Glossodynia

Glossodynia, also known as burning mouth syndrome, refers to the painful, burning sensation of the tongue or oral mucosa, despite a lack of clinical findings and abnormalities in laboratory testing or imaging of the oral cavity.

The definitive cause of glossodynia has not been established; however, studies have suggested that trigeminal small-fiber sensory neuropathy may lead to the symptoms of glossodynia. Another potential cause could be damage to the chorda tympani nerve, a branch of the facial nerve that supplies taste sensation to the anterior two-thirds of the tongue. Additionally, research has identified a higher number of D₂ dopamine receptors in the putamen (i.e., a region of the brain activated during pain) in individuals with glossodynia, which may result in the dysregulation of pain perception. Given that glossodynia has been diagnosed in individuals during the perimenopausal to postmenopausal period, it has been proposed that altered sex hormones and estrogen deficiency may play a role. Lastly, a potential etiologic role of psychological factors, such as anxiety and depression, has been suggested. Further research is needed to elucidate the exact pathomechanism for glossodynia.

The signs and symptoms of burning mouth syndrome include pain of the tongue, commonly the anterior two-thirds, or other oral mucosa (i.e., palate, lip, buccal mucosa, and floor of the mouth) that can be described as burning, scalding, tingling, itchy, or numb. The pain is constant or intermittent and can range from moderate to severe in intensity. Onset may be gradual or sudden. Typically at presentation, the pain is chronic, lasting from 4 to 6 months. The pain may be present upon awakening or it can develop and intensify as the day progresses. Eating, drinking, and talking can either worsen or decrease the severity of symptoms depending on the individual. Stress and fatigue have been reported to worsen symptoms. Additionally, many individuals with glossodynia choose to avoid hot, spicy, or acidic food/liquids or alcoholic beverages as these tend to worsen symptoms.

Typically, no precipitating factor can be identified, however, in some cases, a dental procedure, trauma, side effects of medications (e.g., cancer drugs, such as sorafenib and sunitinib), illness, or a stressful life event can lead to the development of glossodynia. Other associated symptoms include dysesthesia (i.e., altered sensation); dysgeusia, or altered taste, specifically a bitter or metallic taste); and a sensation of having dry mouth secondary to reduced salivation. Psychological comorbidities have been reported, including anxiety, depression, somatization, hypochondria, phobia, and insomnia. This condition predominantly affects postmenopausal individuals, however, both sexes can be affected. It predominantly affects older individuals, particularly those 80 years and older, however, middle-aged individuals can also be affected.

Glossodynia is diagnosed based on a comprehensive medical history, dental history, and a thorough review of systems. According to the International Classification of Headache Disorders (ICHD-3), a diagnosis of glossodynia requires all of the following: 

• Oral pain; 

• Pain recurring daily for more than two hours per day for more than three months;

• Pain has both of the following characteristics: burning quality, felt superficially in the oral mucosa; 

• Oral mucosa is of normal appearance; and clinical examination, including sensory testing, is normal; 

• Symptoms must not be better accounted for by another ICHD-3 diagnosis 

Glossodynia is considered a diagnosis of exclusion and it is therefore imperative to rule out secondary causes of oral pain. Secondary causes include infections of the oral mucosal (e.g., herpes simplex, aphthous stomatitis, oral lichen planus); psychiatric disorders (e.g., post-traumatic stress, depression, chronic anxiety); xerostomia (i.e., dry mouth); medications (e.g., antidepressants including citalopram, fluoxetine), autoimmune disease (e.g., Sjögren syndrome and systemic lupus erythematosus); nutritional deficiencies (e.g., vitamin B12, iron, folate, zinc, vitamin B6); and allergic contact stomatitis. In allergic contact stomatitis, allergy testing may be performed to rule out allergic causes of oral irritation and pain. 

In approximately 30 to 50 percent of individuals, the symptoms of glossodynia can improve spontaneously and treatment is not always required. To manage the symptoms, behavioral modifications can be implemented, including the reduction of teeth clenching and bruxism, or teeth grinding. The use of oral care products containing alcohol and flavoring agents may be minimized, as they can contain irritants. Self-regulatory exercises commonly used for chronic pain conditions, such as regular exercise, diaphragmatic breathing, maintaining a proper diet and adequate hydration, and intentional relaxation, may be beneficial. 

Cognitive-behavioral therapy (i.e., a form of talk therapy provided by trained clinicians) has been used in some cases. Topical treatments for glossodynia include nonsteroidal anti-inflammatory drugs (NSAIDs) (e.g., benzydamine hydrochloride); salivary substitutes (i.e., substances that contain carboxymethylcellulose [CMC], mucin, or xanthan gum), and topical capsaicin (e.g., chili pepper extract). Systemic medications include anticonvulsants (e.g., gabapentin or pregabalin), dopamine agonists (e.g., pramipexole), and antioxidants (e.g., alpha-lipoic acid). Both topical and oral clonazepam, which is a benzodiazepine, may also be used. 

Glossodynia, also known as burning mouth syndrome, refers to a long-term burning, painful sensation of the tongue or oral mucosa without apparent clinical or laboratory abnormalities. While the definitive cause remains uncertain, potential factors include trigeminal small-fiber sensory neuropathy, damage to the chorda tympani nerve, and dysregulation of pain perception. Hormonal changes and psychological factors like anxiety and depression are also implicated. Symptoms involve chronic pain, altered taste, and dry mouth, predominantly in those 80 years or older. Diagnosis involves excluding secondary causes and meeting specific criteria outlined in the ICHD-3. Treatment may include behavioral modifications, self-regulatory exercises, cognitive-behavioral therapy, and various topical or systemic medications, although spontaneous improvement may occur in up to half of all cases.