What structural and functional differences in the brain seem to be related to burning mouth syndrome (BMS), and what is the role of sensory circuits in the pathophysiology of burning mouth syndrome?

Updated: Apr 15, 2021
  • Author: Vincent D Eusterman, MD, DDS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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A study by Tan et al found neurologic differences between patients with burning mouth syndrome (BMS) and controls. Gray matter volume in the bilateral ventromedial prefrontal cortex (VMPFC) was smaller in individuals with burning mouth syndrome (BMS), while functional connectivity between the VMPFC and bilateral amygdala was greater. The investigators suggested that an association exists between such connectivity, as well as between the VMPFC gray matter volume, and the number of years a patient has had burning mouth syndrome (BMS). [13]

One small study proposed that unilateral chorda tympani (taste) hypofunction results in lingual nerve (somatosensory) hyperfunction by disruption of a centrally mediated equilibrium between the two. [14] Observation in other conditions has shown that when a sensory circuit loses afferent signals that hyperactivity may result in hallucinatory sensations. Examples of this include phantom limb sensation following amputation and tinnitus in hearing loss. It would tend to account both for pain and for gustatory disturbances in burning mouth syndrome (BMS). Metallic or sour tastes are considered symptomatic manifestations of an understimulated gustatory circuit while understimulated sensory circuitry manifests burning sensations. The cause of this proposed neuropathy is unknown.

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