Effect of transcutaneous electrical nerve stimulation on vertebral metastatic bone pain of breast cancer patients: single case experimental study

Abstract

BACKGROUND AND OBJECTIVES: To evaluate the analgesic efficacy of transcutaneous electrical nerve stimulation on vertebral metastatic bone pain of breast cancer patients and its impact on analgesic consumption. METHODS: A single case experimental design was used where three females aged between 40 and 60 years were selected. Design was A1-B-A2-C-A3-D-A4, where in phase A participants received no intervention, in phase B they received high frequency transcutaneous electrical nerve stimulation, in phase C low frequency transcutaneous electrical nerve stimulation and in phase D, transcutaneous electrical nerve stimulation turned off - placebo. Each baseline phase lasted 7 days (A: no intervention) and phases B, C and D lasted 10 days (with intervention). Analgesic consumption and pain were evaluated with the visual analog scale. Data were analyzed with Mann-Whitney test to compare analgesic consumption. For visual analog scale analysis, split-middle line and binomial tests were used to verify difference between baseline and intervention phases, considering significant p<0.05. RESULTS: There has been significant analgesic consumption decrease in 66.6% of volunteers after high frequency transcutaneous electrical nerve stimulation and in 33.3% after low frequency transcutaneous electrical nerve stimulation. Pain intensity by the visual analog scale was decreased in 100% of volunteers receiving low frequency transcutaneous electrical nerve stimulation, in 33.3% of those receiving high frequency transcutaneous electrical nerve stimulation and in 33.3% of those receiving transcutaneous electrical nerve stimulation turned off (placebo), between interventions and their respective previous baselines. In 66.6% of participants there has been significant difference of high frequency transcutaneous electrical nerve stimulation compared to their posterior baselines, as well as in 33.3% when comparing transcutaneous electrical nerve stimulation turned off (placebo) and their respective posterior baseline. CONCLUSION: Results suggest that both high and low frequency transcutaneous electrical nerve stimulations may contribute as adjuvant in controlling metastatic vertebral bone pain and decreasing analgesic consumption in breast cancer patients.