Subdural empyema is a collection of pus between the dura mater and arachnoid. Symptoms include fever, lethargy, focal neurologic deficits, and seizures. Diagnosis is by contrast-enhanced CT or MRI. Treatment is with surgical drainage and antibiotics.

Etiology

Subdural empyema is usually a complication of sinusitis (especially frontal, ethmoidal, or sphenoidal), but it can follow ear infections, cranial trauma or surgery, or, rarely, bacteremia. Pathogens are similar to those that cause brain abscess (see Brain Infections: Etiology). In children < 5 yr, the usual cause is bacterial meningitis; because childhood meningitis is now uncommon, childhood subdural empyema is uncommon.

Complications: Cortical venous thrombosis and brain abscess are common complications, and subdural empyema can rapidly spread to involve an entire cerebral hemisphere.

Symptoms and Signs

Fever, headache, lethargy, focal neurologic deficits (suggesting widespread involvement of one cerebral hemisphere), and seizures evolve over several days. Meningeal signs, vomiting, and papilledema are common. Without treatment, coma and death occur rapidly.

Diagnosis

• MRI

Diagnosis 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 herniation. If 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 empyema and any underlying sinusitis should be done. Pending culture results, antibiotic coverage is the same as that for brain abscess except in young children, who may require antibiotics for any accompanying meningitis (see Table 5: Meningitis: Initial Antibiotics for Acute Bacterial Meningitis and Table 7: Meningitis: Common IV Antibiotic Dosages for Acute Bacterial Meningitis*). Anticonvulsants and measures to reduce intracranial pressure may be needed.

Last full review/revision November 2012 by John E. Greenlee, MD

Content last modified December 2012