Morphologic changes in the lumbar spine after lumbar medial branch radiofrequency neurotomy: a quantitative radiological study.

BACKGROUND CONTEXT

Medial branch radiofrequency neurotomy (RFN) is a common treatment for zygapophyseal joint pain. The lumbar medial branch innervates these joints and adjacent structures. The impact of the intended neurotomy on these structures remains unclear. No studies have yet verified quantitatively the effect of medial branch RFN on intervertebral discs, facet joints, and multifidus cross-sectional area.

PURPOSE

The aim of this study was to determine, using objective radiographic measures, whether there is a quantitative difference in the lumbar multifidus muscle cross-sectional area, facet joint degeneration, or intervertebral disc degeneration after segmental medial branch RFN.

STUDY DESIGN/SETTING: This is a retrospective single-cohort study performed at a university spine center.

PATIENT SAMPLE

The patient sample consisted of 27 patients treated with lumbar medial branch RFN, with pre- and posttreatment magnetic resonance images available for analysis.

OUTCOME MEASURE

The primary study outcome measure was interval change in fat-subtracted multifidus cross-sectional area, and intervertebral disc and zygapophyseal joint degeneration grade.

METHODS

In this retrospective study, segmental levels unaffected by RFN treatment were used as controls to compare against levels affected by treatment.

RESULTS

Levels affected by RFN demonstrated a significantly greater amount of disc degeneration compared with unaffected levels (14.9% vs. 4.6%; p=.0489). There was no statistical difference in the multifidus cross-sectional area or rates of deterioration in the zygapophyseal joints observed.

CONCLUSIONS

The full impact of RFN on multifidus function, morphology, and segmental anatomy is unknown. This retrospective study indicates that measurable changes in segmental morphology may occur after lumbar medial branch RFN. These findings require validation in a prospective, controlled study.