Subdural Empyema & Other Intracranial Infections

What is subdural empyema, and where does it fit among intracranial infections?

A severe intracranial infection—most often a complication of an otherwise “routine” sinus or middle-ear infection.

Subdural empyema is a collection of pus between the dura and arachnoid membranes, within the subdural space. It is classified among pyogenic intracranial infections and accounts for roughly 15–25% of pediatric intracranial suppurative collections in reported series.

It is most commonly associated with:

• severe or undertreated sinusitis (especially frontal or ethmoid),
• otitis media / mastoiditis,
• bacterial meningitis,
• head trauma or recent neurosurgery.

Closely related entities include cranial epidural abscess (located outside the dura) and bacterial meningitis, which may coexist or precede the empyema. These conditions require tight coordination between pediatrics, infectious diseases, ENT, and pediatric neurosurgery.

How common is it, and which children are at highest risk?

Rare overall, but an important proportion of the most serious pediatric intracranial infections.

Subdural empyema can occur at any age, but it is more frequently seen in older children and adolescents, with a modest male predominance in many series.

Children at increased risk include:

• those with severe, prolonged sinusitis, particularly with forehead swelling,
• children with recurrent otitis media / mastoiditis,
• patients with immunosuppression or chronic medical conditions,
• children after head trauma or neurosurgical procedures,
• children hospitalized with pyogenic bacterial meningitis.

How does it develop? (Pathophysiology)

Most often, infection spreads from the paranasal sinuses or middle ear into the cranial cavity.

Pathogens can reach the subdural space through several mechanisms:

• Direct extension: erosion of the bony walls of a paranasal sinus (most commonly frontal or ethmoid) or the mastoid, allowing infection to spread intracranially.
• Septic thrombophlebitis of small mucosal veins with retrograde flow into intracranial venous channels.
• Hematogenous spread, particularly in immunocompromised children.
• Direct inoculation after trauma, skull fracture, or neurosurgical intervention.

Common organisms include streptococci (e.g., Streptococcus milleri group) and anaerobes, especially when sinusitis is the primary source. In post-traumatic or postoperative settings, Staphylococcus aureus and Gram-negative organisms may be involved. In up to about one-third of cases, cultures may be negative.

What symptoms are most typical?

It may start like a “bad virus” or sinus infection, then evolve with neurological symptoms and signs of raised intracranial pressure.

Common symptoms and clinical findings include:

• Fever, malaise, and severe headache.
• Meningeal signs: neck stiffness, photophobia.
• Seizures—up to 40% of children may present with a seizure as the first symptom.
• Behavioral or mental-status changes: lethargy, confusion, irritability, reduced alertness.
• Focal neurological deficits (weakness of an arm/leg or one side, speech disturbance, facial asymmetry).

ENT/extracranial findings that should heighten concern:

• marked periorbital swelling, redness, pain with eye movements,
• forehead swelling (“Pott’s puffy tumor”),
• proptosis, diplopia, pain with frontal/zygomatic pressure,
• persistent sinusitis that does not improve with antibiotics.

The combination of fever, severe headache, behavioral change, or seizures in a child with recent sinusitis warrants urgent neuroimaging.

How is it diagnosed? (CT, MRI, blood tests)

Diagnosis relies primarily on contrast-enhanced imaging; lumbar puncture is usually avoided.

Key diagnostic studies include:

• Contrast-enhanced CT of the brain — rapid and widely available; may show a subdural collection with rim enhancement.
• Contrast-enhanced MRI with diffusion sequences — provides higher detail regarding the empyema, its relationship to brain parenchyma, and associated findings such as dural venous sinus thrombosis, ischemia, cerebritis, or epidural abscess.
• Imaging of the paranasal sinuses and mastoids to identify the primary source of infection.

Laboratory evaluation:

• CBC, CRP, ESR — inflammatory markers are often elevated.
• Blood cultures — may identify the causative organism.

Lumbar puncture should NOT be performed when subdural empyema or raised intracranial pressure is suspected, as it may precipitate brain herniation. Clinical series have reported meaningful risk of deterioration (including fatal outcomes) after lumbar puncture in this context.

What complications and risks can occur?

Meaningful morbidity and mortality remain—hence the need for aggressive, coordinated treatment.

Without treatment, subdural empyema is considered almost universally fatal. Even with modern care, some children may experience:

• Permanent neurological deficits (weakness, epilepsy, language difficulties).
• Persistent seizures related to cortical scarring.
• Dural venous sinus thrombosis, stroke, or ischemia.
• Hydrocephalus or refractory intracranial hypertension requiring additional CSF diversion.
• Systemic complications related to sepsis.

Reported overall mortality in larger series remains around 10–15%. With prompt surgery + intensive care + infectious-disease management, more than 80% of children can achieve a good functional outcome.

When is it an emergency, and what should happen immediately?

Any suspicion of subdural empyema is a neurosurgical emergency.

Immediate action is required when, in a child with infection or severe sinusitis, any of the following occur:

• severe headache that persists or worsens,
• confusion, lethargy, or reduced level of consciousness,
• focal deficits or transient “numbness/weakness” episodes,
• seizures,
• forehead/eyelid swelling or pain with eye movements.

These features require urgent contrast-enhanced CT/MRI, hospital admission, initiation of broad-spectrum IV antibiotics, and immediate evaluation by a pediatric neurosurgeon.

How is it treated surgically, and when might medications be enough?

In most cases, surgical drainage is necessary.

Surgical management

The core principle is urgent drainage combined with intensive antimicrobial therapy. Typical approaches include:

• Craniotomy or craniectomy with wide exposure to drain all loculated compartments and relieve intracranial pressure.
• Copious subdural irrigation and culture acquisition.
• Use of intraoperative ultrasound to identify residual collections.
• In cases of profound intracranial hypertension, an extended decompressive craniectomy may be required with delayed bone-flap replacement.

Rarely, a very small, early collection in a neurologically stable child may be managed non-operatively with close clinical and imaging surveillance. This is the exception—not the standard approach.

Medical & supportive treatment

Alongside surgery, treatment typically includes:

• Broad-spectrum IV antibiotics with good CNS penetration—covering Gram-positive, Gram-negative, and anaerobic organisms—then tailored to culture data when available.
• A prolonged course is common (often ≥ 6 weeks), guided by infectious-disease specialists, serial imaging, and laboratory monitoring.
• Antiseizure medications for cortical irritation—prophylactically or following a seizure.
• Measures to control intracranial pressure (ICU-level care, head positioning, osmotherapy when indicated).

ICU admission is often required, particularly in the first several days.

What about cranial epidural abscess and bacterial meningitis?

Related infections that may require neurosurgical intervention or close collaboration with pediatric neurosurgery.

Cranial epidural abscess

A cranial epidural abscess forms outside the dura and also commonly arises from sinusitis or otitis/mastoiditis. The dura can act as a partial “barrier” between the abscess and brain, sometimes lowering the risk of seizures or venous thrombosis, but the same urgent principles apply: drainage + antibiotics.

Bacterial meningitis

Bacterial meningitis in children may present with fever, meningeal signs, headache, lethargy, and seizures. Diagnosis is typically based on CSF analysis (low glucose, high protein, neutrophilic pleocytosis, positive Gram stain).

Pediatric neurosurgical involvement is most relevant when:

• hydrocephalus develops and requires CSF diversion,
• there is an anatomical portal of entry (e.g., dermal sinus tract, cranio-spinal dysraphism),
• intracranial collections develop (empyema or abscess).

The cornerstone of therapy is early, targeted antibiotic treatment and—when appropriate—corticosteroids to reduce the risk of hearing loss and neurologic sequelae, always aligned with pediatric guideline-based care.

What is the prognosis, and what influences outcomes?

The earlier the diagnosis and treatment, the higher the likelihood of full recovery.

Key prognostic factors include:

• Level of consciousness at presentation—coma is associated with worse outcomes.
• Extent and location of infection (unilateral vs bilateral; supratentorial vs infratentorial).
• Time from symptom onset to diagnosis and surgery.
• Underlying immunosuppression or pre-existing neurologic disease.

With rapid recognition, timely surgical drainage, appropriate antimicrobial therapy, and close monitoring, many children recover with minimal or no lasting neurological deficits.

Practical guidance and tips for parents

From the first suspicion through discharge and recovery—what truly helps.

For families, an ICU admission for an intracranial infection is profoundly stressful. A few practical points:

• Do not hesitate to seek urgent emergency evaluation when an “ordinary” sinus infection is accompanied by severe headache, a seizure, or behavioral change.
• Ask your clinicians to explain in clear terms what the CT/MRI shows, the surgical plan, and which organisms are suspected.
• Clarify the expected duration of antibiotics and whether central venous access or home IV therapy may be needed.
• After discharge, monitor for headaches, mood changes, learning difficulties, or new seizures and update the care team promptly.
• Inform the school and request appropriate educational or psychological support as needed.