(See also Introduction to Brain Infections Introduction to Brain Infections Brain infections can be caused by viruses, bacteria, fungi, or, occasionally, protozoa or parasites. Encephalitis is most commonly due to viruses, such as herpes simplex, herpes zoster, cytomegalovirus... read more .)
Etiology
Cranial epidural abscess and subdural empyema are usually complications of sinusitis Sinusitis Sinusitis is inflammation of the paranasal sinuses due to viral, bacterial, or fungal infections or allergic reactions. Symptoms include nasal obstruction and congestion, purulent rhinorrhea... read more (especially frontal, ethmoidal, or sphenoidal) or otitis media Otitis Media (Chronic Suppurative) Chronic suppurative otitis media is a persistent, chronically draining (> 6 weeks), suppurative perforation of the tympanic membrane. Symptoms include painless otorrhea with conductive hearing... read more
, but they can follow other ear infections, cranial trauma or surgery, or, rarely, bacteremia. Pathogens are similar to those that cause brain abscess Etiology A brain abscess is an intracerebral collection of pus. Symptoms may include headache, lethargy, fever, and focal neurologic deficits. Diagnosis is by contrast-enhanced MRI or CT. Treatment is... read more
(eg, Staphylococcus aureus, Bacteroides fragilis).
In children < 5 years old, the usual cause is bacterial meningitis Acute Bacterial Meningitis Acute bacterial meningitis is rapidly progressive bacterial infection of the meninges and subarachnoid space. Findings typically include headache, fever, and nuchal rigidity. Diagnosis is by... read more ; because childhood meningitis is now uncommon, childhood subdural empyema is uncommon.
Complications
Epidural abscess may extend into the subdural space to cause subdural empyema. Both epidural abscess and subdural empyema may progress to meningitis, cortical venous thrombosis, or brain abscess. Subdural empyema can rapidly spread to involve an entire cerebral hemisphere.
Symptoms and Signs
Fever, headache, lethargy, focal neurologic deficits (often indicating subdural empyema when rapidly developing deficits suggest widespread involvement of one cerebral hemisphere), and seizures usually evolve over several days.
Patients with intracranial epidural abscess may also develop a subperiosteal abscess and osteomyelitis of the frontal bone (Pott puffy tumor), and patients with subdural empyema often develop meningeal signs. In epidural abscess and subdural empyema, vomiting is common. Many patients may develop papilledema Papilledema Papilledema is swelling of the optic disk due to increased intracranial pressure. Optic disk swelling resulting from causes that do not involve increased intracranial pressure (eg, malignant... read more .
Without treatment, coma and death occur rapidly, particularly in subdural empyema.
Diagnosis
Contrast-enhanced MRI
Diagnosis of epidural abscess or subdural empyema is by contrast-enhanced MRI or, if MRI is not available, by contrast-enhanced CT. Blood and surgical specimens are cultured aerobically and anaerobically.
Lumbar puncture provides little useful information and may precipitate transtentorial brain herniation Brain Herniation Brain herniation occurs when increased intracranial pressure causes the abnormal protrusion of brain tissue through openings in rigid intracranial barriers (eg, tentorial notch). Because the... read more . If intracranial epidural abscess or subdural empyema is suspected (eg, based on symptom duration of several days, focal deficits, or risk factors) in patients with meningeal signs, lumbar puncture is contraindicated until neuroimaging excludes a mass lesion.
In infants, a subdural tap may be diagnostic and may relieve pressure.
Treatment
Surgical drainage
Antibiotics
Emergency surgical drainage of the epidural abscess or subdural empyema and any underlying fluid in the sinuses should be done.
Pending culture results, antibiotic coverage is the same as antibiotics used to treat brain abscess Treatment (eg, cefotaxime, ceftriaxone, metronidazole, vancomycin) except in young children, who may require other antibiotics for any accompanying meningitis (see tables Initial Antibiotics for Acute Bacterial Meningitis Initial Antibiotics for Acute Bacterial Meningitis
and Common IV Antibiotic Dosages for Acute Bacterial Meningitis Common IV Antibiotic Dosages for Acute Bacterial Meningitis*
).
Antiseizure drugs may be required to control seizures but are not usually used prophylactically. Drugs such as mannitol or dexamethasone may be needed if there is evidence of increased intracranial pressure. Hemicraniectomy may be required if intracranial pressure cannot be otherwise controlled.
Key Points
Epidural abscess and subdural empyema may progress to meningitis, cortical venous thrombosis, or brain abscess; subdural empyema can rapidly spread to involve an entire cerebral hemisphere.
Fever, headache, lethargy, focal neurologic deficits, and seizures usually evolve over several days; vomiting and papilledema are common.
Without treatment, coma and death occur rapidly.
Use contrast-enhanced MRI or, if MRI is not available, contrast-enhanced CT to diagnose epidural abscess or subdural empyema.
Lumbar puncture provides little useful information and may precipitate transtentorial herniation.
Drain the epidural abscess or subdural empyema and any underlying fluid in the sinuses as soon as possible, and treat with antibiotics (eg, cefotaxime, ceftriaxone, metronidazole, vancomycin).