Burning Mouth Syndrome and Atypical Odontalgia Share Neurosensory Abnormalities

Objectives: Burning Mouth Syndrome (BMS) and Atypical Odontalgia (AO), both chronic continuous orofacial pains, are hypothesized to be neuropathic in mechanism, but data are inconclusive. Quantitative sensory testing (QST) has shown promise for studying mechanisms of pain conditions. Aim: to compare QST parameter values in BMS/AO patients with symptom-free controls. Methods: The German Neuropathic Pain QST protocol of 13 somatosensory function tests was adapted for intraoral use. Cases with BMS or AO from a University clinic were tested along with symptom-free controls in 3 sessions over 2 days, 1 to 3 weeks apart. For AO cases, QST was performed intra-orally on symptomatic facial gingiva, asymptomatic contralateral site, and non-trigeminal site (thumb); for BMS cases, QST was performed separately on the right and left anterior dorsal tongue, and on the thumb. Respective controls had the testing performed similarly. Means and t-tests were computed comparing each case anatomic site with controls. Results: Interim analyses are reported for 18 AO cases (mean age 55.6y), 21 controls (44.0y), 10 BMS cases (53.9y) and 15 controls (53.1y). Of the 6 non-painful and 7 painful parameters, only a subset of the painful measures showed any case/control differences, all hyperfunction. At the thumb, significant differences (<.05) between cases/controls were observed for pressure pain threshold (PPT) in both AO- 376 vs. 425 kiloPascals (kPa) and in BMS- 349 vs. 444 kPa. At the painful gingival/tongue site, differences between cases/controls were shown for AO–Cold Pain Threshold 14.6 vs. 8.3 C(p=.003) and BMS-13.2 vs. 9.3 C(p=.16); AO-PPT 109 vs. 165 mN(p=.0001) and BMS-62 vs. 76 mN(p=.02). Taste testing in BMS cases/controls also showed hyperfunction in cases for 4 basic tastes. Conclusions: Results suggest that BMS and AO share neurosensory abnormalities of hyperfunction on the same QST painful parameters, both within the same painful neural segment plus extra-segmental locations. Grant: NIHR21DE018768/R21DE018768-S1.