Chronic Suppurative Otitis Media Overview

Chronic Suppurative Otitis Media (CSOM)

• CSOM is a long-standing infection of the middle ear mucoperiosteum.
• Characterized by ear discharge and TM perforation.
• Duration: 2 weeks to 3 months.

Types of CSOM

• Tubo-tympanic: Chronic inflammation of the anterior inferior mucoperiosteum, often with a central TM perforation. Considered safe.
• Attico-antral: Inflammation involving the posterosuperior region, often associated with cholesteatoma. Considered unsafe or dangerous.

Route of Entry

• Ascending from the Eustachian tube.
• Through a TM perforation.
• Haematogenous spread.

Predisposing Factors

• Mechanical obstruction of the Eustachian tube (e.g., adenoid hypertrophy).
• Immunodeficiency.
• Allergies.
• Ciliary dysfunction (e.g., cystic fibrosis).
• Laryngopharyngeal reflux.
• Genetic predisposition (e.g., certain ethnic groups).
• History of recurrent acute otitis media (AOM).
• Parent with CSOM.
• Craniofacial anomalies.
• Inadequate treatment of AOM.

Pathology

• Thickened, edematous, occasionally polypoid mucosa.
• Granulation tissue.
• TM perforation.
• Osteitis and ossicular necrosis.
• Mucopurulent discharge.

Microbiology

• Gram-negative bacteria (59.7%).
• Gram-positive bacteria (25.6%).
• Fungi (14.7%, e.g., Aspergillus).
• Various bacterial species are commonly present (K. pneumoniae, E. coli, Pseudomonas aeruginosa, Staphylococcus, Proteus, MTB).
• Multibacterial in most cases.

Investigations

• Pus swab for culture and sensitivity.
• Audiological tests (e.g., PTA).
• Imaging:
  • X-ray (for mastoiditis and adenoid hypertrophy).
  • CT scan/MRI.
  • FBP (likely a blood test).

Treatment

• Aural toilet.
• Medical treatment (local antibiotics, e.g., Ciprofloxacin ear drops, systemic antibiotics).
• Surgical treatment (Mastoidectomy, Adenoidectomy, Tympanoplasty).

Attico-antral CSOM

• Inflammation involving the posterosuperior region, often with cholesteatoma.
• Characterized by marginal or attic TM perforation.
• Considered unsafe or dangerous.

Cholesteatoma

• Presence of keratinizing squamous epithelium in an ectopic site (e.g., middle ear, brain).

Site of Attico-antral CSOM

• Located in the epitympanum (attic) and mastoid antrum.

Aetiology Theories

• Congenital theory.
• Metaplasia theory.
• Migration theory.
• Retraction pocket theory.

Congenital Theory

• Persistence of embryonic epidermal rest cells of epithelial origin in the middle ear or temporal bone.
• Eventually forms cholesteatoma.

Squamous Metaplasia Theory

• Middle ear respiratory epithelium transforms into keratinising squamous epithelium.
• Due to chronic inflammation.

Migration Theory

• AKA Invasion theory.
• Movement of squamous epithelium from the external auditory canal into the middle ear.
• Occurs through a drum perforation.

Retraction Pocket (Invagination) Theory

• Eustachian tube dysfunction leads to negative middle ear pressure causing retraction pocket on the tympanic membrane.
• The pocket draws squamous cells into the middle ear.
• Cells multiply to form a keratinised mass (cholesteatoma).

Clinical Features

• Otorrhoea (thick, malodorous discharge, potentially with white, blotting-paper-like cholesteatoma material).
• TM perforation.
• Hearing loss.
• Earache.
• Bleeding (if associated granulation tissue is traumatized).
• Vertigo (if horizontal semicircular canal is involved).
• Tinnitus.
• Headache (suggests pending intracranial complications).

Intracranial Complications

• Meningitis.
• Brain abscess.
• Subdural abscess.
• Epidural abscess.
• Lateral sinus thrombosis.
• Otic hydrocephalus.

Extracranial Complications

• Mastoiditis.
• Petrositis.
• Facial nerve paralysis.
• Labyrinthitis
• Labyrinthine fistula.

Mastoiditis

• Destruction of mastoid air cells by inflammatory exudate under pressure.
• Subperiosteal abscess (post-auricular abscess) may occur.
• Pus may extend along the sternomastoid muscle to the neck (Bezold's abscess).

Petrositis

• Inflammation of the petrous pyramid involving adjacent structures (trigeminal and abducent nerves).
• Triad of symptoms: otorrhoea, diplopia, facial pain (Gradenigo's syndrome).

Facial Nerve Paralysis

• Infection extends into the fallopian canal, through bone erosion or dehiscence.

Labyrinthitis

• Serous type: Labyrinth hyperemia
• Suppurative type: Infections directly entering labyrinth fluid, causing pus.
• Clinical features: Hearing loss, vertigo, tinnitus, spontaneous horizontal nystagmus.

Management of Complications

• Management depends on the type of complication.
• Mastoidectomy is often indicated to control the aural infection.
• Neurosurgeon involvement is critical for intracranial complications.
• Chemotherapy must consider gram-negative bacillus and anaerobic bacteria.