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Intracranial Epidural Abscess and Subdural Empyema

By

John E. Greenlee

, MD, University of Utah School of Medicine

Last full review/revision Jul 2020| Content last modified Jul 2020
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Intracranial epidural abscess is a collection of pus between the dura mater and skull. Subdural empyema is a collection of pus between the dura mater and the underlying arachnoid mater. Symptoms of epidural abscess include fever, headache, vomiting, and sometimes lethargy, focal neurologic deficits, seizures, and/or coma. Symptoms of subdural empyema include fever, vomiting, impaired consciousness, and rapid development of neurologic signs suggesting widespread involvement of one cerebral hemisphere. Diagnosis is by contrast-enhanced MRI or, if MRI is not available, contrast-enhanced CT. Treatment is with surgical drainage and antibiotics.

Etiology

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 Papilledema .

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 Brain Herniation . 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

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).

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