Altered Hippocampal Functional Connectivity Is Closely Related to Pain and Catastrophic Thinking Habits in Patients With Postherpetic Neuralgia

Postherpetic neuralgia (PHN) is a chronic pain condition after a cure of herpes zoster. Patients with PHN often suffer from physical pain and psychological distress. We investigated the relationship between functional alternations in the brains of patients with PHN and their clinical manifestations using resting-state fMRI. We acquired resting-state fMRI data from 17 patients with PHN and matched healthy controls. We performed seed-based functional connectivity (FC) analysis and statistical comparisons in FC. We also performed correlation analysis between FC strengths and clinical scores about pain intensity, anxiety, depression and pain catastrophizing. In FC analysis, brain regions in the salience, default mode, sensorimotor and reward network were set as seeds. FC between the medial prefrontal cortex (mPFC) and hippocampus increased in PHN group. In contrast, FC between the hippocampus and primary somatosensory cortex (SI) decreased in PHN group. Furthermore, the SI-hippocampus FC was negatively correlated with pain intensity and the mPFC-hippocampus FC was positively correlated with pain catastrophizing tendency. Our findings indicate that the hippocampus is related to pain perception and catastrophic thinking habits in patients with PHN. Functional alteration of the hippocampus may have a major role in the development and maintenance of chronic pain condition in patients with PHN.