain abscess, and cerebral venous sinus thrombosis. Extracranial complications include osteomyelitis, facial nerve damage, labyrinthitis, and Bezold’s abscess.

Options for Treatment

When mastoidectomy is performed as a primary procedure, it is usually only done when medical treatment alone fails to clear infections. For mastoiditis, intravenous antibiotics, steroids, and possibly myringotomy/tympanostomy tube placement  may be attempted before mastoidectomy is considered.

Rationale for Treatment

The primary goal of mastoidectomy is to facilitate the drainage of fluids in the middle ear and prevent their accumulation. When mastoidectomy is performed to treat chronic otitis media, tympanostomy tube placement may be performed to improve drainage. Mastoidectomy can be performed to gain access to the middle ear as part of other otologic surgeries such as CI, lateral skull base tumor resection, or facial nerve surgery.

Discussion

Greek physicians noted in their early writings the importance of draining ear infections. However, it wasn’t until the 16th century that surgical drainage was properly described in detail and documented. The first mastoidectomy is credited to Jean Petit.¹ Petit described the procedure of opening the mastoid bone and removing purulent fluids from bone cavities.

Modern mastoidectomy was systematically described by Schwartze and Eysell in the late 19th century. Their writings described the indications of mastoidectomy and the technical details of the procedure.⁹ Their technique is often referred to as simple mastoidectomy. The surgery opens a connection between the mastoid process and the middle ear cavity to allow proper irrigation and drainage.

Kuster and Bergmann developed a more extensive procedure that includes additional dissection of other parts of the mastoid rather than simply creating a connecting channel to the middle ear. It involves the removal of the tympanic membrane and some of the middle ear structures. Their technique is also known as radical mastoidectomy.¹⁰

A modified approach, known as modified radical mastoidectomy, was developed by Bondy in the early 20th century. He noted the importance of preserving parts of the tympanic membrane and ossicles to improve hearing outcomes.^1,10 His technique is mainly used for epitympanic cholesteatoma limited to the pars flaccida.¹⁰

Mastoidectomy can also be classified based on the removal or preservation of the posterior canal wall. In the canal wall down approach, the posterior wall is removed allowing for more exposure to middle ear structures and arguably more access to eradicate all diseased tissue. The canal wall up approach preserves more of the normal anatomy of the external ear canal.¹¹

The first step of this procedure is to dissect the mastoid to gain exposure to the mastoid tip. A drill with a diamond-tip cutting burr is used to remove bone layers and expose deeper parts of the mastoid. Once the boundaries of the mastoidectomy are marked, the cortex of the mastoid and deeper air cells are removed. Further drilling into the posterior wall may be performed depending on the type of mastoidectomy that is performed. At the end of the procedure, the periosteum is brought together, and proper wound closure is performed with an overlaying dressing.

Facial nerve injury is one of the most feared complications of any otologic procedure, especially mastoidectomy. The risk for facial nerve injury during otologic surgeries ranges between 0.6–3.7%.¹² Proper facial nerve landmark identification is essential during surgery. The major landmarks used include the lateral semicircular canal, the chorda tympani nerve, the short process of the incus, the digastric ridge, and the processus cochleariformis.¹³ Facial nerve monitoring is an available option depending on the surgeon’s preference.

Hearing loss following mastoidectomy is another common complication. Hearing outcomes vary and depend on the mastoidectomy approach used and the degree of ossicular involvement.

Postoperative Care

Mastoidectomy surgery as it relates to CI surgery, endolymphatic sac decompression, and chronic ear disease is performed on an outpatient basis. Immediate care following discharge involves dressing/drain removal after 24–48 hours with “dry-ear” precautions. Typically patients may shower 24–48 hours after surgery but should not allow the incision to get wet for one week. Follow up appointment is typically 4–6 weeks after surgery depending on what additional procedures were performed. Topical ear drops may also be used. Facial nerve function is evaluated and recorded in all follow-up visits.³

Equipment

Microscopy is often used for this procedure. The main types of equipment used include otologic drills, diamond cutting burrs, and other common otologic instruments.

Disclosures

Author C. Scott Brown also works as editor of the Otolaryngology section of the Journal of Medical Insight.

Statement of Consent

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.