Spinal epidural abscess
The most common infectious agent is:
- staphylococcus aureus,
- Gram-negative bacilli,
- other organisms include anaerobes,
The initial source of infection may be a skin lesion or endocarditis with bacteraemia or other cases of septicaemia, with haematogenous spread to the vertebra, intervertebral discs, or directly to the epidural space (vertebral or intervertebral disc infections may spread to the epidural space). Blood-borne spread to the epidural space may sometimes occur in intravenous drug abusers.
The presentation is usually with pyrexia and localized back pain, radicular pain at the level of the infection, and the rapid development of a transverse cord syndrome with sensory, motor, and sphincter deficits below the level of the lesion.
Sometimes the picture emerges more slowly. Helpful pointers towards an infectious cause (although not always present) include an elevated erythrocyte sedimentation rate (ESR) and peripheral white blood cell count, and focal tenderness to palpation of the spinal column at the level of the infection.
Examined MRI and CSF
MRI should be obtained immediately and will reveal the extradural compressive lesion, and also may show signal changes due to infection in the adjacent vertebra; gadolinium enhancement of the abscess may be prominent, with a ring shape. MRI should be performed first, and the findings of an epidural lesion causing acute cord compression demands.
The CSF, if examined, will usually reveal a mild pleocytosis, moderately elevated protein, and a normal glucose, which is the typical pattern when there is a parameningeal focus of infection.
Immediate neurosurgical intervention—in this situation, a lumbar puncture before surgery is neither necessary nor wise. In addition to immediate laminectomy and abscess drainage, intravenous antibiotics should be given in large doses.
The prognosis for recovery is uncertain, but a good outcome is more likely when there has been a rapid surgical and medical intervention. Although less common, spinal subdural abscesses may occur; the presentation and management is as that for extradural abscess.