Relationship of specific MRI findings to treatment outcomes in patients receiving transforaminal epidural steroid injections

Abstract

To determine whether specific MRI findings are related to outcomes after lumbar transforaminal epidural steroid injections (TFESI) and to assess the inter-rater reliability of imaging diagnosis. A prospective outcomes study on 156 consecutive patients with 1-month follow-up outcomes data and MRI within 3months of TFESI was conducted. Pain levels (numerical rating scale) (NRS) were recorded prior to injection. Overall 'improvement' was determined using the Patients Global Impression of Change (PGIC) scale and NRS data were collected at three time points post injection. Two radiologists independently evaluated all images blinded to treatment outcome for reliability of diagnosis. The Chi-square test compared MRI findings for the senior radiologist to 'improvement'. NRS change scores were compared to MRI findings with the unpaired t-test or ANOVA. Kappa and percent agreement assessed inter-rater agreement of diagnosis. The only abnormality linked to 'improvement' (p = 0.03) and higher NRS change scores (p = 0.0001) at 1month was the disc herniation morphology 'protrusion + sequestration'. Patients with degeneration by osteophytes (p = 0.034), grade 3 foraminal nerve root compression (p = 0.01) and foraminal/extraforaminal location of herniation (p = 0.014) also had higher 1month NRS change scores. Reliability of diagnosis was 'fair' to 'substantial' depending on MRI findings. Patients with disc protrusion plus sequestration were significantly more likely to report overall improvement and more pain reduction at 1month. Higher pain reduction was noted in patients with degeneration by osteophytes, grade 3 foraminal nerve root compression, or foraminal/extraforaminal disc herniation location.