Acute Mastoiditis
High-Yield Revision Notes for NEET PG / NEXT
Acute mastoiditis is the most common intratemporal complication of Acute Otitis Media (AOM). It involves hyperemic inflammation of the mastoid air cell system mucosal lining, which can progress to bony septal liquefaction and breakdown, culminating in a **coalescent mastoiditis**.
Radiological Profile: Axial HRCT demonstrating asymmetric loss of clear aeration and breakdown of internal bony septa (coalescence) within the affected mastoid cavity.
Microbiology
The causative bacterial spectrum closely mirrors that of acute otitis media, but requires aggressive empiric systemic coverage:
- Streptococcus pneumoniae: The single most common bacterial isolate recovered.
- Streptococcus pyogenes (Group A Beta-hemolytic): Frequently implicated in rapidly progressive or highly erosive disease profiles.
- Staphylococcus aureus & Pseudomonas aeruginosa: More commonly isolated in cases complicating chronic ear disease or recurrent infections.
Clinical Presentation & Signs
- Pinna Displacement: Inflammatory tracking causes swelling over the mastoid process, which pushes the **pinna forward, downward, and outward** (proptosis of the pinna).
- Post-Aural Changes: Erythema, intense warmth, and deep, throbbing pain localized behind the ear. There is exquisite point tenderness over the **mastoid antrum (Macewen’s triangle)**.
- Sagging of the Meatal Wall: Edema tracking anteriorly leads to characteristic thickening and **sagging of the posterosuperior external auditory canal wall**, which narrows the visualization path to the tympanic membrane.
Named Subperiosteal Abscesses (High-Yield Targets)
When purulent collection breaks through the eroded mastoid cortex, it follows specific anatomical paths:
| Abscess Variant | Anatomic Pathway & Presentation |
|---|---|
| Post-Aural Abscess | The most common presentation. Perforates through the outer cortex of the mastoid bone directly under the post-auricular skin layer. |
| Bezold’s Abscess | Perforates through the thin medial wall of the **mastoid tip** into the sheath of the **sternocleidomastoid (SCM) muscle**. Presents as a tender, deep neck swelling along the upper SCM border. |
| Citelli’s Abscess | Breaks through the mastoid tip or digastric fossa tracking posteroinferiorly along the **posterior belly of the digastric muscle** into the occipital space. |
| Luc’s Abscess | Perforates directly through the deep **posterosuperior bony wall of the external auditory canal**, presenting as an abscess within the canal space. |
Diagnostic Workup
- High-Resolution CT (HRCT) of the Temporal Bone: Imaging modality of choice. Demonstrates loss of mastoid air cell definition, diffuse fluid clouding/opacification, and classic **destruction of the intracellular bony septa** indicating coalescence.
- Tympanocentesis / Myringotomy Culture: Performed to aspirate fluid directly from the middle ear cavity for precise culture and sensitivity (C&S) profile checking.
Management Protocol
- Intravenous Antibiotics: Initial management step for early, non-coalescent mastoiditis. Empiric broad-spectrum regimens include high-dose IV third-generation cephalosporins (e.g., **Ceftriaxone**) or anti-pseudomonal beta-lactams if risk factors exist.
- Myringotomy with Grommet Insertion: Indicated to establish active drainage of the middle ear space, reduce internal pressure, and relieve tension.
- Cortical Mastoidectomy (Schwartze Operation): Indicated if there is a failure of medical therapy within 24 to 48 hours, presentation of a subperiosteal abscess (e.g., Bezold’s), or clear radiological evidence of coalescent osteitis. The procedure aims to exenterate all infected mastoid air cells and convert them into a single open cavity while **leaving the middle ear structures untouched**.