Grey matter changes of the pain matrix in patients with burning mouth syndrome.

Burning mouth syndrome (BMS) is characterized by a burning sensation in the mouth, usually in the absence of clinical and laboratory findings. Latest findings indicate that BMS could result from neuropathic trigeminal conditions. While many investigations have focused on the periphery, very few have examined possible central dysfunctions. To highlight changes of the central system of subjects with BMS, we analysed the grey matter concentration in 12 subjects using voxel-based morphometry. Data were compared with a control group (Ct). To better understand the brain mechanisms underlying BMS, the grey matter concentration of patients was also compared with those of dysgeusic patients (Dys). Dysgeusia is another oral dysfunction condition, characterized by a distorted sense of taste and accompanied by a reduced taste function. We found that a major part of the 'pain matrix' presented modifications of the grey matter concentration in subjects with BMS. Six regions out of eight were affected [anterior and posterior cingulate gyrus, lobules of the cerebellum, insula/frontal operculum, inferior temporal area, primary motor cortex, dorsolateral pre-frontal cortex (DLPFC)]. In the anterior cingulate gyrus, the lobules of the cerebellum, the inferior temporal lobe and the DLPFC, pain intensity correlated with grey matter concentration. Dys also presented changes in grey matter concentration but in different areas of the brain. Our results suggest that a deficiency in the control of pain could in part be a cause of BMS and that BMS and dysgeusia conditions are not linked to similar structural changes in the brain.