| Vol. 5, Issue 1 |
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Chhabra A. et al |
Spinal Epidural Space:
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| Infective/Inflammatory Lesions The mean Age for Pyogenic Epidural (EA) is 50-55 years. Concomitant discitis or osteomyelitis is seen in 80% cases. Staph aureus is the most common cause. Initially, there is phlegmonous stage with embedded microabscesses. In the 2nd stage, collection of liquid pus forms a frank abscess6. MR findings are characterized by multilevel involvement, an anterior location, and the abscess appears iso-hypointense to spinal cord on T1W and hyperintense on T2W images. Other findings include, hyperintense signal changes on STIR images in the adjacent vertebrae and intervertebral discs8. Marked edema in the prevertebral soft tissues and dural enhancement extending along multiple vertebral segments is also seen. Diffuse enhancement in the phlegmonous stage (Fig- 17a-d) and peripheral enhancement in necrotic stage (Fig- 18a-d) is seen. Engorgement of the epidural venous plexus is occasionally observed. The changes in abscess size noted on follow-up studies correlate well with clinical improvement or deterioration in most patients. Persistent contrast enhancement, however, is frequently noted at the site of diskitis, osteomyelitis, or surgical drainage sites despite clinicalimprovement.6,7 Tubercular and fungal infections are uncommon except, in immunocompromised and debilitated patients. Late disc involvement is seen in these infections. Also posterior element involvement, skip lesions, kyphotic deformity in the spine, large paraspinal soft tissue mass and calcification is common in tubercular infections. Brucellar spondylitis demonstrates gas within the disk, minimal associated paraspinal soft tissue mass, absence of gibbus deformity, and predilection for the lower lumbar spine. Rheumatoid arthritis (RA) of the spine involves the cervical spine in 60% cases and dens erosion and C1-2 subluxation (AAS) is seen in 5% of patients with cervical RA. Associated pannus appears hypointense on T1W images and heterogenously hyperintense on T2W images with early enhancement on postcontrast images (Fig- 19a-d). Enhancing stenosing pannus occurs both anterior and posterior to the dural sac at the same time and at the same level, with segmental cufflike extension of enhancing tissue around the dural sac. Stenosing tissue enhances more frequently with rheumatoid arthritis than with degenerative disease.15,16 | |
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| Fig. 9-a, b. Axial T1W and fat suppressed T2W (Top) and Sagital pre contrast T1W and post contrast fat suppressed T1W scans (bottom) in a 46 year old woman demonstrate post laminectomy osteomyelitis in L4,5 vertebral bodies, discitis and diffusely enhancing phlegmon in the anterior epidural space. |
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| Fig. 18 a-d. Axial T1W and T2W (Top) and sagital T2W and fat suppressed post contrast T1W scans (bottom) in a 48 year old man demonstrate post laminotomy osteomyelitis in L4 vertebral body & peripherally enhancing epidural abscess in the anterior and posterior epidural spaces and left paraspinal soft tissue planes. The thecal sac is displaced to right side (arrow). |
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| Fig. 19 a-d. Sagital T1W, T2W (Top) and pre contrast T1W and fat-suppressed post contrast T1W scans (Bottom) in a 75 year old man demonstrate eroded dens with AAS and enhancing pannus encroaching the anterior epidural space. |
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