MRI prediction of therapeutic response to epidural steroid injection in patients with cervical radiculopathy.

OBJECTIVE: To analyze whether magnetic resonance imaging (MRI) findings can be used to predict therapeutic responses to cervical epidural steroid injections (CESI) in patients with cervical radiculopathy.

DESIGN: Retrospective single-center study. Patients were categorized by presence or absence of four types of cervical MRI findings (disk herniation, nerve root compromise, neuroforaminal stenosis, and central canal stenosis). Thus, for each of the four types of MRI findings, there was a positive-MRI arm and a negative-MRI arm. Severities of these MRI findings were also noted. The treatment outcome variable was the change in Neck Disability Index (NDI) score after CESI. For each of the four MRI finding types, t test was done to see if there was any significant difference in the outcome between positive-MRI arm and negative-MRI arm. Then, we repeated the same analyses after adjusting the arms to include only those of "major" radiologic severity in the positive-MRI arms.

RESULTS: After inclusion and exclusion criteria were applied, 32 patients were included. Only the presence, vs. absence, of central canal stenosis was associated with significantly superior therapeutic response to CESI (mean NDI improvement of 14.14 in positive-MRI arm, vs. mean NDI worsening of 2.11 in negative-MRI arm; P = 0.012). After controlling for other MRI finding types, the statistical significance still held for central canal stenosis (beta = -0.438; P = 0.022). When only the patients with MRI findings of major severities were considered as positive results, central canal stenosis was still the only finding type associated with significantly superior outcome (mean NDI improvement of 23.00 in positive-MRI arm, vs. mean NDI improvement of 0.85 in negative-MRI arm; P = 0.002). Controlling for other MRI finding types, the statistical significance still held for central canal stenosis (beta = -0.534; P = 0.002).

CONCLUSIONS: Patients with central canal stenosis achieved significantly better functional outcome after CESI than those without. Hence, the MRI finding of central canal stenosis is a potential indication that CESI may be merited.