Article Figures & Data
Figures
- FIG 1.
Images in a 56-year-old woman approximately 5 months following BMP–augmented extreme lateral and transforaminal lumbar interbody fusion of L3–L5 with persistent left-sided L5 radiculopathy. A, Sagittal T1-weighted MR image of the lumbar spine demonstrates a hypointense epidural collection at L5 (arrow). B, Corresponding sagittal STIR MR image shows the epidural cyst at L5 (black arrow), cystic osteolysis of the L4 and L5 vertebral bodies (white arrows), with endplate edema signal (arrowheads) and postoperative changes. C, Axial T2-weighted image at L5 (blue dashed line, A) illustrates the cyst (dashed black arrow) with the fluid-fluid level that narrows the left subarticular recess. Note the connection of the cyst to the bone resorptions within the vertebral body (arrowheads) and the discontinuity of the posterior longitudinal ligament (white arrow).
- FIG 2.
Images in a 49-year-old woman following transforaminal lumbar interbody fusion and left-sided laminotomy of L4–L5 with BMP grafting approximately 8 months ago and new-onset left-sided L4–L5 radiculopathy. A, Sagittal STIR MR image demonstrates a BMP graft with adjacent osteolysis (arrows) and endplate edema signal (arrowheads). B, Axial T2-weighted MR image at L4–L5 (dashed line, A) shows a left-sided epidural cyst (arrows) with a fluid-fluid level. D, Parasagittal T2-weighted MR image at the level of the left laminotomy (dashed blue line, B) illustrates the epidural cyst (arrow) that fills the decompression defect and causes moderate-to-severe foraminal stenosis at L4–L5 (arrowheads). E, Intraoperative photo of the serous cystic structure shows a thick pseudocapsule (asterisks). C and F, Histopathologic specimen (magnification factor, 1.6×/4×, respectively) demonstrates fragments of the thin fibrous cystic lining (arrowheads, F) and a segment of woven bone formation with chondrocytic metaplasia (asterisk, F).
- FIG 3.
MR images in a 58-year-old man 2 months following BMP-augmented combined extreme lateral and posterior lumbar interbody fusion with laminectomy of L4–S1 and new-onset left foot drop. A, Sagittal T2-weighted MR image shows a lobulated epidural cyst at L5–S1 dorsal to the BMP graft (black arrows), endplate edema signal of the adjacent endplates (arrowheads), and the laminectomy defect with seroma formation (bracket). B, Axial T2-weighted MR image at L5–S1 (dashed blue line, A) demonstrates the left subarticular, epidural cyst (white arrow) adjacent to the BMP graft, abutting the left descending S1 nerve root (arrowhead) and the left exiting L5 nerve root (black arrow). Concomitant seroma is present and fills the laminectomy defect (asterisks).
Tables
Patient Age (yr) Diagnosis Interval MR Imaging (days) Procedure Levels 1 49 Congenital spinal stenosis 253 TLIF + laminotomy L4–L5 2 56 Degenerative spinal stenosis 161 XLIF + TLIF L3–L5 3 52 Degenerative spondylolisthesis 204 ALIF L4–L5 4 71 Lumbosacral radiculopathy 70 XLIF L2–L3 5 62 Lumbosacral radiculopathy 119 ALIF L5–S1 6 57 Isthmic spondylolisthesis 101 PLIF + laminectomy L4–S1 7 60 Lumbosacral radiculopathy 35 TLIF + laminectomy L4–L5 8 60 Pseudoarthrosis 480 TLIF L4–L5 9 64 Lumbosacral radiculopathy 465 XLIF L3–L5 10 51 Degenerative spinal stenosis 202 LLIF L3–L5 11 73 Degenerative spinal stenosis 61 XLIF + laminectomy L3–L4 12 49 Degenerative spinal stenosis 19 PLIF + laminectomy L5–S1 13 61 Scoliosis 37 XLIF + PLIF L4–S1 14 58 Degenerative spinal stenosis 60 XLIF + PLIF + laminectomy L4–S1 15 71 Lumbosacral radiculopathy 38 PLIF + laminectomy L3–L5 16 68 Degenerative spinal stenosis 134 TLIF L4–L5 Finding No. of Cases % Epidural cysts with mass effect 8/16 50 Epidural cysts without mass effect 8/16 50 Bone resorptions/osteolysis 11/16 69 Endplate marrow, edema 14/16 88 Seroma 11/16 69
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