Review Question - QID 105016

This patient with fever, back pain, and neurologic deficits localized to the spinal cord in the setting of intravenous drug use most likely has a spinal epidural abscess (SEA). The most appropriate initial step in management of suspected SEA is an MRI of the spine.

An epidural abscess is a collection of pus or inflammatory granulation tissue between the dura mater and surrounding adipose tissue. The majority of cases are the result of hematogenous seeding of bacteria, with Staph aureus being the most common causative organism (50-65% of cases). Patients who use intravenous drugs are at particularly increased risk, as are patients with diabetes mellitus or other immunocompromised states. SEA classically presents with a triad of fever, back pain, and neurologic deficits. SEA is a medical emergency as compression of the spinal cord can result in irreversible damage and permanent disability. Once identified on MRI of the spine, management for most patients consists of emergent surgical decompression as well as antibiotic therapy.

Schwab et. al review the diagnosis and management of spinal epidural abscess. They note that the classic clinical triad of fever, back pain and neurologic deficits is not present in all patients with SEA. They note that MRI of the spine with contrast is the preferred initial step in diagnosis.

Illustration A shows an example of an epidural abscess on MRI of the spine.

Incorrect answers:
Answer 1: CT scan of the lumbar spine would not be appropriate, as it has low sensitivity and specificity for the detection of SEA in comparison to MRI. Generally, MRI is preferred over CT imaging for visualization of the spinal cord.

Answer 2: Electromyography is used to diagnose abnormalities in nerve conduction, such as in neuropathy. This patient’s presentation is more suggestive of SEA, and electromyography is not used in the diagnosis of SEA.

Answer 3: Lumbar puncture is used in the diagnosis of some central nervous system infectious processes such as meningitis and encephalitis. This patient’s constellation of symptoms and specific neurologic deficits points toward SEA rather than meningoencephalitis. Lumbar puncture is not used to diagnose SEA.

Answer 5: X-ray of the lumbar spine may be useful to detect vertebral fractures or metastasis. However, it is not used in the diagnosis of SEA as it is unable to visualize the spinal cord.


Bullet Summary:
MRI of the spine is the first step in management of suspected spinal epidural abscess.