Chronic suppurative otitis media (CSOM) is a chronic purulent inflammation of the middle ear mucosa, periosteum, or even bone. It is characterized by intermittent otorrhea, tympanic membrane perforation, and hearing loss. It often develops as a result of inadequately treated or unresolved acute otitis media. CSOM is a common condition in otology, and severe cases may lead to otogenic intracranial or extracranial complications.
Etiology
CSOM often results from untreated or improperly managed acute suppurative otitis media. Chronic diseases of the nasal cavity, sinuses, and pharynx can lead to recurrent middle ear infections. Other contributing factors include weakened systemic immunity, highly virulent bacteria, or infections with antibiotic-resistant strains.
The common causative pathogens include Staphylococcus aureus, Proteus species, Pseudomonas aeruginosa, and Escherichia coli. Gram-negative bacilli are more frequently involved, and mixed infections may occur. In recent years, infections involving non-spore-forming anaerobic bacteria have been on the rise. Fungal infections may also occur, typically involving the external auditory canal, while fungal infections of the middle ear are rare.
Pathology
The mucosa becomes congested and thickened, with increased glandular secretions and inflammatory cell infiltration. In mild cases, the inflammation is confined to the tympanic cavity but may involve other parts of the middle ear. If inflammation extends beyond the mucosal epithelium to the bone, it can cause resorptive osteitis, leading to bone destruction. Granulation tissue or polyps may form, resulting in extensive tissue adhesions or even sclerosis, which can interfere with the vibration of the ossicular chain. Repeated infections and prolonged exposure to bacterial toxins can increase the bone conduction threshold. In case of tympanic membrane perforation, the entrapment of newly formed epithelium may lead to secondary cholesteatoma, though this is relatively rare.
Clinical manifestations
Pus discharge occurs intermittently and may disappear as the infection is controlled, only to recur due to triggers such as reduced immunity. In some cases, otorrhea may persist. The discharge is typically mucopurulent, and the presence of granulation tissue may occasionally result in blood-tinged secretions.
Most commonly, there is conductive hearing loss. Mild cases may be asymptomatic, but in severe cases with extensive adhesions or ossicular damage, the air-bone gap may exceed 40 dB. Mixed hearing loss may also occur.
Some patients experience low-pitched tinnitus. Prolonged disease with high-pitched tinnitus suggests inner ear damage.
The size of the perforation varies. Depending on the extent of middle ear involvement, perforations may occur in the tense part, flaccid part, centrally, or at the margins. Residual tympanic membrane may show calcification, and during acute episodes, congestion may be observed. Partially healed tympanic membranes may appear thin, while those with ongoing infections may become thickened and congested, losing their normal translucent appearance. The mucosa of the tympanic cavity may show congestion, swelling, or thickening, with granulation tissue or polyps protruding through the perforation into the external auditory canal. Purulent secretions may be present in the external auditory canal and tympanic cavity. The presence of fungal infections should also be assessed.
Figure 1 Various types of tympanic membrane perforations
Figure 2 Chronic suppurative otitis media in the left ear
Large central perforation in the pars tensa with calcification
Figure 3 Chronic suppurative otitis media in the left ear
During the acute phase, the residual tympanic membrane around the perforation margin shows congestion
Pure-tone audiometry typically reveals conductive or mixed hearing loss of varying degrees.
On temporal bone CT, mild cases may show no abnormalities, while severe cases may reveal hypodense opacities in the middle ear, indicating mucosal thickening or granulation tissue formation.
Diagnosis
The diagnosis is straightforward and can be established based on the patient’s medical history, physical examination, and especially otoscopic findings.
Differential diagnosis
Chronic myringitis
It is characterized by recurrent otorrhea, with granulation tissue and ulcers on the surface of the tympanic membrane but without perforation. Temporal bone CT scans are normal, which helps to distinguish it. Misdiagnosis may occur if the tympanic membrane is obscured by uncleared pus.
Middle ear cancer
It is common in middle-aged and older individuals, often presenting squamous cell carcinoma. There is typically a history of long-term otorrhea, with recent development of bloody discharge and ear pain. Associated symptoms may include facial paralysis and difficulty opening the mouth. A neoplasm may be observed in the tympanic cavity or external auditory canal, which bleeds easily upon contact. In advanced stages, cranial nerve symptoms involving cranial nerves VI, IX, X, XI, and XII may appear. CT imaging of the middle ear shows localized bone destruction with irregular erosion, rather than the smooth-edged bone resorption seen in chronic inflammation. Biopsy of the neoplasm aids in differentiation.
Tuberculous otomastoiditis
It is often secondary to pulmonary tuberculosis or tuberculosis in other body sites. The onset is insidious, with thin, watery discharge. Large perforations in the tense part of the tympanic membrane or multiple perforations may be present, sometimes accompanied by pale granulation tissue. Hearing loss is significant. Middle ear CT may show bone destruction or sequestra. Diagnosis can often be confirmed through biopsy of granulation tissue or smear and culture of the discharge.
Treatment
Treatment principles include eliminating the underlying cause, controlling infection, removing lesions, ensuring proper drainage, and improving hearing.
Medication treatment
If drainage is unobstructed, local treatment is prioritized. During acute exacerbations, systemic antibiotics should be used.
When the mucosa of the tympanic cavity is congested and edematous with abundant secretions, antibiotic solutions or a mixture of antibiotics and corticosteroids can be used as ear drops. When the mucosa is moist but with minimal pus, ethanol or glycerin-based preparations can be applied.
Clearing secretions from the tympanic cavity is critical for the successful treatment of CSOM. Before applying medication, the ear should be irrigated with 3% hydrogen peroxide solution to clean the area thoroughly. Ototoxic antibiotics such as aminoglycosides should be avoided to prevent further hearing loss.
Tympanoplasty for chronic suppurative otitis media
Once otorrhea has ceased and the ear is dry, small perforations in the tympanic membrane may spontaneously heal. For persistent perforations, tympanoplasty should be performed promptly to completely treat middle ear lesions and preserve or improve hearing.
Tympanoplasty test is a clinical method used to evaluate the potential for tympanic membrane perforation repair and to predict the outcome of tympanoplasty. The test assesses the epithelialization capacity of the perforation margins by observing whether the edges of the tympanic membrane can cover a biological or artificial membrane. A positive result, where the membrane is successfully covered by epithelial tissue, indicates a high likelihood of successful tympanoplasty.
If the test is positive and there are no irreversible inflammatory changes in the upper tympanic cavity or mastoid, simple tympanic membrane repair can be performed.
Common materials for tympanic membrane repair include autologous or inactivated fascia, cartilage, and perichondrium. Autologous temporalis fascia and tragal cartilage-perichondrium complexes are widely used. During surgery, delicate handling is required to minimize disruption to the ossicular chain.
For weakly positive or negative test results, intraoperative exploration of the ossicular chain is necessary, and ossicular chain reconstruction may be performed before repairing the tympanic membrane.
Surgical techniques for tympanic membrane repair
Tympanic membrane repair is typically performed under a microscope or endoscope and includes the following methods:
- Inlay technique
- Underlay technique
- Overlay technique
Inlay technique
The skin of the posterior wall of the external auditory canal is separated from the bony wall. Upon reaching the annulus, the epithelial and fibrous layers of the tympanic membrane are separated from the bony anterior wall of the external auditory canal. Fascia or perichondrium is placed between the fibrous and epithelial layers, and the separated epithelial layer and skin are repositioned.
The tympanic membrane remains in its physiological position, reducing the risk of adhesions or superficial healing. The fascia receives blood supply from both the epithelial and fibrous layers, ensuring better fixation and survival. This technique requires surgical expertise and precision.
Underlay technique
Fascia is placed against the mucosal side of the tympanic membrane from within the tympanic cavity.
The fascia receives blood supply only from the mucosal side and is prone to adhesion with the tympanic cavity walls. Cartilage or cartilage-perichondrium composites are often used in this technique.
Overlay technique
The epithelial layer of the tympanic membrane is removed, and fascia is placed over it.
The fascia receives blood supply from only one side, which may lead to superficial healing. Incomplete removal of the epithelial layer may result in the formation of cholesteatoma within the tympanic membrane layers.