Burning Mouth Syndrome (BMS)

What Is Burning Mouth Syndrome?

Burning mouth syndrome is a chronic intraoral painful disorder characterized by a burning sensation in specific areas of the tongue or the oral mucosa but without any mucosal lesions or ulcerations. The representation of this disease varies clinically from other oral diseases because the oral mucosa appears healthy without any clinical pathology or disturbance on examination, making it a challenging diagnosis for the dental or the oral and maxillofacial surgeon to determine any underlying systemic links.

The central and peripheral nervous system is affected by this disease. This altered membrane receptivity in the oral mucosa and the oral cavity is distressing to the patient as it is an overexcited stimulus that is felt as a burning sensation. The symptoms are unusual in this condition and may involve a systemic or drug-related etiology. From local disturbances or irritations (like salivary gland dysfunctions and taste receptor disturbances or alterations) to neurogenic and psychogenic systemic factors, the causative factors may be multiple in origin.

The general incidence of the occurrence of BMS is more in women than men, with a clinical ratio of 7:1 (in women- it affects approximately 5.5 percent in the general population and 1.6 percent in the male population). Women post menopause often are prone and particularly at an increased incidence or specific risk for BMS.

What Is the Pathophysiology of BMS?

The biological alterations in the PNS (peripheral nervous system) or CNS (central nervous system) in the case of burning mouth syndrome would be largely attributed to the receptivity or density alterations of membrane receptors in the oral mucosa in these individuals. This receptivity may be aggravated and is affected by systemic health conditions and may be related to stress, anxiety, old age, and climacteric. Depression, anxiety, and high-stress levels modulate the individual perception of pain by increasing or decreasing the pain transmission from peripheral nerve receptors. This often results in an altered taste (dysgeusia) or reduced taste sensitivity (hypogeusia).

Studies have also shown that hyperalgesia or increased perceptivity to pain results from axonal degeneration observed more frequently in BMS patients bilaterally in the anterior two-thirds of the tongue. Gustatory perception is the most affected because the taste buds of the fungiform papillae (on the tongue) have no axons with Schwann cell ensheathment (the axon is the long slender nerve fiber or cell which is protected by the Schwann cells encasement or sheath called the myelin sheath in other organs of the body). This is mainly responsible for the burning sensation reported without any apparent clinical symptoms.

What Are the Symptoms of BMS?

The symptoms of BMS are generally not confined to any specific anatomic boundaries in the oral cavity. Still, the locations commonly referred to in these cases clinically are in the tip of the tongue, lateral border of the tongue, lips, and palate. The most commonly reported oral manifestations may vary from dry mouth or xerostomia to pain and burning in the oral mucosa to general changes like even sleep disturbances, mood swings, depression, decreased potential or desire to socialize, and anxiety as well.

How Are Menopause and BMS Related?

In menopausal women, these symptoms are reported more and most common as they have unusual symptoms of burning mouth syndrome. As per current research, theories have been postulated that link estrogen hormone imbalance to BMS. The imbalance in estrogen levels during menopause may alter the sensory nerve fibers, for which hormone replacement therapies may be useful.

What Are the Types of BMS?

According to Lamb et al., the classification of BMS is as follows:

• Type 1 BMS: Gradual increase in BMS as the day progresses but no pain or burning on usual waking.

• Type 2 BMS: The burning sensation is present constantly without flux, both day and night.

• Type 3 BMS: Burning is a frequent and recurring sensation within a day or more of gap or remission without any specific pattern.

How to Manage Burning Mouth Syndrome?

As the clinical symptoms vary from patient to patient suffering from BMS, treatment modalities depend on symptomatic pain relief management. Topical application of dyclonine 0.5 percent, diphenhydramine 0.5 percent, and lidocaine 2 percent anesthetic combined with analgesic gels usually aids in relieving the symptoms caused by local irritation in the oral mucosa. Mainline therapy for BMS depends on the etiology which include::

• Hormonal changes (post-menopausal distress).

• Diabetes mellitus.

• Hematologic disorders and anemias.

• Viral infections such as the herpes virus cause neuropathic pain.

• Hypothyroidism (decreased levels of T3 or T4 hormone and increased thyroid-stimulating hormone).

• Antiretroviral, anticoagulant, and angiotensin blocker drugs.

• Psychogenic stress, anxiety, and depression.

• Neurogenic factors (cranial nerve dysfunctionalities).

Hence the mainline therapy is a diagnosis based on the patient's oral and systemic health status and history. The underlying systemic diseases must be treated to improve nociceptive pain perception pathways to treat BMS. Centrally acting medications are given for neuropathic pain relief like low dosage Benzodiazepine 0.25 to 0.75 mg (like clonazepam), Tricyclic antidepressants 10 to 40 mg (like amitriptyline, desipramine) by the physician with dosage of these drugs as per the extent of chronic pain.

Studies have also shown alpha-lipoic acid supplements as potent antioxidants and neuroprotective agents so that neuropathic pain-causing BMS can be relieved effectively. Similarly, capsaicin is also known to be a desensitizer for reducing the peripheral burning sensation in the mouth. Cognitive-behavioral therapy, which ensures the patient and enhances the bond between the doctor and patient, is useful in BMS management. Hence the patient is positively reinforced, knowing that the disease is not fatal nor life-threatening that eventually resolves with medications and treatment of systemic or local etiology.

How Can Burning Mouth Syndrome Be Prevented?

The symptoms associated with this condition can be prevented by avoiding the trigger factors. Some common triggers are

• Alcohol.

• Citrus juices are highly acidic.

• Hot and spicy food items.

• Mouthwashes that have alcohol content.

• Tobacco products.

Conclusion:

Although oral health management by the dental surgeon will help relieve the patient's symptoms in BMS, researchers and pharmacologists are investigating other effective treatment strategies to minimize the perceptive suffering in these individuals. It is pivotal for the dentist to establish a differential diagnosis before treating the patient for burning mouth syndrome and provide symptomatic relief as per the patient’s individual presenting complaint in this enigmatic condition.