Dorsal CSF space at CI-II level. Technique of cervical myelography.

The width of the dorsal CSF space at the CI-II lateral puncture site was measured, both in extension and in the neutral position of the head, in 60 patients undergoing cervical myelography. The sagittal diameter of the dorsal CSF space did not change in 22 patients, was larger in extension in 27 patients, and larger in the neutral position in 11 patients. In three patients with a large dorsal CSF space the change in diameter was more than 2 mm whereas in other patients the change was minimal. Lateral CI-II puncture may be performed safely both in extension and in the neutral position. Distribution of the contrast medium was more satisfactory if the head was extended.