Impact of transforaminal epidural steroid injection on pain and disability outcomes by lumbar intervertebral disc herniation class: a prospective study.

Importance: Transforaminal epidural steroid injection (TFESI) is a prevalent treatment modality for lumbosacral radicular pain caused by disc herniation; however, the impact of varying disc morphologies on treatment outcomes remains unclear.

Objective: To evaluate the effects of TFESI on pain and disability across different lumbar disc morphologies using the Michigan State University (MSU) classification system.

Design: Prospective cohort study.

Setting: A single center pain management clinic.

Participants and intervention: A total of 168 patients with single-level lumbar disc herniation at L4-L5 or L5-S1 treated with TFESI. Patients were divided into 7 subgroups according to the MSU classification based on MRI findings.

Main outcomes and measures: The numerical rating scale (NRS) for pain and Oswestry Disability Index (ODI) for assessing disability were measured at baseline, 1-month and 3-months post-procedure.

Results: TFESI significantly reduced NRS and ODI scores in all groups (P < .001). At 1-month follow-up, NRS scores of group 1B were significantly lower than those of groups 2A and 2AB (P < .001 and P = .020, respectively); at the 3-month follow-up, no differences were observed between the groups. Although ODI scores improved over time, they did not exhibit significant differences among the subgroups throughout the study period.

Conclusions and relevance: TFESI effectively reduces pain and disability across varying disc morphologies. At the 1-month mark, pain relief was more pronounced in group 1B compared to 2A and 2AB groups, whereas at the 3-month mark, the results were similar between subgroups. Larger studies with longer follow-up are needed to improve patient selection criteria and optimize treatment strategies.