Characterization of Chronic Ocular Pain Using the Neurologic Pain Signature

Chronic ocular pain is a disabling condition defined by ocular spontaneous pain and allodynia. To determine whether brain network dynamics related to pain are different in patients with chronic pain vs. those without, we analyzed the functional connectivity between the constituent brain regions that comprise the Neurologic Pain Signature (NPS). Subjects were recruited from the Miami Veterans Affairs Medical Center and split into two groups: those with chronic ocular pain (n=60, average ocular pain ≥1/10 over 1 week recall) and those without ocular pain (n=20). MRI was performed using a 3T Siemens MAGNETOM Vida scanner (Erlangen, Germany). Resting state scans were acquired using a gradient echo, echo planar imaging sequence (10 min and 6s). The CONN toolbox processed functional connectivity analyses of resting state fMRI data. Fusiform gyrus and lingual gyrus demonstrated stronger functional connectivity in subjects with chronic ocular pain compared to those without. Furthermore, right insula and lingual gyrus also exhibited increased connectivity in the chronic pain cohort, albeit weaker than that of the fusiform gyrus and lingual gyrus. Our results suggest that NPS areas related to multisensory integration are differentially affected compared to other NPS regions in patients with chronic ocular pain. Funded by: VA-CSR&D-I01CX002015, NIH-U01EY034686, NIH-R01EY034135, VA-BLRD-I01BX004893, VA-RRD-I21RX003883, DOD-GWIRP-W81XWH-20-1-0579, DOD-VRP-W81XWH-20-1-0820, NIH-R61EY032468, NIH-P30EY014801, Research to Prevent Blindness Unrestricted Grant GR004596-1 (institutional).