The Role of Central Sensitization in Responsiveness to Brain Stimulation for Patients with Nonspecific Chronic Low Back Pain - An Exploratory Study.

PURPOSE: This exploratory study aimed to examine (1) the effects of a single session of repetitive transcranial magnetic stimulation (rTMS) on pain thresholds in patients with high vs. low central sensitization (CS) levels, and (2) whether individuals with high vs. low CS levels exhibit different cortical excitability responses to rTMS compared with age- and sex-matched asymptomatic controls.

PATIENTS AND

METHODS

Twenty participants who had low back pain (LBP) for longer than 6 months were dichotomized into the high CS group (n = 10) and the low CS group (n = 10) using a Central Sensitization Inventory cutoff score of 33.5. In addition, 16 age- and sex-matched asymptomatic controls (8 for each CS group) were enrolled. Outcome measures, including pressure pain threshold (PPT), thermal pain threshold, and motor evoked potential (MEP) were collected before and after a single session of rTMS (10 Hz, 10-second pulse trains with a 50-second inter-train interval for 20 minutes). Non-parametric statistics were performed for within-group and between-group comparisons with p < 0.05 for significance.

RESULTS

Only the high CS group had significantly improved PPTs after rTMS (p = 0.037), with a moderate effect size. The low CS group and both matched asymptomatic control groups had an increase of MEPs after rTMS, whereas the high CS group had a decrease of MEPs after rTMS, although none of these MEP changes were statistically significant.

CONCLUSION

This study identifies a patient population that may benefit from rTMS for reduction of pressure sensitivity. The decreased sensitivity to pressure in participants with high levels of CS corresponded to a decrease of cortical excitability after rTMS, which was in contrast with the rTMS effects observed in participants with low levels of CS and asymptomatic controls.