Amplified Brain Processing of Dentoalveolar Pressure Stimulus in Persistent Dentoalveolar Pain Disorder Patients.

AIMS: (1) To determine the brain regions activated by dentoalveolar pressure stimulation in persistent dentoalveolar pain disorder (PDAP) patients, and (2) to compare these activation patterns to those seen in pain-free control subjects.
METHODS: A total of 13 PDAP patients and 13 matched controls completed the study. Clinical pain characteristics and psychosocial data were collected. Dentoalveolar mechanical pain thresholds were determined with a custom-made device over the painful area for patients and were used as the stimulation level during functional magnetic resonance imaging (fMRI) data acquisition. Control subjects received two stimulation levels over matched locations during fMRI scanning: one determined (as above) that evoked equally subjective pain ratings matching those of patients (subjective-pain match) and another nonpainful stimulation level matching the average stimulus intensity provided to patients (stimulus-intensity match). Clinical and psychosocial data were analyzed using independent samples t tests, Mann-Whitney U test, and Spearman rank-order correlation coefficient. fMRI data were analyzed using validated neuroimaging software and tested using a general linear model.
RESULTS: PDAP patients had greater anxiety (P<.0001) and depression scores (P=.001), more jaw function impairment (P<.0001), and greater social impact (P<.0001) than controls. No significant differences were found for brain activation spatial extent (PDAP X Controls subjective pain: P=.48; PDAP X Controls stimulus intensity: P=.12). Brain activations were significantly increased for PDAP patients compared to control subjects when matched to stimulus intensity in several regions related to the sensory-discriminative and cognitive components of pain perception, including the primary and secondary somatosensory cortices, inferior parietal lobule, insula, premotor cortex, prefrontal cortex, and thalamus. When matched to subjective pain ratings, increased brain activations were still present for PDAP patients compared to controls, although to a lesser extent.
CONCLUSION: The present results suggest that dentoalveolar pressure is processed differently in the brain of PDAP patients, and the increased activation in several brain areas is consistent with amplified pain processing.