Burning mouth syndrome in Parkinson's disease: dopamine as cure or cause?

Oral mucosal diseases and psychosocial factors: progress in related neurobiological mechanisms

The aetiology of oral mucosal diseases, such as recurrent aphthous ulcer (RAU), oral lichen planus (OLP) and burning mouth syndrome (BMS), involves many factors, and it remains difficult for clinicians to effectively relieve disease symptoms and formulate coping strategies. With the rapid development of psychology, the role of mental and psychological factors in RAU, OLP and BMS has gradually attracted researchers attention, but the specific mechanism has not been completely determined. This narrative review describes the potential neurobiological mechanism of oral mucosal diseases and detailed psychological factors after introducing relevant research into psychological factors and oral mucosal diseases. Future research strategies and innovations needed to understand and treat oral mucosal diseases and psychological factors, as well as how to prevent oral mucosal diseases by regulation of the neuroendocrine system, are also discussed.

Exploring the Association of Burning Mouth Syndrome with Depressive and Anxiety Disorders in Middle-Aged and Older Adults: A Systematic Review

BACKGROUND

Burning Mouth Syndrome (BMS) is an idiopathic condition mainly affecting middle-aged and older individuals with hormonal disturbances or psychiatric disorders and is characterized by chronic pain. The etiopathogenesis of this multifactorial syndrome is largely unknown. The objective of the present systematic review was therefore to evaluate the relationship of BMS with depressive and anxiety disorders in middle-aged and older individuals.

METHODS

We selected studies evaluating BMS and depressive and anxiety disorders assessed with validated tools, published from their inception up to April 2023, using PubMed, MEDLINE, EMBASE, Scopus, Ovid, and Google Scholar databases and adhering to the PRISMA 2020 guidelines/PRISMA 2020 27-item checklist. This study is registered on PROSPERO (CRD42023409595). The National Institutes of Health Quality Assessment Toolkits for Observational Cohort and Cross-Sectional Studies were used to examine the risk of bias.

RESULTS

Two independent investigators rated 4322 records against the primary endpoint and found 7 records meeting the eligibility requirements. Anxiety disorders were found to be the most common psychiatric disorders related to BMS (63.7%), followed by depressive disorders (36.3%). We found a moderate association of BMS with anxiety disorders, with multiple studies included (n = 7). Moreover, we found a low association of BMS with depressive disorders (included studies, n = 4). The role of pain appeared to be controversial in explaining these associations.

CONCLUSIONS

In middle-aged and older subjects, anxiety and depressive disorders may be potentially related to the development of BMS. Furthermore, also in these age groups, females showed higher risk of developing BMS than males, even when taking into account multimorbidity such as sleep disorders, personality traits, and biopsychosocial changes as suggested by study-specific findings.

Burning mouth disorder and Parkinson's disease: A scoping review of the literature

BACKGROUND

Burning mouth disorder (BMD) is a complex medical condition characterized by a burning sensation in the mouth of fluctuating intensity. BMD is considered a diagnosis of exclusion, as oral burning can occur secondary to local or systemic conditions. Parkinson's disease (PD) is one such condition.

OBJECTIVE

To provide a scoping review of the literature by assessing all articles written in English that investigated the relationship between BMD and PD.

MATERIALS AND METHODS

Various databases (PubMed, Ovid, Web of Science, Science Direct and Scopus) and a search platform (EBSCOhost) were searched following similar investigative approaches. Duplicates were removed and reference lists of original studies were scrutinized for additional articles. Any decision about the inclusion/exclusion in the review was by consensus among the co-authors.

RESULTS

Twenty-five original articles and one supplemental article were included in the final review, of which 13 met the inclusion criteria. These were further divided into five categories based on the study design/article, which included Prevalence studies (n = 6), Letter to the editor (n = 1), Incidence study (n = 1), Case reports (n = 2) and Experimental studies (n = 3). Strongest data was provided by epidemiological studies, which suggest BMD and PD are poorly associated.

CONCLUSIONS

A scoping review of the existing literature does not suggest that PD patients are any more at risk of developing BMD compared to the general population. While there may be a link through the dopaminergic system as determined by imaging studies, it is unlikely that the pathogenesis of PD disease shares significant commonality with BMD.

Association of medications with burning mouth syndrome in Taiwanese aged patients

Background/purpose

Burning mouth syndrome (BMS) occurs more frequently in middle-aged or elderly patients, especially the older female patients. It may relate to multiple medications in the older people. This study aimed to evaluate the association of polypharmacy with BMS.

Materials and methods

Eighty BMS patients aged from 45 to 80 years were recruited into this study, and their medical data, especially the medication records, were collected and analyzed to assess the association of polypharmacy with BMS.

Results

Of the 80 BMS patients, 14 did not take any medication, 38 took 1-4 medicines, 17 took 5-8 medicines, and 11 took ≥9 medicines. The mean number of medicines taken by each BMS patient is 4.49. For the 80 BMS patients, the mean number of medicines taken by each BMS patient was significantly higher in the older age group (7.00 ± 7.76; age ≥65 years; n = 31) than in the relatively younger age group (2.90 ± 2.95; age 45-64 years; n = 49) (P = 0.001). The similar result was also observed in the female BMS patients. We also found that psychotropics, gastroprotectors and gastrointestinal tract (GI)-associated drugs, and antihypertensives were the three most commonly used drugs in our 80 BMS patients. Among them, the relatively high frequencies of using anxiolytics and antidepressants in the psychotropics, and beta-blockers in the antihypertensives were observed.

Conclusion

Our findings suggest that multiple medications (polypharmacy) may play an important role in the development of BMS, especially for the older female BMS patients.

Parkinson's disease: the nutrition perspective

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease and affects about 1% of the population over the age of 60 years in industrialised countries. The aim of this review is to examine nutrition in PD across three domains: dietary intake and the development of PD; whole body metabolism in PD and the effects of PD symptoms and treatment on nutritional status. In most cases, PD is believed to be caused by a combination of genetic and environmental factors and although there has been much research in the area, evidence suggests that poor dietary intake is not a risk factor for the development of PD. The evidence about body weight changes in both the prodromal and symptomatic phases of PD is inconclusive and is confounded by many factors. Malnutrition in PD has been documented as has sarcopaenia, although the prevalence of the latter remains uncertain due to a lack of consensus in the definition of sarcopaenia. PD symptoms, including those which are gastrointestinal and non-gastrointestinal, are known to adversely affect nutritional status. Similarly, PD treatments can cause nausea, vomiting and constipation, all of which can adversely affect nutritional status. Given that the prevalence of PD will increase as the population ages, it is important to understand the interplay between PD, comorbidities and nutritional status. Further research may contribute to the development of interventional strategies to improve symptoms, augment care and importantly, enhance the quality of life for patients living with this complex neurodegenerative disease.

King's Parkinson's Disease Pain Scale (KPPS): Cross-cultural adaptation to Brazilian Portuguese and content validity

Pain is one of the most common and troublesome non-motor symptoms of Parkinson's disease (PD). The King's Parkinson's Disease Pain Scale (KPPS) is the first scale of its kind to evaluate the burden and characterization of various phenotypes of pain in individuals with PD. The purpose of this study was to adapt the KPPS to Brazilian culture and to assess its content validity using the Delphi method. The process of adapting the original instrument to the Brazilian context occurred in six stages according to international standards. Following the pilot tests with individuals with PD, the pre-final version of the KPPS-Brazil was developed and submitted to judges to assess content validity. Three evaluation rounds were conducted, in which several corrections and changes suggested by the judges were accepted. The Content Validity Index (CVI) was calculated to determine the judges' degree of agreement. The results demonstrated that the KPPS-Brazil showed a quite satisfactory level of semantic, idiomatic, cultural, and conceptual equivalence. The judges' opinion showed adequate content validity for all of the KPPS-Brazil items and the scale. The use of the KPPS-Brazil will enable an adequate assessment of pain in individuals with PD, contributing to clinical practice and research.

Oral Health Disorders in Parkinson's Disease: More than Meets the Eye

Despite clinical evidence of poor oral health and hygiene in Parkinson’s disease (PD) patients, the mouth is often overlooked by both patients and the medical community, who generally focus on motor or psychiatric disorders considered more burdensome. Yet, oral health is in a two-way relationship with overall health—a weakened status triggering a decline in the quality of life. Here, we aim at giving a comprehensive overview of oral health disorders in PD, while identifying their etiologies and consequences. The physical (abnormal posture, muscle tone, tremor, and dyskinesia), behavioral (cognitive and neuropsychiatric disorders), and iatrogenic patterns associated with PD have an overall detrimental effect on patients’ oral health, putting them at risk for other disorders (infections, aspiration, pain, malnutrition), reducing their quality of life and increasing their isolation (anxiety, depression, communication issues). Interdisciplinary cooperation for prevention, management and follow-up strategies need to be implemented at an early stage to maintain and improve patients’ overall comfort and condition. Recommendations for practice, including (non-)pharmacological management strategies are discussed, with an emphasis on the neurologists’ role. Of interest, the oral cavity may become a valuable tool for diagnosis and prognosis in the near future (biomarkers). This overlooked but critical issue requires further attention and interdisciplinary research.

Cannabidiol has therapeutic potential for myofascial pain in female and male parkinsonian rats

The musculoskeletal orofacial pain is a complex symptom of Parkinson's disease (PD) resulting in stomatognathic system dysfunctions aggravated by the disease rigidity and postural instability. We tested the effect of cannabidiol (CBD), a non-psychotomimetic constituent of Cannabis sativa, in PD-related myofascial pain. Wistar adult female and male rats orofacial allodynic and hyperalgesic responses were tested by Von Frey and formalin tests, before and 21 days past 6-OHDA lesion. Algesic response was tested after masseter muscle injection of CBD (10, 50, 100 μg in 10 μL) or vehicle. Males compared to females in all estrous cycles' phases presented reduced orofacial allodynia and hyperalgesia. According to the estrous cycle's phases, females presented distinct orofacial nociceptive responses, being the estrus phase well-chosen for nociceptive analysis after 6-OHDA lesion (phase with fewer hormone alterations and adequate length). Dopaminergic neuron lesion decreased mechanical and inflammatory nociceptive thresholds in females and males in a higher proportion in females. CBD local treatment reduced the increased orofacial allodynia and hyperalgesia, in males and females. The female rats were more sensitive to CBD effect considering allodynia, responding to the lowest dose. Although females and males respond to the effect of three doses of CBD in the formalin test, males showed a superior reduction in the hyperalgesic response. These results indicate that hemiparkinsonian female in the estrus phase and male answer differently to the different doses of CBD therapy and nociceptive tests. CBD therapy is effective for parkinsonism-induced orofacial nociception.

Depression and anxiety in recurrent giant cell tumor of bone

Giant cell tumor of bone (GCTB) is a benign neoplasia more frequently encountered in young females. The pathogenic and evolutionary dynamics of the disease is strongly influenced by the presence of depression and cellular mechanisms, especially proinflammatory and immune. Although it is not a malignant tumor, it is often recurrent, which determines a high level of depression, anxiety, and fear of the patients. Cytokine mechanisms, especially through increased tumor necrosis factor alpha (TNFα) and interleukin-6 (IL-6), as well as the involvement of the receptor activator of nuclear factor-kappa B (RANK)–RANK ligand (RANK-L) system, can be correlated with the risk of malignancy. Unfavorable evolution is associated with persistent pain, difficulties of movement and body dysmorphic symptoms. The diagnosis is based mainly on histopathological (HP) assessment. The patients can be treated with pharmacological agents (Denosumab), surgery with tumor excision, reconstruction or osteosynthesis, and radiotherapy. Patients with GCTB require HP and imaging evaluations, especially of relapses, to detect the risk of metastasis or malignancy, simultaneously with psychological and psychiatric monitoring to detect depression, addictive behaviors, and suicide risk. It is necessary to evaluate in a multidisciplinary team to avoid unfavorable oncological and psychiatric developments. Through its clinical, HP, and therapeutic features, GCTB has multiple connections with the psychological and psychopathological dimension.

Association Between Burning Mouth Syndrome and the Development of Depression, Anxiety, Dementia, and Parkinson Disease

Importance

Burning mouth syndrome is a chronic oral pain disorder that is characterized by a generalized or localized burning sensation without the presence of any specific mucosal lesions. It remains unclear, however, whether burning mouth syndrome is associated with the development of psychoneurological conditions among patients with the syndrome.

Objective

To evaluate the risk of developing psychoneurological conditions, including depression, anxiety, dementia, and Parkinson disease, in patients with burning mouth syndrome.

Design, Setting, and Participants

This retrospective population-based cohort study was conducted using a nationwide representative cohort sample from the Korean National Health Insurance Service-National Sample Cohort, which consists of data from approximately 1 million patients in South Korea. The study included 586 patients with burning mouth syndrome (patient group) and 1172 individuals without burning mouth syndrome (comparison group). The patient group included all patients who received inpatient and outpatient care for an initial diagnosis of burning mouth syndrome between January 1, 2002, and December 31, 2012. The comparison group was selected (2 individuals without burning mouth syndrome for each patient with burning mouth syndrome) using propensity score matching for sex, age, location of residence, household income level, and comorbidities. Data were collected and analyzed from January 1, 2002, to December 31, 2013.

Main Outcomes and Measures

Death and the incidence of psychopathological diseases. Affective disorder events that occurred among participants during the follow-up period were investigated using survival analysis, a log-rank test, and Cox proportional hazards regression models to estimate the incidence rates, survival rates, and hazard ratios, respectively, of participants who developed psychoneurological conditions.

Results

Of 1758 total participants, 1086 (61.8%) were female; 701 participants (39.9%) were younger than 45 years, 667 (37.9%) were aged 45 to 64 years, and 390 (22.2%) were older than 64 years. The overall incidence of depression and anxiety was higher in patients with burning mouth syndrome (n = 586; 30.8 incidents and 44.2 incidents per 1000 person-years, respectively) than in individuals without burning mouth syndrome (n = 1172; 11.7 incidents and 19.0 incidents per 1000 person-years, respectively). The results also indicated a similar incidence of dementia and Parkinson disease between the patient group (6.5 incidents and 2.5 incidents per 1000 person-years, respectively) and the comparison group (4.9 incidents and 1.7 incidents per 1000 person-years, respectively). After adjusting for sociodemographic factors (age, location of residence, household income level, and comorbidities), the adjusted hazard ratios for the development of depression and anxiety among patients with burning mouth syndrome were 2.77 (95% CI, 2.22-3.45) and 2.42 (95% CI, 2.02-2.90), respectively. However, no association was found between burning mouth syndrome and the risk of developing dementia and Parkinson disease.

Conclusions and Relevance

Results of this observational study suggest that burning mouth syndrome is associated with increases in the incidence of depression and anxiety but not in the incidence of dementia and Parkinson disease among patients with the syndrome. Clinicians should be aware of this association and be prepared to make referrals to appropriate mental health care professionals.

An overview of pain in Parkinson's disease

Pain is a common non-motor symptom of Parkinson's disease (PD) and the prevalence of pain among PD patients varies because of the disease stage, co-morbidities, and evaluating tools. Risk factors for pain in PD include an early age of onset, long disease duration, motor complications, concomitant depressive symptoms, female gender, and associated medical conditions. In patients with PD, pain can be classified as musculoskeletal pain, chronic body pain (central or visceral), fluctuation-related pain, nocturnal pain, orofacial pain, pain with discolouration/oedema/swelling, and radicular/neuropathic pain; musculoskeletal pain as the most common type. Potential underlying mechanisms include a disruption of peripheral nociception and alterations in central pain threshold/processing. Genetic polymorphisms in genes that confer pain susceptibility might also play a role in the occurrence of pain in PD. In advanced stage of patients with PD, polyneuropathy could occur in patients using high dosage of levodopa. Pain often correlates to other non-motor symptoms of PD, including depression, sleep, and autonomic symptoms. Dopaminergic drugs, non-dopaminergic medications, botulinum toxin, deep brain stimulation, and physiotherapy have shown some benefits for certain types of PD-related pain. An increased awareness of pain as a common non-motor symptom of PD provides further insights into sensory system dysregulation in this disease. In this review, we aim to summarizes the clinical features of pain in patients with PD and emphasize the latest evidence of pain related to levodopa treatment.

An updated review on pathophysiology and management of burning mouth syndrome with endocrinological, psychological and neuropathic perspectives

Burning mouth syndrome (BMS) is a chronic oro-facial pain disorder of unknown cause. It is more common in peri- and post-menopausal women, and sex hormone dysregulation is believed to be an important causative factor. Psychosocial events often trigger or exacerbate symptoms, and persons with BMS appear to be predisposed towards anxiety and depression. Atrophy of small nerve fibres in the tongue epithelium has been reported, and potential neuropathic mechanisms for BMS are now widely investigated. Historically, BMS was thought to comprise endocrinological, psychosocial and neuropathic components. Neuroprotective steroids and glial cell line-derived neurotrophic factor family ligands may have pivotal roles in the peripheral mechanisms associated with atrophy of small nerve fibres. Denervation of chorda tympani nerve fibres that innervate fungiform buds leads to alternative trigeminal innervation, which results in dysgeusia and burning pain when eating hot foods. With regard to the central mechanism of BMS, depletion of neuroprotective steroids alters the brain network-related mood and pain modulation. Peripheral mechanistic studies support the use of topical clonazepam and capsaicin for the management of BMS, and some evidence supports the use of cognitive behavioural therapy. Hormone replacement therapy may address the causes of BMS, although adverse effects prevent its use as a first-line treatment. Selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs) may have important benefits, and well-designed controlled studies are expected. Other treatment options to be investigated include brain stimulation and TSPO (translocator protein 18 kDa) ligands.

Refractory burning mouth syndrome: clinical and paraclinical evaluation, comorbiities, treatment and outcome

BACKGROUND

Burning Mouth Syndrome (BMS) is a chronic pain condition characterized by persistent intraoral burning without related objective findings and unknown etiology that affects elderly females mostly. There is no satisfactory treatment for BMS. We aimed to observe the long-term efficacy of high velanfaxine doses combined with systemic and topical administered clonazepam in a particular subgroup of BMS patients who do not respond to current clinical management.

RESULTS

Eight (66.1 ± 6.2 years old females) out of 14 BMS patients fulfilled the inclusion criteria and were treated with venlafaxine (300 mg/d) and clonazepam (5 mg/d) for 35.4 ± 12.1 (mean ± SD) months. The average duration of the symptoms at baseline was 4.3 ± 1.4 years and the overall mean daily pain intensity score was 8.6 ± 1.3 (VAS); pain was in tongue and within the oral mucosa, accompanying by oral and facial dysesthesia. In five patients tasting was abnormal. All patients had positive history of concomitant primary headache. The average score of Hamilton Rating scale for Anxiety and Depression was 21 ± 4.2, and 26.1 ± 2.9, respectively. Previous ineffective treatments include anticonvulsants and anti-depressants. All patients responded (more than 50% decrease in VAS) after three months treatment (mean VAS 3.2 ± 2.2) with no remarkable adverse events.

CONCLUSION

BMS deserves bottomless psychiatric evaluation and management when current available treatments fail. Treatment with venlafaxine combined with topical and systemic clonazepam may be effective in refractory BMS cases but further investigation in a large-scale controlled study is needed to confirm these results.

Gut dysfunction in Parkinson's disease

Early involvement of gut is observed in Parkinson’s disease (PD) and symptoms such as constipation may precede motor symptoms. α-Synuclein pathology is extensively evident in the gut and appears to follow a rostrocaudal gradient. The gut may act as the starting point of PD pathology with spread toward the central nervous system. This spread of the synuclein pathology raises the possibility of prion-like propagation in PD pathogenesis. Recently, the role of gut microbiota in PD pathogenesis has received attention and some phenotypic correlation has also been shown. The extensive involvement of the gut in PD even in its early stages has led to the evaluation of enteric α-synuclein as a possible biomarker of early PD. The clinical manifestations of gastrointestinal dysfunction in PD include malnutrition, oral and dental disorders, sialorrhea, dysphagia, gastroparesis, constipation, and defecatory dysfunction. These conditions are quite distressing for the patients and require relevant investigations and adequate management. Treatment usually involves both pharmacological and non-pharmacological measures. One important aspect of gut dysfunction is its contribution to the clinical fluctuations in PD. Dysphagia and gastroparesis lead to inadequate absorption of oral anti-PD medications. These lead to response fluctuations, particularly delayed-on and no-on, and there is significant relationship between levodopa pharmacokinetics and gastric emptying in patients with PD. Therefore, in such cases, alternative routes of administration or drug delivery systems may be required.

Burning mouth syndrome: Clinical description, pathophysiological approach, and a new therapeutic option

INTRODUCTION

Burning mouth syndrome is defined as scorching sensation in the mouth in the absence of any local lesions or systemic disease that would explain that complaint. The condition responds poorly to commonly used treatments and it may become very disabling.

METHODS

We prospectively analysed the clinical and demographic characteristics and response to treatment in 6 cases of burning mouth syndrome, diagnosed at 2 tertiary hospital headache units.

RESULTS

Six female patients between the ages of 34 and 82 years reported symptoms compatible with burning mouth syndrome. In 5 of them, burning worsened at the end of the day; 4 reported symptom relief with tongue movements. Neurological examinations and laboratory findings were normal in all patients and their dental examinations revealed no buccal lesions. Each patient had previously received conventional treatments without amelioration. Pramipexol was initiated in doses between 0.36mg and 1.05mg per day, resulting in clear improvement of symptoms in all cases, a situation which continues after a 4-year follow up period.

CONCLUSIONS

Burning mouth syndrome is a condition of unknown aetiology that shares certain clinical patterns and treatment responses with restless leg syndrome. Dopamine agonists should be regarded as first line treatment for this entity.

Disorders of the oral cavity in Parkinson's disease and parkinsonian syndromes

Awareness of nonmotor symptoms of Parkinson's disease is growing during the last decade. Among these, oral cavity disorders are, although prevalent, often neglected by the patients, their caregivers, and physicians. Some of these disorders include increased prevalence of caries and periodontal disease, sialorrhea and drooling, xerostomia, orofacial pain, bruxism, and taste impairment. Though many of these disorders are not fully understood yet and relatively few controlled trials have been published regarding their treatment, physicians should be aware of the body of evidence that does exist on these topics. This paper reviews current knowledge regarding the epidemiology, pathophysiology, and treatment options of disorders of the oral cavity in Parkinson's disease patients.