Otitis Media Supuratif Kronis (OMSK)

01Pathophysiology

CSOM represents a chronic inflammatory process of the middle ear and mastoid cavity characterized by persistent discharge through a non-intact tympanic membrane lasting more than 6 weeks (some sources use 2 to 12 weeks as a threshold, but 6 weeks is the most commonly tested cutoff).

The pathogenesis begins with eustachian tube dysfunction. When the eustachian tube fails to equalize pressure or drain secretions from the middle ear, a negative pressure environment develops. This predisposes to recurrent infections. Over time, repeated bouts of acute otitis media cause progressive damage to the TM, eventually leading to a persistent perforation. Once the TM is no longer intact, the middle ear mucosa is chronically exposed to external pathogens and moisture, which sustains the inflammatory cycle.

The shift in microbiology is a key teaching point. While AOM is dominated by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, CSOM is dominated by Pseudomonas aeruginosa and Staphylococcus aureus. This shift occurs because the perforated TM allows colonization by organisms from the external ear canal. This directly explains why treatment changes from oral amoxicillin (for AOM) to topical fluoroquinolone drops (for CSOM).

Conductive hearing loss results from two mechanisms: the perforation itself reduces the vibrating surface of the TM, and inflammatory debris or fluid in the middle ear impedes ossicular chain movement. If the disease erodes the ossicles, the hearing loss becomes fixed and more severe.

The most feared consequence of CSOM is cholesteatoma formation, particularly in the unsafe (atticoantral) type. Cholesteatoma is not a tumor but an expanding mass of keratinized squamous epithelium that erodes bone through enzymatic activity (collagenase release) and pressure necrosis. This erosion can extend into the mastoid, facial nerve canal, labyrinth, or intracranial cavity.

02Classification and Clinical Manifestation

CSOM is classically divided into two types based on the location of TM perforation and the risk of complications:

The distinction between safe and unsafe types is one of the highest-yield points in this topic. The presence of a marginal or attic perforation should immediately raise concern for cholesteatoma. In a vignette, foul-smelling discharge plus hearing loss plus a posterosuperior or attic perforation points directly to the unsafe type requiring surgical intervention.

Complications of CSOM

03Diagnostic Workup

Otoscopy is the cornerstone of diagnosis. The exam will typically present a patient with weeks of ear discharge, and the expected next step is to look in the ear. The character and location of the perforation guide all subsequent decisions.

Culture of the discharge is not always done in uncomplicated cases but becomes important when the infection fails to respond to empiric topical therapy, or when systemic infection develops.

CT temporal bone is not routinely needed for straightforward tubotympanic CSOM. It becomes necessary when you suspect cholesteatoma (foul discharge, marginal perforation, aural polyp), when there are signs of complication (fever, severe headache, facial weakness, vertigo, signs of meningismus), or for preoperative surgical planning.

Audiometry establishes a baseline and helps quantify the conductive component. An air-bone gap of $\ge \backslash geq$ 25 dB generally indicates a functionally relevant conductive hearing loss. If sensorineural loss is also present (mixed pattern), consider labyrinthine erosion by cholesteatoma.

04Management and Treatment

Step 1: Aural toilet. This is the single most important initial intervention. Clearing the ear canal of discharge and debris allows topical medications to reach the middle ear mucosa. Without adequate aural toilet, topical drops are ineffective. This is a commonly tested principle.

Step 2: Topical fluoroquinolone drops. Ciprofloxacin and ofloxacin are preferred because they cover Pseudomonas, are non-ototoxic, and achieve high local concentrations. Aminoglycoside-containing drops (gentamicin, neomycin) should be avoided when the TM is perforated because they can penetrate into the inner ear and cause sensorineural hearing loss. This is a frequently tested contraindication.

Step 3: Systemic antibiotics are reserved for complications or failure to improve with topical therapy. Oral ciprofloxacin covers Pseudomonas and is the typical choice in adults. In children, fluoroquinolones are used more cautiously.

Step 4: Surgery. Once the infection is controlled and the ear is dry for at least 3 months, tympanoplasty can be performed to close the perforation and improve hearing. For unsafe-type CSOM with cholesteatoma, mastoidectomy is not optional. Cholesteatoma does not resolve with antibiotics; it requires surgical excision to prevent progressive bone destruction.

Key contraindication: Do not instill any ear drops containing alcohol or ototoxic agents (aminoglycosides, polymyxin B) through a perforated TM.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on CSOM questions is by confusing AOM management with CSOM management. A vignette describing a child with recurrent ear infections who now has weeks of painless discharge and a known TM perforation is not another episode of AOM. The answer is not amoxicillin. The answer is aural toilet plus topical fluoroquinolone drops.

The second major trap involves aminoglycoside ear drops. Many students select gentamicin or neomycin-polymyxin drops reflexively because they associate ear infections with these preparations. Through a perforated TM, aminoglycosides are ototoxic. The correct choice is a fluoroquinolone.

Another commonly tested distinction: if a question describes foul-smelling discharge from a marginal or attic perforation, the test-writer is asking you to recognize the unsafe type with cholesteatoma. The next best step is imaging (CT temporal bone) and referral for surgery, not a prolonged trial of ear drops.

Finally, questions testing complications will describe a CSOM patient who suddenly develops facial nerve palsy, vertigo, severe headache, or high fever. These are red flags for intratemporal or intracranial extension. The core competency being tested is recognizing when CSOM has moved beyond a routine outpatient problem and requires urgent intervention, imaging, and surgical consultation.