History
Clinical presentation of spinal epidural abscess may be quite variable. A complete clinical triad of fever, back pain, and neurologic deficit is not present in most patients. [6, 8] Early presentations may be subtle, and atypical presentations are not unusual. A 4-phase sequential evolution of spinal epidural abscess has been described, with (1) localized back pain, (2) radicular pain and paresthesias, (3) muscular weakness, sensory loss, and/or sphincter dysfunction, and, finally, (4) paralysis. [1]
The virulence of the infecting organism and the mode of infection contribute to the tempo of this progression. Abscesses from hematogenous spread tend to progress rapidly, while abscesses from osteomyelitis or discitis may evolve over weeks or months with slow progression of symptoms.
An evident source of infection in skin or soft tissue may be found. As such, in patients with clinical suspicion, blood work, blood cultures, urine cultures, and ESR/CRP should be obtained early during workup to help obtain an accurate diagnosis, which may prompt further imaging studies.
IV drug users are a high-risk group. Occurrences have been cited even in patients with a remote history of IV drug abuse. [3]
Symptoms may include the following:
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Fever is present in only about one third of patients
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Localized, severe back pain is often the first symptom in patients presenting with spinal epidural abscess
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Radiculopathy with radiating or lancinating pain, including chest or abdominal pain (at times this may simulate myocardial infarction or other causes of chest or abdominal pain)
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Spinal cord syndromes, typically involving paraparesis with prospective progression to paraplegia (epidural abscesses at the level of the cauda equina cause symptoms consistent with cauda equina syndrome rather than a spinal cord syndrome) [9]
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Headache and neck pain (nuchal rigidity) may be present, especially with cervical epidural abscesses
Physical Examination
In patients with suspected spinal epidural abscess, a thorough neurological exam is beneficial to evaluate for any deficits.
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Palpation of the spine should be performed to elicit any worsening pain, which also helps localize the level(s) of the suspected epidural abscess.
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A motor exam of each muscle group tested in isolation should be performed to evaluate for any focal weakness, or to elicit any asymmetry between contralateral sides.
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A sensory exam of cutaneous dermatomes (fine touch and pinprick sensation) should be evaluated.
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In patients with suspected cauda equina syndrome, a rectal examination should be performed, including testing for the preservation of pinprick sensation around the perianal area. A post-void residual can be obtained to evaluate for diminished bladder function.
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Testing for upper motor neuron signs, such as clonus, Babinski's, Hoffman's and hyper-reflexia should be tested. These can signify spinal cord compromise as a result of either a compressive lesion or vascular compromise.
Complications
There is limited data available regarding the rate of complications among patients with spinal epidural abscesses. Often, neurological compromise occurs because of delay in diagnosis. Studies have reported a 30-50% failure rate for spinal epidural abscesses managed non-operatively. [10] There are five main criteria that signify failure of medical management, and warrant surgical intervention: (1) neurological compromise; (2) failure of antibiotic treatment; (3) intractable back pain; (4) progressive spinal deformity; and (5) failure of diagnosis.
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Cervical epidural abscess with spinal cord compression and spinal cord edema.
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Spinal epidural abscess lumbar area.
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An MRI of the lumbar spine (T1-weighted, post-contrast) shows a spinal epidural abscess at the level of L3-L4, with an associated left paraspinal muscle abscess.
