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Mastoid Surgery


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The early indications for mastoid surgery involved drainage procedures for acute, life-threatening infections. In current practice, acute coalescent mastoiditis is infrequent and most mastoidectomies are done for chronic infection, usually with cholesteatoma—the focus of this chapter. In the modern era, mastoidectomy is an initial step in neurotologic procedures such as cochlear implantation, surgery of the endolymphatic sac and facial nerve, labyrinthectomy, temporal bone resection, and cranial base approaches to the posterior fossa and petrous apex. For all indications, competent mastoid surgery requires precise surgical sculpting of bone and sequentially identifying and delineating anatomic landmarks. Preoperative planning based on all available information is necessary and yet is usually somewhat open-ended. As disease is exposed, intraoperative decisions must be made. Should the canal wall remain up, down, or reconstructed? Should the cavity be obliterated? Should there be a second-look procedure and/or staged tympanoplasty? What is the best option for ossicular reconstruction?

Subtle variants of normal anatomy and disease extension challenge the surgeon to make appropriate pre- and intraoperative surgical decisions for optimal outcome, which should include the best possible hearing and minimal chance of recurrent/recidivistic disease.

Key Operative Learning Points

  • In chronic ear surgery, preoperative planning, though essential, may be altered by decisions made based intraoperative findings.

  • The status of the contralateral ear will influence the decisions regarding surgical options for the management of cholesteatoma.

  • Skilled use of the operating microscope, otologic drill, otologic endoscopes, and micro instruments are best developed in the temporal bone dissection laboratory.

  • Astute awareness of the tegmen, sigmoid sinus, otic capsule, and the vertical segment of the facial nerve must be maintained throughout the procedure.

Preoperative Period

History

  • 1.

    History of present illness

    • Presence and duration of hearing loss, otorrhea, otalgia, dizziness

    • Factors associated with onset of symptoms: local trauma, water exposure, barotrauma

    • Chronic or recurrent symptoms

    • Efficacy of previous medical intervention

    • Rapid progression of symptoms may require expedited surgical intervention

    • Headache or mental status change may indicate an intracranial complication

  • 2.

    Past otologic history

    • Childhood ear infections or surgery

    • Hearing ability prior to the onset of current symptoms

    • Occupational or other noise exposure

    • Ototoxic medications

    • Past radiotherapy with fields including the temporal bones

    • Previous mastoid surgery

    • Otologic implant: cochlear implant, reconstructed ear canal, stapedectomy prosthesis

    • Use of amplification for either ear should be noted.

  • 3.

    Status of the contralateral ear

    • Contralateral middle disease, perforation, Eustachian tube dysfunction

    • Bilateral cholesteatoma

    • Contralateral hearing loss

    • The patient may benefit from contralateral amplification prior to surgery

  • 4.

    Past medical history

    • Conditions involving referred otalgia can complicate postoperative pain control

    • Past vestibular symptoms should be considered carefully

  • 5.

    Medical illness

    • Conditions adversely affecting wound healing

    • Bleeding disorders

    • Conditions posing increased risk for general anesthesia

  • 6.

    Medications

    • Anticoagulants

    • Drug allergy

  • 7.

    Mental and social issues

    • Ability to comprehend an informed consent

    • Ability to tolerate postoperative otologic instrumentation such as mastoid cavity care

    • Compliance with long-term otologic care and likeliness to return following staged surgery

Physical Examination

  • A complete otolaryngology examination including the nasopharynx and cranial nerves

  • Microscopic examination of the ears with appropriate debridement

  • Repeat microscopic examination after treating suppuration may be enlightening

  • The ear canal may require canaloplasty for surgical exposure and postoperative care

  • The contralateral ear should be carefully examined with an otologic microscope

  • Photo documentation of the otologic findings may be helpful

  • Rinne and Weber tuning fork tests should be recorded preoperatively

  • Postauricular swelling and erythema indicate an abscess and requires emergent intervention

  • Acute facial palsy or other local cranial neuropathies require rapid intervention

  • Papilledema may indicate an intracranial complication

Audiometry

  • Standard bilateral behavioral audiometry is strongly recommended for diagnosis and management

  • Children or mentally impaired adults may require auditory evoked brainstem testing to obtain side-specific thresholds.

  • Emergent surgery for intracranial complications should not be delayed for audiometry

Imaging

  • When planning elective mastoid surgery, imaging is generally obtained to assist in performing safe and expeditious surgery. Nevertheless, imaging is not essential to perform mastoidectomy. For example, if unexpected cholesteatoma is encountered during tympanoplasty, a surgeon may safely proceed with appropriate mastoid surgery without preoperative images.

  • Computed tomography (CT) imaging in axial and coronal planes is the standard anatomic study of the temporal bone.

    • Axial images demonstrate the extent of mastoid pneumatization and the position of the sigmoid sinus

    • Coronal images indicate the contour and level of the tegmen mastoideum and tympani

    • CT is excellent in the delineation of congenital ear malformation

    • CT demonstrates bone erosion: horizontal semicircular canal, tegmen, Fallopian canal, malleus/incus

    • CT cannot usually establish the status of the stapes in the presence of chronic ear disease

    • CT may not distinguish cholesteatoma from other soft tissue or fluid, unless bone expansion or erosion of the scutum is identified

  • Magnetic resonance imaging (MRI) is the standard study to demonstrate retrocochlear pathology

    • MRI (T2 coronal) will identify an encephalocele, Gadolinium enhancement of tumor, and intracranial complications of mastoiditis

    • MRI (T2 weighted) will identify the membranous labyrinth and nerves in the internal auditory meatus

    • MRI (diffusion weighted imaging) can differentiate cholesteatoma from fluid and thickened mucosa

    • MRI does not demonstrate fine details of the middle ear and mastoid anatomy

  • CT and MRI may be required for glomus tumors or lesions of the petrous apex

  • CT guided surgical navigation systems may be used in select cases such as lesions of the petrous apex

Indications

  • Acute coalescent mastoiditis with or without temporal bone/intracranial complications

  • Cholesteatoma involving the epitympanum or mastoid

  • Chronic suppurative mastoiditis without cholesteatoma

  • Temporal bone resection for malignant disease

  • Approach to the facial nerve for tumor, decompression, or cable grafting

  • As an initial step in the majority of neurotologic surgical procedures

  • Intact canal wall

    • Drainage of acute coalescent mastoiditis

    • Cholesteatoma surgery in which disease is removed or a second look is planned

    • Facial nerve surgery, cochlear implantation.

  • Canal wall down (CWD)

    • Limited exposure and underdeveloped pneumatization

    • Unfavorable anatomy with disease affecting the tegmen, sigmoid sinus, and mastoid tip.

    • Cholesteatoma cannot be fully removed, requiring “exteriorization” of disease

    • Risk of surgical complication from repeat procedures is elevated

      • Horizontal canal or other otic capsule fistula

      • In the case of an only hearing ear, CWD mastoidectomy may be wise

      • Cholesteatoma matrix on an eroded footplate or widely dehiscent facial nerve

  • Reconstruction of the canal wall may provide excellent exposure without long-term cavity issues. However, this may involve the use of foreign material in a contaminated field. A second look is generally advised.

  • Obliteration of the mastoid cavity may make long-term care much easier but have some risk of burying cholesteatoma matrix. If foreign material such as hydroxyapatite cement is used, it will be inserted into a potentially contaminated field.

Contraindications

Patient Factors

  • Excessive risk of general anesthesia

  • Poor wound healing

Disease Factors

  • Mastoidectomy alone is inadequate for cholesteatoma extending beyond the boundaries of the temporal bone

  • Auto-epitympanotomy or auto-mastoidectomy may enable adequate exposure for debridement in the office.

Preoperative Preparation

  • Control of infection with systemic/topical antibiotics and debridement when possible

  • Informed consent includes understanding the chronicity of the disease, risks, and hearing outcomes

  • Staged tympanoplasty or second-look procedures should be included in the consent

  • The possible role of postoperative amplification should be discussed

  • Optimize medical fitness for general anesthesia

  • The surgeon should review clinical, audiometric, and imaging data prior to surgery.

  • Imaging studies should be available for intraoperative review

Operative Period

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