The retraction pocket is a partial or complete deformation of the tympanic membrane, most often in the form of an indentation in the middle of the tympanic cavity. Originally, the formation of retraction pockets was associated only with the consequences of closed tympanoplastics, which led to recurrence of cholesteatoma. Later, on the basis of research and observations, the formation of these characteristic pits was confirmed, also when no operations were performed on the tympanic membrane (1). Currently, retraction pockets are mainly referred to as secondary membrane changes that arise as a consequence of excessively long negative pressure inside the tympanic cavity which is maintained for too long. This phenomenon is related to the dysfunction of the Eustachian tube. In a properly functioning ear – air is present in the tympanic cavity. Under physiological conditions, this air is absorbed by the middle ear lining, which determines the formation of negative pressure (normally, in healthy people, a slightly negative pressure is maintained in the middle ear).

In the middle ear, the Eustachian tube is responsible for gas replenishment, which opens during swallowing or yawning, which allows the pressure in the tympanic cavity to equilibrate during this time. Thus, if a patient has impaired functioning of the Eustachian tube, he experiences significant pressure drops in the middle ear. The three-layer structure of the tympanic membrane (skin, elastic layer, mucosa) maintains its strength. However, in a situation of maintaining a strong negative pressure, the elastic layer may be significantly weakened (of a diffuse or limited nature), while the entire tympanic membrane is inclined towards the medial wall of the tympanic cavity. This indentation may be uneven and affect different parts of the tympanic membrane, but the most common location of the retraction pockets is the epitympanal (due to the lack of elastic fibers) and the postero-superior quadrant of the taut eardrum. The location of the indentations in this quadrant and in the flaccid part of the tympanic membrane is probably caused by frequent inflammations of the middle ear, which lead to a particularly intense inflammatory reaction of these parts of the membrane (1, 2).

It is recognized that the indirect causes of the development of retraction pockets may be frequent middle ear infections or recurrent catarrh of the Eustachian tubes. However, the presence of pockets is also strictly associated with the presence of exudative fluid in the tympanic cavity (exudative otitis media) containing numerous enzymes (2).

The formation of retraction pockets includes: loss of collagen fibers of the tympanic membrane, formation of a hernia sac and symptoms of bone or malleolus destruction. The degree and extent of all these processes change as the pocket evolves. The mechanisms causing the formation and evolution of retraction pockets can be divided into: intra-drum and extra-drum. The first are collagenases and other proteolytic enzymes. At the beginning, the structure of collagen fibers in the lamina propria of the tympanic membrane is broken down into parts, which are then digested by proteolytic enzymes. These compounds are present in both the inflammatory exudate and the swollen lining of the middle ear. Destructive processes that affect both the lamina propria and the epidermis, first lead to the suction of the tympanic membrane – the formation of a retraction pocket, and ultimately most often lead to perforation of the membrane. On the other hand, the determinant of the extra-tympanic mechanism is the proteolytic activity of the inflammatory epidermis. The epidermal hydrolases and lysozymes are capable of destroying not only the collagen fibers of the eardrum, but also the adjacent bones and ossicles. This process is very intense in deep pockets with accumulated epidermis inside (possible infection) (2).

It is worth knowing that some pockets may regress spontaneously, some will remain unchanged, some will enlarge, causing the destruction of the ossicles and hearing loss, and some will deepen, leading to the development of cholesteatoma. The new hypotheses interpret the origin of the retraction pocket as a natural attempt by the body to heal the inflammation in the tympanic cavity, just like analogous phenomena in the body, such as the migration of the greater net towards local inflammation in the abdominal cavity (1-6).

The therapeutic management of retraction pockets remains an open topic. At present, there is no unified scheme of action, as well as no single generally accepted classification for the clinical advancement of pockets. Treatment of patients depends mainly on the degree of lesions development, the coexistence of diseases of the upper respiratory tract or the coexistence of exudative inflammation of the middle ear (3). The therapeutic management should take into account in particular:

– regular, thorough examination of changes using an operating microscope and an endoscope,

– elimination of epidermal deposits mainly from the epitympanal part of the pockets,

– efficient and adequate treatment of infections as well as exudative and acute otitis media,

– treatment related to nasal obstruction, inflammation of the nose, sinuses and throat.

If we exclude the presence of fluid in the middle ear, conservative treatment is recommended in various forms: from observation, administering anti-inflammatory and mucolytic drugs, to blowing the Eustachian tube or using KINETUBE or AMSA aerosol therapy (4). Such actions result from clinical observations, and these indicate regression of invaginations with age (such delicate changes most often concern children) (5).

As for the coexistence of the retraction pocket with the exudate, it is usually associated with a worse course and a lower tendency to regress. The rule in this situation is to drain the tympanic cavity or cut out a pocket that will allow the opening of the middle ear space. The healing process, on the other hand, should contribute to the spontaneous closure of the perforation. However, if the eardrum does not rebuild, after some time (when there are frequent infections of the main respiratory tract), myringoplasty can be performer (4).

The third stage of the retraction pocket (according to Charachon’s classification) severity indicates early, preventive tympanoplasty, strengthening of the tympanic membrane with cartilage and drainage. Surgical treatment can effectively protect the patient against the development of cholesteatoma, and also gives a better chance of recovery (4).

Pockets, which are also classified for tympanoplasty surgery, are indentations of the tympanic membrane without the possibility of controlling it under a microscope (usually these are preperlastic states). The only alternative to determine or rule out the development of cholesteatoma is to view them with a 30° endoscope. This type of pockets is often characterized by conduction hearing loss (above 30 dB) caused by the destruction of the ossicular chain or infection of the pocket, which is manifested by: epidermal accumulation, leakage, and even the development of a polyp (4, 7).

As in the case of precocular conditions, actions undertaken in situations of generalized retraction of the tympanic membrane. This is justified because clinical practice shows that conservative treatment gives no results and drainage is usually impossible. Tympanoplasty in these cases consists in increasing the strengthening of the tympanic membrane and ossiculoplasty (if the ossicles have been damaged) (4, 5, 7).