Psychophysical assessment of tactile, pain and thermal sensory functions in burning mouth syndrome.

Tactile, two-point discrimination, thermal change detection and heat pain thresholds as well as oral stereognostic ability, warmth scaling and heat pain tolerance were compared in a group of 72 subjects with burning mouth syndrome (BMS) and 43 age- and sex-matched control subjects. No differences were found between the BMS and control subjects for any of the sensory modalities tested except for heat pain tolerance. Pain tolerance was significantly decreased for the BMS subjects at the tongue tip, a site of clinical pain in approximately 85% of the subjects tested in this study, but not at the cutaneous lower lip which was a site of pain only in approximately 17% of the subjects tested in this study. In addition, no differences in heat pain tolerance were found at the cutaneous lower lip between the control subjects and the BMS subjects who reported pain on the mucosal lower lip (approximately 49% of subjects), but heat pain tolerance was significantly decreased at this site for those BMS subjects tested without pain on the mucosal lower lip (approximately 51% of subjects). These findings do not suggest a psychogenic origin for the alteration of heat pain tolerance in the BMS subjects, but suggest instead specific changes in their peripheral or central sensory functions.