Mucocele of the paranasal sinuses: causes, symptoms, diagnosis, treatment

Mukocele of paranasal sinuses is a kind of retentional saccular cyst of any one paranasal sinus, formed as a result of obliteration of the nasal excretory duct and accumulation of mucous and hyaline secretions inside the sinus, as well as elements of desquamation of the epithelium. Mukocele paranasal sinuses are a rare disease that occurs in both women and men, the latter more often in the interval between 15 and 25 years. Very rarely, the mucoceles of the paranasal sinuses occur in persons up to 10 and after 45 years of age. Most often, the mucoceles of the paranasal sinuses are localized in the frontal sinus, then in the trellis labyrinth or on the border between them, which often leads to the penetration of the "cyst" into the orbit, causing exophthalmos, a fact that explains the frequent detection by its ophthalmologist. Very rarely mukocele is localized in the wedge and maxillary sinuses. But in the latter often localized odontogenic cysts.

Pathogenesis of mucocele of paranasal sinuses. In the pathogenesis of the mucoceles of the paranasal sinuses, various authors considered various "theories" of its occurrence:

1. "Monoglandular theory" explains the occurrence of mucoceles by plugging one mucous gland, as a result of which it extends, the proliferation of the epithelial layer and the formation of a mucous sac;
2. "The morphogenetic theory" appeals to the congenital disruption of the development of cells of the latticed labyrinth, by analogy with odontogenic cysts;
3. "Compression theory" prefers a banal obstruction of the outflow ducts, the formation of aggressive contents of mucoceles and the activation of osteoclasts, which lead to bone destruction.

In any case, however, the obvious causes of mucocelia of the paranasal sinuses are obstruction of the excretory canals, resulting either from the inflammatory process, or the effect of osteoma or the effects of trauma. Contributing factors may be various anomalies in the development of the facial skeleton, including the paranasal sinuses. The absence of drainage function of the sinus and the accumulation of mucus and its decay products in it, the absence of an oxygen medium, which is so necessary for the normal functioning of the mucous membrane of the sinus and its glandular elements, leads to the formation of catabolites with toxic properties, increasing the activity of osteoclasts and irritating nerve endings of the ANS, increases the activity of the mucous glands, causing an increased secretion secretion. The emerging vicious circle promotes the emergence of chronic aseptic inflammation of mucocele, and its infection - to acute empyema of the sinus. Thus, the progressive accumulation of the products of the vital activity of the mucous membrane of the sinus and of the glandular elements leads to an increase in pressure on its mucous membrane and bone walls, their atrophy, thinning and the formation of an usurium, through which the mucoceles penetrate into adjacent cavities and anatomical formations.

Pathological anatomy of mucocele of paranasal sinuses. Histological studies have shown that as a result of the formation of the mucoceles, the ciliated cylindrical epithelium is transformed into a multilayered flat, devoid of a ciliary apparatus. When the cystic formation of the sinus leaves the surrounding soft tissues, its membrane is covered from the outside with a fibrous layer. The content of mucocele has a viscous gelatinous consistency, yellowish white color, aseptic, odorless. Bone walls atrophy and thinner, becoming a kind of parchment paper, then resorbed to form a defect. Osteoclasts predominate in bone tissue.

Evolution and clinical picture. The development of the mucoceles of the paranasal sinuses proceeds very slowly and passes through three periods:

1. latent period;
2. the period of extraterritisation, i.e., the output of the cyst beyond the sinus;
3. period of complications.

The latent period is completely asymptomatic, not showing either subjective or objective signs. In rare cases, there appears a periodic one-sided rhinorrhea, which is caused by the temporary opening of the frontal-nasal canal or the breakthrough of the mucosal contents of the cyst through the holes communicating the cells of the latticed labyrinth with the nasal cavity. If in this period there is infection of the cyst, the clinical course acquires the course of the usual acute purulent sinusitis.

The period of exterritization is characterized by subjective and objective symptoms. With frontal localization of mucoceles, most often there are various eye symptoms, since in this overwhelming majority of cases the cyst is prolabiruer into the orbit. In this case, the patient and others notice a swelling in the upper internal region of the orbit, after which after a while there is a diplopia, indicating the compression effect of mucocele on the eyeball. When the cyst extends to the posterior pole of the eyeball, there is pressure on the optic nerves, which causes the drop in visual acuity and the appearance of the peripheral scotoma of the eye. When the cyst extends anteriorly and downwards, an epiphary arises as a result of a disturbance in the function of tear ducts. With further development of the process, neuralgic pains arise as a result of compression of the cyst of the sensory nerves of the first vein of the trigeminal nerve, which can irradiate into the orbit, upper jaw and teeth of the corresponding side.

The resulting swelling to the touch is smooth, dense, creating the impression of a single whole with the surrounding bone. With a significant thinning of the bone above it, the phenomenon of crepitation is possible, and when a defect in the bone is formed, its edges are uneven, scalloped and bent outward. With anterior rhinoscopy, in most cases, no changes are detected. Sometimes, with a significant prolapse of the cysts downward, one can see in the middle nasal passage a swelling that is covered by a normal mucosa, pushing the middle nasal shell towards the septum of the nose.

The period of complications is characterized by various secondary pathological manifestations.

Diagnosis in the latent period can be made only accidentally in the radiographic study of the skull, conducted for some other reason. The changes in the paranasal sinuses detected in this period do not, in most cases, give direct indications of the presence of mucoceles, only an experienced radiologist may suspect the presence of a volumetric process in the sinus (most often in the frontal) by such signs as its total shading or the presence of a rounded shadow, an unusually large size sinuses, thinning and thinning of its walls, displacement of the interstitial septum beyond the median plane. Sometimes in this period the contours of the affected sinus are erased, indistinct. Sometimes the displacement of the frontal sinus is determined downwards, into the region of the latticed labyrinth. However, all these signs may not be taken into account if the purpose of the radiographic examination is, for example, the contents of the skull, and can be treated as an "individual variant of the norm," especially when there are any neurological symptoms indicative of a brain disease, distracting the physician from evaluation condition of the nasal cavity.

In the period of exterritorialization of mucocele, on the basis of only those features that were described above, the diagnosis of "mucocele" can only appear as one of the versions of the existing disease. Other versions do not exclude the presence of a primary congenital orbital cyst, for example, a dermoid cyst, meningocele, encephalocele, or any neoplasm. In this case, the final diagnosis (not always!) Can be established only as a result of an x-ray (CT, MRI) study.

In the overwhelming majority of cases, in the frontal sinus mucocele, destructive bone changes occur in the upper medial angle of the orbit and its upper wall, which are radiologically manifested by the presence of a homogenous, oval with smooth shadow contours, interrupted orbital contours and bone fractures (bone resorption) in the region tearing bone. Simultaneously, the cyst can penetrate the anterior cells of the latticed labyrinth and, breaking the medial part of the upper wall of the maxillary sinus, penetrate into this sinus.

However, most often the mucoceles of the trellis maze extend in the direction of the orbit, squeezing into it a paper plate and destroying this bone. The localization of mucoceles in the sphenoid sinus is most often due to clinical manifestations related to visual disorders, simulates a swelling of the base of the skull or a latticed labyrinth, or cystic arachnoiditis in the area of the visual crossover. In this case, a thorough X-ray (including CT) examination or MRI can establish a final diagnosis of mucocele. Radiologically mucocele of the sphenoid sinus is manifested by an increase in the sinus volume, the presence of a homogeneous shadow, foci of resorption and thinning of the sinus walls, including the interstitial septum.

Differential diagnosis is carried out with osteoma in the initial stage of exterritorialization of mucocele, when the latter is still covered with a thin layer of softened bone squeezed into the orbit, a latticework labyrinth or maxillary sinus. At this stage, the differentiation of mucocele also follows from osteosarcoma, syphilitic osteoperiostitis or gum, primarily localized in the area. During the exterritorialization period, the mucoceles are differentiated from the congenital orbital cysts, for example from the dermoid cyst or mucoceles and encephalocele localized in the same places as the mucocel is usually manifested.

Meningocele is characterized by protrusion of the meninges beyond the brain cranium with the formation of a hernial sac filled with spinal cord fluid. Then this bag is gradually filled with the substance of the brain with the formation of encephalocele. Usually the menipgoceles are located along the middle line, occupying the frontal-interorbital space, which distinguishes it from the mucocele of the frontal sinus. Radiographically, the shell-brain hernia is visualized as a nonintense shadow located at the root of the nose. Emerging immediately after birth, the mucocele in the process of its growth deforms the bone tissue located in the frontal-latticular-nasal region, therefore on the x-ray patterns made in the supraorbital-frontal projection, the space between the orbits is visualized much broader. Due to its localization, the mucocel covers the upper medial contours of the orbit, deforms the septum, and pushes the eyeball forward, down and sideways, thereby causing exophthalmos and diplopia. In the frontal-nasal projection on the roentgenogram, the hernial opening manifests itself in the form of a significantly expanded dehiscence with smoothed contours.

Complications of the mucoceles are divided into inflammatory and mechanical. Infection with mucocele produces piocele, resulting in a modification of the radiographic pattern: there are more significant bone fractures that multiply those that occurred with the previous uninfected mucocele. In addition, the inflammatory process can spread to adjacent sinuses and tissues, causing them to empyema.

In some cases, suppuration of mucocele leads to the formation of an external fistula, most often in the upper-right corner of the orbit. If, however, the usury of the bone arises in the region of the posterior frontal sinus wall, then the inflammatory process spreads to the anterior cranial fossa, causing one or several intracranial complications: an extra- or suburalal abscess. Purulent meningitis or meningoencephalitis, cerebral abscess or thrombosis of the superior sagittal or cavernous sinus.

Mechanical complications are caused by the pressure of the mucocel, which it exerts on the anatomical structures that are in direct contact with it. The compression of these formations leads to their atrophy and degeneration (the formation of usuras in the bone tissue, degenerative-dystrophic changes in the paranasal sinuses, the desolation of the blood vessels with a disturbance in the nutrition of the corresponding structures, trigeminal neuralgia, etc.), and the constant pressure of the growing mucocele on the eyeball or tear organs leads to their displacement, deformation and impaired function (lacrimation, secondary dacryocystitis, diplopia, epiphary, etc.). As noted by V.Racovenu (1964), these mechanical complications often lead or are accompanied by an abscess or phlegmon orbit, panophthalmitis, etc.

Treatment mucocele only surgical. Usually it is recommended to produce RO on the frontal sinus with complete scraping of the mucosa and removal of the mucous sac, motivating this approach with the fear that the remaining parts of the mucous membrane and their glandular apparatus can lead to relapse of the mucocel. It is also recommended to create a wide sinus drainage with a nasal cavity in place of the obliterated frontal-nasal canal. However, as shown by the experience of a number of domestic and foreign authors, excessive radicalism in surgical intervention with mucocele of the frontal sinus does not justify itself. Sufficient is only the removal of the saccular formation of the cyst and the formation of a broad sinus sinus with the nasal cavity in the endonasal way, while on the one hand there is no need for total scraping of the sinus mucosa, on the other hand, it is mandatory to endonasal dissection of the latticed maze with drainage and aeration postoperative cavity.

If the mucoceles develop only in the latticed labyrinth and prolapse into the nasal cavity, without penetrating into the frontal sinus and much less into the orbit, they are limited to opening the cells of the latticed labyrinth through the bulla ethmoidalis with the widest extirpation of cells of the trellis labyrinth.

When the mucocele of the sphenoid sinus or maxillary sinus is performed by their opening in the usual way, removing the mucous sac with limited scraping of the mucous membrane in those places from which the mucocelus originates, and form a persistent drainage hole of the sinus.

In the postoperative period, the sinus is washed for 2-3 weeks with antiseptic solutions by the endonasal route through the newly formed anastomosis. When purulent complications arise, depending on their location, prevalence and nature of the clinical course, a wide surgical intervention is performed in compliance with the principles of purulent surgery.

[1], [2], [3], [4], [5],