Abstract
The cause for the increased sensitivity of patients with fibromyalgia (FM) to painful stimuli is unclear but sensitization of dorsal horn spinal cord neurons has been suggested. There, critical changes of sensory information occur which depend on the plasticity of second-order neurons and descending pain modulation, including facilitation and inhibition. This study used repetitive stimuli that produce temporal-summation-of-second-pain (TSSP) and central sensitization, relevant mechanisms for patients with chronic pain. We examined spinal cord neural activation during TSSP in patients with FM and healthy controls (HC) and used its functional connectivity with several brainstem nuclei to model the observed blood-oxygen-level-dependent (BOLD) time-course with pain ratings. Sixteen HC and 14 FM participants received repetitive heat stimuli to the hand at 0.4Hz to achieve TSSP during functional imaging with a 3T-Philips Achieva MRI scanner. Stimuli were adjusted to each individual's pain sensitivity to achieve maximal pain ratings of 50±10 on a numerical pain scale (0-100). Using a 16-channel neurovascular coil, multiple image series were obtained from the cervical spinal cord to the brainstem using single-shot turbo-spin echo sequences. During repetitive, sensitivity-adjusted heat stimuli, pain ratings of all subjects increased as predicted, consistent with TSSP. HC and FM participants had similar temporal patterns of spinal activation: initial BOLD increase followed by deactivation. Structural equation modeling showed that the observed spinal activity during TSSP was associated with more BOLD activity across/within the brainstem in FM subjects than HC, suggesting differences in pain modulation.
Original language | English (US) |
---|---|
Pages (from-to) | 946-956 |
Number of pages | 11 |
Journal | Journal of neurophysiology |
Volume | 126 |
Issue number | 3 |
DOIs | |
State | Published - Sep 16 2021 |
Externally published | Yes |
Bibliographical note
Funding Information:This work was supported by the University of Florida.
Publisher Copyright:
Copyright © 2021 the American Physiological Society.
Keywords
- Brainstem
- Fibromyalgia
- FMRI
- Spinal cord
- Windup