A Dysfunctional Descending Pain Modulation System in Chronic Nonspecific Low Back Pain

Abstract

Pain, a protective mechanism turns into a pathologic response when it becomes chronic.Recent evidences are pointing towards neuroplastic brain changes as the primary factor for the persisting pain in chronic nonspecific low back pain (cLBP). To summarise the previous fMRI studies, a coordinate-based ALE meta-analysis of resting functional brain imaging studies is carried out to identify the clusters activated in the brain in cLBP.Literature survey: 'PubMed', 'Scopus' and 'Sleuth' were searched for studies with resting functional whole-brain imaging in cLBP. Till October 2020; 258, 238, and 7 studies were found respectively after search. The activity pattern was documented in 'without stimulation' and 'with stimulation' groups. The risk of bias was assessed by Joanna Briggs Institute critical appraisal checklist for analytical cross-section studies. Total seven (224 cLBP patients, 110 activation foci) and six studies (106 cLBP patients, 66 activation foci) were selected among 277 studies for metanalysis in the 'without stimulation' and 'with stimulation' group respectively. In the 'without stimulation' group 8 statistically significant clusters were found. The clusters are distributed in the prefrontal cortex, primary somatosensory cortex, and primary motor cortex, anterior cingulate cortex, insular cortex, putamen, claustrum, amygdala, and associated white matters in both hemispheres. On the other group, 3 statistically significant clusters were found in the frontal cortex, Parietal cortex, and Insula. In the 'with stimulation' group, significant lateralization was observed and most of the clusters were in the right hemisphere. The white matter involvement was more in All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

Structural and functional brain changes in people with knee osteoarthritis: a scoping review

“…From the aforementioned findings, it is evident that chronic pain can generate both common and specific structural and functional changes in the brain neural networks, dependent on the pathology that affects the person ( Cauda et al, 2014 ) and denote the complexity of the neural mechanisms underlying chronic pain ( Baliki et al, 2014 ). The results of this review also demonstrated that knee OA pain affects brain areas responsible of the sensory-discriminative, cognitive and affective dimensions of pain ( Hazra et al, 2022 ). Concretely, structural and functional alterations in different somatosensory and motor brain regions, such as the precentral and postcentral gyrys, paracentral gyrus (where the primary somatosensory and motor areas from the lower limb are located), cerebellum, and basal ganglia were found and were related to the perception-motor response of pain ( Fenton, Shih & Zolton, 2015 ; Hazra et al, 2022 ).…”

“…The results of this review also demonstrated that knee OA pain affects brain areas responsible of the sensory-discriminative, cognitive and affective dimensions of pain ( Hazra et al, 2022 ). Concretely, structural and functional alterations in different somatosensory and motor brain regions, such as the precentral and postcentral gyrys, paracentral gyrus (where the primary somatosensory and motor areas from the lower limb are located), cerebellum, and basal ganglia were found and were related to the perception-motor response of pain ( Fenton, Shih & Zolton, 2015 ; Hazra et al, 2022 ). Therefore, the frontal cortex also has an important role in the integration of pain sensation, since it is responsible for behaviours related to pain after receiving information from other areas of the brain responsible for processing pain information ( Fenton, Shih & Zolton, 2015 ).…”

“…Other regions, such as the ACC, thalamus, insular cortex, and amygdala are responsible for the sensory-discriminative components of pain given their specific function and reciprocal connections ( Fenton, Shih & Zolton, 2015 ; Kang et al, 2021a ; Hazra et al, 2022 ; Hoskin & Talmi, 2023 ). These three regions are also connected to the thalamus, through the paleospinothalamic nociceptive pathway, which is involved in aspects such as attention and mood related to pain ( Horn et al, 2014 ).…”

“…In addition, the prefrontal and temporal regions, the amygdala, hippocampus, and the basal ganglia are responsible for cognitive domains such as memory, attention, knowledge, and understanding ( Kuner & Kuner, 2021 ; Hazra et al, 2022 ). On the other hand, the cingulate cortex, the orbitofrontal cortex, the amygdala, the insular cortex, and the basal ganglia are also involved in the affective aspects of pain perception ( Borsook et al, 2010 ; Hazra et al, 2022 ).…”

“…In addition, the prefrontal and temporal regions, the amygdala, hippocampus, and the basal ganglia are responsible for cognitive domains such as memory, attention, knowledge, and understanding ( Kuner & Kuner, 2021 ; Hazra et al, 2022 ). On the other hand, the cingulate cortex, the orbitofrontal cortex, the amygdala, the insular cortex, and the basal ganglia are also involved in the affective aspects of pain perception ( Borsook et al, 2010 ; Hazra et al, 2022 ). Furthermore, with respect to the regions involved in the modulatory aspect of the brain matrix of pain ( Hazra et al, 2022 ), the current review identified that the prefrontal cortex and cingulate cortex regions are affected in people with knee OA.…”