Burning Mouth Syndrome Gary D

Burning Mouth Syndrome
Gary D. Klasser, DMD
a,
*, Miriam Grushka, MSc, DDS, PhD
b
, Nan Su, BSc, MBBS
c
INTRODUCTION
Burning mouth syndrome (BMS) is an enigmatic,
idiopathic, chronic, often painful clinical entity for
which there are yet to be well established stan-
dardized and validated definitions, diagnostic
criteria, or classifications. First described by Fox
1
in 1935, BMS has several different definitions
that depend on interpretations from several orga-
nizations that review this ambiguous condition.
The American Academy of Orofacial Pain
2
defines
BMS as a burning sensation in the oral mucosa
despite the absence of clinical findings and abnor-
malities in laboratory testing or imaging. The Inter-
national Association for the Study of Pain (IASP)
3
defines BMS as a burning pain in the tongue or
other oral mucous membrane associated with
normal signs and laboratory findings lasting at
least 4 to 6 months.
4,5
The current (tenth) version
of the International Classification of Diseases of
the World Health Organization (the preeminent
tool for coding diagnoses within the health care
systems of many countries) uses the term glosso-
dynia (K14.6), which includes additional terms
such as glossopyrosis and painful tongue and
describes the condition as painful sensations in
the tongue, including a sensation of burning.
6
The International Headache Society (IHS) in
The International Classification of Headache
Disorders III-beta (ICHD-III-beta)
7
classifies BMS
in Part 3: painful cranial neuropathies, other facial
pains and other headaches within the section con-
cerning painful cranial neuropathies and other
facial pains. BMS (ICHD-III-beta: 13.10), previ-
ously labeled as stomatodynia, or glossodynia
when confined to the tongue, is currently defined
as an intraoral burning or dysesthetic sensation,
recurring daily for more than 2 hours per day
over more than 3 months, without clinically evident
causative lesions. It is further commented that
pain is usually bilateral and its intensity fluctuates,
with the most common site of presentation being
the tip of the tongue. Subjective dryness of the
mouth, dysesthesia, and altered taste often are
accompanying symptoms. There is a high meno-
pausal female prevalence, and some studies
show comorbid psychosocial and psychiatric dis-
orders, whereas recent laboratory and brain imag-
ing investigations have indicated changes in the
central and peripheral nervous systems.
Nomenclature related to BMS has created much
confusion because this condition has been given
many different names, often based on the quality
a
Department of Diagnostic Sciences, Louisiana State University Health Sciences Center, School of Dentistry,
1100 Florida Avenue, Box 140, New Orleans, LA 70119, USA;
b
William Osler Health Centre, 974 Eglinton
Avenue West, Toronto, Ontario M6C 2C5, Canada;
c
974 Eginton Ave W, Toronto, Ontario M6C 2C5, Canada
* Corresponding author.
E-mail address: [email protected]
KEYWORDS
Burning mouth syndrome Glossodynia Oral burning Neuropathic
KEY POINTS
Despite the current knowledge gained from the scientific literature, burning mouth syndrome (BMS)
remains an enigmatic, misunderstood, and under-recognized painful condition.
Symptoms associated with BMS can be varied, which provides a challenge for practitioners and
has a negative impact on oral health–related quality of life for patients.
Management of BMS is a challenge for practitioners, because it is currently only targeted for symp-
tom relief without a definitive cure.
There is a desperate need for further investigations into management, with larger patient samples
and longer duration of intervention and follow-up using multicenter trials.
Oral Maxillofacial Surg Clin N Am 28 (2016) 381–396
http://dx.doi.org/10.1016/j.coms.2016.03.005
1042-3699/16/$ – see front matter Ó2016 Elsevier Inc. All rights reserved.
oralmaxsurgery.theclinics.com

and/or location of pain in the oral cavity. Some of
the nomenclature applied is as follows: glossody-
nia, glossopyrosis, glossalgia, stomatodynia,
stomatopyrosis, sore tongue, burning tongue,
scalded mouth syndrome, oral dysesthesia,
burning mouth condition, and BMS.
8,9
From the
usage of these terms it is unclear whether or not
the oral mucosa appeared normal and therefore
whether these terms were describing BMS or just
an oral burning sensation. Clearly, the use of these
multiple and heterogeneous terms attests to the
confusion and uncertainty that exists in the scien-
tific literature and in clinical practice regarding this
condition.
Furthermore, there is debate among re-
searchers and clinicians as to whether burning
mouth is a syndrome or a disorder.
8,10–13
By defi-
nition, a syndrome (a disease unto itself) is a
collection of several simultaneous signs and
symptoms of varying intensity, which, in the
case of BMS, is a normal-appearing oral mucosa
with a burning sensation, a feeling of oral dryness,
and taste disturbances.
8,14–16
Adisorderis
defined as a condition manifesting symptoms of
other diseases, such as the complaint of dry
mouth being the cause of the burning sensation
often reported by patients with BMS.
11
Overall,
BMS is likely more than 1 disease process with
a multifactorial cause, thereby making it a diag-
nosis of exclusion.
From these various definitions and multiple
names applied to BMS it is easy to comprehend
the frustration experienced by the patients and
the difficulties encountered by practitioners in
evaluating these individuals, because the patients
are usually experiencing continuous burning pain
in the mouth and the practitioners are struggling
to identify any obvious clinical signs even with
the accompaniment of additional diagnostic
testing or imaging. This situation often produces
a dilemma when developing and presenting a
definitive diagnose. This article helps oral and
maxillofacial surgeons in recognizing, understand-
ing, and managing BMS.
EPIDEMIOLOGY
The prevalence of BMS is thought to range from
0.7% up to 15% of the population depending on
the diagnostic criteria used.
17–19
The condition is
most commonly reported in postmenopausal
women, generally in the fifth to sixth decade of
life. Men may also develop BMS, with a reported
ratio of approximately 1:5 to 1:7 compared with
women, depending on the study population.
17,20
Prevalence seems to increase with age in both
men and women.
21
DIAGNOSTIC CRITERIA
Over the years there have been several formal
diagnostic criteria applied to BMS. Scala and col-
leagues
9
provided diagnostic criteria as the first
step in an initial diagnosis of BMS by assessing
the symptom pattern experienced by each patient.
They reported the identification of full-blown forms
of BMS to not be problematic, whereas the detec-
tion of either oligosymptomatic or monosympto-
matic variants to be much more complex and the
investigators thought their criteria would alleviate
difficulties in the diagnostic process. Fortuna and
colleagues
12
suggested renaming BMS as com-
plex oral sensitivity disorder, which they described
as an oropharyngeal discomfort caused by 1 or
more symptoms for which no specific cause of
any type can be identified. The IHS in the
ICHD-III-beta and the IASP also present criteria
to be used for the diagnosis of BMS.
3,7
Table 1
provides the proposed diagnostic criteria used to
identify BMS. Even though there are similarities
among some components of these criteria there
is no absolute consensus, nor has there been vali-
dation of any specific criteria.
CLASSIFICATION
Several classification systems have been pro-
posed with the goal of improving the characteriza-
tion for BMS. Lamey
8
and Lamey and Lewis
22
proposed a classification system that comprises
3 subtypes based on variations in pain intensity
over 24 hours. Type 1 is characterized by patients
having burning every day. However, the burning is
absent on waking, but presents as the day goes
on, being maximal in the evening. This type may
be linked to systemic disorders such as nutritional
deficiencies and endocrine disorders.
23
Approxi-
mately 35% of patients with BMS give such a
history. Type 2 is characterized by burning that oc-
curs every day, is present on awakening, and often
makes falling asleep at night difficult. This sub-
group of patients often reports mood changes, al-
terations in eating habits, and decreased desire to
socialize, which seems to be caused by an altered
sleep pattern.
4,24
Approximately 55% of patients
with BMS describe this type of history. Type 3 is
characterized by intermittent burning, present
only on some days, with burning affecting unusual
sites such as the floor of the mouth, buccal mu-
cosa, and throat. Frequently, these patients
display anxiety and allergic reactions, particularly
to food additives.
25
About 10% of patients with
BMS report this pattern of symptoms. In a demo-
graphic study by Killough and colleagues
26
comparing BMS populations in the United
Klasser et al
382

Kingdom and United States, there were similar
prevalence rates using these subtypes within
these 2 populations. Gremeau-Richard and col-
leagues
27
classified BMS as being peripherally or
centrally mediated according to the results of a
lingual nerve injection with local anesthesia.
Another classification schema differentiated BMS
into 3 distinct categories based on neuropathic
pain statuses that may overlap in individual pa-
tients.
28
The first was a peripheral small fiber neu-
ropathy within the intraoral mucosa (50%–65%),
the second was categorized as a subclinical major
trigeminal neuropathy (20%–25%), and the third
was related to a central pain that may be caused
by hypofunction of dopaminergic neurons in the
basal ganglia resulting in deficient dopaminergic
top-down inhibition (20%–40%). Note that these
classification schemes are not universally
accepted, nor are they essential for the manage-
ment of patients with BMS.
A more pragmatic approach in classifying pa-
tients with BMS is to divide patients into either
primary (essential/idiopathic) BMS (no other
evident disease) or secondary BMS (oral burning
from other clinical abnormalities).
9
Because
secondary BMS is associated with a preexisting
condition or cause, it should be remembered that
once such a condition is treated the symptoms
will either improve or disappear. Danhauer and
colleagues
29
examined 69 patients with BMS
(83% female; average age of 62 years; pain dura-
tion of 2.45 years; visual analog scale pain rating of
49 mm rated from 0 to 100 mm) with all patients
completing pain (Multidimensional Pain Inventory
[MPI]) and psychological (Symptom Checklist
90-Revised [SCL-90R]) questionnaires in addition
to having a clinical examination. There were no
differences between patients with primary and
secondary BMS with respect to age, pain duration,
pain intensity, or levels of psychological distress.
However, there were substantial differences in
burning symptom cessation with treatment
because the patients with secondary BMS
improved if the underlying clinical abnormality
Table 1
Proposed diagnostic criteria to identify BMS
Source, Year Criteria
Fortuna et al,
12
2013 1. Any type of oropharyngeal symptom that can be persistent or intermit-
tent with possible phases of remission/exacerbation during the day
2. Absence of any clinically and instrumentally detectable oropharyngeal
lesion
3. Absence of any type of local and/or systemic factors, such as oral diseases,
drugs, trauma, hypersensitivity reactions, physical/chemical agents
In addition (but not mandatory): state of being symptomatic is persistent
(typically 3 mo)
ICHD-III-beta,
7
2013 1. Oral pain fulfilling criteria B and C
2. Recurring daily for >2 h per day for >3 mo
3. Pain has both of the following characteristics:
a. Burning quality
b. Felt superficially in the oral mucosa
4. Oral mucosa is of normal appearance and clinical examination, including
sensory testing, is normal
5. Not better accounted for by another ICHD-III diagnosis
IASP,
3
1994, revised 2011 Burning tongue or other parts of oral mucosa, usually bilateral, dysgeusic
taste and/or altered taste perception, dry mouth, and denture intolerance
Scala et al,
9
2003 1. Daily deep burning sensation of oral mucosa (bilateral)
2. Pain is unremitting for at least 4–6 mo
3. Continuous throughout all or almost all the day
4. Seldom interferes with sleep
5. Characteristic symptoms are not getting worse/sometimes there may be
an improvement over the ingestion of food and liquid
Additional inclusion symptomatic criteria are:
6. Occurrence of other oral symptoms, such as dysgeusia and/or xerostomia
7. Presence of sensory/chemosensory anomalies
8. Presence of mood changes and/or specific disruptions in patient person-
ality traits
Data from Refs.
3,7,9,12
Burning Mouth Syndrome 383

was treated, whereas the primary BMS group did
not report such positive outcomes.
CLINICAL SIGNS AND SYMPTOMS
Most patients with BMS describe their symptoms
in the oral mucosa using the following words: pain-
ful, burning, tender, tingling, hot, scalding, and
numbness, but sometimes the sensation is merely
described as discomfort, raw, and annoying. BMS
is characterized by both positive (burning pain,
dysgeusia, and dysesthesia) and negative (taste
loss and paresthesia) sensory symptoms.
30
The
pain is mainly located bilaterally, and symmetri-
cally in the anterior two-thirds of the tongue
(71%–78%) followed by the dorsum and lateral
borders of the tongue (72%), the anterior aspect
of the hard palate (25%), and the labial mucosa
of the lips (24%), and often occurs in multiple
sites.
5,14,31–33
There have been suggestions that
burning of the lips should be considered as a
single entity because this has been described
featuring a thinned labial mucosa and inactive
minor labial salivary glands.
34
Other less
commonly reported sites include the buccal
mucosa, floor of the mouth, hard and soft palate,
and the throat (36%).
31
Unlike other painful condi-
tions (trigeminal neuralgia [TN]), the burning pain
does not follow peripheral nerve distributions.
The sites of pain do not seem to affect the course
of the disorder or the response to treatments.
35,36
Approximately 50% of patients with BMS experi-
ence a spontaneous onset of symptoms without
any identifiable triggering factor.
15,37
However,
about 17% to 33% of the patients attribute the
onset of their symptoms to a previous illness,
such as an upper respiratory tract infection, previ-
ous dental procedure, or medication use (including
antibiotic therapy),
37–40
suggesting the possibility
of neurologic alterations preceding the onset of
burning in some patients.
41–43
Other individuals
claim the onset of symptoms relate to traumatic
life stressors.
15,32,37
Typically, the symptoms
occur continuously for months or years without
periods of cessation or remission,
37
with some re-
ports suggesting an average duration of 2 to
3 years.
44,45
There have been reports
37
of com-
plete/partial remission (with or without interven-
tion) in approximately 50% of patients and a
complete spontaneous remission in approximately
20% of patients within 6 to 7 years of onset. The
remission of symptoms, either complete or partial,
is often characterized by a change in pain pattern
from a constant to an episodic form.
37,46
Contrary
to these optimistic findings, Sardella and
colleagues,
47
in an investigation to specifically
evaluate the spontaneous remission rate in BMS,
reported that a complete spontaneous remission
was observed in only 3% of the patients within
5 years after BMS onset.
The pattern of daily symptoms is reportedly con-
stant with fluctuation in pain intensity and with
approximately one-third of patients experiencing
symptoms both day and night.
5,32,48
Most patients
report minimal symptoms on awakening, after
which the symptoms gradually increase during
the day and become more severe toward the
evening.
4,5
About one-third of the patients have
difficulty with sleep onset and some awaken dur-
ing the night because of the burning pain.
19,32
The intensity of the burning pain has been
described as moderate to severe, and in some
cases it is comparable with the intensity of tooth-
ache pain with regard to severity but not quality.
24
In most patients, the burning sensation intensifies
in the presence of personal stressors, fatigue, and
with the intake of hot/spicy/acidic foods, and in
about half the patients the intake of food or liquids
and distraction seem to reduce or alleviate the
symptoms (dissimilar to pain caused by organic le-
sions or neuralgia).
5,30,49,50
It is unclear what the
effects of tobacco, ethanol, or dietary factors are
on the symptoms of BMS. Patients with BMS
have a significantly higher incidence of dry mouth,
thirst, and taste disturbances but they do not differ
from healthy controls regarding changes in oral
mucosa or dental problems.
5,15,51,52
Furthermore,
patients had no greater prevalence of medical
conditions such as diabetes, arthritis, and cardio-
vascular and gastrointestinal disorders compared
with age-matched and sex-matched controls.
5
Patients with BMS have more nonspecific health
complaints and more severe menopausal
symptoms compared with healthy controls.
5
Headaches, dizziness, neck and back pain,
dermatologic disorders, irritable bowel syndrome,
anxiety, depression, personality disorders, and
other psychiatric disorders are reported more
frequently in these patients.
32,38,40,51–55
However,
many of these studies are unclear as to whether
these symptoms are risk factors for development
of BMS or a consequence of the syndrome, indi-
cating a need for longitudinal cohort studies.
CAUSE
At present, the cause for primary BMS has
remained largely unknown. The presumed cause
is best explained as being multifactorial, involving
the interaction between biological (neurophysio-
logic mechanisms) and psychological factors.
16
Even though multiple local, systemic, and psycho-
logical factors have been found related to BMS,
several of these factors should be considered as
Klasser et al
384

conditions important to the differential diagnosis of
oral burning rather than as causal factors impli-
cated in BMS.
Local Factors
Several local factors (physical, chemical, or
biological) have been considered as possible
causal factors for BMS. Some of these are:
Xerostomia, which is the subjective sensation
of dry mouth and is found to be a frequent
complaint (25% of patients with BMS)
23,44,56
in addition to drug-induced xerostomia
44,57
Hyposalivation, which denotes objectively
reduced salivary flow measured by
sialometry
15,23,31,58
Taste disturbances involving either an alter-
ation in taste perception, a persistently altered
taste, or a combination of these
5,18,59,60
Oral bacterial, viral, and/or fungal (candidi-
asis) infections
61–68
Oral mucosal abnormalities, such as benign
migratory glossitis (geographic tongue), scal-
loped and fissured tongue,
14,44,69
and dis-
eases such as lichen planus
57,70
Parafunctional oral habits, such as clenching,
bruxing, or tongue posturing
47,71
Mechanical and chemical irritations, such as
galvanism and denture-related problems
23,72
Allergic reactions
23,73
Grushka
5
reported no significant differences on
clinical examination between subjects with BMS
and controls with any intraoral soft or hard tissue
findings. The discrepancy between this study
and the studies that found higher prevalences of
oral change may be caused by differences in def-
initions of BMS and/or its diagnosis or may be a
result of the condition creating these changes
rather than being causative of the condition.
Systemic Factors
Many systemic factors have been considered for
explaining the cause of BMS. Some of these are:
Autoimmune, gastrointestinal, and endocrine
disorders, such as connective tissue dis-
eases, gastroesophageal reflux disease, dia-
betes, and thyroid disorders
15,30,46,73–80
Hormonal deficiencies and menopausal
alterations
5,74,81
Drug-induced conditions, especially involving
angiotensin-converting enzyme inhibitors
such as captopril, enalapril, and lisinopril
82,83
Nutritional deficiencies involving vitamins and
minerals, especially those associated with
anemia (iron and vitamin B
12
deficiency),
zinc, and vitamin B complexes
84–88
However, despite some evidence from these
studies supporting a possible association of these
systemic factors as causal agents, there are many
inconsistencies within the literature.
5,14,23,56,89–91
Studies have also reported a relationship between
other facial pains,
72
pains in other parts of the
body,
72
and headache pain
5
as being more
frequent in patients with BMS. However, the
meaning and relevance of these associations
remain unclear.
Psychological Factors
Psychological phenomena such as alterations in
states of anxiety and depression, somatization,
and certain aberrant personality traits, are com-
mon findings in patients with BMS,
45,92–95
thereby
supporting psychological factors as major causal
factors for BMS. At least one-third of patients
may have an underlying psychiatric diagnosis.
44
A phobic concern regarding cancer is also found
in 20% of patients
23
and is often manifested as
repeated self-examination by the patient.
8
Although BMS may be a somatic symptom of
depression, the association does not always
equate to a causal relationship. Carlson and col-
leagues
96
used the MPI and SCL-90R on 33
BMS cases and compared the data with those
from population samples that included both pa-
tients without BMS but with chronic pain and a
normal nonclinical sample. They concluded that
there was no evidence for significant clinical in-
creases on any of the SCL-90R subscales,
including depression, anxiety, and somatization.
Moreover, BMS patients reported significantly
fewer disruptions in normal activities as a result
of their oral burning pain than did a large sample
of patients with chronic pain. It was noted that
21% of the BMS cases had substantially increased
psychological distress. Despite the presence of
psychological issues and the need for treatment
of these underlying issues, BMS may also occur
in the absence of a psychological diagnosis.
97
The uniqueness of the frequency of occurrence
of these psychological conditions in the BMS pop-
ulation as being consistent with that of other
chronic painful conditions has not been well docu-
mented. It is possible for these psychological con-
ditions to be comorbidities, modifiers of the
burning mouth condition, or a behavioral conse-
quence of having BMS rather than causal factors.
Regardless, these psychological issues must be
addressed because of their impact on the quality
of life as well on treatment outcomes.
98
Hence,
appropriate management should therefore include
Burning Mouth Syndrome 385