Needle tip, mean angle, and contrast distribution by nerve root levela
| Nerve Root Level | Needle-Tip Location | Mean Needle Angle for Needle-Tip Locations and Level (°) | Mean Needle Angle for all Needle-Tip Locations (°) | Contrast Distribution | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Foraminal Zone | Junctional | Extra-Foraminal | Foraminal Zone | Junctional | Extra-Foraminal | Mean | SD | Intra-Foraminal | Extra-Foraminal | Central Epidural | Other | |
| C4 | 1 | 3 | 1 | 32 | 50 | 23 | 41.1 | 16.4 | 4 | 5 | 2 | 0 |
| C5 | 8 | 11 | 3 | 31 | 49 | 58 | 43.8 | 17.8 | 20 | 22 | 4 | 0 |
| C6 | 17 | 13 | 16 | 28 | 39 | 33 | 32.7 | 19.1 | 34 | 42 | 6 | 3 |
| C7 | 3 | 7 | 2 | 19 | 31 | 33 | 28.1 | 15.5 | 11 | 11 | 0 | 0 |
| C8 | 1 | 2 | 2 | 18 | 6 | 5 | 7.6 | 22.6 | 3 | 3 | 0 | 0 |
| Total (%) | 30 (34) | 36 (39) | 24 (27) | 72 (80) | 83 (92) | 12 (13) | 3 (3) | |||||
↵a Contrast distribution could be seen in >1 site for each injection.