Dataset Information

Greater Somatosensory Afference With Acupuncture Increases Primary Somatosensory Connectivity and Alleviates Fibromyalgia Pain via Insular γ-Aminobutyric Acid: A Randomized Neuroimaging Trial.

ABSTRACT:

Objective

Acupuncture is a complex multicomponent treatment that has shown promise in the treatment of fibromyalgia (FM). However, clinical trials have shown mixed results, possibly due to heterogeneous methodology and lack of understanding of the underlying mechanism of action. The present study was undertaken to understand the specific contribution of somatosensory afference to improvements in clinical pain, and the specific brain circuits involved.

Methods

Seventy-six patients with FM were randomized to receive either electroacupuncture (EA), with somatosensory afference, or mock laser acupuncture (ML), with no somatosensory afference, twice a week over 8 treatments. Patients with FM in each treatment group were assessed for pain severity levels, measured using Brief Pain Inventory (BPI) scores, and for levels of functional brain network connectivity, assessed using resting state functional magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy in the right anterior insula, before and after treatment.

Results

Fibromyalgia patients who received EA therapy experienced a greater reduction in pain severity, as measured by the BPI, compared to patients who received ML therapy (mean difference in BPI from pre- to posttreatment was -1.14 in the EA group versus -0.46 in the ML group; P for group × time interaction = 0.036). Participants receiving EA treatment, as compared to ML treatment, also exhibited resting functional connectivity between the primary somatosensory cortical representation of the leg (S1_leg ; i.e. primary somatosensory subregion activated by EA) and the anterior insula. Increased S1_leg -anterior insula connectivity was associated with both reduced levels of pain severity as measured by the BPI (r = -0.44, P = 0.01) and increased levels of γ-aminobutyric acid (GABA+) in the anterior insula (r = 0.48, P = 0.046) following EA therapy. Moreover, increased levels of GABA+ in the anterior insula were associated with reduced levels of pain severity as measured by the BPI (r = -0.59, P = 0.01). Finally, post-EA treatment changes in levels of GABA+ in the anterior insula mediated the relationship between changes in S1_leg -anterior insula connectivity and pain severity on the BPI (bootstrap confidence interval -0.533, -0.037).

Conclusion

The somatosensory component of acupuncture modulates primary somatosensory functional connectivity associated with insular neurochemistry to reduce pain severity in FM.

SUBMITTER: Mawla I

PROVIDER: S-EPMC8197768 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Fibromyalgia (FM) is a chronic functional pain syndrome characterized by widespread pain, significant pain catastrophizing, sympathovagal dysfunction, and amplified temporal summation for evoked pain. While several studies have demonstrated altered resting brain connectivity in FM, studies have not specifically probed the somatosensory system and its role in both somatic and nonsomatic FM symptoms. Our objective was to evaluate resting primary somatosensory cortex (S1) connectivity and to explore how sustained, evoked deep tissue pain modulates this connectivity.We acquired functional magnetic resonance imaging and electrocardiography data on FM patients and healthy controls during rest (the rest phase) and during sustained mechanical pressure-induced pain over the lower leg (the pain phase). Functional connectivity associated with different S1 subregions was calculated, while S1(leg) connectivity (representation of the leg in the primary somatosensory cortex) was contrasted between the rest phase and the pain phase and was correlated with clinically relevant measures in FM.During the rest phase, FM patients showed decreased connectivity between multiple ipsilateral and cross-hemispheric S1 subregions, which was correlated with clinical pain severity. Compared to the rest phase, the pain phase produced increased S1(leg) connectivity to the bilateral anterior insula in FM patients, but not in healthy controls. Moreover, in FM patients, sustained pain-altered S1(leg) connectivity to the anterior insula was correlated with clinical/behavioral pain measures and autonomic responses.Our study demonstrates that both somatic and nonsomatic dysfunction in FM, including clinical pain, pain catastrophizing, autonomic dysfunction, and amplified temporal summation, are closely linked with the degree to which evoked deep tissue pain alters S1 connectivity to salience/affective pain-processing regions. Additionally, diminished connectivity between S1 subregions during the rest phase in FM may result from ongoing widespread clinical pain.

Project description:Central pain augmentation resulting from enhanced excitatory and/or decreased inhibitory neurotransmission is a proposed mechanism underlying the pathophysiology of functional pain syndromes such as fibromyalgia (FM). Multiple functional magnetic resonance imaging studies implicate the insula as a region of heightened neuronal activity in this condition. Since glutamate (Glu) is a major cortical excitatory neurotransmitter that functions in pain neurotransmission, we undertook this study to test our hypothesis that increased levels of insular Glu would be present in FM patients and that the concentration of this molecule would be correlated with pain report.Nineteen FM patients and 14 age- and sex-matched pain-free controls underwent pressure pain testing and a proton magnetic resonance spectroscopy session in which the right anterior insula and right posterior insula were examined at rest.Compared with healthy controls, FM patients had significantly higher levels of Glu (mean +/- SD 8.09 +/- 0.72 arbitrary institutional units versus 6.86 +/- 1.29 arbitrary institutional units; P = 0.009) and combined glutamine and Glu (i.e., Glx) (mean +/- SD 12.38 +/- 0.94 arbitrary institutional units versus 10.59 +/- 1.48 arbitrary institutional units; P = 0.001) within the right posterior insula. No significant differences between groups were detected in any of the other major metabolites within this region (P > 0.05 for all comparisons), and no group differences were detected for any metabolite within the right anterior insula (P > 0.11 for all comparisons). Within the right posterior insula, higher levels of Glu and Glx were associated with lower pressure pain thresholds across both groups for medium pain (for Glu, r = -0.43, P = 0.012; for Glx, r = -0.50, P = 0.003).Enhanced glutamatergic neurotransmission resulting from higher concentrations of Glu within the posterior insula may play a role in the pathophysiology of FM and other central pain augmentation syndromes.