Pain‐related reorganization in the primary somatosensory cortex of patients with postherpetic neuralgia. Issue 17 (25th June 2022)

• Record Type: Journal Article
• Authors: Li, Hong; Li, Xiaoyun; Wang, Jiyuan; Gao, Fei; Wiech, Katja; Hu, Li; Kong, Yazhuo
• Is Part Of: Human brain mapping. Volume 43:Issue 17(2022)
• Page Start: 5167
• Page End: 5179
• Publication Date: 2022-06-25
• Subjects: functional magnetic resonance imaging -- pain perception -- postherpetic neuralgia -- primary somatosensory cortex (S1) -- reorganization; Brain mapping -- Periodicals; 611.81
• DOI: 10.1002/hbm.25992
• Languages: English
• ISSNs: 1065-9471

Abstract

Abstract: Studies on functional and structural changes in the primary somatosensory cortex (S1) have provided important insights into neural mechanisms underlying several chronic pain conditions. However, the role of S1 plasticity in postherpetic neuralgia (PHN) remains elusive. Combining psychophysics and magnetic resonance imaging (MRI), we investigated whether pain in PHN patients is linked to S1 reorganization as compared with healthy controls. Results from voxel‐based morphometry showed no structural differences between groups. To characterize functional plasticity, we compared S1 responses to noxious laser stimuli of a fixed intensity between both groups and assessed the relationship between S1 activation and spontaneous pain in PHN patients. Although the intensity of evoked pain was comparable in both groups, PHN patients exhibited greater activation in S1 ipsilateral to the stimulated hand. Pain‐related activity was identified in contralateral superior S1 (SS1) in controls as expected, but in bilateral inferior S1 (IS1) in PHN patients with no overlap between SS1 and IS1. Contralateral SS1 engaged during evoked pain in controls encoded spontaneous pain in patients, suggesting functional S1 reorganization in PHN. Resting‐state fMRI data showed decreased functional connectivity between left and right SS1 in PHN patients, which scaled with the intensity of spontaneous pain. Finally, multivariate pattern analyses (MVPA) demonstrated that BOLD activity and resting‐state functional connectivity of S1 predicted within‐subject variations of evoked and spontaneous pain intensities across groups. In summary, functional reorganization in S1 might play a key role in chronic pain related to PHN and could be a potential treatment target in this patient group. Abstract : Studies on functional and structural changes in the primary somatosensory cortex (S1) have provided important insights into neural mechanisms underlying several chronic pain conditions. Whereas, the role of S1 plasticity in postherpetic neuralgia (PHN), a typical chronic peripheral neuropathic pain, remains unclear. Using multimodality MRI and a stimulus‐response paradigm, we reported that the functional S1 reorganization in PHN patients was associated with acute evoked as well as spontaneous pain, while the structural features were comparable between PHN patients and healthy controls. Our results suggest that functional reorganization in S1 might play a key role in chronic pain related to PHN, and could be a potential treatment target in this patient group.