Does paramedian approach preferentially secure optimal drug delivery onto ventral epidural space and subsequent superior clinical efficacy over a dorsal midline approach during cervical interlaminar epidural injection?

Background: There is paucity in the literature directly comparing the clinical results between the paramedian and the midline interlaminar cervical epidural injections. Objective: To compare the proportion of ventral epidural spread of injectate and consequent clinical outcome between the paramedian and midline approach during interlaminar epidural injection in patients with axial neck and/or interscapular pain triggered from the underlying cervical spine pathologic condition. Study Design: Retrospective study. Setting: Primary pain clinic and spine hospital. Methods: Two hundred and twenty-three patients with axial neck and/or interscapular pain due to cervical problem underwent interlaminar epidural injection through either a paramedian approach (PM group, n = 93) or a midline approach (ML group, n = 130). We compared the portion of ventral epidural filling, Numeric Rating Scale (NRS), and McNab criteria between both groups. The NRS and McNab criteria were also separately compared between the ventrally spread (VS) group and non-ventral spread (non-VS) group inside each PM and ML group, respectively, at 2 weeks and 10 weeks post-injection. Results: The PM group showed a significantly higher proportion of ventral spread, successful NRS reduction, and satisfactory McNab criteria than the ML group at 10 weeks. In the PM group, the VS group showed the same results as above compared to the non-VS group. Limitations: A retrospective analysis based on the relatively short-term follow-up period clinical results. Conclusions: The paramedian approach showed the better direct injectate transfer over the ventral epidural space and subsequently superior clinical efficacy for the patients suffering from axial neck and/or interscapular pain secondary to cervical spine problems.