P23-T Altered functional connectivity in trigeminal neuralgia

Abstract

Background Trigeminal neuralgia (TN) is one of the most common causes of chronic neuropathic pain. Chronic pain is currently seen as a result of impaired interaction between different brain structures that provide pain processing. We aimed to assess functional brain abnormalities in TN by an analysis of connectivity using resting-state fMRI. Methods 15 classical TN patients (2 men, age median 56, quartiles 38, 66) and 15 matched healthy volunteers were enrolled in the study. Resting-state fMRI was acquired using a T2∗-weighted echo planar sequence (3T, resolution 3.0 × 3.0 × 3.0 mm3, TR = 2.4 s, 190 scans). The data was preprocessed using the CONN and SPM12 packages. The images from patients with right-sided facial pain were right–left flipped. Denoising included regressing out the BOLD signal from the white matter and CSF masks, scrubbing and motion regression. ROI-to-ROI FC was computed for the regions from the CONN resting-state networks atlas. The results were compared between the patient and control groups. The connectivity values were tested for correlation with the severity of pain measured by the numeric analogue scale. Results TN patients showed increased FC within the frontoparietal control network and decreased FC within the default mode and visual networks. No statistically significant correlations between the pain level and FC were detected. Conclusions The described patterns of FC abnormalities in TN reveal novel aspects of the pathophysiology of chronic pain and may serve as a background for the development of new therapeutic methods, such as non-invasive brain stimulation.