The Five Senses and Beyond: The Encyclopedia of Perception - Jennifer L. Hellier 2017

Burning Mouth Syndrome

Burning mouth syndrome is a physical condition known to arise spontaneously, characterized by a burning sensation in the mucous membrane of the mouth that persists for extended periods of time; the burning usually originates with the tongue, but has been known to spread to the lips, gums, and inside of the cheeks. The most common symptoms of burning mouth syndrome, in addition to a burning sensation in the mouth, include dry mouth (xerostomia), increased thirst, taste changes, and loss of taste.

The Mouth

The inside of the mouth is lined with mucous membranes, referred to as oral mucosa, that serve to protect fat and muscle tissue from mechanical injury and bacterial infection. The oral mucosa contains a vast network of nerves, which allows for parts of the mouth to be incredibly receptive to temperature and pressure. On the tongue, soft palate, upper esophagus, and parts of the cheek, the mucosa contains taste buds that serve to recognize various aspects of taste, such as sweet, salty, sour, bitter, and umami (a Japanese word meaning “savory”).

Diagnosis

There are no universally accepted diagnostic criteria, laboratory tests, or imaging studies that definitively diagnose or exclude burning mouth syndrome. Therefore, it is a clinical diagnosis that can only be made after the exclusion of all other causes. Currently, there are three classifications of burning mouth syndrome that are dependent on the apparent cause of the condition. Type 1, or “true burning mouth syndrome,” arises spontaneously: upon waking, no symptoms are initially present, but as the day progresses there is a gradual escalation in the severity of the condition. While Type 1 has no clear cause, Type 2 is often associated with chronic anxiety. Patients diagnosed with Type 2 have continuous symptoms that persist throughout the day, but typically cease upon going to sleep. A Type 3 diagnosis is dependent on the consistency of symptoms; often, patients will have intermittent symptoms throughout the day and even symptom-free days (Bergdahl & Bergdahl, 1999). Since there is clear flux in the prominence of symptoms, food allergies have been suggested as a potential mechanism for the portrayal of the condition.

Epidemiology

While no definitive connections have been established, burning mouth syndrome seems to be most prevalent in women. Specifically, older women who are postmenopausal face the greatest risk for developing the condition. Burning mouth syndrome rarely presents in individuals under the age of 30 and has not been associated with any particular race. While the majority of diagnosed cases are Type 1, cases that begin spontaneously with no known triggering factor, other types are suggested to be correlated with upper respiratory tract infections, food allergies, medications, and anxiety. However, these conditions have not been consistently linked with the syndrome. Additionally, treatment of suspected correlated conditions has done little to consistently reduce the prevalence of the syndrome. Currently, there is no definitive cure for the condition.

Future Research

There is no consensus regarding a definitive cause for burning mouth syndrome. Understanding the cause for the condition could provide insight into how the oral mucosa is connected to other aspects of the body. Specifically, a better understanding of how the taste buds and sensory nerves relay information about temperature to the brain could reveal possible ways to treat the syndrome. The broad definition of the condition and variability in the way the condition presents have prevented homogeneous research from being established. For instance, Type 1 burning mouth syndrome is, by definition, not known to be linked to other factors, whereas Type 2 is suspected of being connected to the endocrine system, nutritional habits, bacterial infection, pharmaceutical drugs, and possibly even neuropsychiatric factors. Currently, the broad definition serves to fill an absence of knowledge in the medical community. Research should be directed at developing methodologies to test for the presence or absence of the condition, and at the ways in which burning mouth syndrome is connected to other aspects of the body.

James Danahey

See also: Bartoshuk, Linda; Nociception; Taste Aversion; Taste Bud; Taste System

Further Reading

Bergdahl, Maud, & Jan Bergdahl. (1999). Burning mouth syndrome: Prevalence and associated factors. Journal of Oral Pathology & Medicine, 28(8), 350—354. http://dx.doi.org/10.1111/j.1600-0714.1999.tb02052.x

Gruska, Miriam, Joel B. Epstein, & Meir Gorsky. (2002). Burning mouth syndrome. American Family Physician, 65(4), 615—620. Retrieved from http://www.aafp.org/afp/2002/0215/p615.html

Nelson, Linda P. (2013). Consumer version: Biology of the mouth—Mouth and dental disorders. Merck Manuals. Retrieved from http://www.merckmanuals.com/home/mouth-and-dental-disorders/biology-of-the-mouth-and-teeth/biology-of-the-mouth