Comparison of Clinical Efficacy Between Interlaminar and Transforaminal Epidural Injection in Patients With Axial Pain due to Cervical Disc Herniation

Transforaminal (TF) approach is preferred by physician to interlaminar (IL) approach because it can deliver injectates directly around nerve root and dorsal root ganglion, which is regarded as main pain sources. Axial neck pain is originated from sinuvertebral nerve located in ventral epidural spaces, which has been described to be related to central or paramedian disc herniation. It is very questionable that TF injection is also more effective than IL injection in the patients with axial neck or interscapular pain. This study was to evaluate clinical efficacy of cervical epidural injection in patients with axial pain due to cervical disc herniation and to compare the clinical outcomes between TF and IL approaches. Fifty-six and 52 patients who underwent IL and TF epidural injections, respectively, for axial neck/interscapular pain due to central or paramedian cervical disc herniation were included. Numeric Rating Scale (NRS) and Neck Disability Index (NDI) were compared between both groups at 2 and 8 weeks after treatment. Successful pain relief was defined if a 50% or more reduction of NRS score was achieved in comparison with pretreatment one. Successful functional improvement was defined if at least a 40% reduction of NDI was obtained. Overall, 79 (73.1%) and 57 (52.8%) among 108 patients showed successful pain relief at 2 and 8 weeks, respectively. Seventy-six (70.4%) and 52 (48.1%) had successful functional improvement at 2 and 8 weeks, respectively. The IL and TF groups showed no significant difference in proportion of successful results of NRS 2 weeks (73.2% vs 67.3%) and 8 weeks (48.2% vs 48.1%). Also, no significant difference was obtained in proportion of successful NDI between 2 groups at 2 weeks (75.0% vs 71.2%) and 8 weeks (53.6% vs 51.9%). Cervical epidural injection showed favorable results in 2 weeks and moderate results in 8 weeks in patients with axial pain due to cervical disc herniation. IL and TF showed no significant difference in clinical efficacy. Considering TF was relevant to more serious side effects, IL was more recommendable in these patients.