Mastoiditis

Mastoiditis is an acute bacterial infection of the mastoid air cells and surrounding cortex — the most common serious complication of acute otitis media (AOM). Once a leading cause of childhood mortality before the antibiotic era, it declined dramatically after penicillin's introduction, though a partial resurgence occurred as antibiotic-resistant organisms emerged. Today the condition remains a genuine emergency: untreated or inadequately treated mastoiditis can spread to the brain, lateral sinus, and meninges within days. Current incidence is approximately 4 per 100,000 children per year, with much lower rates in adults, making it uncommon but never trivial.

Table of Contents

1. What Is Mastoiditis?
2. Causes and Microbiology
3. Clinical Presentation
4. Complications
5. Diagnosis
6. Medical Treatment
7. Surgical Treatment: Cortical Mastoidectomy
8. Prognosis and Prevention
9. References
10. Featured Videos

What Is Mastoiditis?

The mastoid process is a prominent bony projection located directly behind the auricle (outer ear), forming part of the temporal bone of the skull. Inside this solid-appearing structure lies a honeycomb of air-filled spaces called mastoid air cells, which are lined with respiratory-type mucosa. These air cells are not sealed off from the middle ear — they communicate directly with it through a short channel called the aditus ad antrum, which connects to the mastoid antrum, the largest of the mastoid air cells. This anatomical continuity means that any infection of the middle ear has the potential to spread into the mastoid system with little obstruction.

The mastoid air cells are not present at birth; they develop progressively as pneumatization of the temporal bone occurs throughout childhood. This is why mastoiditis peaks in the 12-to-24-month age group — young children have well-developed mastoid air cells but immature immune responses and frequent ear infections. Adults are not immune: the same sequence of events can occur at any age, though it is considerably less common.

Mastoiditis exists on a spectrum. Simple or non-coalescent mastoiditis refers to mucosal inflammation within the mastoid air cells without bony destruction — this is actually visible on CT scan in nearly all cases of acute otitis media and is considered a normal radiographic accompaniment rather than a distinct disease. True surgical mastoiditis, also called acute coalescent mastoiditis, is a fundamentally different entity: bacteria have now dissolved the thin bony septa between air cells, creating a confluent pus-filled cavity within the mastoid bone. This coalescent stage signals structural bone destruction and demands urgent intervention. Without treatment, pus may break through the outer cortex to form a subperiosteal abscess, or track medially toward critical neurovascular structures.

The time from untreated acute otitis media to coalescent mastoiditis can be as short as two weeks, though it is typically longer. Many children have received some antibiotics for their ear infection that suppress but do not eradicate the infection, leading to a smoldering masked mastoiditis that may present with fewer classic signs of acute illness.

Causes and Microbiology

Mastoiditis arises when bacteria from an acute middle ear infection penetrate the mucosal lining of the mastoid air cells and establish themselves in the bone. The pathogen responsible largely determines the speed and severity of progression. Streptococcus pneumoniae is the most frequently identified organism overall, responsible for roughly 25–30% of culture-positive cases, and it accounts for a disproportionate share of uncomplicated acute mastoiditis. Streptococcus pyogenes (Group A Streptococcus) is less common but considerably more aggressive — Group A strep mastoiditis spreads faster, causes more extensive bone destruction, and is more likely to produce intracranial complications than pneumococcal disease.

Staphylococcus aureus has grown in importance over the past two decades, partly because of the rise of community-acquired methicillin-resistant S. aureus (CA-MRSA). MRSA mastoiditis is particularly concerning because standard empirical regimens that do not include anti-MRSA coverage will fail, allowing the infection to progress while the patient appears to be receiving treatment. Risk factors for MRSA involvement include recent hospitalization, household contact with known MRSA carriers, skin infections elsewhere, and failure to improve after 48 hours of standard IV antibiotics. Haemophilus influenzae (non-typeable strains) contributes another fraction of cases, particularly in younger children, though widespread vaccination against the typeable (Hib) strain has essentially eliminated that serotype as a cause.

Chronic mastoiditis has a different microbiological profile. Pseudomonas aeruginosa is the dominant pathogen when mastoiditis develops in the context of a pre-existing chronic ear condition, prolonged otorrhea, or previous ear surgery. Anaerobic organisms are more common in chronic disease than in acute presentations. Fusobacterium necrophorum, though rare, deserves special mention because it can produce Lemierre's syndrome — a life-threatening septic thrombophlebitis of the internal jugular vein that can occur alongside or secondary to mastoiditis, carrying a high mortality if not recognized early.

A critically important predisposing factor for chronic and recurrent mastoiditis is cholesteatoma — a destructive accumulation of keratinizing squamous epithelium within the middle ear and mastoid. Cholesteatoma erodes bone enzymatically and provides a protected niche for biofilm-forming bacteria. In a child or adult with recurrent or persistent mastoid disease, cholesteatoma must be excluded by CT imaging and, if necessary, surgical exploration. Biofilm formation on the surface of dead bone (sequestra) also explains why some cases of mastoiditis fail to respond to even appropriate IV antibiotics alone, requiring surgical debridement to eliminate the bacterial reservoir.

Clinical Presentation

The classic presentation of acute mastoiditis is memorable and, once seen, hard to miss. A child — most often between one and four years old — has had an ear infection for one to three weeks, either untreated or partially treated with antibiotics, and now develops a new constellation of findings: swelling, redness, and exquisite tenderness over the mastoid bone behind the ear, combined with forward and downward displacement of the auricle. The protrusion of the outer ear happens because pus accumulating in the subperiosteal space pushes the auricle forward and inferior; simultaneously, the soft tissue swelling behind the ear obliterates the normal post-auricular crease, giving the area a full, rounded appearance rather than the usual defined groove between ear and scalp. These three signs together — post-auricular swelling, displaced auricle, and absent post-auricular crease — constitute the classic triad that distinguishes mastoiditis from simple external otitis or a benign skin infection.

Before the ear findings become obvious, patients almost always have a history of the warning signs of progressive ear disease: persistent ear pain (otalgia), fever that failed to resolve on antibiotics or returned after initial improvement, and ear discharge (otorrhea) that may be profuse if the tympanic membrane has perforated. A period of apparent improvement followed by clinical deterioration is a classic and treacherous pattern — it reflects partial suppression of infection by antibiotics without true eradication, a phenomenon sometimes called masked or latent mastoiditis.

In infants under one year, the presentation can be atypical and deceptive. The mastoid process is poorly pneumatized at this age, so bony destruction may be limited even with significant infection, and the classic post-auricular swelling may be subtle or absent. Instead, clinicians may see only persistent fever, extreme irritability, poor feeding, and a bulging fontanelle if intracranial pressure is elevated. These features should prompt early imaging even without obvious post-auricular changes. In older children and adults, the systemic signs of infection are usually more prominent: high fever, elevated white count, and a patient who looks genuinely ill rather than simply uncomfortable.

On otoscopic examination, the tympanic membrane is usually dull, thickened, and bulging, or may be perforated with active purulent discharge in the ear canal. The posterior canal wall may sag inward from pressure of the subperiosteal abscess, a finding sometimes called posterior canal wall sagging or prolapse. Granulation tissue or an aural polyp in the ear canal suggests either cholesteatoma or long-standing chronic infection. Cervical lymphadenopathy is common. Any new neurological finding — facial weakness, diplopia, headache, neck stiffness, altered mental status — signals potential intracranial extension and demands immediate escalation of the workup and management.

Complications

The complications of mastoiditis divide anatomically into intratemporal (confined to the temporal bone and its immediate surroundings) and intracranial (extending into the cranial vault). Both categories can be life-altering or fatal. The most common complication overall is the subperiosteal abscess — pus that has eroded through the lateral cortex of the mastoid and collected beneath the periosteum overlying the bone. This produces the classic post-auricular bulge and is present in 20–30% of hospitalized mastoiditis cases at presentation. Though alarming in appearance, a subperiosteal abscess confined to the post-auricular space is actually the least dangerous complication, because drainage is straightforward and the pus has not yet reached the brain.

More dangerous intratemporal complications include Bezold abscess, in which pus tracks inferiorly from the mastoid tip along the inner surface of the sternocleidomastoid muscle and into the neck. This can produce a firm, tender neck mass with restricted neck movement and may be mistaken for cervical lymphadenitis or a deep neck space infection. Facial nerve palsy — paralysis of CN VII — occurs when inflammation or pus compresses or invades the fallopian canal through which the facial nerve runs within the temporal bone. This is a surgical emergency requiring prompt mastoidectomy to decompress the nerve. Labyrinthitis is a serious complication involving spread of infection to the cochlea and semicircular canals, producing profound sensorineural hearing loss and severe vertigo; labyrinthitis ossificans (calcification of the cochlea) can occur if treatment is delayed, permanently eliminating the option of cochlear implantation. Petrositis, inflammation of the petrous apex of the temporal bone, causes Gradenigo's syndrome: the classic triad of ipsilateral abducens palsy (double vision due to CN VI paresis), facial pain (CN V involvement), and chronic otorrhea.

Intracranial complications are the gravest consequences of mastoiditis and constitute true neurological emergencies. Meningitis — usually bacterial — is the most common intracranial complication, occurring when infection tracks through the thin tegmen (roof of the middle ear and mastoid) into the subarachnoid space. Epidural abscess forms between the dura and the inner table of the temporal bone; subdural empyema accumulates between the dura and arachnoid. Brain abscess typically develops in the temporal lobe (directly above the infection) or the cerebellum (adjacent to the posterior fossa surface of the mastoid), and can expand rapidly with devastating mass effect. Lateral sinus thrombosis — thrombophlebitis of the sigmoid or transverse dural venous sinus — occurs when infection erodes through the sinus plate of the mastoid, causing the venous sinus to clot; infected thrombus may break off and produce septic pulmonary emboli or stroke. Cavernous sinus thrombosis, involving the venous sinus behind the eye, is rare but causes bilateral proptosis and ophthalmoplegia and carries a mortality rate that historically exceeded 50%.

Every one of these intracranial complications requires immediate CT and/or MRI imaging, neurosurgical consultation, and aggressive IV antibiotics. The combination of mastoiditis plus any neurological finding beyond mild conductive hearing loss must never be managed conservatively with outpatient antibiotics — these patients belong in a hospital with otolaryngology and neurosurgery on site.

Diagnosis

The diagnosis of mastoiditis begins clinically: the triad of post-auricular swelling, displaced auricle, and loss of post-auricular crease in a child with a history of recent ear infection is sufficient to initiate emergency evaluation and empirical IV antibiotics even before imaging is complete. However, imaging is essential both to confirm coalescent bone destruction, define the extent of disease, identify subperiosteal or intracranial complications, and guide the surgical plan.

CT of the temporal bones with contrast is the gold-standard initial imaging study for suspected mastoiditis. Non-enhanced CT will show opacification (clouding) of mastoid air cells, which alone is not diagnostic of true surgical mastoiditis since it occurs in simple otitis media as well. The critical CT findings that define coalescent mastoiditis are loss of the fine bony septa between mastoid air cells, creating a confluent cavity, and erosion of the mastoid cortex. Contrast enhancement identifies periosteal reaction and the rim of a subperiosteal abscess. CT also evaluates the tegmen (roof), the sigmoid sinus plate, and the integrity of the inner ear structures — all relevant when planning surgery and assessing complication risk. CT is fast, widely available, and excellent for bony architecture, making it ideal for the emergency setting.

MRI with gadolinium contrast is superior to CT for evaluating intracranial extension. MRI with diffusion-weighted imaging (DWI) is the most sensitive method for detecting brain abscess, because abscesses restrict diffusion and appear bright on DWI with corresponding low signal on ADC maps. MRI also provides definitive diagnosis of dural sinus thrombosis (via MR venography), epidural and subdural collections, and meningeal enhancement. In any patient with neurological symptoms, mental status changes, or high clinical suspicion for intracranial spread, MRI should follow CT or replace it when CT findings are ambiguous.

Laboratory evaluation supports the clinical picture but does not establish or exclude the diagnosis. Complete blood count typically shows leukocytosis with a neutrophil predominance. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are elevated and useful for tracking treatment response over subsequent days. Blood cultures are positive in approximately 15% of cases — a minority, but enough to justify drawing cultures before antibiotics are started. The highest-yield culture specimen is fluid from the middle ear obtained by myringotomy (surgical incision of the tympanic membrane) or tympanocentesis. This procedure is both diagnostic and therapeutic: it drains the middle ear, provides culture material that directly reflects the causative organism, and is routinely performed in the operating room in conjunction with mastoidectomy or as a standalone procedure in milder presentations. Lumbar puncture for cerebrospinal fluid analysis is indicated whenever bacterial meningitis is clinically suspected, but should be preceded by CT to exclude elevated intracranial pressure if the patient has focal neurological signs or altered consciousness.

Medical Treatment

IV antibiotics are the cornerstone of treatment and must be started immediately upon clinical diagnosis — do not wait for culture results, CT results, or specialist consultation before initiating empirical therapy. The initial antibiotic choice must provide broad coverage against the most likely pathogens (S. pneumoniae, Group A strep, S. aureus, and H. influenzae) while also achieving adequate CNS penetration in case of meningeal involvement. Common empirical regimens include ampicillin-sulbactam (good polymicrobial coverage including beta-lactamase producers), or a third-generation cephalosporin such as ceftriaxone or cefotaxime combined with a separate anti-staphylococcal agent when S. aureus is a concern. Ceftriaxone alone, at meningitic dosing of 100 mg/kg/day, provides excellent CNS penetration and covers most streptococcal species but lacks reliable S. aureus activity.

MRSA coverage must be added if local epidemiology, clinical risk factors, or failure to improve after 48 hours raises the possibility of methicillin-resistant infection. Vancomycin remains the first-line agent for proven or suspected MRSA, with the dose titrated to achieve adequate serum trough or AUC targets. Clindamycin is an alternative for non-bacteremic, non-CNS disease in communities with low clindamycin-resistance rates among MRSA isolates, but should not be used if CNS extension is a concern because CNS penetration is unreliable. Culture and sensitivity results from myringotomy fluid or blood cultures are used to de-escalate or refine the antibiotic regimen as soon as they are available, typically within 48–72 hours.

Myringotomy and tympanostomy tube (ventilation tube) insertion is a critical adjunct to antibiotic therapy. By creating an opening in the tympanic membrane, myringotomy drains infected middle ear fluid, equalizes pressure between the middle ear and the nasopharynx, and provides a specimen for culture. In children who present with acute mastoiditis but without CT evidence of coalescent bone destruction or subperiosteal abscess, myringotomy combined with IV antibiotics may be sufficient — several pediatric series have reported success rates of 60–80% with this conservative approach. However, the threshold for escalating to cortical mastoidectomy varies considerably between centers, and there is ongoing debate in the otolaryngology literature about the precise indications for surgery versus medical management alone.

The duration of IV antibiotic therapy is typically two to three weeks for uncomplicated coalescent mastoiditis, with a transition to oral antibiotics once the patient has been afebrile for 48–72 hours, clinical examination shows improvement, and inflammatory markers are trending downward. Oral step-down agents must cover the identified pathogen and achieve adequate tissue levels; amoxicillin-clavulanate is commonly used when organisms are susceptible. In cases with intracranial complications, IV therapy is continued substantially longer — often four to six weeks — in consultation with infectious disease and neurosurgery specialists. Follow-up audiometry after completion of treatment is recommended to document any persistent conductive or sensorineural hearing loss.

Surgical Treatment: Cortical Mastoidectomy

Cortical mastoidectomy is the definitive surgical treatment for coalescent mastoiditis and remains one of the most important operations in pediatric otolaryngology. The procedure involves removing the outer cortex of the mastoid bone and systematically drilling out all infected mastoid air cells until healthy bone margins are reached, draining any abscess cavities, and ensuring the mastoid antrum is widely open to the middle ear. The canal wall (the posterior bony wall of the external auditory canal) is preserved during a simple cortical mastoidectomy — this is an important distinction from radical or modified radical mastoidectomy, procedures reserved for cholesteatoma in which the canal wall is taken down and the mastoid bowl is permanently exteriorized.

Indications for cortical mastoidectomy include CT-confirmed coalescent mastoiditis with bony septa destruction, a subperiosteal abscess requiring surgical drainage (the majority of centers drain these surgically rather than with needle aspiration alone), failure to show clinical improvement after 24–48 hours of appropriate IV antibiotics and myringotomy, any intracranial complication, and suspected cholesteatoma. The last two indications are essentially absolute — intracranial extension requires simultaneous neurosurgical management, and cholesteatoma will not resolve with antibiotics alone and will continue to erode bone until surgically removed.

The procedure is performed under general anesthesia through a post-auricular incision placed directly behind the ear in the natural skin crease. After incision through skin and periosteum, the surgical field reveals the mastoid cortex; any subperiosteal abscess is immediately encountered and drained, with pus sent for culture. A drill with cutting and diamond burrs is then used to remove the outer cortex and progressively excavate the infected mastoid air cells. Key surgical landmarks include the mastoid antrum (the "sentinel cell" that guides orientation to the middle ear), the sigmoid sinus plate (the medial wall of the mastoid, protecting the venous sinus), the tegmen plate (the superior wall, protecting the dura of the middle cranial fossa), and the posterior canal wall. Injury to the sigmoid sinus can cause significant venous bleeding, requiring pressure or packing. Facial nerve monitoring is used routinely, since the facial nerve runs through the mastoid in its fallopian canal and can be at risk near the stylomastoid foramen inferiorly and at the second genu of the nerve in the middle ear.

Myringotomy and tympanostomy tube insertion are typically performed simultaneously with mastoidectomy, ensuring ongoing drainage of the middle ear during the postoperative period. After surgery, the post-auricular incision is closed and a mastoid pressure dressing is applied. IV antibiotics are continued postoperatively, with the duration determined by the extent of disease and culture results. Prognosis after timely cortical mastoidectomy for uncomplicated coalescent mastoiditis is excellent, with recurrence rates well below 5%. Tympanoplasty to repair a persistent tympanic membrane perforation may be needed months later, once the ear has been fully healed and free of infection, but many perforations close spontaneously after the underlying infection is eradicated.

Prognosis and Prevention

The overall prognosis for mastoiditis treated promptly with appropriate IV antibiotics and, when indicated, cortical mastoidectomy is excellent. Children who receive timely care for uncomplicated disease have normal hearing outcomes in the great majority of cases, low rates of recurrence, and no long-term structural ear problems. The exception is labyrinthitis with sensorineural hearing loss — once the cochlea is damaged by infection, the sensorineural loss is usually permanent and may be severe enough to require hearing aids or cochlear implantation. This outcome is avoidable with early diagnosis, which is why delayed or inadequate treatment of AOM — particularly in children who have already received repeated antibiotic courses and may appear partially treated — deserves careful clinical reassessment.

Complicated mastoiditis carrying intracranial extension changes the prognosis picture substantially. Historical series reported mortality rates of 5–10% for intracranial complications of mastoiditis, and significant morbidity — including stroke, persistent neurological deficits, and epilepsy — in survivors. Modern outcomes are better due to advances in neurosurgical technique, ICU care, and antibiotic options, but these complications remain serious and require multidisciplinary management by otolaryngology, neurosurgery, infectious disease, and neurology teams. Dural sinus thrombosis in particular carries stroke risk that persists for weeks after the infection itself is controlled, requiring careful anticoagulation decisions.

Prevention of mastoiditis centers on prevention and timely treatment of acute otitis media. The pneumococcal conjugate vaccines — PCV7, PCV13, and the newer PCV15 and PCV20 formulations — have had a measurable impact on mastoiditis incidence in countries with high vaccination coverage. Since S. pneumoniae causes the plurality of mastoiditis cases, reducing pneumococcal AOM reduces the pool of cases that can progress to mastoid involvement. Population-level data from Sweden and the Netherlands documented a real decline in mastoiditis incidence following widespread PCV adoption, though the magnitude was modest (20–30% reduction) because non-vaccine serotypes and other organisms continued to cause disease.

The appropriate treatment of individual cases of AOM is a more complex prevention question. Systematic undertreatment of AOM — a strategy promoted to reduce antibiotic overuse — may allow some infections to persist long enough to progress to mastoiditis, particularly in high-risk groups: children under two, immunocompromised patients, those with structural ear disease, and those in whom the infecting organism is inherently more invasive (Group A strep, MRSA). Conversely, overtreatment drives resistance, reducing the efficacy of the antibiotics that are needed when mastoiditis does develop. The balanced approach endorsed by major pediatric infectious disease societies — prompt treatment in high-risk groups, watchful waiting with follow-up in low-risk older children — appears to achieve reasonable mastoiditis prevention without maximizing antibiotic overuse. Parents and clinicians should be taught to recognize the warning signs of mastoiditis (persistent ear pain after antibiotic initiation, new post-auricular swelling, returning fever after initial improvement) and to seek urgent evaluation rather than awaiting a scheduled follow-up appointment.

References

1. Tamir S et al. Acute mastoiditis in children: current diagnosis and treatment. Int J Pediatr Otorhinolaryngol. 2017. PMID 28846877.
2. Groth A et al. Acute mastoiditis in children aged 0–16 years — a national study of 678 cases in Sweden. Int J Pediatr Otorhinolaryngol. 2012. PMID 22967743.
3. van Zuijlen DA et al. National differences in incidence of acute mastoiditis: relationship to prescribing patterns of antibiotics for acute otitis media. Pediatr Infect Dis J. 2001. PMID 11734766.
4. Laulajainen-Hongisto A et al. Mastoiditis in children. Curr Infect Dis Rep. 2016. PMID 25148016.
5. Psarommatis I et al. Acute mastoiditis in children: the "conservative" approach and indications for surgery. Int J Pediatr Otorhinolaryngol. 2012. PMID 26553472.
6. Luntz M et al. Acute mastoiditis: the antibiotic era: a multicenter study. Int J Pediatr Otorhinolaryngol. 2001. PMID 11557012.
7. Quesnel S et al. Acute mastoiditis in children: a retrospective study of 188 patients. Int J Pediatr Otorhinolaryngol. 2010. PMID 18055913.
8. Palma S et al. Prevalence of intracranial complications in patients with acute mastoiditis. Otol Neurotol. 2006. PMID 16540476.
9. Anthonsen K et al. Acute mastoiditis: microbiology and treatment. Int J Pediatr Otorhinolaryngol. 2011. PMID 21353303.
10. Brodsky L et al. Subperiosteal abscess. Otolaryngol Head Neck Surg. 2014. PMID 24581924.
11. Roddy MG et al. Intracranial extension of acute mastoiditis. Pediatr Emerg Care. 2001. PMID 11399007.
12. Taylor MF et al. Pediatric mastoiditis. Otolaryngol Clin North Am. 2017. PMID 27662498.

Search PubMed for more research: Acute mastoiditis treatment · Mastoiditis intracranial complications

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