Changes between the first and second MRI measurements of 65 patients who were scheduled for decompressive surgery in a total of 78 levels due to lumbar spinal stenosis.
| Outcome Measure | Levels (N = 78) |
| Schizas | |
| No change, n (95% CI) | 42 (42%–65%) |
| Increased, n (95% CI) | 28 (25%–48%) |
| +1 | 24 |
| +2 | 2 |
| +3 | 2 |
| Decreased, n (95% CI) | 8 (4.5%–19%) |
| −1 | 7 |
| −2 | 1 |
| Dural sac cross-sectional area | |
| No change | 3 |
| Increased | 47 |
| +1–10 mm2 | 7 |
| +11–20 mm2 | 7 |
| +21–30 mm2 | 4 |
| Decreased | 28 |
| −1 to 10 mm2 | 9 |
| −11 to 20 mm2 | 14 |
| −21 to 30 mm2 | 5 |
| Spondylolisthesis | |
| No change | 46 |
| Increased | 21 |
| +1 mm | 8 |
| +2 mm | 9 |
| +3 mm | 2 |
| +4 mm | 1 |
| +5 mm | 0 |
| +6 mm | 1a |
| Decreased | 11 |
| –1 mm | 9 |
| –2 mm | 1 |
| –3 mm | 1 |
| Forminal stenosis, left | |
| No change, n (95% CI) | 63 (70%–89%) |
| Increased, n (95% CI) | 9 (5%–21%) |
| +1 | 7 |
| +2 | 2 |
| Decreased, n (95% CI) | 6 (3%–16%) |
| −1 | 5 |
| −2 | 1 |
| Foraminal stenosis, right | |
| No change, n (95% CI) | 64 (72%–90%) |
| Increased (+1), n (95% CI) | 7 (4%–18%) |
| Decreased (−1), n (95% CI) | 7 (4%–18%) |
| Disc degeneration | |
| No change | 53 |
| Increased (+1) | 12 |
| Decreased (−1) | 13 |
Note: Data presented as n for number of levels unless otherwise specified. All patients presented with 2 preoperative MRIs of the lumbar spine within the year before planned surgery. The MRIs were investigated for disc degeneration (Pfirrmann’s classification), foraminal stenosis (Lee’s classification), spondylolisthesis, and central canal stenosis (Schizas score and dural sac cross-sectional area).
↵a Due to lumbosacral transitional vertebra.
MRI, magnetic resonance imaging.