Table 3.
Studies using QST for SFN assessment.
| Author | Test | Site | Relevant Outcomes | SFN Implication Comments |
|---|---|---|---|---|
| Grushka et al. 1987 [43] | QST: Thermal stimuli between 34–46 °C in 2 °C steps |
Tongue tip, lower lip mucosa | No significant difference in the thermal change detection threshold between BMS and controls. Heat pain tolerance significantly lower in BMS than in controls |
No significant differences in thermal change detection thresholds between BMS patients and controls Lower heat pain tolerance in BMS patients, suggesting that while Aδ and C fibers may respond similarly to temperature changes, there might be an abnormal pain processing, particularly involving Aδ fibers |
| Svensson et al. 1993 [45] | QST: Brief argon laser stimulation (2.15 W, 200 ms) |
Tongue tip, lower lip mucosa, buccal mucosa, anterior part of hard palate | Significantly increased sensory across various oral and facial sites in BMS patients Significantly decreased heat pain tolerance at tongue tip in BMS patients |
Increased sensory thresholds and decrease of heat pain tolerance suggest potential degeneration of peripheral nerve fibers |
| Ito et al., 2002 [46] | QST: Thermal stimuli between 0–50 °C; Mechanical stimulation |
Tongue | Higher thermal pain thresholds (apex and left and right margins of the tongue) in BMS patients compared to controls | Higher thermal pain thresholds may indicate peripheral neurophysiological dysfunction |
| Kaplan et al., 2011 [51] | QST: Thermal stimuli between 8–50 °C |
Middle anterior dorsal tongue surface | No differences in WDT and CDT, HPT and CPT between BMS and healthy controls | The lack of difference in WDT, CDT, HPT, and CPT suggests that SFN may not be a defining feature of BMS highlighting the potential variability in the condition |
| Mo et al., 2015 [54] | QST: Thermal stimuli between 0–50 °C |
Tip of the tongue; lower lip mucosa | Significantly lower CDT and CPT in BMS Significantly higher HPT in BMS |
Localized loss of thermal function supports the hypothesis that BMS could be a neuropathic pain condition with the involvement of peripheral and/or central pain mechanisms |
| Puhakka et al., 2016 [40] | QST: Thermal stimuli between 10–50 °C |
Lingual nerve distribution, bilateral | Significantly higher CDT in BMS No significant changes in WDT and HPT |
Peripheral neuropathy in BMS might not be confined to small fiber systems alone, potentially involving other nerve fibers or central mechanisms as well |
| Yilmaz et al., 2016 [56] | QST: Thermal stimuli between 0–50 °C |
Anterior two-thirds of the tongue | Significantly lower CDT, WDT, and CPT in BMS No significant differences in HPT in BMS |
This pattern suggests impairments in ion channels within Aδ and C fiber nerve endings |
| Hartmann et al., 2017 [57] | QST: Thermal Stimuli between 5–50 °C |
Left and right side of tongue | Significant higher CDT and WDT Significant lower CPT |
Small fiber loss and impaired function |
| Kolkka et al., 2019 [59] | QST: Thermal stimuli between 10–55 °C |
Lingual nerve distribution, bilateral | Higher WDT and CDT in BMS | Neuropathic pain condition due to focal SFN |
Abbreviations: BMS: burning mouth syndrome; SFN: small fiber neuropathy; QST: quantitative sensory testing; WDT: warm detection threshold; CDT: cool detection threshold; HPT: heat pain threshold; CPT: cold pain threshold.