Neuroradiology Case of the Week

Case 3

Matthew Cham, MD and and P-L Westesson, MD, PhD, DDS

Clinical Presentation: A 62-year-old man presented with acute onset quadriplegia and fever.

Radiological Findings: Sagittal T2-weighted MR images show an epidural fluid collection centered around the C4/5 disk space (Fig.1). Anterior to the vertebral column there is also slightly increased T2 signal indicating a phlegmon and less likely a fluid collection. These each measure approximately 4 mm in AP dimension. The cervical cord is displaced posteriorly and there is compression of the cord but there is no appreciable signal alterations. The fluid collection is in a left paracentral region (Fig. 2).
    The sagittal T1 post-contrast enhanced image (Fig. 3) shows a fluid collection presumed to be an abscess (posterior to the C4 and C5 vertebral bodies). The abnormality in front of the cervical spine does not show any fluid collection and is therefore a phlegmone (Fig. 4).

Figure 1	Figure 2
Figure 3	Figure 4

Diagnosis: Epidural abscess

Discussion: Epidural abscess typically results from direct hematogeneous seeding of an epidural space from a cutaneous, pulmonary, or urinary tract source [1]. Some cases result from direct extension of infection from the spine or paraspinal tissues. Staphylococcus aureus is by far the most common organism responsible for spine infections of all types [2].
    When epidural abscess is suspected, immediate MRI imaging of the spinal canal and cord is the exam of choice [3]. If MRI is unavailable, CT myelography or conventional myelography can reveal an intraspinal extramedullary mass. Lumbar puncture is relatively contraindicated, as it runs the risk of introducing purulent material into the subarachnoid space.
    Two basic stages are seen in epidural abscesses. Initially there is inflamed tissue with granulomatous material and imbedded microabscesses. This is evident as phlegmon, and can be seen anterior to the spine in this patient [4]. In the second stage, there is frank fluid collection with pus, which can be seen posterior to the spine in this patient.
    Spinal epidural abscesses are uncommon, representing approximately one out of 10,000 hospital admissions [4]. All ages are affected, with an average between 15-55 years [5,6]. Patients with a history of diabetes, intravenous drug use, or multiple medical illnesses are all predisposed to developing spinal epidural abscess.
    Physical findings vary with the degree of spinal cord compression or dysfunction.
    With early infection, fever and localized tenderness are common. Nuchal rigidity may be present with cervical epidural abscesses. In the most advanced cases, a transverse cord syndrome is seen with motor, reflex, and sensory levels found upon neurologic examination. Complete transverse spinal cord syndrome may occur with sphincter dysfunction, paraplegia, and/or quadriplegia, such as that seen in this patient.
    Treatment consists of both medical and surgical therapy. Empiric antibiotic coverage should include antistaphylococcal drugs. Culture results guide definitive therapy. Emergency surgical decompression of the spinal cord and drainage of the abscess is the usual surgical treatment [7]. Marked neurologic deficits, persistent fever, and leukocytosis were all indications for surgery in this patient.

References:

1. Mark AS. MRI of infections and inflammatory diseases of the spine. MRI Decisions 1991; March/April:12-26.
2. Numaguchi Y, Rigamonti D, Rothman MI et al. Spinal epidural abscess: evaluation with gadolinium0enhanced MR imaging. RadioGraphics 1993;13:545-559.
3. Butler KH: Spinal epidural abscess: Current diagnostic and management protocols. Emerg Med Rep 2000; 21: 95-104.
4. Sandhu FS, Dillon WP. Spinal epidural abscess: evaluation with contrast-enhanced MR imaging. AJNR 1991;12:1087-1093.
5. Nussbaum ES, Rigamonte D, Standiford H et al. Spinal epidural abscess: a report of to cases and review. Surg Neurol 1992;38:225-231.
6. Kricun R, Shoemaker IE, Chovanes GI, Stephens HW. Epidural abscess of the cervical spine: MR findings in five cases. AJR 1992;158:1145-1149.
7. Rigamonti D, Liem L, Sampath P: Spinal epidural abscess: contemporary trends in etiology, evaluation, and management. Surg Neurol 1999; 52(2): 189-97.