Dynamic abnormalities of spontaneous brain activity in women with primary dysmenorrhea

PURPOSE This study aimed to investigate the regional spontaneous brain activity changes in primary dysmenorrhea (PD) patients in different phases of the menstrual cycle by regional homogeneity (ReHo) analysis. PATIENTS AND METHODS Thirty-three PD patients and 32 healthy controls (HCs) separately received resting-state functional magnetic resonance imaging during menstrual phase and follicular phase (non-menstrual phase). Cox retrospective symptom scale (RSS), Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) were applied to assess related symptoms and emotions. RESULTS There was no significant difference between the two groups in demographic data. The PD patients obtained higher RSS score, SAS score and SDS score than HCs. Compared with HCs, the ReHo values of the PD patients were increased in left midbrain and hippocampus, right posterior cingulate cortex (PCC), insula and middle temporal cortex (MTC) and decreased in left dorsolateral prefrontal cortex and right medial prefrontal cortex (mPFC) in menstrual phase. In non-menstrual phase, enhanced ReHo values were found in bilateral S1 and precuneus, left S2 and MTC, and reduced ReHo values were observed in left mPFC and orbital frontal cortex. RSS score positively correlated with ReHo values of midbrain and negatively correlated with mPFC and PCC. CONCLUSION Our results suggested that PD is accompanied by dynamic regional spontaneous activity changes across the menstrual cycle, and the altered regions were involved in descending pain modulation, default mode network and sensory modulation. These abnormal activations might contribute to maintain the menstrual pain.