Pain is a major symptom of BMS and will vary with each patient. Lamey and Lewis divide the patterns of oral pain into:23
Type 1: Pain absent on waking and developing during the day.
Type 2: Pain present day and night.
Type 3: Intermittent pain, with pain-free days.
Type 1 and Type 2 are unremitting and present every day. Type 3 is also noted as having unusual sites that are localized such as the floor of the mouth or the throat.23
Two types of BMS are reported by Sun, et al.38
The primary form - Presents with complaints of burning, pain free waking, leading to a continuous burning sensation as the day progresses. The pain reaches intensity at night. However, other patients report a more continuous pain with varying intensity.
The secondary form - A secondary form of BMS is associated with thyroid disease, psychiatric conditions, oral infections, drug use, dental treatment, vitamin/mineral deficiencies. The secondary form may be caused by local, systemic and or psychological factors.17,21,38
Taste abnormalities often associated with BMS has led some authorities to suggest that an interaction exists between taste and oral pain in the central and peripheral nervous system.45,57 This concept is strengthened by the observation the BMS is more likely to occur in “supertasters” who have more fungiform papilla per area on their tongue than usually noted. Supertasters with BMS are noted to have dense innervation of nociceptors in the taste buds. Taste and smell are intertwined.20,45,48 (Click here to view the dentalcare.com CE course “Are You a Supertaster?”)
Forabosco, et al. correlated the loss of estrogen receptors in the fungiform papillae of the tongue in symptomatic postmenopausal symptoms with relief from hormonal replacement, but other studies have not found similar results.14 However, it has been reported that fungiform papillae are more numerous and dense, with innervation of nociceptors in the fungiform papillae taste buds of patients with BMS, and this has also been reported in supertasters who also have a higher rate of BMS.44,45,48 See Figure 1 for the clinical appearance of a supertaster.
Figure 1. Tongue of a Supertaster. Note the numerous fungiform papillae.
A young adult may have approximately 10,000 taste buds within the total papillae. Taste is classified as sweet, sour, bitter, salty and savory (Umami). When mixed with saliva, taste occurs throughout the mouth with a mixture of taste.
Three cranial nerves are involved in taste (Figure 2):
Figure 2. Nerve Diagram.
Karrer, et al. believe damage to the nerve, the loss of estrogen, or viral insult may play a role in the perception of pain and explain some of the complaints of patients with BMS.20 The glossopharyngeal nerve, the ninth cranial nerve, supplies the tongue, throat and the parotid gland and difficulties in swallowing and tasting occur when this nerve is damaged or affected in some way. It is suggested there is a central loss of inhibition to pain and this produces pain “phantoms” as observed in BMS. Supertasters have an increased sense of perceived taste phantoms as well. Patients with BMS also report a metallic taste and sometimes a bitter taste and even a combination of these tastes as well as pain. A large percentage of patients with BMS are women who are in the age range of menopause. It is known that the perception of bitter recognition is decreased in menopause. Researchers believe atypical odontalgia or toothache pain, for which no explanation can be found, is higher in this group as well. Supertasters have more pronounced fungiform papillae that are also very dense in number (see Figure 1) and taste and smell are intertwined.44 Odors are sensed retro-nasally through the dispersion of airflow molecules into the nasopharynx and contribute to the sensation of taste.48 It is believed there is dense innervation of nociceptors that are associated within supertaster taste buds (Figure 3). There is a further suggestion that the loss of bitter taste sensations that occurs in some women, especially supertasters, at the time of menopause, may promote the development of oral pain.10,45 Usually the patients with BMS may not be aware of specific heightened taste function or the loss of specific types of taste. BMS is usually chronic with increasing taste changes that may not make it easy for the patient to differentiate those changes that have occurred over time. Specific taste in various locations may serve to also document loss of taste in specific areas of the mouth.
Figure 3. Histology of a Papillae.
BMS may be accompanied by subjective xerostomia. Grushka, et al. make the case that alterations in taste can also lead to alterations in parasympathetic/sympathetic output to the salivary glands resulting in dry mouth.43 The symptoms appear better in the morning, worsen during the day and subside at night. However, some patients report a constant discomfort without any relief. Interestingly, the pain, in most cases, subsides when eating. Other mucocutanous disorders such as lichen planus, mucous membrane pemphigoid, contact mucositis, oral allergies and candidiasis may cause the person to complain of a burning sensation orally as well. Therefore, differentiation and exclusion of other disease states is paramount.