Functional limitation of the masticatory system in patients with bulbar involvement in amyotrophic lateral sclerosis

Reliability, reference values and factors related to maximum bite force measured by the Innobyte system in healthy adults with natural dentitions

OBJECTIVES

We aimed to determine the predictors of maximum bite force (MBF), as measured with the Innobyte system, and to assess the reliability and reference values for MBF in young adults with natural dentitions.

METHODS

This cross-sectional test-retest study included 101 dental students with natural dentitions. Participants had their dental occlusion examined and completed three questionnaires: the Temporomandibular disorders Pain Screener, Oral Behavior Checklist, and Jaw Functional Limitation Scale. Body mass index and muscle mass percentage were determined, and handgrip strength was measured with a dynamometer. The MBF was measured with Innobyte, with reliability assessed by the intraclass correlation coefficient, expressing reference values as MBF percentiles. Bivariate tests and multiple linear regression models were used for statistical analysis.

RESULTS

The intraclass correlation coefficient for the MBF was 0.90, with 10th to 90th percentiles of 487-876 N for females and 529-1003 N for males. A positive relationship existed between the MBF and male sex, muscle mass percentage, overbite, handgrip strength, and possible sleep/awake bruxism. Stepwise regression showed that overbite, handgrip strength, and possible sleep/awake bruxism had the greatest effect on the MBF, explaining 27% of the variation.

CONCLUSIONS

This study provides reference values for MBF when using the Innobyte system and shows excellent reliability. Overbite, general strength, and self-reported bruxism appear to be important predictors of MBF.

CLINICAL RELEVANCE

Innobyte is a reliable device that can be used to measure MBF bilaterally. Self-reported bruxism is associated with an 8%-10% increase in MBF.

Risdiplam Real World Data - Looking Beyond Motor Neurons and Motor Function Measures

BACKGROUND

Risdiplam is an orally administered treatment for spinal muscular atrophy which leads to an improvement in motor function as measured by functional motor scales compared with placebo. Although risdiplam has been registered since 2020, real-world data in adults is still scarce. There have been no new safety signals so far, with some results pointing that risdiplam may be effectiveObjective:The objective was to present real-world data of 31 adult patients with spinal muscular atrophy type 2 and type 3 treated with risdiplam in the Republic of CroatiaMethods:Treatment effects were assessed with motor function tests and patient reported outcome measures, including Individualized Neuromuscular Quality of Life questionnaire, and Jaw Functional Limitation Scale. Side effects, as well as subjective improvements and symptoms, were noted.

RESULTS

Majority of patients did not report any side effects. During treatment, we have observed clinically meaningful improvements in some patients, with stabilization of motor functions in the remaining patients. The majority of patients with bulbar function impairment experienced bulbar function improvement, all patients reported an increased quality of life with treatment. An unexpected observed treatment effect was weight gain in a third of all patients with some patients reporting an increase in appetite and subjective improvement in digestion.

CONCLUSIONS

Risdiplam treatment was well tolerated with subjective and objective positive outcomes registered as measured by functional motor scales and patient-reported outcomes. Since risdiplam is administered orally and acts as a systemic therapy for a multisystemic disorder, effects in systems other than neuromuscular can be expected and should be monitored. Due to systemic nature of the disease patients need multidisciplinary monitoring.

Growth curves for mandibular range of motion and maximum voluntary bite force in healthy children

Mandibular range of motion and bite force are indispensable variables for the evaluation of mandibular function. There are a variety of medical and dental conditions that can negatively affect mandibular function. Values for mandibular range of motion (i.e., active and passive maximum interincisal mouth opening, protrusion, and laterotrusion) and anterior maximum voluntary bite force (AMVBF) in healthy children and adolescents can help in recognizing temporomandibular dysfunction. In this longitudinal study, 169 healthy children aged 6-18 years were included. They were examined at four time points over 1 year. Mixed model analysis was performed to produce growth curves of mandibular range of motion and AMVBF. Average active maximum interincisal mouth opening was significantly higher in boys with 50.0 mm compared to 47.8 mm in girls. Boys also had a significantly higher AMVBF than girls with an average of 169.0 N versus 140.0 N, respectively. Growth curves of active and passive maximum interincisal mouth opening showed an increase with age, albeit levelling off through puberty. The growth curves of AMVBF in girls reach a plateau phase at ages 12-14 years, after which the curve descends; in boys, the AMVBF tended to increase up to 18 years of age, although a slow-down after 14 years of age was noted.

Oral function in amyotrophic lateral sclerosis patients: A matched case-control study

BACKGROUND & AIMS

Patients with amyotrophic lateral sclerosis (ALS) develop swallowing difficulties with the progression of the disease. The present study aimed at comparing oral function and body composition between ALS patients and healthy controls, and at evaluating which parameters are the most discriminant between both groups.

METHODS

We included ALS patients at the start of their multidisciplinary follow-up at the Geneva University Hospitals and healthy age-, gender-, and dental status-matched adults. We assessed the severity of the disease through the ALS Functional Rating Scale and the swallowing difficulties through the EAT-10 score. We performed an intraoral examination of the dental status, and measured chewing performance, bite, lip and tongue force, saliva weight, and body composition. Group comparisons were performed with t-tests or Mann-Whitney tests as appropriate. Linear discriminant analysis was used to determine the most discriminant parameters between groups.

RESULTS

Twenty-six ALS patients (bulbar onset: n = 7, median (IQR) ALS Functional Rating Scale: 37 (11)) were included. The ALS patients had a significantly lower chewing performance (p < 0.001), lip force (p < 0.001), tongue force (p = 0.002), saliva weight (p < 0.004) and fat-free mass index (p < 0.001) as compared to the healthy individuals, and a higher EAT-10 score (p < 0.001). In ALS patients, a low chewing performance was correlated with a low bite (r = -0.45, p < 0.05)) and tongue force (r = -0.59, p < 0.05). The most discriminant parameters between both groups, by order of importance, were chewing performance, fat-free mass index and saliva weight and allowed the calculation of a discriminant function.

CONCLUSION

Compared to healthy controls, ALS patients have significant alterations of oral function and body composition. The most discriminant parameters between both groups were chewing performance, fat-free mass index and saliva volume. It remains to be demonstrated whether oral parameters predict outcome. CLINICAL TRIAL REGISTRY: clinicaltrials.gov, identifier: NCT01772888.

Biological Treatments for Temporomandibular Joint Disc Disorders: Strategies in Tissue Engineering

The temporomandibular joint (TMJ) is an important structure for the masticatory system and the pathologies associated with it affect a large part of the population and impair people's lifestyle. It comprises an articular disc, that presents low regeneration capacities and the existing clinical options for repairing it are not effective. This way, it is imperative to achieve a permanent solution to guarantee a good quality of life for people who suffer from these pathologies. Complete knowledge of the unique characteristics of the disc will make it easier to achieve a successful tissue engineering (TE) construct. Thus, the search for an effective, safe and lasting solution has already started, including materials that replace the disc, is currently growing. The search for a solution based on TE approaches, which involve regenerating the disc. The present work revises the TMJ disc characteristics and its associated diseases. The different materials used for a total disc replacement are presented, highlighting the TE area. A special focus on future trends in the field and part of the solution for the TMJ problems described in this review will involve the development of a promising engineered disc approach through the use of decellularized extracellular matrices.

[Screening for temporomandibular disorders : A sensible approach?]

BACKGROUND

Temporomandibular disorders (TMDs) are typically characterized by pain in the masticatory muscles and temporomandibular joints (TMJs) and by limitation of mandibular mobility. In June 2019, the German Society of Craniomandibular Function and Disorders presented a screening tool to identify individuals with TMDs. The assessment tool consists of patient history (three questions related to jaw pain, one question related to impaired mandibular mobility) and a clinical examination (palpation of masticatory muscles and TMJs; evaluation of maximum jaw opening; assessment of the presence of occlusal disturbances; documentation of TMJ noises).

OBJECTIVES

The present article focusses on two questions: (1) Which of the nine parts of the tool are appropriate, and which are not? (2) In general, can screening for TMDs be recommended?

CONCLUSION

While the anamnestic questions, as well as the assessment of maximum mandibular opening, reflect the clinically relevant symptoms and signs of TMD patients, the remaining four clinical measures do not. Furthermore, TMD screening for painful TMDs appears unnecessary because patients suffering from orofacial pain and/or restricted mandibular mobility are likely to consult a therapist by themselves. Therefore, the use of this screening tool may lead to overdiagnosis, possibly resulting in nonindicated diagnostic and therapeutic measures.

Validation of a Chinese version of the Jaw Functional Limitation Scale in relation to the diagnostic subgroup of temporomandibular disorders

BACKGROUND

Oro-facial function is usually impaired by temporomandibular disorders (TMDs). Several studies on TMDs have used the Jaw Functional Limitation Scale (JFLS) to assess mandibular dysfunction. However, it was originally created in English and hence needs to be validated for use among Chinese people.

OBJECTIVE

To develop a Chinese version of the JFLS for Chinese TMD patients and to investigate the validity and reliability of the scale.

METHODS

Content validity and temporal stability were evaluated at two different occasions. The reliability and validity of the JFLS were tested in 483 TMD patients. Cronbach's alpha coefficient and split-half reliability were used to assess internal consistency, while the validity was evaluated by factor analysis.

RESULTS

Three factors were extracted during exploratory factor analysis, accounting for 62.39% of the variance. The three-factor model was then measured using confirmatory factor analysis (χ² /df = 3.6, root mean square error of approximation = 0.091, comparative fit index = 0.896). Internal (coefficient alpha values of .906 for all items and Guttman split-half reliability of 0.756) and test-retest (intra-class correlation coefficient = .851-.897, 95% confidence interval = 0.656-0.950) reliabilities were excellent.

CONCLUSION

The Chinese version of the JFLS is reliable and valid for use in Chinese TMD patients.

Circuit-Specific Early Impairment of Proprioceptive Sensory Neurons in the SOD1G93A Mouse Model for ALS

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which motor neurons degenerate, resulting in muscle atrophy, paralysis, and fatality. Studies using mouse models of ALS indicate a protracted period of disease development with progressive motor neuron pathology, evident as early as embryonic and postnatal stages. Key missing information includes concomitant alterations in the sensorimotor circuit essential for normal development and function of the neuromuscular system. Leveraging unique brainstem circuitry, we show in vitro evidence for reflex circuit-specific postnatal abnormalities in the jaw proprioceptive sensory neurons in the well-studied SOD1^G93A mouse. These include impaired and arrhythmic action potential burst discharge associated with a deficit in Nav1.6 Na⁺ channels. However, the mechanoreceptive and nociceptive trigeminal ganglion neurons and the visual sensory retinal ganglion neurons were resistant to excitability changes in age-matched SOD1^G93A mice. Computational modeling of the observed disruption in sensory patterns predicted asynchronous self-sustained motor neuron discharge suggestive of imminent reflexive defects, such as muscle fasciculations in ALS. These results demonstrate a novel reflex circuit-specific proprioceptive sensory abnormality in ALS.SIGNIFICANCE STATEMENT Neurodegenerative diseases have prolonged periods of disease development and progression. Identifying early markers of vulnerability can therefore help devise better diagnostic and treatment strategies. In this study, we examined postnatal abnormalities in the electrical excitability of muscle spindle afferent proprioceptive neurons in the well-studied SOD1^G93A mouse model for neurodegenerative motor neuron disease, amyotrophic lateral sclerosis. Our findings suggest that these proprioceptive sensory neurons are exclusively afflicted early in the disease process relative to sensory neurons of other modalities. Moreover, they presented Nav1.6 Na⁺ channel deficiency, which contributed to arrhythmic burst discharge. Such sensory arrhythmia could initiate reflexive defects, such as muscle fasciculations in amyotrophic lateral sclerosis, as suggested by our computational model.