eMedicine Specialties > Pediatrics: Surgery > Otolaryngology

Cholesteatoma

Author: Peter S Roland, MD, Professor, Department of Neurological Surgery, Professor and Chairman, Department of Otolaryngology-Head and Neck Surgery, Director of Clinical Center for Auditory, Vestibular and Facial Nerve Disorders, Chief of Pediatric Otology, University of Texas Southwestern Medical Center; Adjunct Professor of Communicative Disorders, School of Human Development.
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Updated: Mar 7, 2008

Introduction

Background

For decades, cholesteatoma has been recognized as a destructive lesion of the skull base that can erode and destroy important structures within the temporal bone. Its capacity for CNS complications, such as brain abscess and meningitis, make it a potentially fatal lesion.

History

Although Cruveilhier first described cholesteatoma in 1829, Müller first named the lesion in 1858. Throughout the early half of the 20th century, cholesteatoma was managed by exteriorization. The mastoid air cells were exenterated, the posterior external auditory canal was removed, and the opening into the resulting cavity was enlarged to ensure adequate air exchange and to make visual inspection simple.

During the 1950s and 1960s, the House Otologic Group developed a new approach. The group attempted to leave the basic underlying anatomic structure of the ear and temporal bone intact, principally by preserving the canal wall. These aggressive attempts to conserve the normal anatomy of the ear created great controversy. Surgeons tended to align themselves with either the old "canal wall down" (ie, open cavity)¹ philosophy or with the new "canal wall up" (ie, closed cavity) philosophy.² Throughout the last 2 decades, otologic surgeons have migrated to an intermediate position. Most otologic surgeons in the United States now perform both techniques, selecting a particular operation based on the individual circumstances of each patient.

Pathophysiology

A cholesteatoma consists of squamous epithelium that is trapped in the skull base. Squamous epithelium trapped within the temporal bone (ie, middle ear or mastoid) can expand only at the expense of the bone that surrounds and contains it. Consequently, complications associated with a growing cholesteatoma can include injury to any of the structures normally found within the temporal bone. Occasionally, a cholesteatoma escapes the confines of the temporal bone and skull base. Extratemporal complications can occur in the neck, CNS, or both. Occasionally, a cholesteatoma fills with keratinous debris and reaches a size within the cranium sufficient to distort normal brain function and produce mass effects and CNS dysfunction.

Bony erosion occurs by 2 principal mechanisms. Pressure effects produce bony remodeling, which occurs regularly throughout the normal skeleton. Enzymatic activity at the margin of the cholesteatoma enhances osteoclastic activity, which greatly increases the speed of bone erosion. These osteolytic enzymes appear to increase when a cholesteatoma becomes infected.

Frequency

United States

The incidence is unknown, but a cholesteatoma is a relatively common reason for otologic surgical procedures that occur on a weekly basis in children's hospitals.

Mortality/Morbidity

Death from intracranial complications of cholesteatoma is now uncommon because of earlier recognition, timely surgical intervention, and supportive antibiotic therapy. Cholesteatoma remains a relatively common cause of permanent, moderate, conductive hearing loss.

Clinical

History

• The hallmark symptom of cholesteatoma is either unremitting (or frequently recurrent) painless discharge from the ear (ie, otorrhea).
• Hearing loss is also a common symptom of cholesteatoma. Large cholesteatomas fill the middle ear space with desquamated epithelium with or without associated mucopurulent discharge. Associated ossicular damage also can produce or magnify a conductive loss.
• Dizziness is a relatively uncommon symptom of cholesteatoma but occurs if bony erosion produces a labyrinthine fistula or if the cholesteatoma lies directly on the footplate of stapes. Dizziness is a worrisome symptom because it may presage the development of more serious complications.
• Occasionally, cholesteatoma presents initially with the symptoms of CNS complications, sigmoid sinus thrombosis,³ epidural abscess, or meningitis.

Physical

• Upon physical examination, the most common signs of cholesteatoma are drainage and granulation tissue that are unresponsive to antimicrobial therapy.
• Tympanic membrane (TM) perforation commonly accompanies cholesteatoma, as evidenced by its presence in more than 90% of patients.
  • Congenital cholesteatomas are the exception.
  • Occasionally, a cholesteatoma produced by surgical implantation of squamous epithelium presents prior to disruption of the TM.
• Quite frequently, the only finding upon physical examination is a canal filled with mucopus and granulation tissue.
  • Occasionally, by using ototopical antibiotic drops, limiting the infection and resolving the granulation tissue is possible.
  • When the ototopical therapy is successful, the surgeon often can observe the deep tympanic retraction pocket in the pars flaccida (the portion of the TM superior to the short process of the malleus) or posterior quadrant, the collection of squamous epithelium, or the absent TM.
• Very rarely, a cholesteatoma is initially identified on the basis of one of its complications.
  • This situation occasionally occurs in children.
  • An infection associated with the cholesteatoma can erupt through the inferior mastoid cortex and present as an abscess in the neck.
• Occasionally, cholesteatoma initially manifests with the signs of central nervous complications, sigmoid sinus thrombosis, epidural abscess, or meningitis.

Causes

The etiology of cholesteatoma varies, and at least 3 types are identified with different pathophysiologies.

• Congenital cholesteatoma as a consequence of squamous epithelium trapped within the temporal bone during embryogenesis⁴
  • Congenital cholesteatoma is usually found in the anterior mesotympanum or in the peri eustachian tube area.
  • They are most commonly identified in early childhood (ie, age 6 mo to 5 y).
  • As congenital cholesteatomas expand, they can obstruct the eustachian tube, thus producing chronic middle ear fluid and conductive hearing loss.
  • They can also produce conductive hearing loss by expanding posteriorly to encase the ossicular chain.⁵
  • Unlike other forms of cholesteatoma, congenital cholesteatomas are most commonly identified behind an intact and normal-appearing TM.
• Primary acquired cholesteatoma caused by TM retraction
  • The classic primary acquired cholesteatoma is a result of increasingly severe medial retraction of the pars flaccida into the epitympanum.
    • As this process continues, the lateral wall of the epitympanum (ie, scutum) is slowly eroded, producing an ever-larger defect in the lateral wall of the epitympanum.
    • The medially retracting TM continues to pass over the heads of the ossicles into the posterior epitympanum. Ossicular destruction is common.
    • If the cholesteatoma passes posteriorly through the aditus ad antrum into the mastoid, erosion of the tegmen mastoideum with exposure of the dura and/or erosion of the lateral semicircular canal with deafness and vertigo can result.
  • A second type of primary acquired cholesteatoma arises when the posterior quadrant of the TM is retracted into the posterior middle ear.
    • The drum initially adheres to the long process of the incus.
    • As retraction continues medially and posteriorly, squamous epithelium envelops the superstructure of the stapes and retracts into the sinus tympani.
  • Primary acquired cholesteatomas arising from the posterior TM are likely to produce facial nerve injury and destruction of the stapedial superstructure. Surgical removal from the sinus tympani can be challenging.
• Secondary acquired cholesteatoma as a direct consequence of injury to the TM
  • Injury to the TM can be a perforation that occurs as a result of acute otitis media or trauma, or it can be caused by surgical manipulation of the drum.
  • Posterior marginal perforations are the type most likely to result in cholesteatoma formation.
  • Although considered unlikely to produce cholesteatomas, central perforations occasionally can result in cholesteatoma formation.
  • A procedure as simple as the insertion of tympanostomy tubes can implant squamous epithelium into the middle ear and ultimately produce a cholesteatoma.
  • Any deep retraction pocket can result in cholesteatoma formation, if the retraction pocket becomes deep enough to trap desquamated epithelium.

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