Burning Mouth Syndrome (BMS)

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Burning Mouth Syndrome (BMS)

Burning mouth syndrome is a common disorder afflicting many thousands of people in the US. This disorder most commonly affects older people, mainly women. Because there are few if any associated physical signs of pathology in the oral cavity it has not been studied as a serious medical problem although the persistence of oral burning (pyrosis) can become the predominant controlling element in the lives of those who suffer with this complaint rendering the patient incapable of leading a productive, healthy life.

We have evaluated 53 patients with this complaint at The Taste and Smell Clinic, Washington, DC over the last 20 years. With the assistance of a summer intern, Jennifer Yeh, an undergraduate student at MIT, and our outstanding technician, Irina Velicu, we have systematically evaluated the clinical history, metabolic and sensory characteristics of these patients. We also initiated specific therapeutic clinical trials with these patients in an effort to obviate their clinical symptoms.

The patients were 42 women (79% of patients) and 11 men, aged 32-73y (57±2y, mean±SEM). 36 patients (68 %) had burning limited to their tongue whereas 17 patients (32 %) had burning which extended to their entire oral cavity, including tongue, palate, lips, gums, cheeks and/or pharynx.

No oral pathology of any type was observed in any of these patients despite their complaints of persistent, severe oral burning.

20 patients (38 %) complained of loss of taste and all of these (100 %) had taste loss verified by measurement of taste function tests for one or more tastant. 26 patients (49%) complained of smell loss and all of these (100 %) had smell loss verified by measurement of smell function in tests for one or more odorants.

In prior studies these patients were treated with a variety of drugs before their visit to The Taste and Smell Clinic, Washington, DC. These included intramuscular injection of vitamin B12, various mineral, vitamin and hormonal preparations. None of these interventions were useful in decreasing, eliminating or altering their pyrosis.

Because we considered the symptoms of oral burning as a type of hyperalgesia and/or allodynia related in some manner to the symptoms of an aura of an unexpressed seizure disorder we hypothesized that localized decreased brain gamma aminobutyric acid (GABA), the normal inhibitory brain neurotransmitter, was the underlying mechanism causing this symptom. This mechanism is similar in concept to the decreased localized GABA concentrations observed in patients with phantom distortions of taste and/or smell that we had previously measured by functional magnetic resonance imaging (fMRI).

To test this hypothesis we treated 37 patients with either (1) a neurophysiological technique to increase brain GABA [transcranial magnetic stimulation (TCMS)] or (2) a GABAergic drug (Haldol or haloperidol). Of the 37 treated patients 24 or 65% improved with significant reduction in their oral pyrosis whereas 13 or 35% did not.

These results indicate that there are specific clinical characteristics common to patients with BMS. These clinical characteristics assist in the definition of the syndrome. They offer objective findings which help define the parameters of the syndrome. These results also suggest that there are specific therapies to relieve symptoms of pyrosis in patients with BMS.

These results lend support to our hypothesis that the primary pathology for these symptoms lie not in the oral cavity but in the brain and is related to localized decreases in brain GABA.