Occassionally, false-positive epidural injection are encountered due to unintentional flow of contrast into the facet joints during cervical interlaminar epidural injection. In this study of 2006 cases, the prevalence of injection into the retroligamentous space of Okada was 6.0%, higher compared to 2.9% described earlier. Cervical interlaminar epidural injection at C5–6 and above and the paramidline method for epidural injection were linked with injection into the retroligamentous space of Okada.

This study aims to assess the degree of facet flow of contrast and examine different factors linked with injection into the space of Okada with the use of fluoroscopy-guided cervical interlaminar epidural injection (CIEI).

The images of Fluoroscopy-guided CIEI from total 2,006 cases were gathered and assessed. The cases of epidural injection were categorized as either facet flow or no facet flow. The predictive factors of unintended injection into the Okada space were recognized via multivariate logistic regression.

As found, the intra-articular flow was recognized in 121 out of 2,006 cases i.e 6.0% cases. All the cases of flow of contrast into facet joints were identified. Then, the suitable epidurograms were attained during the processes. Highest rate of unintended facet flow of the contrast (10.1%, 44/436) was observed at C5–6. The CIEI at C5–6 and above and paramidline approach for epidural injection were linked with shot into the space of Okada.

To sum up, the injection into the space of Okada during fluoroscopy-guided CIEI in 6.0% of procedures was observed. The CIEI at C5–6 and above and the paramidline method for epidural injection were positive interpreters of unintentional facet flow of the contrast.