Comparison of clinical efficacy in epidural steroid injections through transforaminal or parasagittal approaches

Background: The transforaminal (TF) epidural steroid injection (ESI) is suggested as more effective than the interlaminar (IL) route due to higher delivery of medication at the anterior epidural space. However, serious complications such as spinal cord injury and permanent neural injury have been reported. The purpose of this study is to evaluate and compare the clinical effectiveness, technical ease, and safety of the TF and parasagittal IL (PIL) ESI. Methods: A total of 72 patients were randomized to either the PIL group (n = 41) or the TF group (n = 31) under fluoroscopic guidance. Patients were evaluated for effective pain relief by the numerical rating scale (NRS) and Oswestry Disability Index (ODI) (%) before and 2 weeks after the ESI. The presence of concordant paresthesia, anterior epidural spread, total procedure time, and exposed radiation dose were also evaluated. Results: Both the PIL and TF approach produced similar clinically significant improvements in pain and level of disability. Among the 72 patients, 27 PIL (66%) and 20 TF (64%) patients showed concordant paresthesia while 14 (34%) and 11 (36%) patients in the same respective order showed disconcordant or no paresthesia. Radiation dose and total procedure time required were compared; the PIL group showed a significantly lower radiation dose ($30.2{\pm}12$ vs. $80.8{\pm}26.8$ [$Cgy/cm^2$]) and shorter procedure time ($96.2{\pm}31$ vs. $141.6{\pm}30$ seconds). Conclusions: ESI under fluoroscopic guidance with PIL or TF approach were effective in reducing the NRS and ODI. PIL ESI was a technically easier and simple method compared to TF ESI.