Burning mouth syndrome

Introduction:

Burning mouth syndrome is defined as an idiopathic condition involving the mucosal lining of oral cavity causing excess deep burning pain in the absence of identifiable cause lasting atleast for a period of 6 months. This condition was first described by Fox in 1935.

Synonyms:

Glossodynia, Glossopyrosis, Oral dysesthesia, Stomatodynia & Sore tongue. Among these terms Glossodynia is favoured by ICD (International Classification of Diseases).

Sex prediliction:

It affects females 7 times more commonly than males. Studies have shown about 90% of sufferers are perimenopausal women.

Common sites involved:

1. Tongue

2. Hard palate

3. Lips

4. Buccal / Labial mucosa

5. Soft palate

6. Floor of mouth

Associated symptoms:

a. Dryness of mouth – This is purely a subjective sensation not backed by real time reduction in the amount of saliva secreted. Hence this sensation could mean altered sensation to be the cause rather than hyposalivation.

b. Altered taste

Patients invaraibly dont lose sleep due to burning mouth syndrome. It is usually present only during the period of wakefullness.

Clinical examination of these patients show lack of findings. Some of these patients give history of taking medicines that interfered with taste mechanism.

Etiology:

Till date no identifiable cause for Burning mouth syndrome has been demonstrated. Studies attribute the burning pain to be due to neuropathy. Studies have also demonstrated a reduction in the level of salivary neuropeptides. Histopathological studies have demonstrated that these patients have significantly lower densities of epithelial nerve fibers than normal individuals. Epithelial and subpapillary nerve fibers showed changes suggestive of axonal degeneration.

Studies have demonstrated increased levels of nerve growth factor peptides and tryptase activity in the saliva of patients suffering from this syndrome. The levels of substance P has found to be significantly lower in the salivary secretions of these patients. Measurements of these substances could prove as useful markers in identifying these patients.

Trigeminal dysfunction as a cause for Burning mouth syndrome: Blink reflexes in these patients were found to be abnormal. This lends credance to the theory that trigeminal dysfunction could probably cause Burning Mouth Syndrome.

Central neuropathy as a potential cause of Burning mouth syndrome: Studies have demonstrated decreased dopaminergic inhibition of the dominant Putamen in these patients. Endogenous dopamin levels in the putamen of these patients showed significant levels of reduction.

Burning mouth syndrome: Could it be phantom pain? Due to secondary damage to gustatory system. Supertasters with genetically caused increase in the number of fungiform papillae in the tongue may be under increased risk of Burning Mouth Syndrome.

Two subtypes of Burning Mouth Syndrome have been identified:

1. Due to peripheral cause

2. Due to central cause

Identification of these two types became possible when studies were conducted by infiltrating the lingual nerve with xylocaine. Burning mouth syndrome patients due to peripheral causes had beneficial reduction in symptoms while patients with central cause did not show any response at all.

Psychogenic associated factors:

1. Obsessive compulsive disorder

2. Depression

3. Cancerophobia

4. Anxiety

Differences between Burning mouth syndrome and secondary oral burning:

Burning mouth syndrome	Secondary oral burning
Complaints decrease while eating and chewing	Complaints increase while eating and chewing
Typically bilateral	Typically unilateral
Multiple sites are involved	Multiple site involvement uncommon
Associated mucosal lesions absent	Associated mucosal lesions present

Systemic causes of secondary oral burning:

a. Salivary dysfunction

b. Nutritional disorders like deficiency of folate, B complex, iron and zinc

c. GI disturbances like gastritis, GERD, H pylori infections.

d. Probable psychiatric disturbances

Diagnosis:

Usually diagnosis is possibly by exclusion.

History taking in these patients should include:

Location of burning

Characteristics of burning sensation

Onset

Duration

Loss of sleep due to burning sensation

Is the burning sensation worse on speaking / eating?

Aggravating & releiving factors if any should be ascertained.

Associated symptoms like taste disturbances & oral dryness should be sought.

History of ear disorders should be sought.

History of oral disorders, dentures etc.

Menopause, diabetes, depression / anxiety

History of surgery in the ear, oral cavity and intracranial procedures.

History of irradiation of malignant lesions.

Drug history should include: ACE inhibitors, antiretroviral drugs, tricyclic antidepressants etc.

Investigations:

1. Complete blood count

2. Blood sugar including GTT if necessary

3. Thyroid function tests

4. Estimation of serum iron, ferritin levels

5. ESR

6. Serum antinuclear antibodies

7. Serum antibodies for H pyrlori

8. Oral swab for candida

Management:

Alpha – lipoic acid – This is a mitochondrial co-enzyme with antioxidant effect. It has neuroprotective property which can be made use of in managing these patients. It is usually adminstered in doses of 400mg twice a day for a month.

Clonazepam & chlordiazepoxide – These drugs have been found to be useful in managing patients with Burning mouth syndrome. Clonazepam when administered in systemic dose of 1 mg /day for a period of one month proved beneficial in these patients. Clonazepam as topical application (i.e. Use of powdered medicine in a topical manner) also showed promising results. Trials with chlordiazepoxide did not show positive results. Gabapentin – Administration of gabapentin in doses of 400 mg /day for a period of one month showed varying responses.

Lafutidine – This is a H2 receptor antagonist with sensitizing effect on capsaicin – sensitive neurons. Lafutidine is usually used as oral rinse preformed atleast twice a day.

Topical anesthetics / antiinflammatory drugs – These are of questionable value in managing these patients.

Psychotherapy – Has been used with varying effects to treat these patients.