Secretory otitis media, also known as non-suppurative otitis media, exudative otitis media, catarrhal otitis media, serous otitis media, seromucous otitis media, otitis media with effusion, and glue ear, is a non-suppurative inflammatory disease of the middle ear characterized by conductive hearing loss and tympanic effusion, mostly in winter and spring, and is one of the common causes of hearing deterioration in children and adults. The effusion in the middle ear can be serous secretion, exudate, and mucus. This disease can be acute and chronic. Acute secretory otitis media lasts for 8 weeks. If unhealed in 8 weeks, it can be called chronic secretory otitis media. Chronic secretory otitis media is mostly derived from acute secretory otitis media, but also with slow onset.
Etiology
The disease is mostly caused by upper respiratory tract infection, but also radiotherapy for head and neck tumors. It is currently believed that eustachian tube dysfunction, local infection of the middle ear, and allergic reaction are the main etiology.
Eustachian tube dysfunction
Mechanical obstruction is caused by adenoid hypertrophy, hypertrophic rhinitis, nasopharyngeal tumor, lymphoid hyperplasia, and long-term obstruction of the posterior nares and nasopharynx.
Weak muscles responsible for open and close of the eustachian tube, poor elasticity of the eustachian tube cartilage, and the wall of the cartilaginous segment of the eustachian tube prone to collapse lead to dysfunction. The short and wide, nearly horizontal, eustachian tube in children results in extension of nasal and pharyngeal infections to the middle ear, which is one of the anatomical and physiological bases for the high incidence of secretory otitis media in children. Patients with cleft palate are susceptible to this disease, because the palate muscles are poor in contraction and have no midline attachment point, resulting in inability of the eustachian tube to open actively.
Dysfunction of the mucociliary transport system of the eustachian tube mucosa, including impaired surface tension and allergic reactions, is also an important pathogenic factor. For example, secretory otitis media caused by radiotherapy for head and neck tumors is caused by dysfunction of the mucociliary transport system of the middle ear and eustachian tube mucosa.
Local infection of the middle ear
It is found that positive bacterial culture in middle ear effusion is as high as 1/3 - 1/2, and the main pathogens are Haemophilus influenzae and Streptococcus pneumoniae. Bacteriological and histological examination results and clinical signs indicate that secretory otitis media may be a mild bacterial infection of the middle ear. Endotoxins produced by bacteria may play a role in the pathogenesis, particularly in the progression to chronic disease.
Allergic reactions
The immune system is not yet fully developed in children, which may also be one of the reasons for the high incidence of secretory otitis media in children. In the middle ear effusion, there are inflammatory mediators such as prostaglandins. Bacterial specific antibodies and immune complexes have also been detected in the effusion, and complement system and lysosomal enzymes are present, suggesting that chronic secretory otitis media may be a pathological process mediated by anti-infection immunity.
Barotrauma
Rapid ascents and descents during flight and diving can also cause this disease, which is clinically termed barometric otitis media. Systemic or local immune dysfunction caused by any reason, such as older adults, children, overexertion, and alcohol and tobacco abuse, can induce the occurrence of secretory otitis media.
Pathology
When the eustachian tube is dysfunctional, the external air cannot enter the middle ear, and the existing air in the middle ear is gradually resorbed by the mucosa, forming a negative pressure in the cavity, causing the middle ear mucosal dilation, congestion, increased permeability of the vascular wall, and exudate in the tympanic cavity. If the negative pressure cannot be relieved, a series of pathological changes may occur in the middle ear mucosa, mainly manifested by epithelial thickening, epithelial cell metaplasia, the low pseudostratified columnar epithelium in the anterior tympanic cavity turning into thickened ciliated epithelium, the simple epithelium in the posterior tympanic cavity turning into pseudostratified columnar epithelium, goblet cells increasing in count, hypersecretion, subepithelial pathological glandular tissue formation, and infiltration of round cells dominated by lymphocytes and plasma cells around the blood vessels in the lamina propria. During the recovery period of the disease, the glands gradually degenerate, the secretions decrease, and the mucosa gradually returns to normal.
Middle ear effusion is mostly a mixture of transudate, exudate, and secretion, dominated by one of the components depending on the course of the disease. It is generally believed that the effusion is serous in the early stage of the disease and mucous in the late stage. The extremely viscous middle ear effusion is called glue ear, which is grayish white or brownish yellow and contains large amounts of protein, such as glycoprotein and nucleoprotein.
Clinical manifestations
Hearing deterioration and autophony occur. When the head is tilted forward or toward the healthy side, hearing improves as the accumulated fluid leaves the cochlear window (positional hearing improvement). Children often seek medical attention because of slow response to sounds and poor concentration. If one ear is affected and the other ear has normal hearing, the condition may not be noticed for a long time.
Figure 1 Tympanic effusion in secretory otitis media
In acute patients, there may be dull otalgia, which may be continuous or intermittent. In chronic patients, otalgia is inapparent.
Tinnitus is mostly low pitched and intermittent, such as crackling, buzzing, and sound of running water. Valsalva maneuvre reveals sounds of air passing through water in the ear.
Aural fullness can be temporarily relieved by repeatedly pressing the tragus.
In acute patients, the flaccid part or the entire tympanic membrane is congested and retracted, manifested by shortening, deformation, or absence of the light cone, backward and upward displacement of the handle of the malleus, and significant protrusion of the short process of the malleus. When the tympanic cavity is filled with fluid, the tympanic membrane loses its normal luster and turns into light yellow, orangish red, or amber. In chronic patients, tympanic membrane may be grayish blue or milky white, and there are dilated microvessels in the tense part of the tympanic membrane. If the fluid does not fill completely the tympanic cavity, fluid levels can be seen through the tympanic membrane. Sometimes, bubbles can still be seen through the tympanic membrane, and the number of bubbles may increase after the eustachian tube is inflated.
Pneumatic otoscopy shows limited mobility of the tympanic membrane.
Tuning fork test and pure tone audiometry show conductive hearing loss. The degree of hearing loss varies, and in severe patients, it can reach about 40 dB HL. Because the amount of effusion often changes, the hearing threshold may fluctuate to a certain extent. Hearing loss is generally in low frequency, but due to the changes of sound transmission structure in the middle ear and the impedance of the two windows, high frequency air conduction and bone conduction hearing may also decrease. Hearing improves after the effusion is discharged. Acoustic immittance is of great value in diagnosis, the flat type (type B) is a typical curve for secretory otitis media, while the negative pressure type (type C) indicates poor eustachian tube function and some tympanic effusion.
CT scan shows opacities with increased density in the middle ear, and the CT value is mostly below 40Hu.
Diagnosis
Based on the medical history and clinical manifestations in combination with the results of the hearing test, a diagnosis can be readily established. Diagnostic tympanocentesis can confirm the diagnosis.
Differential diagnosis
Nasopharyngeal tumor
Secretory otitis media, particularly chronic secretory otitis media, may be the initial symptom of nasopharyngeal carcinoma, and nasopharyngeal carcinoma should be excluded. Nasopharyngeal examination should be a routine examination item, and nasopharyngeal biopsy should be performed for suspected patients. Nasopharyngeal CT or MRI has a high diagnostic value.
Cerebrospinal fluid otorrhea
In patients with temporal bone fracture or ruptured congenital defect and cerebrospinal fluid otorrhea and intact tympanic membrane, cerebrospinal fluid accumulates in the tympanic cavity, which can produce clinical manifestations analogous to secretory otitis media. A history of head trauma, laboratory test results of tympanic fluid, temporal bone CT, and radionuclide scan can be helpful for identification. Children with cerebrospinal fluid otorrhea may have a history of recurrent meningitis infection.
Cholesterol granuloma
Cholesterol granuloma is also known as idiopathic hemotympanum. The etiology is unknown and may be a complication of late secretory otitis media. The tympanic membrane is blue or blueish black. Temporal bone CT shows increased density in the tympanic cavity and mastoid.
Jugulotympanic paraganglioma
Jugulotympanic paraganglioma is a vascular tumor that can protrude into the tympanic cavity. Patients have pulsatile tinnitus and hearing deterioration. Patients with huge tumor have significant bone destruction, and temporal bone CT scan is helpful for diagnosis.
Treatment
Initial conservative treatment for 3 months is required, and etiological treatment should be used for improvement of ventilation and drainage of the middle ear and removal of the middle ear effusion.
Nonsurgical treatment
In the acute stage, appropriate antibiotics can be selected according to the severity of the lesion.
1% ephedrine solution and hormone-containing antibiotic nasal drops can be used alternately for 3 to 4 times a day to keep the nasal cavity and eustachian tube unobstructed, and supine head-down tilt position can be utilized.
Mucolytic drugs are beneficial for the ciliary excretion function, reducing the surface tension of the eustachian tube mucosa and the pressure of the eustachian tube opening.
Glucocorticoids such as dexamethasone and prednisone can be orally administered as an auxiliary treatment.
In the chronic stage, valsalva maneuvre, politzerization, and catheterization can be used to dilate the eustachian tube.
Surgical treatment
Tympanocentesis and fluid extraction can be performed under local anesthesia in adults and general anesthesia in children. A 22G needle with a short bevel is used to puncture the tympanic cavity from the anterior inferior quadrant of the tympanic membrane under aseptic conditions to aspirate the effusion. If necessary, tympanocentesis can be repeated in 1 - 2 weeks, and glucocorticoids can be injected after the fluid is aspirated.
Figure 2 Schematic diagram of the position for tympanocentesis
When the fluid is viscous and the fluid cannot be aspirated completely in tympanocentesis, tympanotomy should be performed. The operation can be performed under local anesthesia (general anesthesia in children). A radial or arcuate incision can be placed in the anterior inferior quadrant of the tympanic membrane, attention should be paid to the intact mucosa of the inner wall of the tympanic cavity, and the effusion is completely aspirated.
Figure 3 Schematic diagram of tympanotomy
In patients with protracted course, recurrence, and extremely viscous effusion, tympanostomy can be considered to improve ventilation and drainage and promote the restoration of eustachian tube function. Balloon eustachian tuboplasty can also be considered to promote the restoration of eustachian tube function.
In patients with protracted course and recurrence and CT value over 40Hu, irreversible lesions such as granulation tissue in the mastoid cavity of the middle ear should be suspected, and tympanotomy should be performed for appropriate treatment.
Adenoidectomy, septoplasty, and nasal polypectomy should be performed. If there is recurrent tonsillitis or the tonsil is excessively hypertrophic and is related to the recurrence of secretory otitis media, tonsillectomy can be considered.
Complications
Secretory otitis media can develop into adhesive otitis media, tympanosclerosis, cholesterol granuloma, and acquired primary middle ear cholesteatoma.
Prevention
Screening acoustic immittance can be performed for children under age 10 if needed. Nasal and pharyngeal diseases should be properly treated.