Brain Imaging of Pain-Related Processing and Structural Properties in Disc Degenerative Disease

In this study, we apply brain MR imaging techniques at 3 Tesla to assess pain-relevant processing in patients with disc degenerative disease (DDD) scheduled for back surgery and age- and gender-matched controls without back pain. Data collection pre-surgery is performed over two days: On the first day, all participants undergo a battery of questionnaires relevant for individuals with chronic pain and pain sensitivity testing, including temporal summation and pressure pain thresholds. On the second day, participants undergo a MRI protocol, which includes functional MRI (fMRI) and diffusion tensor imaging to assess microstructural properties and structural connectivity. During fMRI, an experimental pressure pain paradigm is performed at the calf i.e. a location not connected to patients' chronic pain condition. Instead, the experimental pain paradigm serves as a condition to test processing of noxious stimulation unrelated to patients' experienced chronic pain. The noxious input pressure is individually calibrated to 50 on a 0-100 VAS scale to ensure that individual pain perceptions, despite different pressure intensities, are comparable across participants. The sensory stimulation will consist of a low standardized pressure intensity (150kPa). In an additional fMRI paradigm, participants do not receive stimulation but are instructed to continuously rate fluctuating spontaneous ongoing back pain (DDD) or perceived unpleasantness (controls).

This project aims at investigating measures of brain architecture, neural response connected with evoked pain, connectivity (structural and functional) and pain-relevant psychometrics and questionnaire data in disc degenerative disease patients scheduled for back surgery. Specifically, MRI is performed to test whether i) patients display differences in properties of the mesolimbic circuit compared to healthy individuals and ii) behavioural as well as clinical characteristics related to the acquired MRI markers. This study is intended to serve as a baseline in a longitudinal project testing associations with between findings at baseline and following surgery (fusion/disc implants).