Cholesteatoma of the middle ear

Most often, cholesteatoma is defined as a type of epidermoid cyst that is localized in the middle ear and the mastoid process of the temporal bone of the skull. So it is not a tumor histologically. According to ICD-10, this pathological formation of the middle ear has the code H71.

Epidemiology

According to experts from the European Academy of Otology and Neurootology (EAONO), globally, out of more than 20 million people with chronic inflammatory ear diseases, up to 25% of patients have cholesteatoma. [1]

The prevalence of acquired cholesteatoma is estimated at 95-98%; the share of congenital accounts for 2-5% of cases.

Statistics of the annual detection of this formation in the middle ear: per 100 thousand children - on average three cases and nine cases for the same number of adults. In the United States, one study reported six cholesteatomas per 100,000 people. The average age of children diagnosed with acquired cholesteatoma was 9.7 years. Acquired cholesteatomas are about 1.4 times more likely to occur in men than in women. One UK study showed an increased incidence of cholesteatoma in socio-economically disadvantaged areas, suggesting that the incidence of acquired cholesteatoma is higher among low-income patients, although more research is needed in this area. [2]

Causes cholesteatomas

By origin, cholesteatomas are divided into primary (congenital), secondary (acquired, formed at any age) and idiopathic (when it is impossible to determine the exact etiology). [3]

Experts name such key causes of the most common secondary form of this pathology as  perforation of the tympanic membrane of  inflammatory, traumatic or iatrogenic etiology; exudative otitis media  and purulent otitis media, more precisely,  chronic purulent otitis media .

Among the etiological factors, purulent inflammation of the middle ear is also distinguished, which develops in the erythematosus (epithympan-antral) region - epitympanitis with cholesteatoma.

Often cholesteatoma is the result of problems with the  auditory (Eustachian) tube : a violation of its function due to inflammation - tubo -  otitis  or infections of the middle ear and paranasal sinuses.

The congenital form of cholesteatoma is a rather rare diagnosis. Primary cystic formation of an intact tympanic membrane (membrana tympani), as a rule, forms in its weakly stretched part (pars flaccida), but can occur in the middle ear (near the cochlear process of the tympanic cavity or near the Eustachian tube), as well as in the adjacent bones of the skull. [4]

Congenital cholesteatoma in a child is a heteroplastic epidermoid formation formed during intrauterine development. In more than half of the cases in children and adolescents, such an education is revealed when contacting an otolaryngologist for hearing loss.

Risk factors

In otiatrics, risk factors for the development of cholesteatoma are usually associated with frequent acute infectious and chronic  diseases of the middle ear ; perforation and other  damage to the tympanic membrane ; violation of the patency of the auditory tubes (often with a history of chronic nasopharyngitis, allergic rhinitis or enlarged adenoids); Certain otologic procedures (such as tympanostomy tube drainage of the middle ear) [5]

The risk of developing this pathology is increased in children with  ear anomalies , which are observed in congenital syndromes of Treacher Collins, Cruson, Goldenhar, and also in children with Down syndrome, Jessner-Cole syndrome and  cleft palate .

Pathogenesis

In appearance, cholesteatomas are a whitish-nacreous elastic formation of an oval shape - a thin-walled cyst containing layered waxy or caseous keratin fragments (called keratin debris by physicians). And inside the congenital cholesteatoma, keratinized cells of stratified squamous epithelium of exodermal origin are histologically found. [6]

Exploring the clinic, etiology and pathogenesis of this formation, otiatrists and otoneurologists put forward different theories of the formation of cholesteatoma. 

According to the most convincing version, the mechanism of formation of congenital cholesteatoma is due to abnormal movement of cells in the mesenchyme of the dorsal neural crest during the establishment of the pharyngeal arches and the rudiment of the middle ear during embryogenesis or during the formation of the ear canal and tympanic membrane of the fetus in early gestation. Another hypothesis suggests the penetration of cells of the extraembryonic ecto and mesoderm of the amnion into the middle ear space. [7]

One of the theories explaining the appearance of acquired cholesteatom relates increased keratinization of the epithelium of the mucous membrane of the middle ear with an inflammatory reaction leading to the release of cyclooxygenase-2, interleukins, vascular endothelial growth factors and epidermal growth, which stimulate the proliferation of epithelial keratinocytes. In addition, the researchers found that osteoclastic resorption of the auditory ossicles of the middle ear or the bone of the mastoid process during the formation of cholesteatoma occurs due to the action of prostaglandins, collagenolytic and lysosomal enzymes, which are synthesized by connective (granulation) tissue formed near bone structures.

According to another theory, in cases of Eustachian tube dysfunction, negative pressure in the middle ear pulls the tympanic membrane inward (to the auditory ossicles) to form a fold (called a retraction pocket), which fills with detached cells of the keratinized squamous epithelium and turns into a cyst.

Another theory suggests that when the tympanic membrane is perforated, the squamous epithelium lining the external auditory canal spreads (migrates) into the middle ear cavity, that is, it grows along the edges of the membrane defect.

Symptoms cholesteatomas

As clinical practice shows, cholesteatomas, especially congenital ones, can be latent for a long time, and the emerging symptoms usually concern only one ear.

In the case of acquired cholesteatoma, the first signs are manifested by constant or periodic otorrhea - watery discharge from the ear, which, in the presence of an infection, can be purulent (with an unpleasant odor), and sometimes bloody. With advanced otitis media, there may be ear pain. [8]

As the cystic formation increases, the list of patient complaints expands and includes:

• a feeling of discomfort and pressure in one ear;
• tinnitus (constant noise or ringing in the ear);
• headache;
• dizziness;
• pain in the ear or behind the ear;
• unilateral hypoacusia (hearing loss);
• muscle weakness on one side of the face (in rare cases)

However, the severity of the symptoms varies, and some patients may have only mild discomfort in the ear.

In addition to all the listed symptoms, with a cholesteatoma of the cerebellopontine angle, which has reached a significant size, there is an involuntary contraction of the facial muscles and progressive  paralysis of the facial nerve .

Forms

There are types of cholesteatoma and the place of their formation. Cholesteatoma of the external ear is rarely diagnosed, but it can spread to the tympanic membrane, middle ear or mastoid process, it is also possible to damage the facial nerve canal located in the temporal bone (os temporale).

Cholesteatoma of the external auditory canal is a cystic mass in the area of the damaged cortex of the bone in the wall of the bony part of the external auditory canal (meatus acusticus externus).

Cholesteatoma of the middle ear or cholesteatoma of the tympanic cavity (which is located in the center of the middle ear - between the eardrum and the inner ear) is in most cases a complication of chronic otitis media.

Congenital cholesteatoma of the temporal bone occurs in its mastoid process (processus mastoideus) or in the thin tympanic part (pars tympanica) fused with it, which limits the external auditory canal and the auditory opening. If a cystic formation is formed in the process of the temporal bone of the skull located behind the auricle and having air cavities, then mastoid cholesteatoma is diagnosed.

The middle ear cavity with the tympanic membrane is located in the petrous (petrous) part of the temporal bone, which, due to its triangular shape, was called a pyramid. Part of its anterior surface is the upper wall (roof) of the tympanic cavity. And this is the place where the cholesteatoma of the temporal bone pyramid, that is, its stony part (pars petrosa), can form. And the cholesteatoma of the apex of the temporal bone pyramid means its localization in the anterior surface of the pyramid facing upward, where the half-channel of the Eustachian tube is located.

The upper wall of the tympanic cavity of the middle ear separates it from the cranial cavity, and if the cholesteatoma formed in the middle ear or in the pyramid of the temporal bone spreads into the brain - through the elytra of the middle cranial fossa - cerebral cholesteatoma can be observed, which experts attribute to otogenic intracranial complications.

And the cholesteatoma of the cerebellopontine angle is a congenital formation that slowly grows in the space filled with cerebrospinal fluid between the brain stem, cerebellum and the posterior surface of the temporal bone.

Specialists determine the stages of the middle ear cholesteatoma: cholesteatoma pars flaccida (loosely stretched part of the tympanic membrane), cholesteatoma of the stretched part (pars tensa); congenital and secondary cholesteatoma (with perforation of the tympanic membrane).

At stage I, the cholesteatoma is localized in one place; in stage II, two or more structures can be affected; at stage III, there are extracranial complications; Stage IV is determined with intracranial spread of education. [9]

Complications and consequences

Aggressive growth of cholesteatoma - including congenital - can cause dangerous consequences and complications:

• destruction of the chain of the auditory ossicles with  hearing impairment  (conductive or mixed hearing loss);
• destruction of the wall of the bony part of the external auditory canal and erosion of the walls of the tympanic cavity;
• the development of the inflammatory process and its spread to the surrounding areas, including the inner ear (labyrinth). Due to the penetration of the cholesteatoma into the labyrinth, its inflammation (labyrinthitis), as well as a fistula (fistula) of the inner ear, can occur.
• Spread of the mass outside the ear can lead to:
• obturation of the antrum (cave) of the mastoid process of the temporal bone, which is fraught with inflammation -  mastoiditis ;
• thrombosis of the cavernous sinus of the dura mater of the brain;
• the development of purulent meningitis;
• intracranial (epidural or subdural) abscess;
• brain abscess .

Diagnostics cholesteatomas

Clinical diagnosis of cholesteatoma is carried out during a thorough  examination of the ear .

For this, instrumental diagnostics are used:

• otoscopy  and otomicroscopy;
• x-ray of the ear and temporal bone ;
• tympanometry .

A  hearing test  (using audiometry or impedance testing ) is performed.

Detection or visual confirmation of cholesteatoma requires computed tomography or magnetic resonance imaging. If cholesteatoma is suspected, all patients should undergo diffusion-weighted MRI. Cholesteatoma on MRI (on T2-weighted images in the frontal and axial planes) looks like a hyperintense (bright) area.

And the cholesteatoma of the middle ear on CT is visualized as a sharply delineated accumulation of homogeneous soft tissues (low density) in the middle ear cavity, but due to the low specificity of computed tomography, it is almost impossible to distinguish it from the granulation tissue surrounding the bone structures. However, CT shows all bone changes, including defects in the auditory ossicles and erosion of the temporal bone, so this examination is necessary to plan an operation to remove this formation.

It is difficult to distinguish congenital cholesteatoma from acquired cholesteatoma, so the diagnosis, first of all, takes into account the history and clinical signs.

Differential diagnosis

Differential diagnosis of cholesteatoma with keratosis and erosive tumor of the external auditory canal, atheroma and adenoma of the middle ear, eosinophilic granuloma, oto and tympanosclerosis, glomangioma of the tympanic cavity, ectopic meningioma, squamous cell carcinoma is of great importance.

Treatment cholesteatomas

To suppress inflammation in cases of secondary cholesteatoma, treatment includes ear cleaning, antibiotics, and ear drops. All details in publications:

• Antibiotics for otitis media
• Drops for otitis media
• Treatment of chronic suppurative otitis media in hospital and at home
• Physiotherapy for otitis media

There is no medicine that can remove this formation, therefore the only way is surgical treatment, the tactics of which is determined by the stage of the disease at the time of the operation.

Usually, by means of mastoidectomy (opening the air cells of the mastoid process of the temporal bone), the cholesteatoma is removed. The standardized microsurgical procedure is down-wall mastoidectomy (contraindicated in children) - modified radical mastoidectomy with removal of the bony wall of the external auditory canal (also requiring reconstruction of the tympanic membrane). Another technique is mastoidectomy up the canal wall, during which all pneumatized parts of the mastoid process are removed while preserving the posterior wall of the ear canal. [10]

At the same time, surgeons can perform tympanoplasty - restoration of the tympanic membrane (cartilage or muscle tissue of another part of the ear).

Examination for the operation to remove the cholesteatoma consists of X-ray and CT of the ear and temporal bone, ECG. It is also necessary to pass blood tests (general, biochemical, for coagulation).

How long does it take to remove the cholesteatoma? The average duration of such surgery, performed under general anesthesia, is two to three hours.

In the postoperative period (for several weeks), patients should not remove the bandage (until the doctor's permission); it is recommended to sleep with your head elevated (this will reduce swelling and improve the outflow of exudate from the ear cavity); avoid getting water into the operated ear, exercising, and flying. [11]

Quite often, even a successfully performed operation is not able to prevent the recurrence of cholesteatoma, which occurs in 15-18% of cases in adults and in 27-35% of cases in children.

Taking this into account, 6-12 months after surgery, a revision is performed after removal of the cholesteatoma - by surgery or using MRI. According to some reports, in almost 5% of cases, there is a need for a second operation. [12]

Prevention

It is impossible to prevent the formation of congenital cholesteatoma, and the prevention of secondary epidermoid formation of the middle ear is the timely detection and treatment of its inflammatory diseases.

Forecast

In general, the prognosis of cholesteatoma depends on its location, ethology, stage of development and age of the patient.

Almost always, this formation can be removed, but its uncontrolled increase can cause serious problems, primarily with hearing.

When asked whether disability is given with cholesteatoma, experts answer as follows. This diagnosis is not included in the list that gives the right to register a disability, but there is a hearing disability, including with third degree hypoacusia, provided that its compensation with the help of a hearing aid is insufficient for full-fledged professional activity.