The reliability of a novel magnetic resonance compatible electro-pneumatic device for delivering a painful pressure stimulus over the lumbar spine

Abstract

Background: Chronic lower back pain (CLBP) is a significant public health problem in the USA. The complexity of CLBP necessitates an assessment tool that can objectively evaluate the aspects of CLBP that lead to disability. Here we present a novel means by which to provide pressure stimuli to the lumbar spine through the use of an electro-pneumatic circuit that can be used in conjunction with functional magnetic resonance imaging (fMRI) technology to assess the cortical activity changes associated with CLBP.

Methods: A test–retest experimental design was used to objectively quantify pressure pain sensitivity of the lumbar spine. Sensitivity was investigated through the identification of pressure pain thresholds of the lumbar spine using a multiple random staircase method (5-s stimuli) and continuous pain intensity rating (25-s stimuli).

Results: Data presented here were consistent and reliable from day to day with an interclass-correlation coefficient (ICC) value of 0.913 for threshold values overall and individual ICC values of 0.652, 0.818, and 0.851 for mild, moderate, and intense thresholds, respectively. Linear regression analysis for longer trials indicated a large variation on day 1, R² values ranged from 0.222 to 0.882, however, the number of low correlation values decreased with only three subjects having R²< 0.6 for trial 2 on day 2.

Conclusion: This project has successfully developed a device that can deliver a reliable and reproducible stimulus over the lumbar spine that mimics the palpatory technique used in clinical practice, and can be used in conjunction with fMRI to assess cortical response.

• Lower back pain
• fMRI
• pain stimulus
• MRI compatible devices

Acknowledgements

We would like to thank Pat Weber for her technical expertise in setting up the hardware and protocol to be fMRI compatible. We would also like to thank Amy Lerner, Eddie Schwarz, and Richard Gracely for their general scientific guidance. Last we would like to acknowledge Vaibhav Kakkad, Diana Ladkany, Alexander Lee, and David Parker for the hard work involved in the prototype developed as part of their senior design project for the Department of Biomedical Engineering at the University of Rochester in the development testing apparatus.

Declaration of interest

The authors report no conflicts of interest.