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Chronic Suppurative Otitis Media

Definition and Pathogenesis

Chronic suppurative otitis media (CSOM) is characterized by a persistent infection of the middle ear cleft, manifesting with a continual ear discharge lasting at least two weeks through a tympanic membrane perforation. The perforation becomes permanent when the outer squamous epithelial layer of the tympanic membrane merges with the inner mucosal layer of the tympanic membrane at the perforation margins, preventing spontaneous healing. CSOM often starts from episodes of acute suppurative otitis media (ASOM), negative middle ear pressure, or otitis media with effusion (OME) in childhood. OME can lead to thinning of the tympanic membrane, hearing loss, delayed speech development, and potentially hinder a child’s educational progress.


The incidence of CSOM is notably higher in developing countries, attributable to poor socioeconomic conditions, inadequate nutrition, and a lack of health education. CSOM affects individuals of all sexes and age groups. In India, the prevalence rate is approximately 46 per thousand in rural areas and 16 per thousand in urban populations, making it the leading cause of hearing impairment in rural communities.

Types of CSOM

CSOM is clinically classified into two types:

  1. Tubotympanic (Safe or Benign Type): This type remains localized to the mucosa of the anteroinferior part of the middle ear cleft, involving the eustachian tube and mesotympanum, and is associated with a central perforation. The healing and destructive processes occur concurrently, influenced by the virulence of the infecting organism and the host’s resistance. While serious complications are rare, the cochlea may sustain damage due to toxins absorption from the oval and round windows, potentially resulting in mixed hearing loss.
  2. Atticoantral (Unsafe or Dangerous Type): This type is characterized by a posterosuperior lesion or cholesteatoma, affecting the attic, antrum, and mastoid regions of the middle ear cleft and is associated with an attic or marginal perforation. The disease often involves bone erosion caused by cholesteatoma, granulations, or osteitis, and carries a high risk of complications.

Tubotympanic type of CSOM

Aetiology. The condition typically begins in childhood.

  1. It often follows acute otitis media, which may result from exanthematous fever and lead to a large central perforation.
  2. Permanent perforation allows repeated infections through the external ear canal, causing otorrhea. The exposed middle ear mucosa becomes sensitized to environmental allergens such as dust and pollen.
  3. Ascending infections from the eustachian tube, often originating from infected tonsils, adenoids, or sinuses, can perpetuate the infection.
  4. Persistent mucoid otorrhea may sometimes result from allergies to certain foods such as milk, eggs, or fish.

Pathology. The tubotympanic disease remains confined to the mucosa, primarily affecting the anteroinferior part of the middle ear cleft. The pathological changes observed include:

  1. Perforation of Pars Tensa: Central perforation, varying in size and position.
  2. Middle Ear Mucosa: Appears normal when inactive, but is oedematous and velvety during active disease.
  3. Polyp Formation: A polyp is a smooth, swollen mass of inflamed mucous membrane that has protruded through a perforation and appears in the external canal. Typically, it is pale in colour, distinguishing it from the pink, fleshy polyps commonly seen in atticoantral disease.
  4. Ossicular Chain Integrity: Generally intact and mobile, but may exhibit necrosis, particularly in the long process of the incus.
  5. Tympanosclerosis: It is hyalinization and calcification of subepithelial connective tissue, potentially impairing the mobility of ossicular structures and causing conductive hearing loss. It is considered a long-term, irreversible consequence of an unresolved inflammatory process in ears with long-standing, silent chronic otitis media. Hyalinization and subsequent calcification of subepithelial connective tissue are observed in the remnants of the tympanic membrane or under the mucosa of the middle ear. This condition manifests as white, chalky deposits on the promontory, ossicles, joints, tendons, and the oval and round windows. Tympanosclerotic masses can interfere with the mobility of these structures, causing conductive deafness.
  6. Fibrosis and Adhesions: Resulting from the healing process, further impeding ossicular chain mobility or eustachian tube function.


CSOM involves multiple aerobic and anaerobic organisms:

  • Aerobic: Pseudomonas aeruginosa, Proteus species, Escherichia coli, Staphylococcus aureus.
  • Anaerobic: Bacteroides fragilis, anaerobic Streptococci.

Clinical Features.

  1. Ear Discharge: The discharge from the ear is typically non-offensive, odourless, and can be either mucoid or mucopurulent. The amount of discharge may vary from profuse to scanty, and it can be constant or intermittent. This discharge often occurs during upper respiratory tract infections or when water accidentally enters the ear.
  2. Hearing Loss: The hearing loss associated with this condition is of the conductive type, with a severity that rarely exceeds 50 dB. Sometimes, patients experience a paradoxical effect where they hear better when there is discharge in the ear compared to when the ear is dry. This is due to the “round window shielding effect” created by the discharge, which helps maintain phase differential. In a dry ear with perforation, sound waves strike both the oval and round windows simultaneously, cancelling each other’s effects.
  3. Long-standing Cases: In chronic cases, the cochlea may suffer damage due to the absorption of toxins from the oval and round windows, resulting in mixed-type hearing loss.
  4. Perforation: The perforation is always central and may be located anterior, posterior, or inferior to the handle of the malleus. The size of the perforation can vary, being small, medium, large, or extending up to the annulus, known as subtotal.
  5. Middle Ear Mucosa: When the perforation is large, the middle ear mucosa can be observed. Normally, it appears pale pink and moist. When inflamed, it looks red, edematous, and swollen.
  6. Polyp may be present. An edematous and inflamed mucosa can protrude through the perforation into the external canal, presenting as a polyp, which is usually pale (in contrast to the pink and fleshy polyp seen in cases of atticoantral cholesteatoma).
  7. Otoscopy/Microscopy/Endoscopy: During examination, a central perforation of the pars tensa is noted, with attention to the following points:
    • Size: The perforation can be small, medium, large, or subtotal.
    • Position: It can be located anterior, posterior, or inferior to the handle of the malleus.


  1. Microscopic Examination: Essential for detailed assessment, revealing granulations, epithelial ingrowth, ossicular chain status, tympanosclerosis, and adhesions.
  2. Audiometry and Tuning Fork Tests: Assess hearing loss degree and type.
  3. Culture and Sensitivity: Identifies microorganisms to guide antibiotic selection.
  4. Mastoid X-ray: Shows sclerotic mastoid or pneumatized with clouded air cells; no bone destruction, which is indicative of atticoantral disease.


  1. Aural Toilet: Removing all discharge and debris from the ear is essential. This can be achieved through dry mopping with absorbent cotton buds, suction cleaning under a microscope, or irrigation with sterile normal saline (not forceful syringing). It is crucial to ensure the ear is dried thoroughly after irrigation.
  2. Ear Drops: Antibiotic ear drops, which may contain neomycin, polymyxin, chloromycetin, or gentamicin, are commonly used. These are often combined with steroids to provide a local anti-inflammatory effect. For proper application, the patient should lie down with the affected ear facing upwards, instil the antibiotic drops, and then apply intermittent pressure on the tragus to facilitate the antibiotic solution’s entry into the middle ear. This procedure should be repeated three to four times daily. An acidic pH can help eliminate Pseudomonas infections; therefore, irrigations with 1.5% acetic acid are beneficial. However, caution is necessary as ear drops can cause maceration of the canal skin, local allergies, fungal growth, or resistance in organisms. Ear drops should be discontinued once the ear is dry to prevent it from becoming wet and discharging again. Some ear drops also carry a risk of ototoxicity.
  3. Systemic Antibiotics: These are particularly useful during acute exacerbations of a chronically infected ear. However, their role in the treatment of chronic suppurative otitis media (CSOM) is generally limited.
  4. Precautions: Patients should be advised to keep water out of the ear during bathing, swimming, and hair washing. Rubber inserts can be used for protection. Hard nose blowing should be avoided as it can push the infection from the nasopharynx to the middle ear. Additionally, patients should be cautioned against self-cleaning of the ear.
  5. Treatment of Contributory Causes: Concomitantly infected tonsils, adenoids, maxillary antra, and nasal allergies should be treated to address contributory causes of ear infection.
  6. Surgical Treatment: If an aural polyp or granulations are present, they should be removed prior to local treatment with antibiotics. This will facilitate aural toilet and allow for the effective use of ear drops. However, an aural polyp should never be avulsed as it may arise from structures such as the stapes, facial nerve, or horizontal canal, leading to potential complications like facial paralysis or labyrinthitis.
  7. Reconstructive Surgery: Once the ear is dry, myringoplasty with or without ossicular reconstruction can be performed to restore hearing. Closing the perforation will also help prevent repeated infections from the external canal. Although it is preferable for the ear to be dry before surgery, this is not always achievable, and surgery should not be postponed on this account. Cortical mastoidectomy combined with myringoplasty can be performed even in active ears.

Atticoantral type of CSOM

Atticoantral disease involves the posterosuperior part of the middle ear cleft and is associated with cholesteatoma. Cholesteatoma is a benign cystic structure characterized by a keratinizing epithelial lining, commonly located in the middle ear and mastoid. Despite its benign nature, cholesteatoma can cause significant destruction of local anatomical structures, including the ossicular chain and the otic capsule. Such destruction can result in various complications, including hearing loss, vestibular dysfunction, facial paralysis, and intracranial disease or infection. For this reason, the disease is also called unsafe or dangerous type.


Cholesteatomas most commonly originate from a retraction pocket in the pars flaccida or the posterosuperior part of the pars tensa. The initiating factor is likely the dysfunction of the Eustachian tube, resulting in negative middle ear pressure. Due to their greater blood supply compared with the rest of the tympanic membrane, the pars flaccida and the posterosuperior quadrant of the pars tensa are more susceptible to inflammatory cell infiltration in acute otitis media (AOM) and otitis media with effusion (OME). This susceptibility may result in a thinner fibrous layer in these areas compared to the rest of the tympanic membrane.

Cholesteatomas can also occur due to epithelial metaplasia of the middle ear mucosa or due to migration of epithelial layer into the middle ear through pre-existing tympanic membrane perforation.


Atticoantral diseases are associated with the following pathological processes:

  1. Cholesteatoma. Once cholesteatoma enters the middle ear cleft, it invades surrounding structures, initially following the path of least resistance and subsequently through enzymatic bone destruction. An attic cholesteatoma may extend backward into the aditus, antrum, and mastoid, downward into the mesotympanum, and medially surrounding the incus and/or head of the malleus. Cholesteatoma exhibits the capacity to destroy bone, potentially causing the destruction of ear ossicles, erosion of the bony labyrinth, canal of the facial nerve, sinus plate, or tegmen tympani, leading to several complications. Bone destruction by cholesteatoma is attributed to various enzymes, such as collagenase, acid phosphatase, and proteolytic enzymes, released by osteoclasts and mononuclear inflammatory cells associated with cholesteatoma. The earlier theory that cholesteatoma causes bone destruction by pressure necrosis is no longer widely accepted.
  2. Osteitis and Granulation Tissue. Osteitis, which involves the outer attic wall and the posterosuperior margin of the tympanic ring, is a critical aspect of middle ear pathology. This condition is characterized by a mass of granulation tissue that surrounds the affected area of osteitis. The granulation tissue may proliferate to fill the attic, antrum, posterior tympanum, and mastoid. In some cases, a fleshy red polypus can be observed occupying the meatus.
  3. Ossicular Necrosis. Ossicular necrosis is commonly associated with atticoantral disease. The destruction typically affects the long process of the incus but can extend to the superstructure of the stapes, the handle of the malleus, or the entire ossicular chain. Consequently, the resultant hearing loss is generally more severe than that observed in tubotympanic disease. Interestingly, in certain cases, the cholesteatoma bridges the gap left by the destroyed ossicles, resulting in no apparent hearing loss, a phenomenon referred to as “cholesteatoma hearer.”
  4. Cholesterol Granuloma. Cholesterol granuloma is a pathological entity characterized by a mass of granulation tissue containing foreign body giant cells that encircle cholesterol crystals. This condition arises as a reaction to the prolonged retention of secretions or haemorrhage and may or may not coexist with cholesteatoma. When cholesterol granuloma is present in the mesotympanum, behind an intact tympanic membrane, the latter may appear blue.


Pus culture in both types of aerobic and anaerobic CSOM may show multiple organisms.

  • Common aerobic organisms are Pseudomonas aeruginosa, Proteus, Escherichia coli and Staphylococcus aureus.
  • Anaerobes include Bacteroides fragilis and anaerobic Streptococci.


  1. Ear Discharge: Typically, ear discharge is scanty but consistently foul-smelling due to underlying bone destruction. The discharge may be so minimal that the patient remains unaware of its presence. A sudden cessation of discharge from an ear that had previously been active should be considered a serious sign. This cessation could indicate that the perforation has been sealed by crusted discharge, inflammatory mucosa, or a polyp, thereby obstructing the free flow of discharge. In such cases, pus may accumulate internally, leading to further complications.
  2. Hearing Loss: Hearing loss may not be immediately evident if the ossicular chain remains intact or if a cholesteatoma bridges the gap caused by ossicular destruction (referred to as a “cholesteatoma hearer”). While hearing loss is predominantly conductive, there may also be a sensorineural component.
  3. Bleeding: Bleeding may occur from granulations or polyps during the cleaning of the ear.


  1. Perforation: Perforation can occur either in the attic or as a posterosuperior marginal type. A small attic perforation may be easily missed due to the presence of a small amount of crusted discharge. Occasionally, the area of perforation may be obscured by a small granuloma. A marginal perforation is characterized by a posterior perforation with a contiguous pathological loss of the annulus, allowing direct exposure of the bony canal wall, or by an attical perforation with a defect in the pars flaccida. Marginal and attical defects of the tympanic membrane expose the attic, the antrum, and the mastoid cell system, historically referred to as “attico-antral disease.” These perforations, occurring above the tympanic diaphragm, are commonly associated with cholesteatoma and are thus termed “unsafe ears” due to the risk of unfavourable prognosis and life-threatening complications.

Stages of Pars Tensa retraction (Sade and Berco).

    • Grade 1. Tympanic membrane is slightly retracted but does not contact the incus. There is loss of light reflex.
    • Grade 2. Tympanic membrane is retracted on long process of incus (adhesion is called tympanoincudopexy) or contacting the stapes (adhesion is called tympanostapediopexy) ; middle ear mucosa is not affected.
    • Grade 3. Also called middle ear atelectasis. Tympanic membrane comes to lie on the promontory but not adhered. It moves on Valsalva maneuverer or suction tip. Tympanic membrane comes to lie on the promontory and ossicles. Middle ear space is totally or partially obliterated but middle ear mucosa is intact. Tympanic membrane can be lifted from the promontory with suction tip. It also balloons up when N2O is used during anaesthesia. Tympanic membrane is thin because its collagenous middle layer has been absorbed due to prolonged retraction. In these cases long process of incus and stapes superstructure are absorbed. Placement of a ventilation tube helps to restore the position of tympanic membrane.
    • Grade 4. Also called adhesive otitis media. Tympanic membrane is adhered to the promontory. It does not moves on Valsalva maneuverer or suction tip. Tympanic membrane is very thin and wraps the promontory and ossicles. There is no middle ear space, mucosal lining of the middle ear is absent and tympanic membrane gets adherent to the promontory. Retraction pockets are formed which may collect keratin plugs and form cholesteatoma. Erosion of the long process of incus and stapes superstructure is common in such cases.
    • Grade 5. Grade III or IV with perforation in the tympanic membrane.

Stages of Pars Flaccida retraction (Tos et al.).

    • Grade 1. The pars flaccida is dimpled and more retracted than normal but not adherent to the malleus neck.
    • Grade 2. The retraction is adherent to the neck of the malleus.
    • Grade 3. Partial erosion of the bony attic wall with fundus visible.
    • Grade 4. Definitive erosion of bony attic wall, unable to visualize its fundus.
  1. Retraction Pockets: Retraction pockets are invaginations of the tympanic membrane, observed in the attic or posterosuperior area of the pars tensa. The degree of retraction and invagination can vary. In the early stages, the pocket is shallow and self-cleansing. However, as the pocket deepens, it accumulates keratin mass and becomes infected.
  2. Cholesteatoma: Pearly-white flakes of cholesteatoma can be extracted from retraction pockets. Suction clearance and examination under an operating microscope are crucial components of the clinical examination and assessment of any type of chronic suppurative otitis media (CSOM).

Assessment and Imaging

  1. Microscopic Examination under microscope. It allows thorough cleaning of the discharge and confirmation of the diagnosis. All patients of chronic middle early disease should be examined under microscope.
    • Classify the retraction according to Tos. Can I see the fundus of the retraction pocket or not? Is this thought to be self- cleansing or not? Whether a retraction pocket is self-cleansing or not is a qualitative judgement based upon size and appearance. A small, clean retraction pocket in the pars flaccida or pars tensa is likely to be self-cleansing, but such judgements can only be confirmed over time by clinical review.
    • Examination of cholesteatoma, its site and extent, evidence of bone destruction, granuloma, condition of ossicles and pockets of discharge.
  1. Audiometry and Tuning Fork Tests: Essential for preoperative assessment.
  2. CT Scan: Preferred over mastoid X-rays, provides detailed anatomical landmarks and extent of bone destruction.
  3. DW-MRI: Differentiates cholesteatoma from inflammatory tissue and brain, useful for detecting residual cholesteatoma post-surgery.
  4. Endoscopy: Useful for outpatient assessment, especially in patients with narrow ear canals.

Features Indicating Complications in CSOM

  1. Pain: Pain is uncommon in uncomplicated chronic suppurative otitis media (CSOM). Its presence is considered serious as it may indicate extradural, perisinus, or brain abscess. Sometimes, it is due to otitis externa associated with a discharging ear.
  2. Vertigo: Vertigo indicates erosion of the lateral semicircular canal, which may progress to labyrinthitis or meningitis. A fistula test should be performed in all cases.
  3. Persistent Headache: Persistent headache is suggestive of an intracranial complication.
  4. Facial Weakness: Facial weakness indicates erosion of the facial canal.
  5. Listless Child: A listless child refusing to take feeds and easily falling asleep may indicate an extradural abscess.
  6. Fever, Nausea, and Vomiting: These symptoms are indicative of an intracranial infection.
  7. Irritability and Neck Rigidity: These symptoms are suggestive of meningitis.
  8. Diplopia: Diplopia may indicate Gradenigo syndrome or petrositis.
  9. Ataxia: Ataxia may indicate labyrinthitis or cerebellar abscess.
  10. Abscess Around the Ear: This indicates mastoiditis.


The aim of treatment is to relieve the patient’s symptoms and to minimize the risks of complications.

  1. Retraction Pockets: Assess whether the retraction is likely to progress, remain static, or resolve.
  2. Cholesteatoma: Surgery is the mainstay of treatment. The primary aim in surgical treatment is the eradication of disease and the creation of an epithelialized, self-cleaning ear that does not require regular aural toilet. The secondary priority is to preserve or reconstruct hearing, but never at the expense of the primary aim. Two types of surgical procedures are performed to address cholesteatoma:

Canal Wall Down Procedures (Open Cavity): These procedures leave the mastoid cavity open into the external auditory canal, fully exteriorizing the diseased area. Commonly performed operations include:

    • Atticotomy: Limited to the attic region; the defect in the attic wall is closed with tragal or conchal cartilage.
    • Atticoantrostomy: An anterior-to-posterior approach where cholesteatoma is identified in the epitympanum or posterior mesotympanum and followed backward.
    • Modified Radical Mastoidectomy: A posterior-to-anterior approach where the mastoid is opened behind the external auditory canal, the cholesteatoma is identified, and the posterior bony wall of the canal is removed.
    • Radical Mastoidectomy: Extensive removal of diseased tissue.

      Common causes of ear discharge following canal wall down procedures include:
      • a high facial ridge
      • a sump in the cavity below the floor of the external auditory canal
      • perforation in the tympanic membrane
      • small external auditory meatus.

Canal Wall Up Procedures (Closed Cavity or Combined Approach Tympanoplasty): Disease is removed through a combined approach via the meatus and mastoid, retaining an intact external auditory canal without creating a mastoid cavity. This approach is technically more challenging and time-consuming, but it results in a dry ear and facilitates the reconstruction of the hearing mechanism. However, there is a risk of leaving residual cholesteatoma behind, leading to a high incidence (20-50%) of recurrent disease. Long-term follow-up and second-look operations after 12-18 months are essential. Second looks can often be avoided with the use of diffusion-weighted MRI (DW-MRI). In the combined approach or intact canal wall mastoidectomy, disease is removed both permeatally and through a cortical mastoidectomy and posterior tympanotomy approach, creating a window between the mastoid and middle ear through the facial recess to reach the sinus tympani.

  1. Reconstructive Surgery: Hearing can be restored by myringoplasty or tympanoplasty, performed either at the time of primary surgery or as a second-stage procedure.
  2. Conservative Treatment: Conservative treatment has a limited role in managing cholesteatoma but can be attempted in selected cases where the cholesteatoma is small and easily accessible to suction clearance under an operating microscope. Repeated suction clearance and periodic check-ups are essential. Conservative treatment is also considered for elderly patients above 65, those unfit for general anesthesia, or those refusing surgery. Polyps and granulations can be surgically removed by cup forceps or cauterized with chemical agents like silver nitrate or trichloroacetic acid. Additional measures such as aural toilet and dry ear precautions are also necessary. Hearing aids should always be considered in cases of hearing disability.


Alternative Classification of Chronic Otitis Media

Another commonly used classification system for chronic otitis media is gaining prevalence in contemporary medical practice. This system provides a detailed framework for understanding and diagnosing the condition, allowing for more precise treatment plans and better patient outcomes. This classification categorises the disease based on specific clinical features, anatomical involvement, and complications.

1. Mucosal disease, is characterized by the absence of squamous epithelial invasion and primarily involves the mucosal lining of the middle ear.

i. Inactive Mucosal Chronic Otitis Media (COM) (Dry Perforation)
– This condition is marked by a permanent perforation of the pars tensa, with the middle ear and mastoid remaining non-inflamed. Inactive mucosal COM indicates that the middle ear structure and hearing may be compromised due to the tympanic membrane perforation, but there is no active infection or mucoid discharge. Such an ear can remain inactive, become active, or occasionally heal spontaneously.

ii. Active Mucosal Chronic Otitis Media (COM) (Perforation with Ear Discharge)
– This form of COM presents with a perforation of the pars tensa, accompanied by mucopurulent discharge and inflammation of the middle ear and mastoid mucosa. The condition may persist, become inactive, or lead to complications.

iii. Healed Chronic Otitis Media (COM)
– In this condition, the tympanic membrane has healed, usually forming a two-layer structure that is atrophic and prone to retraction under negative middle ear pressure. Healed otitis media may also feature tympanosclerosis patches on the tympanic membrane or within the middle ear, affecting the promontory, ossicles, and tendons of the stapedius and tensor tympani muscles. 

2. Squamosal Disease

i. Inactive Squamous Epithelial Chronic Otitis Media (COM) (Retraction, Atelectasis, and Epidermization)
– This condition is characterized by retraction pockets in the pars tensa (typically the posterosuperior region) or pars flaccida. While there is no discharge, the retraction pockets may harbor squamous debris (cholesteatoma) that can become infected and start discharging. Some retraction pockets are shallow and self-cleansing. Negative static middle ear pressure can cause the tympanic membrane to retract (atelectasis). ‘Epidermization’ refers to a more advanced stage where the middle ear mucosa is replaced by keratinizing squamous epithelium without the retention of keratin debris.

ii. Active Squamous Epithelial Chronic Otitis Media (COM) (Acquired Cholesteatoma)
– This condition is characterized by the presence of cholesteatoma in the posterosuperior region of the pars tensa or in the pars flaccida. The cholesteatoma erodes bone, forms granulation tissue, and produces a purulent, offensive discharge.

———- End of the chapter ———–

Learning resources.

  • Scott-Brown, Textbook of Otorhinolaryngology Head and Neck Surgery.
  • Glasscock-Shambaugh, Textbook of  Surgery of the Ear.
  • P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
  • Salah Mansour. Textbook of Middle Ear Diseases Advances in Diagnosis and Management.
  • Gordon B. Hughes, Textbook of Clinical Otology.
  • Mario Sanna, Textbook of Color Atlas of Endo-Otoscopy.
  • Marcos V Goycoolea, Atlas of Otologic Surgery and Magic Otology.

Dr. Rahul Bagla ENT Textbook

Dr. Rahul Bagla
MBBS (MAMC, Delhi) MS ENT (UCMS, Delhi)
Fellow Rhinoplasty & Facial Plastic Surgery.
Designation: Faculty, Associate Professor
Government Institute of Medical Sciences,
Greater Noida, India

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