Physical Factors Associated with Non-Specific Neck Pain: Correlations Among Pain, Disability, Posture, Endurance, and Compensatory Movement.

BACKGROUND This study was conducted to investigate physical risk factors in patients with non-specific neck pain. The correlations among pain intensity, pressure pain threshold, range of motion (ROM), and disability index were analyzed in 50 patients with non-specific neck pain at a hospital in Korea. MATERIAL AND METHODS We enrolled 50 patients diagnosed with non-specific neck pain by a doctor. All subjects were evaluated for pain intensity, pressure threshold, degree of disability, active range of motion (ROM) of the neck, upper cervical rotation ROM, muscular endurance of deep cervical flexor, compensatory movements for neck flexion, forward head posture, shoulder height difference, and rounded shoulder posture. The correlation between each variable was analyzed. RESULTS Pain intensity had a significant correlation between cervical rotation ROM, cervical flexion-rotation ROM, rounded shoulder posture, shoulder height difference, and forward head posture (P<.05). There was a significant correlation between the pressure pain threshold and the cervical extension ROM, cervical flexion-rotation ROM, and rounded shoulder height (P<.05). The disability index had a significant correlation between the cervical rotation ROM, cervical flexion-rotation ROM, rounded shoulder posture, and the compensatory movement of neck flexion (P<.05). CONCLUSIONS Physical risk factors for non-specific neck pain included cervical rotation ROM, upper cervical rotation ROM, rounded shoulder posture, shoulder height difference, and cervical flexion compensatory movements, which can affect pain intensity and pressure pain threshold.

Results of neck-specific exercise for altered postural sway in individuals with chronic whiplash-associated disorders: a longitudinal case-control study.

Postural sway has not been investigated before or after a neck exercise intervention in individuals with chronic whiplash-associated disorders (WAD). The aim of the study was to investigate postural sway in individuals with chronic WAD grades 2 and 3: (a) compared with healthy matched controls at baseline; (b) after three months of neck-specific exercise and (c) to investigate the correlation between postural sway with self-reported dizziness during motion and balance problems/unsteadiness. This is a longitudinal prospective experimental case-control intervention study. Individuals with WAD (n = 30) and age- and gender-matched healthy volunteers (n = 30) participated. Postural sway was assessed using an iPhone application. Measurements were carried out at baseline, and for those with WAD a second measurement was performed at the three-month follow-up when neck-specific exercise intervention ended. The WAD group performed significantly worse than the healthy group in both pathway and ellipse area double stance eyes closed at baseline (main outcome), but not at the three-month follow-up. The WAD group significantly improved after rehabilitation in both pathway double stance eyes closed and pathway single stance eyes open. The correlation between postural sway and self-rated dizziness during motion and balance problems was low to moderate. One may conclude that postural sway was improved after a neck-specific exercise programme. The study results strengthen earlier findings that individuals with WAD have worse balance outcome when they have to rely on neck proprioception (eyes closed). The study results may be important for the development of improved rehabilitation methods for WAD.

Neck Kinematics in Patients With Chronic Mechanical Neck Pain: An Observational Study to Explore the Integration of Multiple Influencing Factors Through a Bayesian Model-Based Approach.

The aim of this observational, cross-sectional study is to evaluate potential differences in kinematics, specifically range of motion (ROM) and velocity, during planar cervical movements between patients with non-traumatic chronic neck pain and disability and asymptomatic controls, while accounting for potential influencing variables of age, sex and fear of movement. The influence of pain intensity, neck disability, age, sex or fear of motion on kinematics was analyzed through robust multivariate Bayesian regression models fitted using the brms library in R. Forty-three patients with neck pain (aged 36.70 ± 13.75 years; 10 men and 33 women) and 42 asymptomatic participants (aged 32.74 ± 13.24 years; 25 men and 17 women) completed the study protocol. The presence of neck pain/disability was associated with lower ROM and peak velocity during all planar movements when considering the influence of age, sex or fear of motion, with standardized regression coefficients that had a small effect size (ranged from 0.11 to 0.28) and estimated differences of less than 2.21° in ROM and 25.61°/s in peak velocity. Although patients with chronic mechanical neck pain showed reduced ROM and peak velocity, the small effect sizes and the low estimated differences between groups question the relevance and clinical usefulness of kinematic analysis of planar movements in samples of patients similar to those included in our study. It is probable that there are differences between the groups, but it is insufficient to rely solely on kinematic variables for patient discrimination. This limitation likely arises from the substantial variability in patient kinematics.

Characteristics of head and neck alignment and function of deep cervical flexor muscles in patients with nonspecific neck pain.

OBJECTIVES: The objectives were to compare forward head posture (FHP) in natural and corrected head postures between patients with nonspecific neck pain (NSNP) and controls and to clarify the relationship between natural and corrected head posture angle differences and deep cervical flexor function. This study aimed to provide useful evidence for postural assessment and treatment in patients with NSNP. METHODS: In this cross-sectional study, 19 patients with NSNP reporting a pain score of 3-7 for at least 3 months and 19 participants with no neck pain within the previous 12 months were recruited. To evaluate FHP, the cranial rotation and vertical angles were measured using lateral head and neck photographs. The craniocervical flexion test was used to evaluate deep cervical flexor activation and endurance. We evaluated the head and neck alignment in natural and corrected head postures and the relationship between the degree of change and deep cervical flexor function. RESULTS: FHP in the natural head posture did not differ between groups. In the corrected head posture, FHP was significantly smaller in the NSNP group than in the control group. In the NSNP group, the cranial rotation and vertical angles were significantly different between the natural and corrected head postures, and the angle difference correlated significantly with deep cervical flexor function. CONCLUSIONS: Patients with NSNP show hypercorrection in the corrected head posture, which may be correlated with deep cervical flexor dysfunction. Further investigation into the causal relationship between hypercorrection, deep neck flexor dysfunction, and neck pain is required.

Preliminary Study on Effects of Neck Exoskeleton Structural Design in Patients With Amyotrophic Lateral Sclerosis.

Neck muscle weakness due to amyotrophic lateral sclerosis (ALS) can result in dropped head syndrome, adversely impacting the quality of life of those affected. Static neck collars are currently prescribed to hold the head in a fixed upright position. However, these braces are uncomfortable and do not allow any voluntary head-neck movements. By contrast, powered neck exoskeletons have the potential to enable head-neck movements. Our group has recently improved the mechanical structure of a state-of-the-art neck exoskeleton through a weighted optimization. To evaluate the effect of the structural changes, we conducted an experiment in which patients with ALS were asked to perform head-neck tracking tasks while using the two versions of the neck exoskeleton. We found that the neck muscle activation was significantly reduced when assisted by the structurally enhanced design compared to no assistance provided. The improved structure also improved kinematics tracking performance, allowing users to better achieve the desired head poses. In comparison, the previous design did not help reduce the muscle effort required to perform these tasks and even slightly worsened the kinematic tracking performance. It was also found that biomechanical benefits gained from using the structurally improved design were consistent across participants with both mild and severe neck weakness. Furthermore, we observed that participants preferred to use the powered neck exoskeletons to voluntarily move their heads and make eye contact during a conversation task rather than remain in a fixed upright position. Each of these findings highlights the importance of the structural design of neck exoskeletons in achieving desired biomechanical benefits and suggests that neck exoskeletons can be a viable method to improve the daily life of patients with ALS.

Responsiveness of the cervical joint position error test to detect changes in neck proprioception following four weeks of home-based proprioceptive training.

INTRODUCTION: People with chronic neck pain (CNP) commonly exhibit a range of physical impairments including cervical proprioceptive deficits. Assessing proprioception using a head mounted laser to assess joint position error (JPE) is a reliable and valid measure. However, the responsiveness of this measure has not been assessed. OBJECTIVE: To assess the responsiveness of the measure of cervical JPE after a 4-week home-based neck proprioceptive training intervention in people with CNP. DESIGN: An observational study to assess the responsiveness of the measure of cervical JPE. METHODS: The JPE test was assessed in people with CNP before and after 4 weeks of neck proprioception training. JPE was assessed as participants performed neck joint position sense tests for flexion, extension, right rotation, and left rotation in sitting and standing which were performed in a random order. Both the absolute and constant JPE were assessed. The intervention consisted of neck repositioning exercises as well as movement sense exercises. Cohen's d effect size was used to assess the internal responsiveness of the JPE test. The Pearson's correlation was used to assess the change of scores of the laser pointer and measures from inertial measurement units (IMUs) (external responsiveness). RESULTS: After 4 weeks of proprioception training, JPE assessed in sitting reduced from 2.69◦-3.57◦ to 1.88◦-1.98◦ for flexion, extension, and right rotation with large effect sizes (Cohen's d range: 1.25-2.00). For left rotation, JPE reduced from 3.23◦ to 1.9◦, and the effect size was close to being large (Cohen's d: 0.79). When assessed in standing, JPE reduced from 3.49◦-4.52◦ to 1.5◦-2.33◦ with large effect sizes (Cohen's d range: 0.89-1.25) for flexion, extension, right rotation, and left rotation. Large effect sizes were not observed for the constant JPE when assessed in either sitting or standing. The assessment of the external responsiveness revealed weak correlations between the change of scores obtained from the laser pointer and the IMUs for all movements, apart from the constant JPE in sitting for left rotation, which showed a strong correlation (r = 0.7). CONCLUSION: The results of this study showed that the measure of the JPE has sufficient internal responsiveness, however, the external responsiveness was inadequate. Further research is advised.

Can symptoms or signs of cervical dystonia occur without abnormal movements of the head or neck?

INTRODUCTION: Cervical dystonia is defined by excessive contraction of muscles that produce abnormal postures and movements of the head, neck, and sometimes the shoulders. Many affected individuals also have pain, local muscle hypertrophy, and/or abnormally increased EMG activity. However, abnormal movements are considered the defining feature. CASES: Three cases are described suggesting that some features of cervical dystonia may occur without abnormal movements. In these cases, the only clinical features are pain, local muscle hypertrophy, or abnormal EMG activity. These features may occur years before abnormal movements emerge, or they may occur coincidentally with dystonia affecting regions other than the neck. In some cases, some features associated with cervical dystonia may occur without any obvious abnormal movements. CONCLUSIONS: Some symptoms of cervical dystonia may occur without abnormal movements of the head or neck. The purpose of this report is not to question current diagnostic criteria for cervical dystonia, but to call attention to a phenomenon that deserves further attention. Such cases may be considered to have a pro-dromal form of cervical dystonia or a formes fruste of cervical dystonia. Whatever diagnostic label is applied, the phenomenon is important to recognize, because symptoms may be readily alleviated with botulinum toxin.

Validation of the Cervical Torsion Test and Head-Neck Differentiation Test in Patients With Peripheral Vestibular Hypofunction.

OBJECTIVE: This study compared adults with peripheral vestibular hypofunction (VH) to healthy controls and assessed the sensitivity and specificity of the Cervical Torsion Test (CTT) and the Head-Neck Differentiation Test (HNDT). This study aimed to determine whether neck problems affected primary outcomes. METHODS: This cross-sectional study included adults from a specialist consultation for dizziness. VH had been diagnosed with the video Head Impulse Test. Exclusion criteria were conditions following head or neck trauma and diseases of the central nervous system. The sensitivity and specificity of the index tests were calculated, and regression analyses were performed to test for contributing factors. RESULTS: A total of 19 patients with VH and a historical cohort of 19 matched healthy controls were included. Most patients with VH (84.2%) experienced symptoms in at least 1 test component, compared to 5.2% of the control group. Of patients with VH, 78.9% had symptoms during the HNDT "en bloc" (en bloc = head and trunk rotated together), whereas only 26.3% reported symptoms during the CTT en bloc. The best discriminatory validity was found for the HNDT en bloc, with a sensitivity of 0.79 (95% CI = 0.54-0.94), a specificity of 0.86 (95% CI = 0.65-0.97), and a positive likelihood ratio of 5.79 (95% CI = 1.97-17.00). The number of symptoms of CTT "in torsion" (in torsion = trunk rotated actively with fixed head) was increased by a factor of 1.13 (95% CI = 1.01-1.27) for every additional point on the Neck Disability Index. CONCLUSION: The CTT and HNDT can serve as non-laboratory tests for patients with dizziness. The HNDT en bloc has the best discriminatory validity, finding those with and those without VH. Symptom reproduction during torsion may help to identify when neck problems may contribute to dizziness. IMPACT: The HNDT en bloc may be useful for ruling VH in or out in patients with dizziness. Positive CTT and HNDT in torsion components may verify the likelihood of additional neck involvement.

The role of the deep cervical extensor muscles in multi-directional isometric neck strength.

Clinical management of whiplash-associated disorders is challenging and often unsuccessful, with over a third of whiplash injuries progressing to chronic neck pain. Previous imaging studies have identified muscle fat infiltration, indicative of muscle weakness, in the deep cervical extensor muscles (multifidus and semispinalis cervicis). Yet, kinematic and muscle redundancy prevent the direct assessment of individual neck muscle strength, making it difficult to determine the role of these muscles in motor dysfunction. The purpose of this study was to determine the effects of deep cervical extensor muscle weakness on multi-directional neck strength and muscle activation patterns. Maximum isometric forces and associated muscle activation patterns were computed in 25 test directions using a 3-joint, 24-muscle musculoskeletal model of the head and neck. The computational approach accounts for differential torques about the upper and lower cervical spine. To facilitate clinical translation, the test directions were selected based on locations where resistance could realistically be applied to the head during clinical strength assessments. Simulation results reveal that the deep cervical extensor muscles are active and contribute to neck strength in directions with an extension component. Weakness of this muscle group leads to complex compensatory muscle activation patterns characterized primarily by increased activation of the superficial extensors and deep upper cervical flexors, and decreased activation of the deep upper cervical extensors. These results provide a biomechanistic explanation for movement dysfunction that can be used to develop targeted diagnostics and treatments for chronic neck pain in whiplash-associated disorders.

Neck circumference and its association with anthropometric, clinical, and biochemical parameters in patients with chronic kidney disease on hemodialysis / Circunferência do pescoço e sua associação com parâmetros antropométricos, clínicos e bioquímicos em pacientes com doença renal crônica em hemodiálise

ABSTRACT Objective: To investigate the association between neck circumference and anthropometric, clinical, and biochemical parameters in chronic kidney failure patients on hemodialysis. Methods: This is a cross-sectional study with patients with chronic kidney disease undergoing hemodialysis in Western Bahia. For the data collection, anthropometric measures were taken and clinical and biochemical data were gathered from the patient records and employing a structured questionnaire. A multiple linear regression was applied to evaluate the relationship between neck circumference and the anthropometric, clinical, and biochemical parameters. Results: A total of 119 patients were evaluated, of which 63.03% were men and 57.98% were aged between 35 and 59 years old. The mean neck circumference of the patients was 36.2±3.8 cm. A negative association was found between neck circumference and the female sex (p<0.001), while waist circumference (p<0.001), the body adiposity index (p=0.002), and pre-dialysis serum urea concentration (p=0.006) were positively associated with neck circumference. Conclusion: Neck circumference is inversely associated with the female sex and positively associated with a high waist circumference, body adiposity index, and serum urea concentration in patients with chronic kidney disease on hemodialysis.

RESUMO Objetivo: Investigar a associação entre circunferência do pescoço e parâmetros antropométricos, clínicos e bioquímicos em pacientes renais crônico sem hemodiálise. Métodos: Trata-se de um estudo transversal com pacientes com doença renal crônica em hemodiálise no Oeste da Bahia. Para a coleta de dados foram aferidas medidas antropométricas e dados clínicos e bioquímicos foram coletados dos prontuários dos pacientes e por meio de um questionário estruturado. A análise de regressão linear múltipla foi aplicada para avaliar a relação entre a circunferência do pescoço e os parâmetros antropométricos, clínicos e bioquímicos. Resultados: Foram avaliados 119 pacientes, sendo 63,03% homens e 57,98% com idade entre 35 e 59 anos. A média da circunferência do pescoço dos pacientes foi de 36,2±3,8 cm. Foi encontrada associação negativa entre a circunferência do pescoço e sexo feminino (p<0,001), enquanto a circunferência da cintura (p<0,001), o índice de adiposidade corporal (p=0,002) e a concentração sérica de ureia pré-diálise (p=0,006) foram positivamente associados à circunferência do pescoço. Conclusão: A circunferência do pescoço está inversamente associada ao sexo feminino e positivamente associada a uma circunferência abdominal elevada, índice de adiposidade corporal e concentração sérica de ureia em pacientes com doença renal crônica em hemodiálise.

Clinical Evaluation of Neck in Patients with Proprioceptive Cervicogenic Dizziness.

OBJECTIVE: To establish a functional connection between neck physical evaluations, dizziness discomfort and image findings among subjects diagnosed with proprioceptive cervical dizziness. METHODS: After exclusion of peripheral vestibular disorders, 20 subjects with proprioceptive cervical dizziness hypothesis were selected. A Visual Analogue Scale (VAS) was used to quantify pain and vertigo. The active neck Range of Motion (ROM) and the Muscle Strength (MS) of the neck region were examined. The manipulation of vertebral bodies by the Maitland method and imaging scan were performed. RESULTS: A positive correlation between pain and vertigo VAS scores was found. The ROM of the cervical spine was limited and vertebral joint movement was restricted, especially at C3 and C5. No loss of MS was noticed. CONCLUSIONS: Proprioceptive cervical dizziness is usually an exclusion diagnosis among episodic chronic vertigos. Characteristically, it is reported by patients as instability or vertigo in crises. It is directly related to the neck ache severity and worsens with neck movements. The common pattern on clinical examination includes restriction and pain during neck flexion without loss of MS. Reduction of joint mobility and pain are also observed, especially at C3 and C54 kHz.

Demonstration of central conduction time and neuroplastic changes after cervical lordosis rehabilitation in asymptomatic subjects: a randomized, placebo-controlled trial.

A randomized controlled study was conducted to evaluate the effect of rehabilitation of the cervical sagittal configuration on sensorimotor integration and central conduction time in an asymptomatic population. Eighty (32 female) participants with radiographic cervical hypolordosis and anterior head translation posture were randomly assigned to either a control or an experimental group. The experimental group received the Denneroll cervical traction while the control group received a placebo treatment. Interventions were applied 3 × per week for 10 weeks. Outcome measures included radiographic measured anterior head translation distance, cervical lordosis (posterior bodies of C2-C7), central somatosensory conduction time (latency) (N13-N20), and amplitudes of potentials for spinal N13, brainstem P14, parietal N20 and P27, and frontal N30. Outcomes were obtained at: baseline, after 10 weeks of intervention, and at 3 months follow up. After 10 weeks and 3-months, between-group analyses revealed statistically significant differences between the groups for the following measured variables: lordosis C2-C7, anterior head translation, amplitudes of spinal N13, brainstem P14, parietal N20 and P27, frontal N30 potentials (P < 0.001), and conduction time N13-N20 (P = 0.004). Significant correlation between the sagittal alignment and measured variables were found (P < 0.005). These findings indicate restoration of cervical sagittal alignment has a direct influence on the central conduction time in an asymptomatic population.

Kinesiophobia and its correlations with pain, proprioception, and functional performance among individuals with chronic neck pain.

Chronic neck pain (CNP) incidence in the general population is high and contributes to a significant health problem. Kinesiophobia (fear of pain to movement or re-injury) combined with emotions and physical variables may play a vital role in assessing and managing individuals with CNP. The study's objectives are 1) to evaluate the relationship between kinesiophobia, neck pain intensity, proprioception, and functional performance; 2) to determine if kinesiophobia predicts pain intensity, proprioception, and functional performance among CNP individuals. Sixty-four participants with CNP (mean age 54.31 ± 9.41) were recruited for this cross-sectional study. The following outcome measures were evaluated: Kinesiophobia using the Tampa Scale of Kinesiophobia (TSK), neck pain intensity using the visual analog scale (VAS), cervical proprioceptive joint position errors (in flexion, extension, and rotation directions) using cervical range of motion (CROM) device and handgrip strength as a measure of functional performance using the Baseline® hydraulic hand dynamometer. Kinesiophobia showed a strong positive correlation with neck pain intensity (r = 0.81, p<0.001), a mild to a moderate positive correlation with proprioception joint position errors (JPE) in extension, rotation left and right directions (p<0.05), but no correlation in flexion direction (p = 0.127). Also, there was a moderate negative correlation with handgrip strength (r = -0.65, p<0.001). Regression analysis proved that kinesiophobia was a significant predictor of pain intensity, proprioception, and functional performance (p<0.05). This study infers that kinesiophobia in individuals with CNP predicts pain, proprioception, and functional performance. Kinesiophobia assessment should be considered in regular clinical practice to understand the barriers that can influence rehabilitation outcomes in CNP individuals.

Impact of Neck and Shoulder Pain on Health-Related Quality of Life in a Middle-Aged Community-Living Population.

PURPOSE: Neck and shoulder pain (NSP) is very common in the general population. However, scarce information exists on the relationship between NSP and health-related quality of life (HRQOL) outcomes in this population. The present study described NSP prevalence and its impact on the HRQOL of middle-aged and older persons undergoing a routine medical checkup. METHODS: This study recruited 318 subjects (125 males and 193 females; average age, 63.4 years) in good health, collected underwent anthropometric measurements, physical function examinations, and blood testing. This study defined NSP as the presence of muscle tension, stiffness, pressure, or dull pain in areas between the neck and the arch of the scapular. Study subjects were divided into two groups (NSP (+) and NSP (-) groups). The subjects completed questions on the Medical Outcomes Study 36-item short-form health survey (SF-36) and the EuroQol 5-dimension, 5-level version (EQ-5D-5L) tool. RESULTS: Of the patients, 150 and 168 were NSP (+) and NSP (-), respectively. The NSP complaint rate was 47.2%. The NSP (+) group had younger and more female participants than the NSP (-) group. In the multivariate regression analysis, the NSP (+) group had lower physical QOL based on the SF-36 physical component summary (odds ratio (OR), 2.45) and lower mental QOL based on the SF-36 mental component summary (OR, 2.05). Overall, the NSP (+) group had a higher risk of having low QOL scores (EQ-5D-5L index; OR, 1.76). CONCLUSIONS: The NSP (+) rate in healthy middle-aged and older persons was 47.2%. Furthermore, NSP (+) status was directly related poor HRQOL. NSP is a predictor of suboptimal physical and mental QOL. Therefore, NSP prevention or intervention for NSP may improve middle-aged and older adults' QOL.

Expert consensus on the important chronic non-specific neck pain motor control and segmental exercise and dosage variables: An international e-Delphi study.

BACKGROUND: Chronic non-specific neck pain is highly prevalent, resulting in significant disability. Despite exercise being a mainstay treatment, guidance on optimal exercise and dosage variables is lacking. Combining submaximal effort deep cervical muscles exercise (motor control) and superficial cervical muscles exercise (segmental) reduces chronic non-specific neck pain, but evaluation of optimal exercise and dosage variables is prevented by clinical heterogeneity. OBJECTIVE: To gain consensus on important motor control and segmental exercise and dosage variables for chronic non-specific neck pain. METHODS: An international 3-round e-Delphi study, was conducted with experts in neck pain management (academic and clinical). In round 1, exercise and dosage variables were obtained from expert opinion and clinical trial data, then analysed thematically (two independent researchers) to develop themes and statements. In rounds 2 and 3, participants rated their agreement with statements (1-5 Likert scale). Statement consensus was evaluated using progressively increased a priori criteria using descriptive statistics. RESULTS: Thirty-seven experts participated (10 countries). Twenty-nine responded to round 1 (79%), 26 round 2 (70%) and 24 round 3 (65%). Round 1 generated 79 statements outlining the interacting components of exercise prescription. Following rounds 2 and 3, consensus was achieved for 46 important components of exercise and dosage prescription across 5 themes (clinical reasoning, dosage variables, exercise variables, evaluation criteria and progression) and 2 subthemes (progression criteria and progression variables). Excellent agreement and qualitative data supports exercise prescription complexity and the need for individualised, acceptable, and feasible exercise. Only 37% of important exercise components were generated from clinical trial data. Agreement was highest (88%-96%) for 3 dosage variables: intensity of effort, frequency, and repetitions. CONCLUSION: Multiple exercise and dosage variables are important, resulting in complex and individualised exercise prescription not found in clinical trials. Future research should use these important variables to prescribe an evidence-informed approach to exercise.

DNAJC6 mutation causing cranial-onset dystonia with tremor dominant levodopa non-responsive parkinsonism: A novel phenotype.

DNAJC6 mutation causes two types of phenotypes: slowly progressive parkinsonism with levodopa response and rapidly progressive parkinsonism with additional manifestations like intellectual disability, epilepsy etc. We report a new phenotype wherein an adolescent girl developed blepharospasm followed by jaw opening, lingual and cervical dystonia followed by tremors of limbs (rest and action) with rigidity, bradykinesia. The dystonia-parkinsonism phenotype has not been described. She had novel homozygous missense mutation in DNAJC6 gene.

Spread of segmental/multifocal idiopathic adult-onset dystonia to a third body site.

BACKGROUND: Adult-onset focal dystonia can spread to involve one, or less frequently, two additional body regions. Spread of focal dystonia to a third body site is not fully characterized. MATERIALS AND METHODS: We retrospectively analyzed data from the Italian Dystonia Registry, enrolling patients with segmental/multifocal dystonia involving at least two parts of the body or more. Survival analysis estimated the relationship between dystonia features and spread to a third body part. RESULTS: We identified 340 patients with segmental/multifocal dystonia involving at least two body parts. Spread of dystonia to a third body site occurred in 42/241 patients (17.4%) with focal onset and 10/99 patients (10.1%) with segmental/multifocal dystonia at onset. The former had a greater tendency to spread than patients with segmental/multifocal dystonia at onset. Gender, years of schooling, comorbidity, family history of dystonia/tremor, age at dystonia onset, and disease duration could not predict spread to a third body site. Among patients with focal onset in different body parts (cranial, cervical, and upper limb regions), there was no association between site of focal dystonia onset and risk of spread to a third body site. DISCUSSION AND CONCLUSION: Spread to a third body site occurs in a relative low percentage of patients with idiopathic adult-onset dystonia affecting two body parts. Regardless of the site of dystonia onset and of other demographic/clinical variables, focal onset seems to confer a greater risk of spread to a third body site in comparison to patients with segmental/multifocal dystonia at onset.

Vestibulocollic and Cervicocollic Muscle Reflexes in a Finite Element Neck Model During Multidirectional Impacts.

Active neck musculature plays an important role in the response of the head and neck during impact and can affect the risk of injury. Finite element Human Body Models (HBM) have been proposed with open and closed-loop controllers for activation of muscle forces; however, controllers are often calibrated to specific experimental loading cases, without considering the intrinsic role of physiologic muscle reflex mechanisms under different loading conditions. This study aimed to develop a single closed-loop controller for neck muscle activation in a contemporary male HBM based on known reflex mechanisms and assess how this approach compared to current open-loop controllers across a range of impact directions and severities. Controller parameters were optimized using volunteer data and independently assessed across twelve impact conditions. The kinematics from the closed-loop controller simulations showed good average CORA rating to the experimental data (0.699) for the impacts following the ISO/TR9790 standard. Compared to previously optimized open-loop activation strategy, the average difference was less than 9%. The incorporation of the reflex mechanisms using a closed-loop controller can provide robust performance for a range of impact directions and severities, which is critical to improving HBM response under a larger spectrum of automotive impact simulations.