An fMRI Study Of Brain Response In Patients With Fibromyalgia

Single voxel spectra obtained from the anterior and posterior right insula at rest to compare ratios for Gln/Cr, Glu/Cr, and combined Glutamate + Glutamine (Glx/Cr) for pregabalin and placebo. Gln, Glu, Glx calculated as ratios to the internal standard creatine.

BOLD fMRI imaging modality to assess brain activation signals across the whole brain in defined Region of Interest (ROI) brain regions in response to blunt pressure pain; acquired during resting state (no evoked pain) and during evoked pain (thumb pressure device with non-painful pressure, 2 kilograms [kg] pressure/equal stimulus conditions, and high pain pressure/up to 10 kg). Estimated as magnitude (percent change) of the betas representing brain signal activation associated with pressure induced pain. Any observation with a studentized residual >3 or <-3 was considered an outlier.

BOLD fMRI imaging modality to assess brain activation signals across the whole brain in defined ROI brain regions in response to checkerboard visual stimuli (flashing at 8 hertz [Hz]). Reported as percent change between the pre-dose (baseline) and post-dose values.

Resting state brain activity assessed for correlation of brain seed region (pIns, anIns) to ROI connectivity at baseline (pre-dose) and post-dose (pre minus post) measured using z-score (mean of 0, standard deviation [SD] of 1); range approximately -3 to +3. Positive (+) z-scores reflect greater connectivity (+correlation between seed region and ROI). Negative (-) z-scores reflect -connectivity (anti-correlation between seed region and ROI). ROIs include PCC and IPL from within the default mode network (DMN). DMN is a constellation of regions in which connectivity is augmented in fibromyalgia.

Minimum and maximum pain intensity acquired during resting state (no evoked pain) and during evoked pain (thumb pressure device with non-painful pressure, 2 kg pressure/equal stimulus conditions, and high pain pressure/up to 10 kg) measured during fMRI and scored from 0 (no pain sensation) to 20 (extremely intense). Baseline and Post-dose data for Period 1 and Period 2 summarized as Least Squares Mean (LS Mean). Any observation with a studentized residual >3 or <-3 was considered an outlier.

Minimum and maximum pain unpleasantness acquired during resting state (no evoked pain) and during evoked pain (thumb pressure device with non-painful pressure, 2 kg pressure/equal stimulus conditions, and high pain pressure/up to 10 kg) measured during fMRI and scored from 0 (neutral) to 20 (very intolerable). Baseline and Post-dose data for Period 1 and Period 2 summarized as LS Mean. Any observation with a studentized residual >3 or <-3 was considered an outlier.

The daily pain diary consisted of the mBPI item regarding participant-rated average of pain over the past 24 hours. Scored on an 11-point numeric scale ranging from 0 (no pain) to 10 (pain as bad as you can imagine). The 7 day average pain score was defined as the mean daily pain NRS value for the last 7 days prior to fMRI scanning visit. Baseline and Post-dose data for Period 1 and Period 2 summarized as LS Mean. Any observation with a studentized residual >3 or <-3 was considered an outlier.

The daily pain diary consisted of the mBPI item regarding participant-rated average of pain over the past 24 hours. Scored on an 11-point numeric scale ranging from 0 (no pain) to 10 (pain as bad as you can imagine). The 3 day average pain score was defined as the mean daily pain NRS value for the last 3 days prior to fMRI scanning visit. Baseline and Post-dose data for Period 1 and Period 2 summarized as LS Mean. Any observation with a studentized residual >3 or <-3 was considered an outlier.

The daily pain diary consisted of the mBPI item regarding participant-rated average of pain over the past 24 hours. Scored on an 11-point numeric scale ranging from 0 (no pain) to 10 (pain as bad as you can imagine). The individual daily pain score was defined as the final score recorded in the last pain diary of the treatment period 24 hours prior to fMRI scanning visit. Baseline and Post-dose data for Period 1 and Period 2 summarized as LS Mean. Any observation with a studentized residual >3 or <-3 was considered an outlier.

SF-MPQ was completed to assess pain over the past week and to assess present pain and consists of 15 pain descriptors: sensory dimension of pain experience (sum of items 1 to 11) and affective dimension (sum of items 12 to 15). Each descriptor was ranked by participant on a 4-point intensity scale (0=none to 3=severe) and totaled in each subclass (sensory range 0 to 33; affective range 0 to 12); higher scores indicated higher pain/impact. Baseline and Post-dose data for Period 1 and Period 2 summarized as LS Mean. Any observation with a studentized residual >3 or <-3 was considered an outlier.

SF-MPQ was completed to assess pain over the past week and to assess present pain and consists of 15 pain descriptors: sensory dimension of pain experience (sum of items 1 to 11) and affective dimension (sum of items 12 to 15). Each descriptor was ranked by participant on a 4-point intensity scale (0=none to 3=severe) and totaled in each subclass (sensory range 0 to 33; affective range 0 to 12); higher scores indicated higher pain/impact. Baseline and Post-dose data for Period 1 and Period 2 summarized as LS Mean. Any observation with a studentized residual >3 or <-3 was considered an outlier.

SF-MPQ was completed to assess pain over the past week and to assess present pain and consists of 15 pain descriptors: sensory dimension of pain experience (sum of items 1 to 11) and affective dimension (sum of items 12 to 15). Each descriptor was ranked by the participant on a 4-point intensity scale (0=none to 3=severe) and totaled in each subclass (sensory range 0 to 33; affective range 0 to 12). Total (overall) score was sum of items 1 to 15, range 0 to 45; higher scores indicated higher pain/impact. Any observation with a studentized residual >3 or <-3 was considered an outlier.

BP cuff evoked allodynia assessed based on participant response to the following question "When I take your blood pressure, tell me if the cuff's pressure is painful". A standard BP cuff was inflated at approximately 10 millimeters of mercury (mm Hg) per second up to 180 mm Hg or to point when participant experienced pain; performed 3 times on each arm whether or not pain was reported. If no pain elicited at 180 mm Hg, it was recorded that no sphygmomanometry-evoked allodynia occurred. If pain was reported, value (in mm Hg) at which pain first occured was recorded for each of the assessments.

Participant rated severity of pain upon application of 4 kilograms (kg) pressure via dolorimeter at the bilateral epicondyle tender points (2 tender points, 2 centimeters distal to the epicondyles) described in the American College of Rheumatology (ACR) classification criteria and scored on a 0 (no pain) to 10 (worst possible pain) rating scale. Each arm was to be assessed for any pain (one point on each arm) with the application of pressure.