Chronic Middle Ear Diseases: Classification, Etiology, Diagnosis and Treatment

Chronic middle ear diseases are a group of long-term or recurrent pathological conditions that affect the structures of the middle ear (tympanic cavity, tympanic membrane, auditory ossicles). They are characterized by persistent inflammation, fluid (exudate), structural changes in the mucous membrane and bone elements, which often leads to progressive hearing loss.

Chronic middle ear diseases include:

• Exudative otitis media (serous, secretory) is a pathology characterized by the presence of exudate in the middle ear cavity without pain syndrome. Clinically distinguish between acute (up to 3 weeks), subacute (3-8 weeks) and chronic (> 8-12 weeks) exudative otitis media. In practice, however, it is often difficult to establish the exact time of onset and only acute and chronic forms are distinguished.
• Adhesive otitis media is a disease of the middle ear characterized by changes in the tympanic membrane and its retraction into the tympanic cavity.
• Otosclerosis is an osteodystrophic process affecting the bone tissue of the middle and inner ear.
• Tympanosclerosis – sclerotic changes in the tympanic membrane and tympanic cavity mucosa.

Chronic exudative otitis media

Etiology of chronic exudative otitis media

The causes of this condition are similar to those of acute exudative otitis media (see Ref. «Acute Otitis Media: Classification, Etiology, Diagnosis and Treatment»).

The underlying cause of this condition is obstruction of the auditory tube orifice in the nasopharynx, which can be either inflammatory or allergic in nature.

Without adequate treatment of acute exudative otitis media, especially with recurrent upper respiratory tract infections, the pathologic process in the ear becomes chronic.

Anatomy of chronic exudative otitis media

On the background of the already existing exudate in the middle ear cavities, further transformations take place. During 12-24 months, the exudate becomes saturated with a protein component and becomes thicker and more viscous, turning into a mucosal content.

After 24 months the processes in the mucous membrane undergo reverse development, there is degeneration of serous glands and a decrease in the number of bocaloid cells. The fluid component is not formed in such quantity and mucociliary transport is restored. In some cases, without adequate treatment, the mucosal content further organizes into fibrous strands, which subsequently leads to adhesive processes in the middle ear cavity.

Clinical picture in chronic exudative middle otitis media

It is characterized by progressive hearing loss up to deafness, noise and congestion in the ear on the affected side.

Diagnosis of chronic exudative otitis media

Patients are examined according to the same scheme as in acute exudative otitis media:

• Otoscopy: turbid dull gray dull tympanic membrane, bulging in the lower parts, light cone is deformed. Behind the tympanic membrane a whitish turbid content is noted in a continuous level.

• Tympanometry: performed when exudate is suspected, it is fundamental to the diagnosis. If contents are present, the tympanogram corresponds to type B.
• Chambertonal tests: are performed to determine the nature of the hearing loss.
• Nasopharyngeal endoscopy: recommended to determine the cause of the disease.
• CT scan of temporal bones and nasopharynx: is indicated in difficult or doubtful cases to clarify the diagnosis and assess the extent of the process.

Treatment of chronic exudative otitis media

As with acute exudative otitis media, it is initially necessary to treat the cause that caused the process. Due to the fact that the content in the ear cavity is characterized by increased viscosity and prolonged stay, if there is no effect from conservative therapy, surgical treatment is recommended.

The purpose of surgical intervention is evacuation of exudate and aeration of the middle ear cavity. Paracentesis with aspiration of pathologic contents is performed. In some cases, a drainage tube (shunt) is inserted to maintain constant pressure and aeration of the tympanic cavity.

Adhesive otitis media

Etiology of adhesive otitis media

This pathology is an outcome of sluggish chronic exudative otitis media and recurrent acute otitis media.

Adhesive otitis media is also characterized by auditory tube dysfunction. Persons with year-round allergic rhinitis and poorly developed mastoid cells are most susceptible.

Anatomy of adhesive otitis media

The process develops against a background of constant inflammation with the presence of exudate in the tympanic cavity. The pathological content over time undergoes a number of changes, is organized, fibrin falls out in the form of adhesions, which then becomes more dense and sclerosed.

Scar tracts are formed that fix middle ear structures, especially the middle ear, to each other:

• The eardrum;
• The chain of auditory ossicles;
• Hearing tube.

The tympanic membrane is retracted so severely in some areas that retraction pockets form, which may be the source of retraction cholesteatoma formation.

As a result, the mobility of the sound-conducting circuit is reduced, leading to conductive hearing loss.

Clinical picture in adhesive middle otitis media

Patients notice a pronounced hearing loss that increases over time. Noise and crackling in the affected ear may be bothersome.

Diagnosis of adhesive otitis media

• Otoscopy: tympanic membrane is thin, turbid, scarring and calcifications are present, light reflex is not visualized. Retraction of the tympanic membrane into the tympanic cavity is detected.
• Tympanometry: tight tympanic membrane (type B) is noted.
• Audiography: conductive hearing loss.
• Assessment of auditory tube patency: function is reduced.

Treatment of adhesive otitis media

Treatment consists of restoring eardrum mobility, reducing the amount of scar tissue, and restoring the function of the auditory tube.

In initial cases, pneumatic massage of the tympanic membrane and blowing of the auditory tubes are performed. Proteolytic enzymes, glucocorticosteroids are administered intratympanally. Sanation of the nasopharynx and adenotomy are performed.

In case of severe disorders or no effect from conservative therapy, surgical treatment is performed. Scars are excised, mobility of the auditory ossicles is restored. In advanced cases, tympanoplasty with prosthesis of the auditory ossicles is performed.

If the auditory tube function is impaired, a shunt is placed in the tympanic membrane to prevent recurrence.

Otosclerosis

Etiology of otosclerosis

The etiology of otosclerosis is unknown. The disease is more common in women 30-40 years old and may manifest with hormonal changes such as pregnancy or menopause. It has a genetic predisposition. Otosclerosis is thought to be associated with autoimmune processes as well as with measles virus.

Anatomy of otosclerosis

The disease is associated with a disturbance in the organization of the bone tissue of the ear. The process is more often bilateral, and may manifest itself unevenly with predominant changes on one side.

Foci of otosclerosis may occur in the bony labyrinth or around the stapes. The healthy bone tissue of the cochlea undergoes resorption and is replaced by new spongiosa tissue, soft and saturated with many vessels, which is subsequently sclerosed.

When the process spreads to the foot of the stapes, bone tissue grows pathologically around the base of the stapes, anchoring it to the oval window of the cochlea. Ankylosis of the stapes impairs sound conduction, resulting in conductive hearing loss.

The formation of foci of otosclerosis in the labyrinth ladder region causes sensorineural hearing loss.

Clinical picture in otosclerosis

Hearing loss, noise and ear stuffiness are observed. Patients note slurred speech, which, however, improves in noisy rooms. Complaints increase over time as the disease progresses.

Diagnosis of otosclerosis

• Otoscopy: pathognomonic changes are usually absent. In some cases, thinning of the tympanic membrane is noted, as well as visualization of hyperemic mucosa in the promontory area (Schwartz symptom), indicating an active phase of the process. A wide ear canal with a reduced amount of earwax or its complete absence is a characteristic feature.
• Chambertonal tests: are performed to determine the type of hearing loss, which can be conductive, sensorineural or mixed.
• Tone audiometry: performed to accurately establish the type and degree of hearing loss.
• CT scan of temporal bones: is prescribed to assess the extent of the process and the condition of the bone tissue.

Treatment of otosclerosis

Surgical treatment – stapedectomy – is used to restore hearing. The aim of this treatment method is to remove foci of otosclerosis and the affected stapes and replace it with a titanium prosthesis.

Tympanosclerosis

Etiology of tympanosclerosis

Tympanosclerosis develops against the background of chronic purulent or exudative otitis media, as well as after acute otitis media. Genetic predisposition to the development of tympanosclerosis has been proved.

Anatomy of tympanosclerosis

Sclerotic processes develop as an outcome of a prolonged inflammatory process in the tympanic cavity. As a result of degenerative and fibroplastic changes in the tympanic membrane and mucoperiosteum, tympanesclerotic (TSC) foci located in the deep layers of the mucosa appear.

It is important to note that the mucoperiosteum (middle ear mucosa), in addition to the bony walls of the tympanic cavity, also lining the auditory ossicles.

Histologically, TSC formations are scar tissue with foci of hyaline degeneration and deposits of phosphorus-calcium salts. Visually they are white dense “wax-like drops” with a clear border in the mucosa thickness.

TSC foci restrict the mobility of the tympanic membrane and the chain of auditory ossicles, impairing sound conduction.

The favorite localization of TSC deposits is narrow and blindly closed places where aeration is reduced. Such places are represented in the attic, in the area of the malleus-anvil joint, around the window of the vestibule.

Clinical picture in tympanosclerosis

The leading complaint of the patient is hearing loss. In addition, there may be complaints consistent with the underlying disease (purulence, murmurs and ear pain).

Diagnosis of tympanosclerosis

• Otoscopy: Characteristic tympanosclerotic (TSC) plaques may be visualized on the tympanic membrane. However, in some cases typical changes may not be present.
• Tone audiometry: reveals conductive hearing loss.
• CT scan of the temporal bones: allows detection of multiple irregular foci of ossification (thickening) in the tympanic cavity or on the tympanic membrane.

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Treatment of tympanosclerosis

In this pathology, only surgical treatment is applicable. Patients undergo sanation of the tympanic cavity with tympanoplasty and ossiculoplasty. An important point is the complete removal of TSC foci to prevent recurrences.