Acute Mastoiditis

Acute Mastoiditis
Other Names	Acute coalescent mastoiditis, Acute suppurative mastoiditis
Left-sided acute mastoiditis
Identifiers
ICD-9	383.9
ICD-10	H70.90
MeSH	D008416
Outside Resources
Radiopaedia	Acute Mastoiditis

1. Acute Mastoiditis

Overview

Acute mastoiditis is a suppurative infection of the mastoid air cells, typically arising as a complication of acute otitis media (AOM). It represents the most common intratemporal complication of otitis media and can progress to life-threatening intracranial complications if untreated.

The condition predominantly affects children under 2 years of age, corresponding to the peak incidence of AOM. Prompt diagnosis and treatment are essential to prevent progression to subperiosteal abscess, intracranial complications, or chronic mastoiditis.

Epidemiology

Historical Trends

The incidence of acute mastoiditis decreased dramatically with the introduction of antibiotics, from approximately 20% of AOM cases in the pre-antibiotic era to 0.002-0.004% in developed countries by the early 2000s. Pre-COVID baseline epidemiological data suggested an incidence of 1.2-6.1 per 100,000 children, with acute mastoiditis complicating acute otitis media in approximately 0.24% of cases.

Post-COVID-19 Epidemiologic Surge

A dramatic and sustained increase in acute mastoiditis incidence has been documented following the COVID-19 pandemic, representing one of the most significant epidemiologic shifts in recent otolaryngology practice.

Incidence increases by region:

• France: Increased from 27 cases/year (2001-2008) to 74 cases/year (2021-2024) — a nearly 3-fold increase
• France national data: 71.7% increase in post-COVID period compared to expected trend (95% CI: 26.4%-133.3%)
• Germany: 10-fold increase in cases after COVID-19 restrictions lifted in 2022
• New Zealand: Increased from 3.62 to 6.22 cases/100,000 person-years in 2022 (RR 1.72, 95% CI 1.28-2.30)

Complication rates have increased dramatically:

• Intracranial complications: Increased from 4% to 39% (2001-2008 vs 2021-2024)
• Subperiosteal abscess: Now present in 95% of cases (2021-2024)
• Lateral sinus thrombosis: 25% of cases
• Extradural empyema: 29% of cases

This represents a sustained increase (not a temporary spike) persisting through 2024-2025, likely related to reduced natural immunity from decreased pathogen exposure during pandemic restrictions ("immunity debt").

History

The mastoid bone has been recognized as a site of infection since ancient times. Hippocrates described temporal bone infections and their potential for fatal outcomes. Jean-Louis Petit performed the first documented mastoidectomy in 1736, establishing surgical drainage as definitive treatment.

Hermann Schwartze standardized the simple mastoidectomy technique in 1873, and this procedure remained the primary treatment until the antibiotic era. William House and others developed modified radical and canal wall-up mastoidectomy techniques in the mid-20th century that preserved hearing function while eradicating disease.

The introduction of sulfonamides in the 1930s and penicillin in the 1940s dramatically reduced mastoiditis incidence. Current management emphasizes early antibiotic therapy with surgery reserved for complications or treatment failure, though recent evidence supports increasingly conservative management approaches.

Pathophysiology

Relevant Anatomy

The mastoid process is the posterior portion of the temporal bone, located behind the external auditory canal. Key anatomical features include:

Mastoid air cell system:

• Pneumatized spaces communicating with the middle ear via the aditus ad antrum
• The mastoid antrum is the largest air cell, connecting directly to the epitympanum
• Air cell development begins in utero and continues until adolescence
• Pneumatization varies from well-pneumatized (most common) to sclerotic or diploic

Critical adjacent structures:

• Tegmen mastoideum: Thin bone separating mastoid from middle cranial fossa
• Sigmoid sinus: Major venous structure in posterior mastoid
• Facial nerve: Courses through mastoid in vertical (descending) segment
• Lateral semicircular canal: Lies medial to antrum
• Digastric ridge: Landmark for facial nerve identification

Cortical boundaries:

• Lateral cortex is thinnest in children, predisposing to subperiosteal abscess
• Medial cortex separates mastoid from posterior fossa

Stages of Disease Progression

Acute mastoiditis develops through several pathophysiological stages:

Stage 1: Acute mastoiditis with periostitis

• Mucosal inflammation of mastoid air cells
• Purulent material accumulates but bony septae remain intact
• Periosteal inflammation causes postauricular tenderness

Stage 2: Acute coalescent mastoiditis

• Osteoclastic resorption of bony septae
• Air cells coalesce into single cavity
• May progress to abscess formation

Stage 3: Subperiosteal abscess

• Pus erodes through lateral cortex
• Abscess forms between bone and periosteum
• Classic postauricular fluctuance and protrusion of auricle

Microbiology: Major Post-COVID Shift

A dramatic shift in causative organisms has occurred since 2020, with major clinical implications:

Organism	Pre-COVID (2001-2008)	Post-COVID (2021-2024)	Clinical Significance
Streptococcus pyogenes	9.7%	37% (now #1)	Associated with severe/complicated disease
Streptococcus pneumoniae	32.3%	23% (now #2)	Decreased despite PCV-13 changes
Fusobacterium necrophorum	Rare	19%	Associated with intracranial complications, Lemierre syndrome
Staphylococcus aureus	Variable	16% (UK data)	Including MRSA; local epidemiology varies
Haemophilus influenzae	5%	Decreased post-Hib vaccination
Pseudomonas aeruginosa	Variable	7%	Consider in chronic/immunocompromised

Critical clinical correlation: In cases with intracranial complications, S. pyogenes and F. necrophorum were causative in over 70% compared with 46% in uncomplicated cases (P < .001).

UK tertiary center data (2017-2022):*

• Streptococcus spp.: 27%
• Staphylococcus spp.: 16%
• Pseudomonas aeruginosa: 7%
• Fusobacterium: 6%
• Haemophilus influenzae: 5%

Diagnosis

Clinical Presentation

Clinical presentation typically follows or occurs during an episode of AOM:

• Otalgia: Persistent or worsening ear pain despite treatment
• Otorrhea: Purulent discharge if tympanic membrane perforated
• Fever: Present in majority of cases
• Hearing loss: Conductive hearing loss
• Postauricular symptoms: Pain, swelling, erythema behind ear
• Systemic symptoms: Irritability (children), malaise, decreased oral intake

Red flags suggesting complications:

• Severe headache (meningitis)
• Neck stiffness (meningitis)
• Altered mental status (intracranial complications)
• Visual changes (increased intracranial pressure)
• Facial weakness (facial nerve involvement)
• Vertigo (labyrinthitis)

Physical Examination

Otoscopy:

• Bulging, erythematous tympanic membrane
• Tympanic membrane perforation with otorrhea
• Sagging of posterosuperior canal wall (pathognomonic)

Postauricular examination:

• Erythema and tenderness over mastoid
• Fluctuance (indicates subperiosteal abscess)
• Loss of postauricular crease
• Anteroinferior displacement of auricle

Neurological examination:

• Facial nerve function (House-Brackmann grading)
• Signs of meningitis (Kernig sign, Brudzinski sign)
• Cerebellar signs (abscess)
• Cranial nerve VI palsy (Gradenigo syndrome)

Laboratory Tests

• Complete blood count: Leukocytosis with left shift
• C-reactive protein: Elevated; associated with complications
• Blood cultures: Obtain before antibiotics if systemically ill
• Middle ear/mastoid cultures: From myringotomy or surgical specimens

2024 IDSA/ASM Microbiology Guidelines:

• Recommend Gram stain and aerobic/anaerobic culture from middle ear fluid (tympanocentesis) or mastoid tissue
• Swabs not recommended
• Emphasize culture-directed therapy for antibiotic stewardship

Imaging: 2025 ACR Appropriateness Criteria

ACR Appropriateness Criteria (2025) provide evidence-based imaging guidance:

CT temporal bone with IV contrast (imaging of choice):

• High spatial resolution for assessing bony erosion, coalescence, and cortical destruction
• IV contrast improves detection of inflammatory tissue and abscesses
• Indications: Failure to improve in 48 hours, clinical deterioration, or suspected complications

CT findings:

• Opacification of mastoid air cells
• Loss of bony septae (coalescence)
• Cortical erosion
• Subperiosteal abscess
• Intracranial complications (epidural abscess, sigmoid sinus thrombosis)

MRI head and IAC without and with IV contrast:

• Superior to CT for intracranial complications (higher sensitivity and specificity)
• Better soft tissue differentiation for labyrinth involvement and juxta-osseous enhancement
• Preferred when intracranial complications clinically suspected
• MR venography for sigmoid sinus thrombosis

ESR Guidelines (2025):

• Imaging not indicated for uncomplicated acute otomastoiditis
• Emergency imaging warranted only with: facial swelling, severe pain, neurological symptoms, or eye signs

Differential Diagnosis

• Acute otitis externa with postauricular lymphadenopathy
• Postauricular lymphadenitis
• Infected sebaceous cyst
• Langerhans cell histiocytosis
• Rhabdomyosarcoma
• Bezold Abscess (extension into sternocleidomastoid)
• Chronic mastoiditis with acute exacerbation

Management

Evidence-Based Treatment Algorithm

Recent systematic reviews provide specific guidance for treatment stratification based on disease severity:

Treatment success rates by modality:

Treatment Modality	Success Rate (95% CI)
Mastoidectomy	99.7% (77.5%-100%)
Myringotomy ± tubes	94% (84.5%-97.8%)
SPA drainage + myringotomy	86.5% (66.4%-95.4%)
Medical therapy alone	72.9% (60.5%-82.5%)

Definition of "Uncomplicated" Mastoiditis

Critical distinction (2024): Truly uncomplicated mastoiditis should exclude any bony erosion (including coalescence), not just SPA/intracranial complications.

Using this stricter definition:

• 36.2% of cases are truly uncomplicated (vs 46.3% with traditional definition)
• No patients with truly uncomplicated disease required mastoidectomy
• These patients can receive shorter antibiotic courses

Tiered Management Algorithm

TIER 1: Uncomplicated Mastoiditis (no bony erosion, no SPA, no intracranial complications):

• First-line: IV antibiotics alone — 95.9% cure rate
• Consider myringotomy for culture/drainage
• 48-72 hour trial before escalating to surgery
• Shorter antibiotic courses (10-14 days total) adequate

TIER 2: Subperiosteal Abscess:

• Needle aspiration + myringotomy: Successful in 83.6% of cases, avoiding mastoidectomy
• Mastoidectomy if aspiration fails or extensive abscess

TIER 3: Intracranial Complications or Treatment Failure:

• Mastoidectomy + antibiotics — superior outcomes with greater reduction in complications at discharge and follow-up
• Failed medical therapy (48-72 hours): Proceed to mastoidectomy
• Neurosurgical consultation for intracranial abscess drainage

Medical Management

Empiric antibiotic regimens (updated for current microbiology):

Standard empiric therapy:

• Ceftriaxone 50-100 mg/kg IV daily (pediatric) or 2 g IV daily (adult)
• Provides coverage for S. pyogenes, S. pneumoniae, H. influenzae
• Consider adding metronidazole 7.5 mg/kg IV q8h for Fusobacterium coverage given increased prevalence

Severe disease or suspected intracranial complications:

• Vancomycin 15 mg/kg IV q6h PLUS ceftriaxone or cefepime
• Metronidazole for anaerobic coverage

Antibiotic stewardship considerations:

• Routine vancomycin may not be necessary in most cases given low MRSA rates in many centers
• Culture-directed therapy preferred over prolonged empiric broad-spectrum coverage
• Shorter courses (10-14 days total) adequate for uncomplicated cases without affecting readmission rates
• Oral step-down therapy appropriate for most patients (73% in one series) once clinically improving

Adjunctive therapy:

• Myringotomy with or without tube placement for middle ear drainage
• Topical antibiotic drops if tube placed or tympanic membrane perforated
• Antipyretics and analgesics

Surgical Management

Indications for mastoidectomy:

• Intracranial complications
• Failed medical therapy after 48-72 hours of IV antibiotics
• Large subperiosteal abscess not amenable to needle aspiration
• Cholesteatoma
• Facial nerve paralysis
• Labyrinthitis

Surgical techniques:

Cortical (simple) mastoidectomy:

• Removal of mastoid cortex and air cells
• Preserves canal wall and middle ear
• Most common procedure for acute mastoiditis

Canal wall-down mastoidectomy:

• Reserved for cholesteatoma or extensive disease
• Removes posterior canal wall creating mastoid bowl

Abscess drainage:

• Incision and drainage of subperiosteal abscess
• Often combined with cortical mastoidectomy
• Needle aspiration increasingly successful as first-line for SPA

Evolving Surgical Trends

U.S. national trends (2010-2019) show successful shift toward more conservative management:

• Myringotomy: Decreased from 64% (2010) to 47% (2019) (p < .001)
• Mastoidectomy: Decreased from 22% (2010) to 10% (2019) (p < .001)
• Overall surgical rate: 57.5% of patients

Outcomes remain excellent despite less surgery:

• 30-day readmission rates: Similar between surgical and non-surgical groups
• In-hospital mortality: Similar between groups
• ICU utilization higher in surgical group (8.6% vs 2.2%) reflects disease severity, not surgical complications

Outcomes

Complications

Extracranial complications:

• Subperiosteal abscess: Now 95% of cases in post-COVID era (most common)
• Bezold Abscess (extension into neck along sternocleidomastoid muscle)
• Facial nerve paralysis
• Labyrinthitis with sensorineural hearing loss
• Petrositis (Gradenigo syndrome)
• Lemierre syndrome (internal jugular vein thrombophlebitis) — associated with F. necrophorum

Intracranial complications (dramatic increase in post-COVID era):

Complication	Historical Rate (pre-COVID)	Post-COVID Rate (2021-2024)
Intracranial complications (any)	4-6%	39%
Subperiosteal abscess	14-25%	95%
Lateral sinus thrombosis	2-4%	25%
Extradural empyema	1-2%	29%
Meningitis	2-4%	Increased
Brain abscess	1-2%	Increased

Prognosis

With appropriate treatment, prognosis remains excellent:

• Mortality remains rare (<1%) in developed countries even with increased complications
• Complete resolution without sequelae in majority of cases
• Hearing loss: Usually conductive and reversible; sensorineural loss rare
• Recurrence: Approximately 3-5% with adequate treatment

Prognostic factors associated with complications:

• Older age: Associated with complications
• Elevated CRP: Associated with complications
• Prehospital antibiotic use: Associated with complications (possibly marker of delayed diagnosis or resistant organisms)

Surgical rates have increased in post-COVID era:

• Mastoidectomy performed: 54% (2021-2024) vs 33% (2001-2008)
• Reflects increased disease severity, not change in indications

See Also

• Bezold Abscess
• Citelli Abscess
• Acute Otitis Media
• Chronic Suppurative Otitis Media
• Cholesteatoma
• Sigmoid Sinus Thrombosis
• Gradenigo Syndrome