fMRI-Measured Brain Activation Evoked by Dentoalveolar Pressure in Atypical Odontalgia: IADR/AADR/CADR 89th General Session

Objectives: Atypical odontalgia (AO) is a chronic intraoral pain condition of unknown etiology that may involve peripheral and central mechanisms. We used functional magnetic resonance imaging (fMRI) to identify cortical and subcortical activation patterns in AO and control subjects following dentoalveolar pressure stimuli. Methods: 13 AO (11 females; mean age 55±10yrs, 12 right-handed) and 13 age-, gender- and handedness-matched control subjects received dentoalveolar pressure stimuli during fMRI using blood-oxygenation-level-dependent (BOLD) contrast (Siemens 3T Trio scanner; TR=3000ms; TR=30ms; voxel size=3x3x5.375mm; matrix size=64x64x36 voxels). Intraoral stimulation was delivered using a MR-compatible custom device (30s baseline, 3x 30s-ON/30s-OFF) over the reported dentoalveolar pain location for AO (8 right-sided) and to matched locations in controls. AO and controls received pressure stimulus evoking pain ratings between 3-5 in a 0/10 verbal scale (painlock), while only controls received a second stimulation level to match the mean pressure delivered for AO (stim-lock). Results: Brain activations overlapped for AO and controls (pain-lock), including primary/secondary somatosensory cortices, inferior parietal lobe, thalamus and cerebellum (see table/figure). Mean brain activation area for the AO group (306,662 mm3) was larger compared to controls (pain-lock=88,272 mm3; stim-lock=4,772mm3). AO group displayed significantly greater activation than controls for both stimulus levels, whilst controls had no greater activation than AO for either pain- or stim-lock stimuli. Conclusions: At non-painful stimulus level for controls, AO subjects had wider distribution of cortical and subcortical activation patterns than those – consistent with reduced pain thresholds in AO patients. When stimulus was matched for subjective pain ratings, AO still presented greater brain activation than controls that overlap. Our findings suggest that AO subjects recruit more widespread brain pathways following dentoalveolar pressure stimuli compared to controls. Supported by grants K12-RR023247, P41-RR008079 and P30-NS057091.