Subdural Empyema and Epidural Abscess

A. Clinical manifestations

1. Cranial subdural empyema: fever, headache, altered mental status, symptoms and signs of raised intra-cranial pressure, meningeal irritation or focal irritation.

2. Spinal subdural empyema: back pain, radiculopathy and spinal cord compression.

3. Cranial epidural abscess: fever and headache (can be quite asymptomatic), focal neurological signs and seizures, raised intra-cranial pressure.

4. Spinal epidural abscess: back pain, radiculopathy and spinal cord compression.

B. Aetiology

1. Cranial subdural empyema: polymicrobial infection is common and includes aerobic streptococci, staphylococci, aerobic Gram negative bacilli, anaerobic streptococci and other anaerobes. Propionibacterium acnes is also common especially in conditions related to trauma, neurosurgical procedures or use of dural grafts.

2. Spinal subdural empyema: a rare condition usually secondary to metastatic infection from a distant site. The most common isolates are Staphylococcus aureus, streptococci and Gram negative bacilli.

3. Cranial epidural abscess: similar to cranial subdural empyema.

4. Spinal epidural abscess: usually secondary to haematogenous dissemination from foci elsewhere in the body or by local extension from vertebral osteomyelitis. The most common agent is Staphylococcus aureus, follow by aerobic and anaerobic streptococci, aerobic Gram negative bacilli, especially E. coli and Pseudomonas aeruginosa.

C. Diagnosis and management

Imaging modalities followed by aspiration or drainage of the empyema or abscess. Antibiotics should be guided initially by underlying predisposing factors and later by culture results.