A subdural empyema is a collection of pus that develops under the top layer of tissue (dura mater) covering the brain, rather than in the brain itself.
A subdural empyema develops between the outer (dura mater) and middle (arachnoid mater) layers of the tissues that cover the brain (meninges).
A subdural empyema may result from a sinus infection, a severe ear infection, a head injury, surgery involving the head, or a blood infection. The same kinds of bacteria that cause brain abscesses can cause subdural empyemas. In children younger than 5 years, meningitis often accompanies a subdural empyema.
Like a brain abscess, a subdural empyema can cause headache, sleepiness, seizures, and other signs of brain dysfunction. The symptoms can evolve over several days, and without treatment, they progress rapidly to coma and death.
Diagnosis and Treatment
Use of a dye visible on x-rays (radiopaque dye also known as contrast) makes a subdural empyema visible on magnetic resonance imaging (MRI) or computed tomography (CT). A spinal tap is of little help and may be dangerous. In infants, a needle can sometimes be inserted directly into the empyema through a fontanelle (a soft spot between the skull bones) to drain the pus, relieve pressure, and help doctors make the diagnosis.
Subdural empyemas must be drained surgically. If the infection occurred because of an abnormality in the sinuses, the surgeon usually repairs the abnormality at the same time. Antibiotics are given intravenously.
Last full review/revision May 2008 by Michael Jacewicz, MD