A preliminary fMRI study on the effects of burning perception on cognitive-related brain networks in burning mouth syndrome patients

Abstract

Burning mouth syndrome (BMS) is a rare, idiopathic pain condition characterized by bilateral-burning sensations of tongue, lips, and oral mucosa. Most BMS patients are relatively pain free in the mornings, while pain and burning intensity increase substantially by late afternoon. We hypothesized that when BMS symptoms are strongest, patients activate more brain areas to a greater extent while performing a cognitive task, despite comparable performance levels. Seven women with BMS (mean age 54, range 40-67) underwent two sessions in one day (early morning and late afternoon). Participants performed the multi-source interference task (MSIT) with two levels of difficulty (low and high cognitive load) during an fMRI scan (3T Siemens Tim-Trio). Questionnaires completed at the two sessions included: short form McGill Pain Questionnaire; State-Trait Anxiety Inventory; Profile of Mood States. Patients also rated their BMS pain intensity and burning intensity on a numerical rating scale of 0-10. Patients had significantly higher burning intensity ratings in the afternoon sessions, but no significant change in pain intensity, anxiety, or mood, and there was no difference in MSIT performance between sessions. MSIT performance activated a cognitive network including bilateral premotor, midcingulate, posterior parietal, anterior insula, visual motion area (MT+), and cerebellum. In the high cognitive load condition, patients had increased activity in the afternoon in left caudate. Three additional clusters that were marginally significant included bilateral posterior/mid insula, and brainstem/periaqueductal gray (PAG). Increased activity in these regions was not correlated with changes in burning intensity or any other measured behavioral variable. Interestingly, we also found significantly increased activity during the afternoon session for the low cognitive load condition in left mid and posterior insula, left thalamus, and bilateral paracentral lobule. Our findings thus suggest that ongoing burning pain can influence cognitive networks, and do so differentially depending on the difficulty of the task. Burning mouth syndrome (BMS) is a rare, idiopathic pain condition characterized by bilateral-burning sensations of tongue, lips, and oral mucosa. Most BMS patients are relatively pain free in the mornings, while pain and burning intensity increase substantially by late afternoon. We hypothesized that when BMS symptoms are strongest, patients activate more brain areas to a greater extent while performing a cognitive task, despite comparable performance levels. Seven women with BMS (mean age 54, range 40-67) underwent two sessions in one day (early morning and late afternoon). Participants performed the multi-source interference task (MSIT) with two levels of difficulty (low and high cognitive load) during an fMRI scan (3T Siemens Tim-Trio). Questionnaires completed at the two sessions included: short form McGill Pain Questionnaire; State-Trait Anxiety Inventory; Profile of Mood States. Patients also rated their BMS pain intensity and burning intensity on a numerical rating scale of 0-10. Patients had significantly higher burning intensity ratings in the afternoon sessions, but no significant change in pain intensity, anxiety, or mood, and there was no difference in MSIT performance between sessions. MSIT performance activated a cognitive network including bilateral premotor, midcingulate, posterior parietal, anterior insula, visual motion area (MT+), and cerebellum. In the high cognitive load condition, patients had increased activity in the afternoon in left caudate. Three additional clusters that were marginally significant included bilateral posterior/mid insula, and brainstem/periaqueductal gray (PAG). Increased activity in these regions was not correlated with changes in burning intensity or any other measured behavioral variable. Interestingly, we also found significantly increased activity during the afternoon session for the low cognitive load condition in left mid and posterior insula, left thalamus, and bilateral paracentral lobule. Our findings thus suggest that ongoing burning pain can influence cognitive networks, and do so differentially depending on the difficulty of the task.