Sensory and pain thresholds to orofacial argon laser stimulation in patients with chronic burning mouth syndrome.

Abstract

Psychophysical assessments of orofacial sensory function were performed in order to investigate neurophysiological aspects of the burning mouth syndrome (BMS). Sensory and pain thresholds to brief argon laser stimulation were determined on six test regions, which included the tip of tongue, the lower lip mucosa and skin, the buccal mucosa, the anterior hard palate, and the dorsum of the hand. The experimental examination was performed at the Pain Clinic Unit at the Royal Dental College. Twenty-three elderly denture-wearing patients diagnosed as suffering from BMS were studied, and a control group included 23 age-, sex-, and denture-matched subjects. The obtained thresholds were compared between groups. Sensory thresholds were significantly higher and ratios between pain and sensory thresholds significantly lower in patients with BMS on all the tested regions. Pain thresholds were significantly elevated on the lower lip skin, the anterior hard palate, and the hand in patients with BMS. At sensory threshold level, a faint pinprick perception was often reported by patients with BMS contrary to a perception of warmth described by control subjects. The intraregional variations in sensory and pain thresholds on the hard palate, the lower lip mucosa, and on the skin were similar in both groups, but differences occurred in sensory thresholds on the tongue in patients with BMS. The presence of abnormal prepain perceptions and disturbances in the perception of nonnociceptive and nociceptive thermal stimuli applied on both pain-affected and normal regions suggest a perceptual deficit unrelated to specific pathophysiological mechanisms in BMS. However, it appears that a psychological explanation of BMS should be used cautiously, as the present results suggest alterations in sensory function.