Altered Functional Connectivity of The Amygdala in Postherpetic Neuralgia

Postherpetic neuralgia (PHN) is a common type of neuropathic pain, the central mechanism of which is still unclear. The amygdala has recently garnered increased attention in pain processing. The purpose of this study is to investigate the functional neural networks of the amygdala in PHN and explore the mechanism of chronic neuropathic pain. Conventional magnetic resonance imaging (MRI) and resting-state functional MRI (fMRI) were performed in eight PHN patients and eight healthy controls. The functional connectivity (FC) of each subregion of the amygdala with the whole brain was computed. Paired t tests of the FC data were performed between the two experimental groups. Correlation analysis was applied between disease duration, visual analog scale (VAS), and FC strength. We found increased FC between the laterobasal (LB) and superficial (SF) amygdala and several brain regions including the temporal lobe and frontal lobe. We observed decreased FC between the SF amygdala and the precentral cortex, as well as the SF amygdala and parietal lobe. Correlation analysis showed that FC strength of the LB amygdala with both the temporal lobe and frontal lobe changed with disease duration and VAS in PHN patients. This altered FC in PHN suggests that the amygdala and several other brain regions involved in emotion, recognition, and attention play an important role in the modulation of chronic neuropathic pain.