Urinary retention with elevated inflammatory markers, rule out epidural abscess. Examination is motion degraded especially the sagittal post gadolinium sequences. There is no evidence of abscess within the lumbar spinal canal. There is an 11 x 12 x 7 mm focus (axial series 13, image 37) with T2 hyperintensity and peripheral enhancement at the right L4-L5 level posterior lateral to the thecal sac which may represent postoperative fluid collection, with abscess not excluded. This finding is grossly unchanged in size since 9/29/2016. There is right lower lumbar paraspinous enhancement consistent with postoperative change. Mild epidural enhancement at the L3-L5 levels is nonspecific and is not associated with a discrete fluid collection.Again seen is evidence of posterior instrumented fusion is again seen with pedicle screws on the right at L4-S1, and on the left at L5 and S1. Interbody devices have also been placed at L4-5 and L5-S1. Evidence of laminectomy/facetectomy is also seen on the right at L4-5 and on the left at L5-S1. There is edema involving the L4 and L5 vertebral bodies similar to prior study from 9/29/2016 including involvement of the prevertebral space. This finding is nonspecific given recent spine surgery.Straightening of the cervical lordosis is again seen. Vertebral body heights are preserved. At L3-4, facet arthropathy, ligamentum flavum thickening, and a disc bulge contribute to moderate spinal canal stenosis. There is also some effacement of the left lateral aspect of the thecal sac at the L4-L5 level but without high-grade central canal stenosis. Spinal canal at the L5-S1 level is also well decompressed. Right L4-L5 neural foramen is surgically decompressed. There is fairly mild multilevel neural foraminal narrowing in the remainder of the lumbar spine as seen previously but suboptimally evaluated due to artifact at the level of the pedicle screws.
1. There is an 11 x 12 x 7 mm fluid collection posterior lateral to the thecal sac in the laminectomy bed at the right L4-L5 level which may represent postoperative fluid although abscess is not excluded by imaging. There is also edema and enhancement involving the right posterior paraspinous and prevertebral soft tissues as well as the L4 and L5 vertebral bodies. These findings are nonspecific in the postoperative setting and suggest correlation with clinical findings for possibility of infection. There is also minimal epidural enhancement from L3 to L5 which may be reactive without discrete epidural fluid collection to suggest epidural abscess.2. Moderate spinal canal stenosis at the L3-L4 level. There is also stenosis involving the left aspect of the thecal sac at the L4-L5 level.