Burning mouth syndrome (BMS) is defined as "idiopathic orofacial pain with intraoral burning or dysesthesia recurring daily for more than 2 hours per day and more than 3 months, without any identifiable causative lesions, with or without somatosensory changes. (Russo et al, 2022).
Location: The most affected site is the anterior two-thirds of the tongue, followed by the palate, although multiple oral sites may be involved.
Associated symptoms: Burning mouth syndrome generally presents as a triad: mouth pain, alteration in taste (dysgeusia), and dry mouth. The burning may be unilateral or bilateral and tends to be relieved by eating or drinking.
Comorbidities: sleep disturbance, headache, anxiety, depression, carcinophobia, and chronic neuropathic pain disorders.
Risk factors:
Clinical subtypes of BMS based on the fluctuation of symptoms during the day
Type- 1: the symptoms are present daily but are absent on awakening. Worsening of the symptoms occurs during the day and reaches its maximum in the afternoon.
Type- 2: the daily symptoms are continuous from the time of awakening, but they disappear at night.
Type- 3: the symptoms disappear for days and then reappear for only a few days, affecting atypical regions (neck).
Pathophysiology theories
1. Peripheral mechanisms
2. Central Mechanisms
3. Central & peripheral mechanisms
Steroid dysregulation: chronic anxiety or stress results in the alteration of gonadal, adrenal, and neuroactive steroid levels in the skin and oral mucosa. (Woda et al, 2009).
Diagnosis:
Primary BMS is diagnosed after the exclusion of all local and systemic factors associated with secondary BMS.
Suggested diagnostic criteria for primary (idiopathic) BMS (Scala et al, 2003)
Additional supportive criteria are
(1) Dysgeusia and/or xerostomia
(2) Sensory or chemosensory alterations
(3) Mood changes or psycho-pathological alterations.
Differential diagnosis:
Idiopathic BMS should be differentiated from secondary local and systemic conditions that can cause a burning sensation in the oral cavity; previously called collectively ‘Secondary BMS’.
Examples of such conditions include diabetes, nutritional deficiency, trauma to the oral tissues, candidiasis, lichen planus, and dry mouth caused by drugs, radiation, or chemical therapy.
Management and treatment interventions
BMS is a challenging medical condition to treat. The treatment of BMS is purely symptomatic and is aimed at managing this disease as a type of chronic neuropathy.
Pharmacological treatments can be topical or systemic and include one or a combination of the following: capsaicin, topical analgesics, benzodiazepines (clonazepam), antidepressants (TCAs & SNRIs), anticonvulsants (gabapentin & pregabalin), alpha lipoic acid (ALA), and hormone replacement therapy (HRT).
Non-pharmacologic treatments include CBT, LLLT, and acupuncture.
Prognosis
About 50% of the patients will have no change in their symptoms, while the other 50% might either have improvement or worsening of their symptoms. Spontaneous remission is rare but can occur.
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