What are the causes and treatment options for burning mouth in a postmenopausal woman?

Causes of Burning Mouth in Postmenopausal Women

Burning mouth syndrome in postmenopausal women is primarily a neuropathic disorder affecting peripheral nerve fibers with central nervous system changes, but secondary causes including nutritional deficiencies, oral candidiasis, medication side effects, and systemic diseases must be systematically excluded before diagnosing primary burning mouth syndrome. 1, 2

Primary vs. Secondary Burning Mouth Syndrome

Primary Burning Mouth Syndrome

Primary BMS is a disorder of peripheral nerve fibers with central nervous system changes, confirmed through neurophysiological testing, biopsies, and functional MRI. 2 The condition manifests as:

• Continuous burning, stinging, or itchy sensation most commonly affecting the tongue tip bilaterally, lips, palate, and buccal mucosa, with normal-appearing oral mucosa on examination 1, 2
• Predominantly affects peri- and post-menopausal women with prevalence up to 12-18% in this population 3
• Associated symptoms include dry mouth, abnormal taste, depression, and poor quality of life 1
• Significantly lower density of epithelial nerve fibers in tongue biopsies compared to controls 2

The pathophysiology involves at least three distinct neuropathic mechanisms that may overlap: peripheral small diameter fiber neuropathy (50-65% of cases), subclinical trigeminal system pathology (20-25%), and central pain related to dopaminergic neuron hypofunction in basal ganglia (20-40%). 3

Secondary Causes That Must Be Excluded

Local Factors:

• Oral candidiasis diagnosed by scraping and KOH preparation 2
• Mucosal lesions including traumatic ulceration from sharp edges of residual roots/crowns, thermal burns, or chemical injury 2, 4
• Ill-fitting dentures or other traumatic factors 4

Nutritional Deficiencies:

• Vitamin B12 deficiency is a well-established cause requiring serum level testing 2, 4
• Iron deficiency anemia frequently presents with burning tongue, requiring ferritin, serum iron, and TIBC testing 2, 4
• Anemia identified through complete blood count with differential 2, 4

Systemic Diseases:

• Autoimmune diseases such as Sjögren's syndrome and sicca syndrome 2, 4
• Thyroid disorders, particularly hyperthyroidism causing tongue erythema and burning 2, 4
• Diabetes requiring fasting glucose and HbA1c testing 4

Neuropathic Causes:

• Post-herpetic neuralgia following herpes zoster causing continuous burning at the site of previous infection 4
• Post-traumatic trigeminal neuropathic pain developing within 3-6 months following dental procedures or facial trauma 4

Pharmacological Side Effects:

• Various medications can cause oral burning and must be reviewed in medication history 2, 4

Diagnostic Algorithm

Step 1: Clinical Assessment

• Document onset, duration, character of pain, and location specificity (tongue tip and anterior two-thirds most commonly affected) 4
• Perform thorough oral examination to identify visible mucosal lesions 4
• Assess for traumatic factors including sharp tooth edges, ill-fitting dentures, or thermal/chemical injury 4

Step 2: Laboratory Workup Order the following essential tests to exclude secondary causes: 4

• Complete blood count with differential
• Iron studies (ferritin, serum iron, TIBC)
• Vitamin B12 level
• Fasting glucose and HbA1c
• Vitamin D 25(OH)
• Thyroid function tests (TSH, free T4)

Step 3: Specialized Testing When Indicated

• Tongue biopsy if suspicious lesions present, unilateral pain, ulceration, or non-healing lesions to rule out malignancy 4
• Qualitative sensory testing if neuropathic etiology suspected 2

Treatment Approach

For Secondary Causes

Address underlying conditions: 4

• Treat nutritional deficiencies
• Manage diabetes
• Control thyroid dysfunction
• Discontinue offending medications
• Treat candidiasis

For Primary Burning Mouth Syndrome

First-Line Pharmacological Treatment:

• Gabapentin is the first-line pharmacological option, showing efficacy in reducing burning sensation in 50% of patients 1
• Alpha-lipoic acid combined with gabapentin demonstrates good outcomes, outperforming monotherapy 1

Alternative Pharmacological Options:

• Amitriptyline when gabapentin is ineffective or not tolerated 1
• Topical clonazepam or diazepam have shown some effect 1, 4
• Topical capsaicin may provide benefit 1

Non-Pharmacological Interventions:

• Cognitive behavioral therapy is recommended as a primary intervention to address psychological components that contribute to or exacerbate symptoms 1, 5
• Combination approaches (CBT plus pharmacotherapy) generally outperform monotherapy 1

Supportive Management:

• Reassurance and education about the chronic nature of the condition is crucial; inadequate reassurance and failing to emphasize that the condition won't worsen increases patient anxiety 1
• For dry mouth: improve hydration, limit caffeine intake, use saliva substitutes and moisture-preserving mouth rinses/sprays 1
• For taste disturbances: regular oral hygiene with bland rinses (salt and sodium bicarbonate solution) 1
• Avoid irritating oral care products containing alcohol or strong flavoring agents 1
• Avoid crunchy, spicy, acidic, or hot food and drinks that may exacerbate discomfort 1

Important Clinical Considerations

Common Pitfalls:

• Treatment failures are common in BMS management, and patients should be informed about this reality 1
• If inadequate response after 4-6 weeks, consider referral to pain specialist or neurologist 1
• For refractory cases, evaluate for comorbid depression or anxiety and treat appropriately, and consider combination therapy with multiple agents 1

Extraoral Manifestations: Higher odds of extraoral dryness exist in BMS patients, particularly affecting lips, eyes, skin, and genitalia, suggesting a potential central mechanism. 6 This pattern should be assessed and documented as part of comprehensive management.