MRI analysis of the lumbar spine: can it predict response to diagnostic and therapeutic facet procedures?

OBJECTIVES: To determine the correlation between magnetic resonance imaging (MRI) pathology and the response to diagnostic facet medial branch block (MBB) and L5 dorsal ramus medial branch block and radiofrequency (RF) denervation of lumbar facet joints.
METHODS: The medical records of 127 consecutive patients who underwent MBB for suspected zygapophysial joint pain were reviewed. The lumbar spine MRI of these patients was systematically graded by 2 musculoskeletal radiologists for loss of disc height, spinal stenosis, facet joint degeneration, and other forms of spinal pathology.
RESULTS: Patients with central or foraminal spinal stenosis had statistically significant correlation with positive outcome of RF (P=0.02), but not with MBB (P=0.08). The presence of facet joint degeneration or hypertrophy was positively correlated with response to MBB (71% vs. 51%; P=0.04), but not RF. Loss of disc height did not correlate with outcome of MBB (P=0.08) and RF (P=0.29). For other spinal pathology, no significant differences were noted for either the response to diagnostic blocks or the RF denervation. Younger patients were more likely to fail MBB (P<0.01) but not RF denervation (P=0.38). DISCUSSION: Whereas some relationships were noted between MRI findings and the response to lumbar facet joint interventions, many of these correlations tended to be weak. However, this study does suggest the possibility that patients with spinal stenosis, often considered an exclusion criterion for facet interventions, may respond to RF denervation of facet joints. Prospective studies are needed to confirm these observations.