Cervical Epidural Contrast Spread Patterns in Fluoroscopic Antero-Posterior, Lateral, and Contralateral Oblique View: A Three-Dimensional Analysis.

ABSTRACT

Objective: To describe and to analyze cervical epidural contrast patterns seen in antero-posterior (AP), contralateral oblique (CLO), and lateral view. To identify factors that might help in predicting contrast distribution pattern and extent. Method: Spread of contrast in the cervical epidural space was prospectively studied in AP, lateral, and three CLO views. Results: CLO view showed contrast spread of variable thickness with its posterior margin overlying the ventral interlaminar line (VILL). In the lateral view, the spread was also of variable thickness, but the posterior margin of the contrast lay on the spinolaminar line in only 10 of 24 patients. Ventral contrast spread was not visualized in any patient. In the AP view, bilateral spread was seen in 14 of 24 subjects, and nerve root spread was seen in 16 of 24 subjects. No association of the pattern of spread or dispersion was seen to patient age, volume injected, or needle location. Conclusions: The CLO view provides a consistent radiological landmark for the posterior margin of contrast in the dorsal epidural space; the lateral view fails to provide such a consistent landmark. The thickness of the spread is variable, both in the CLO and in the lateral view. Thick spread extending into the foramen in the CLO view and over the articular pillars in the lateral view is frequent and should not be misconstrued as subdural or intrathecal spread. In contradistinction to previous studies, true ventral spread was not seen in any patient. When using low volumes, contrast spread is independent of patient age, volume injected, or needle tip location in the AP view.