Mastoiditis and intracranial complications

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Acute mastoiditis is more than a prolonged painful ear infection. Inflammation within the connected middle-ear and mastoid spaces can progress to bony destruction and collections, with potential access to nearby venous and intracranial structures. The familiar swollen area behind the ear is a useful sign, but the clinician must also look for a child who is becoming less interactive, vomiting repeatedly or developing a new squint. These changes may be more important than the amount of discharge in the canal.

Management is a coordinated hospital process. Resuscitation, microbiological sampling, antimicrobial treatment, imaging and surgical decisions often proceed in parallel. The purpose of imaging is to identify anatomy and complications that change treatment, not to delay action in an unstable patient. Some uncomplicated cases respond to intravenous treatment and close observation; others require early drainage. A decision to observe must include repeated examination and a clear trigger for intervention.

Key points

The middle-ear cleft communicates with mastoid air cells, allowing acute infection to extend into the mastoid.
Clinical mastoiditis is suggested by painful postauricular inflammation and displacement of the pinna.
Mastoid fluid on a scan alone does not establish acute mastoiditis or mandate surgery.
Intracranial infection can occur even when classic external mastoid findings are absent.
Initial hospital treatment commonly includes intravenous antibiotics, analgesia and close reassessment.
Collections, destructive disease, complications or inadequate response may require operative drainage and mastoid surgery.
CT is useful for temporal bone and collections; MRI is particularly useful when intracranial involvement is suspected.
Route and duration of antibiotics depend on response, source control and the specific complication.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Extension from acute otitis media

An acute middle-ear infection can involve the communicating mastoid air-cell system. Ask about the preceding illness and antibiotics while recognising that complications can occur despite treatment having already begun.

Underlying chronic ear disease

A chronically diseased ear or cholesteatoma can create a different microbial and anatomical context. Previous surgery, resistant isolates and recurrent discharge should influence specialist assessment and empirical antibiotic selection.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Inflammation and coalescence
Exudate within mastoid cells may progress to destruction of the bony partitions between them. Coalescent disease is therefore a structural complication, whereas uncomplicated fluid within air cells is a less specific imaging finding.
2
Subperiosteal extension
Infection can reach the outer mastoid surface and lift the periosteum, producing a collection behind the ear. Fluctuance and pinna displacement make the need for drainage an urgent specialist question.
3
Intracranial and venous pathways
Spread can involve the meninges, adjacent brain or dural venous sinuses. Neurological features may arise without striking external mastoid inflammation, so examination must extend beyond the ear.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Assess the whole patient first

Check observations, perfusion, hydration, interaction and level of consciousness. A distressed or lethargic child should not undergo a prolonged ear examination before urgent physiological needs have been addressed.

Inspect behind and within the ear

Look for swelling, tenderness, fluctuance and a changed pinna position, then assess the canal and drum as tolerated. Describe the anatomical findings clearly when contacting the receiving team.

Ask targeted neurological questions

Ask about headache pattern, persistent vomiting, visual change, double vision, limb function and walking. In young children, a new hand preference or covering one eye may reveal a deficit they cannot describe.

Follow the trajectory after treatment

Record whether fever, pain and local swelling improve after initial therapy. Persistent or worsening findings require reassessment of source control and complications, rather than reassurance that an IV antibiotic has been prescribed.

Red flags requiring action

Tender postauricular swelling, fluctuance, loss of the ear crease or a pinna pushed outwards suggests infection involving the mastoid or a subperiosteal collection.
A headache that is severe despite analgesia, worse when lying down or associated with persistent vomiting requires assessment for intracranial complications.
Drowsiness, meningism, diplopia, visual deterioration, new limb weakness or unsteady gait requires urgent senior review and neuro-otological imaging.
Shock, rapidly worsening physiology or a toxic appearance requires resuscitation and urgent assessment of the need for drainage.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Blood tests and microbiologyFirst step
Why
Assess inflammatory burden and guide antimicrobial treatment safely.
Interpretation and limitations
Hospital assessment usually includes FBC, CRP, blood cultures, renal function and other tests directed by severity. Obtain discharge or operative samples where possible, without postponing time-critical treatment in sepsis.
02
Contrast-enhanced CT of relevant temporal-bone and intracranial anatomy
Why
Identify bony destruction, a drainable collection or extension requiring intervention.
Interpretation and limitations
ENT and radiology should agree the appropriate study. Interpret mastoid opacification with bony changes and the examination; fluid alone is not equivalent to coalescent mastoiditis.
03
MRI of brain and petrous bones when indicated
Why
Define suspected intracranial, dural or venous complications more fully.
Interpretation and limitations
Neurological symptoms or concerning CT findings may require MRI with sequences selected for the suspected complication. Imaging choice must fit clinical urgency, availability and the need for anaesthetic support in a child.
04
Lumbar puncture only after an appropriate safety assessment
Why
Investigate suspected accompanying meningitis when the procedure can be performed safely.
Interpretation and limitations
New focal neurological signs or risk of an evolving space-occupying lesion require imaging and specialist assessment; do not perform lumbar puncture until the relevant risk factors have resolved. NICE NG240 advises blood sampling, antibiotics and stabilisation before imaging in this situation. A scan must not delay treatment, and completing one does not automatically make lumbar puncture safe.
05
Serial examination and subsequent hearing assessment
Why
Measure treatment response and identify functional consequences after recovery.
Interpretation and limitations
Repeated observations, neurological assessment and review of mastoid findings detect deterioration that a baseline scan cannot predict. Hearing assessment after the acute illness establishes any continuing deficit or need for rehabilitation.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Otitis externa with periauricular cellulitis

A swollen painful canal can produce surrounding skin inflammation and mimic mastoid disease. The drum, canal, postauricular anatomy and wider clinical picture help distinguish the likely origin.

Postauricular lymphadenitis

An inflamed lymph node may produce a local tender lump behind the ear. Its relationship to the pinna, mastoid surface and preceding illness should be assessed rather than relying on location alone.

Uncomplicated mastoid opacification

Fluid may be seen in mastoid air cells during middle-ear disease or incidentally on imaging. A radiological description must be reconciled with symptoms, bony findings and specialist examination.

Alternative intracranial illness

Meningitis, venous thrombosis or an intracranial mass may present with headache and neurological change. An ear abnormality should not prevent assessment of other causes or the wider emergency pathway.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Initial hospital careStabilise and start coordinated treatmentFirst stepClinical findings suggest mastoiditis or a complication of middle-ear infection.

1Arrange urgent ENT and senior paediatric or adult medical assessment, with anaesthetic or critical-care help for threatened airway or physiological instability.
2Assess and treat airway, breathing and circulation, give appropriate analgesia and address dehydration using the age-appropriate acute-care pathway.
3Obtain cultures promptly where feasible and start empirical intravenous antibiotics from the current hospital pathway without waiting for elective imaging.
4Agree the need and urgency for CT or MRI, especially when a collection or intracranial extension is suspected.

02Source controlDecide whether drainage is requiredExamination, imaging or treatment response suggests a collection or ongoing destructive infection.

1Have ENT review the clinical and imaging findings together, including any subperiosteal collection, bony erosion and evidence of chronic disease.
2Consider drainage with middle-ear ventilation and mastoid surgery according to the identified source and the child’s or adult’s condition.
3If intracranial disease is present, involve neurosurgery and infection specialists promptly to coordinate drainage and appropriate antimicrobial penetration.
4EscalationIf initial medical management is chosen, arrange close reassessment; failure to improve within the specialist review period or any deterioration demands escalation.

03Recovery and dischargeSwitch treatment only after clinical reviewThe patient is improving and the source-control plan is established.

1Review fever, pain, local findings, neurological state, oral intake and laboratory trends before deciding that inpatient IV care is no longer required.
2Select an oral agent and total duration with ENT and microbiology, taking culture results and any intracranial complication into account.
3Use an outpatient IV service only when its monitoring, daily review where required and family circumstances support safe treatment.
4Provide clear return advice and arrange ENT and hearing follow-up, ensuring that the underlying ear disease is also addressed.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

One current local first-line regimen for acute mastoiditis when allergy, previous microbiology and the clinical extent make it appropriate.

Intravenous co-amoxiclav for selected adult mastoiditis

The NHS Forth Valley adult hospital pathway uses co-amoxiclav 1.2 g intravenously every eight hours, adjusted for renal impairment. Its total treatment range is seven to fourteen days, with longer treatment for severe or extensive disease and an individually reviewed IV-to-oral switch.

Avoid with penicillin hypersensitivity, a previous severe immediate reaction to another beta-lactam or previous co-amoxiclav-associated jaundice or hepatic dysfunction. Check renal dosing, liver function and relevant interactions. This adult regimen is not a paediatric dose or a sufficient universal regimen for intracranial infection; resistant Pseudomonas and other specific pathogens require a different specialist plan.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Subperiosteal or deeper abscess

A collection may persist despite an antibiotic that is microbiologically active. Drainage obtains useful samples and provides source control when specialist assessment identifies an operative indication.

Hearing and facial nerve injury

Local disease can impair sound transmission, injure the inner ear or affect the facial nerve. Document baseline hearing and facial movement, and protect the cornea if eye closure is impaired.

Meningitis and intracranial abscess

Intracranial spread can threaten life and neurological function. Treatment requires antibiotics appropriate for the central nervous system, specialist imaging and neurosurgical assessment when a collection is present.

Dural venous sinus thrombosis

Septic venous complications require coordinated infection, ENT and neurological expertise. Anticoagulation is an individual multidisciplinary decision alongside source control, not a universal automatic treatment for every mastoid infection.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Repeat age-appropriate observations and neurological assessment at a frequency matching illness severity.
Review postauricular swelling, pain and fever for improvement, and re-escalate promptly if the trajectory is unsatisfactory.
Monitor renal function, antimicrobial adverse effects and culture results while revising treatment as necessary.
Ensure an improving CRP does not override new headache, cranial nerve findings or another concerning examination change.
After discharge confirm follow-up of hearing, membrane healing and any underlying cholesteatoma or recurrent middle-ear disease.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

An imaging word is not the whole diagnosis

A report of mastoid fluid requires clinical interpretation. Conversely, a patient with neurological red flags needs investigation for intracranial disease even when external mastoid swelling is absent.

Source control may be decisive

Continuing the same antibiotic may not resolve a walled collection. Repeated clinical review and operative assessment are part of infection treatment, rather than evidence that medical care has failed as a concept.

Separate ordinary and intracranial regimens

A local mastoiditis antibiotic table cannot be applied unchanged to meningitis or brain abscess. The infected compartment, likely organisms and adequate central nervous system exposure determine the specialist regimen.

Duration follows the disease

The BSAC paediatric pathway describes fourteen days for mastoiditis in its relevant treatment branch, while the adult Forth Valley table gives seven to fourteen days and longer for extensive disease. Neither is a universal stop date for intracranial complications.

11Common pitfallsFrequent interpretation and management errors.

01
Do not send a child with convincing mastoiditis home with only routine AOM safety-netting.
02
The absence of classic mastoid swelling does not exclude an intracranial complication of ear infection.
03
A scan showing fluid alone should not be treated as proof that mastoid surgery is necessary.
04
Do not delay urgent antimicrobial treatment while waiting for a scan or an operative sample in an unstable patient.