What are the differentials for bilateral facial burning?

Differential Diagnosis of Bilateral Facial Burning

Bilateral facial burning is most commonly caused by burning mouth syndrome (BMS) in peri- and post-menopausal women, bilateral temporomandibular disorders (TMD), or post-traumatic trigeminal neuropathic pain, with critical red flags including giant cell arteritis in patients over 50 years and progressive cancer-related neuropathic pain. 1

Primary Differential Diagnoses

Burning Mouth Syndrome (BMS)

• Most likely diagnosis for bilateral continuous burning, particularly affecting the tongue tip, lateral borders, lips, palate, and buccal mucosa 1, 2
• Predominantly affects peri- and post-menopausal women with normal-appearing oral mucosa on examination 1
• Associated features include dry mouth, abnormal taste, depression, and poor quality of life 1, 2
• Pain severity ranges from mild to severe, with continuous timing in most instances 1
• Eating may aggravate symptoms in some patients while relieving them in others 1

Bilateral Temporomandibular Disorders (TMD)

• Second most common cause of bilateral facial pain, involving muscles of mastication 1
• Pain is musculoskeletal in nature and may be associated with other chronic pain conditions 1
• Typically presents without the burning quality characteristic of neuropathic pain 1

Post-Traumatic Trigeminal Neuropathic Pain

• Can present bilaterally if trauma affected both sides of the face 1, 3
• Characterized by continuous burning, tingling pain within 3-6 months of trauma 1
• History of dental procedures (root canal therapy, extractions, dental implants) or facial trauma is key 1
• May have allodynia or other sensory changes on examination 1

Secondary Causes to Exclude

Local Oral Conditions

• Oral candidiasis, mucosal lesions requiring direct visualization and testing 1, 2
• Poor oral hygiene or irritating oral care products containing alcohol 2

Systemic Conditions

• Hematological disorders (anemia, vitamin B12 deficiency) requiring laboratory evaluation 1, 2
• Autoimmune disorders (Sjögren's syndrome, lupus) 1, 2
• Pharmacological side effects from medications 1, 2

Critical Red Flags Requiring Urgent Evaluation

Giant Cell Arteritis

• Must be distinguished from TMD, especially in patients over 50 years old 1, 4
• Presents with temporal artery tenderness, jaw claudication, visual symptoms, and elevated inflammatory markers 1

Malignancy

• Cancer can present as progressive neuropathic pain with burning quality 1, 4
• Requires MRI of brain and trigeminal nerve to exclude structural lesions or tumors 3

Diagnostic Approach

Essential History Elements

• Timing: continuous versus episodic, onset duration, and periodicity 1, 4
• Quality: burning, stinging, itchy versus sharp or electric shock-like 1, 4
• Aggravating factors: eating, light touch, temperature changes 1, 4
• Associated symptoms: dry mouth, taste changes, sensory alterations, autonomic features 1, 4
• Trauma history: recent dental procedures, facial injury, or herpes zoster 1

Physical Examination Findings

• Inspect oral mucosa for lesions, erythema, or candidiasis 1
• Test for allodynia with light touch in all three trigeminal divisions 1, 3
• Palpate temporomandibular joints and muscles of mastication for tenderness 1
• Perform qualitative sensory testing to quantify sensory abnormalities 1, 3

Investigations

• Laboratory: complete blood count, vitamin B12, folate, glucose, thyroid function, inflammatory markers (ESR/CRP if over 50 years) 2, 3
• Microbial testing: oral swab for candidiasis if mucosal changes present 2, 5
• Imaging: MRI of brain and trigeminal nerve mandatory to exclude structural lesions, tumors, or nerve compression 3

Management Algorithm

If BMS is Diagnosed (After Excluding Secondary Causes)

• First-line: Reassurance that condition will not worsen, patient education, and cognitive behavioral therapy 1, 2
• Pharmacological: Gabapentin 300mg at bedtime, titrating to 900-3600mg daily in divided doses (reduces burning in 50% of patients) 2, 3
• Alternative agents: Amitriptyline, alpha lipoic acid combined with gabapentin, or topical clonazepam 2
• Symptomatic management: Saliva substitutes for dry mouth, avoid irritating oral products, bland oral rinses (salt and sodium bicarbonate) for taste disturbances 2

If TMD is Diagnosed

• Early diagnosis with reassurance and simple physiotherapy for patients with good coping strategies 1
• Night splints fabricated by dentists 1

If Post-Traumatic Trigeminal Neuropathic Pain

• Neuropathic pain medications following standard guidelines 1, 3
• Gabapentin as first-line agent with same dosing as BMS 3
• Cognitive behavioral therapy initiated early 3

Common Pitfalls to Avoid

• Failing to exclude secondary causes before diagnosing primary BMS leads to missed treatable conditions 1, 2
• Inadequate reassurance about BMS prognosis increases patient anxiety and worsens quality of life 1, 2
• Missing giant cell arteritis in patients over 50 years can result in permanent vision loss 1, 4
• Performing invasive procedures without objective findings or when pain is the only symptom 4
• Treatment failures are common in BMS management; patients should be informed about the chronic nature and referred to pain specialists or neurologists if inadequate response after 4-6 weeks 2, 3