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Although improvements in acute care for traumatic brain injury (TBI) have increased the patient survival rate, many survivors often suffer from neuropsychiatric sequelae such as depression. This study investigated the influence of TBI on the risk of depression using South Korean nationwide data. Data were extracted from the National Health Insurance Service database for patients who experienced TBI from 2010 to 2017 (

Background This study examined how meeting the medical needs of injured workers after initial treatment may affect their return to work, using data from the Panel Study of Workers’ Compensation Insurance. Methods This study was designed as a longitudinal study, which used data from the second-year, follow-up survey conducted in the secondary cohort of the Panel Study of Workers’ Compensation Insurance. The odds ratio (OR) and 95% confidence interval were estimated through binomial and multinomial logistic regression analyses to examine the effects of unmet medical needs on workers’ return to original work and return to work overall (including reemployment). Results The returned to original work OR of workers whose rehabilitation needs were met was 1.35 (1.12–1.63) while the return to work OR was 1.20 (1.03–1.41). The returned to original work OR of workers whose medical needs were met was 1.64 (1.18–2.27) while the return to work OR was 1.39 (1.07–1.80). In terms of disability rating, the return to work ORs of workers with mild disabilities whose medical/rehabilitation needs were not met and those of workers without disabilities were 1.71 (1.17–2.49) and 1.97 (1.27–3.08), respectively. In the case of regular/temporary workers, the returned-to-work ORs of workers whose medical/rehabilitation needs were not met were 1.54 (1.12–2.13) and 1.27 (1.03–1.56), respectively. Conclusions For workers who sustained work-related injuries, providing medical accessibility and meeting rehabilitation needs were found to be important predictors of return to work after initial treatment.

Brain-machine Interface (BMI) is a system that translates neuronal data into an output variable to control external devices such as a robotic arm. A robotic arm can be used as an assistive living device for individuals with tetraplegia. To reflect users' needs in the development process of the BMI robotic arm, our team followed an interactive approach to system development, human-centered design, and Human Activity Assistive Technology model. This study aims to explore the perspectives of people with tetraplegia about activities they want to participate in, their opinions, and the usability of the BMI robotic arm. Eight people with tetraplegia participated in a focus group interview in a semistructured interview format. A general inductive analysis method was used to analyze the qualitative data. The 3 overarching themes that emerged from this analysis were: 1) activities, 2) acceptance, and 3) usability. Activities that the users wanted to do using the robotic arm were categorized into the following 5 activity domains: activities of daily living (ADL), instrumental ADL, health management, education, and leisure. Participants provided their opinions on the needs and acceptance of the BMI technology. Participants answered usability and expected standards of the BMI robotic arm within 7 categories such as accuracy, setup, cost, etc. Participants with tetraplegia have a strong interest in the robotic arm and BMI technology to restore their mobility and independence. Creating BMI features appropriate to users' needs, such as safety and high accuracy, will be the key to acceptance. These findings from the perspectives of potential users should be taken into account when developing the BMI robotic arm.

Background This study validated the Korean version of the Readiness to Return to Work (RRTW) scale, as an assessment measure, following a musculoskeletal, work-related injury and as a measure of following return to work. Methods The participants of this study were workers with experience in rehabilitation programs at the Workers’ Compensation and Welfare Service (KCOMWEL) Hospital in Korea. Factor analyses were employed to ensure the validity and reliability of the RRTW scale in claimants who were in treatment without working (the not-working group) or who had already returned to work (the working group). To test structural validity, we analyzed exploratory factor analysis (EFA) respectively for the not working group (exploratory factor analysis (EFA) (n = 200), confirmatory factor analysis (CFA) (n = 109), and the working group (n = 123). To verify concurrent validity (multidimensional and assignment approach), the variables that were identified as relevant variables in previous studies were analyzed. Results The not working group EFA, as shown in the original scale, had four dimensions, and one item was deleted: (1) Precontemplation (PC), (2) Contemplation (C), (3) Prepared for Action-Self-evaluative (PAS), and (4) Prepared for Action-Behavioral (PAB). The CFA revealed that a good model fit and reliability were suitable. Regarding the working group of EFA, it appeared in two dimensions as in the original scale, one item was modified from the UM scale to the PM scale, and the reliability was appropriate. Concurrent validity was satisfied based on the correlation between the RRTW factor and related variables. Conclusions RRTW in the Korean version of the instrument was similar to those reported for the original scale, indicating that it may be used in research and clinical settings.

Few studies have investigated the factors associated with assisted ventilation use in amyotrophic lateral sclerosis (ALS) in western countries with a relatively small number of participants. This study aimed to evaluate the factors associated with assisted ventilation use using a large nationwide cohort covering the entire Korean population. We selected patients with primary or secondary diagnoses of ALS (ICD-10 code: G12.21) and a registration code for ALS (V123) in the rare intractable disease registration program. Covariates included in the analyses were age, sex, socioeconomic status and medical condition. Factors associated with non-invasive ventilation (NIV) and tracheostomy invasive ventilation (TIV) were evaluated. Logistic regression analyses were performed using odds ratios and 95% confidence intervals. In total, 3057 patients with ALS were enrolled. During the 6-year follow-up period, 1228 (40%) patients started using assisted ventilation: 956 with NIV and 272 with TIV. There was no significant difference in the assisted ventilation use according to sex, whereas different patterns of discrepancies were noted between the sexes: Females living in non-metropolitan areas showed decreased use of assisted ventilation, whereas high income levels showed a positive relationship with assisted ventilation use only in males. Patients aged ≥ 70 years showed decreased use of NIV. NIV use was more affected by socioeconomic status than TIV, whereas TIV showed a significant relationship with medical conditions such as nasogastric tube insertion and gastrostomy. We found that various factors, including age, socioeconomic status, and medical condition, were related with assisted ventilation use. Understanding the pattern of assisted ventilation use would help set optimal management strategies in patients with ALS.

The partial weight-bearing protocol after lower limb fracture is an important issue in postoperative rehabilitation. Because it is difficult to quantify the actual weight load and provide a constant weight, the protocol is unestablished. By training with a lower-body positive-pressure treadmill and using an in-shoe pressure-measuring device, partial weight-bearing exercise can be performed with quantified loads. This case series illustrates the applicability of an early quantitative partial weight-bearing rehabilitation program using lower-body positive-pressure treadmill with an in-shoe pressure-measuring device after periarticular tibial fractures, which provides a quantitatively predetermined constant load.

Traumatic brain injury (TBI), a global public health concern, may lead to death and major disability. While various short-term, small-sample, and cross-sectional studies on TBI have been conducted in South Korea, there is a lack of clarity on the nationwide longitudinal TBI trends in the country. This retrospective study investigated the epidemiological TBI trends in South Korea, using a population-based dataset of the National Health Insurance (2008&ndash, 2017). The crude and age adjusted TBI incidence and mortality values were calculated and stratified by age, sex, and TBI diagnosis. The age-adjusted incidence per 100,000 people increased until 2010 and showed a decreasing trend (475.8 cases in 2017) thereafter, however, a continuously decreasing age-adjusted mortality trend was observed (42.9 cases in 2008, 11.3 in 2017). The crude incidence rate increased continually in those aged &gt, 70 years across all the TBI diagnostic categories. The mortality per 100,000 people was significantly higher among participants aged &ge, 70 years than in the other age groups. We observed changing trends in the TBI incidence, with a continuously decreasing overall incidence and a rapidly increasing incidence and high mortality values in older adults. Our findings highlight the importance of active TBI prevention in elderly people.

Background This study aimed to develop a Korean version of the Return-to-Work Self-Efficacy (RTWSE)-19 Scale using forward- and backward-translation and investigate the validity of the RTWSE Scale specifically for Korean workers with work-related injuries. Methods Participants were 202 injured workers who had filed a claim accepted by the workers’ compensation system and had received medical rehabilitation at workers’ compensation hospitals following a work-related musculoskeletal injury. Among these participants, 88.1% were male, 54.5% were over 45 years, 45.5% were manufacturing employees, and 54.5% were craft or machine operator and assemblers. The 19 item RTWSE-19 scale was developed by Shaw et al. and have three underlying subscales: (i) meeting job demands, (ii) modifying job tasks, and (iii) communicating needs to others. Statistical analysis included exploratory factor analysis (maximum likelihood estimation with oblique quartimin rotation), internal consistency reliability using Cronbach’s alpha, and correlations with related measures: pain intensity; fear-avoidance beliefs; general health; depression; and general self-efficacy. Results Using exploratory factor analysis, three factors with 17 items were identified: meeting job demands, modifying job tasks, and communicating needs to others. The removal of two items in the modifying job tasks domain resulted in an increased reliability. The Korean version of the RTWSE-17 showed reasonable model fit (CFI = .963; TLI = .943; RMSEA = .068; SRMR = 0.029), satisfactory reliability (r = 0.925), no floor and ceiling effect, and construct validity. Conclusions The Korean RTWSE-17 scale was found to possess good psychometric properties and could address different injury types ranging from fractures to amputations involved in sub-acute and rehabilitation phases in the Korean context. This study’s findings provide insights for practitioners and researchers to return to work after rehabilitation in a Korean clinical and workplace setting.

Background : This study aimed to develop a Korean-language version of the RTWSE-19 through a forward and backward translation process and to investigate the validity of the Return-to-Work Self-Efficacy Scale specifically for Asian workers with work-related injuries. Methods : Participants were 202 injured workers who had filed a claim accepted by the workers’ compensation system following a work-related musculoskeletal injury. Among participants, 88.1% were male, 54.5% were over 45 years, 45.5% had an occupation in manufacturing, and 54.5% were craft or machine operator and assemblers. Results : Using exploratory factor analysis, three factors with 17 items were identified: (i) meeting job demands, (ii) modifying job tasks, and (iii) communicating needs to others. Removal of two item in modifying job tasks domain resulted in an increased reliability. The Korean version of the RTWSE-17 showed reasonable model fit (CFI = .963; TLI = .943; RMSEA = .068; SRMR = 0.029), satisfactory reliability (r = 0.925), no floor and ceiling effect, and construct validity. Conclusions : The scale was found to possess good psychometric properties and could address different injury types ranging from fractures to amputations involved in sub-acute and rehabilitation phases in a Korean context. The results from this study provide practitioners and researchers with insight into return to work after rehabilitation in Asian clinical and workplace setting.

Background Cardiac rehabilitation (CR) after acute myocardial infarction (AMI) is recommended as a mandatory intervention in several national clinical practice guidelines published in America, Europe, and Korea to reduce recurrence and mortality. However, underutilization of CR is an established worldwide issue. In Korea, the promotion of CR is expected due to coverage by National Health Insurance. Nevertheless, the national status of CR use has not been reported. This retrospective cohort study aimed to investigate the current status of CR use in patients with AMI using nationwide data from the National Health Insurance Service of Korea. Methods Patients with AMI admitted with the diagnosis of ‘I21’ code (from International Classification of Diseases, 10th revision, Clinical Modification) from July 1st, 2017 to June 30th, 2018 were included. CR use was defined as CR treatment or evaluation being performed during an outpatient follow-up period within 6 months after discharge. Participation rate and density were calculated nationally and by administrative division. Logistic regression analysis was performed to identify the influencing factors of CR participation. Results Nationally, 1.5% of AMI patients (960/64,982) underwent CR during outpatient treatment after discharge. CR density was approximately 10. Logistic regression analysis revealed that influencing factors included old age, female sex, rural residence, and low Charlson comorbidity index. Conclusion Hospital-based CR after AMI is underutilized despite its coverage by the National Health Insurance. More CR facilities have to be installed according to the needs of CR in various regions., Graphical Abstract

Objective To investigate medical comorbidities and needs for medical and rehabilitation services of adults with cerebral palsy (CP) in Korea. Methods This was a prospective cross-sectional study. One hundred fifty-four adults with CP were enrolled in the study between February 2014 and December 2014. Information was obtained from participants regarding functional status, demographic and socioeconomic data, medical problems, and requirements for and utilization of medical and rehabilitation services. Results The participants included 93 males and 61 females with a mean age of 40.18±9.15 years. The medical check-up rate of adults with CP was lower than that of healthy adults and the total population with disabilities (53.2% vs. 58.6% vs. 70.4%). A quarter of the subjects failed to visit the hospital during the past year, and the main reason was the financial burden. Due to a cost burden and lack of knowledge, more than one-third of the subjects had unmet needs for rehabilitation services; the majority reported needs for rehabilitation services, such as physical therapy for pain management. Conclusion The medical check-up rate was lower in the adults with CP, even though their medical comorbidities were not less than those of healthy people. Several non-medical reasons hindered them from receiving proper medical and rehabilitation services. Such barriers should be managed effectively.

Cervical dystonia is a common issue in patients with athetoid cerebral palsy. Botulinum toxin injection to dystonic cervical muscles is a well-recognized treatment option, but it is known to be associated with dysphagia. Previously reported cases of dysphagia after botulinum toxin injection to the sternocleidomastoid muscle were related to the regional spread of toxin to the pharyngeal muscles. We report a unique case of posture-dependent dysphagia due to preactivation of the suprahyoid and infrahyoid muscles to compensate for impaired head stabilization by the weakened sternocleidomastoid muscle while swallowing. This case suggests a possible mechanism of dysphagia in patients with athetoid cerebral palsy.

ObjectivesThis study aimed to measure the burden of work-related upper limb amputation in Korea over a 10-year period and assess its trend.DesignEcological study.SettingNational level data in Korea between 2004 and 2013.Participants49 535 subjects who claimed Korea industrial accident compensation insurance due to upper limb amputation.Main outcome measuresThe disability-adjusted life years (DALYs) were calculated by sex, age and the site of amputation using annual incidence.ResultsThe burden of work-related upper limb amputations in Korea reached its peak in 2007 and decreased thereafter. Males showed a higher burden of disease. Finger amputations showed a decreasing trend from 2007, whereas arm amputations continued to show an increasing trend. An increasing trend was found among participants older than 50 years.ConclusionsThe decrease in the burden of finger amputations may be attributable to the lower incidence as a result of policy efforts. The increase in the burden of arm amputations was particularly noticeable among the elderly population over 50 years old. This could be attributable to the high proportion of the elderly population working in the manufacturing sector and the lack of policy efforts regarding major amputations in Korea. Future regulatory efforts are needed to prevent amputations.

OBJECTIVE Given the lack of a Korean version of the Spinal Cord Independence Measure III (KSCIM-III) that accurately reflects the contextual and cultural aspect of the assessment tool, the aims of the study were to develop a new Korean version of the Spinal Cord Independence Measure III and to investigate its reliability and validity. DESIGN Forty (N = 40) consecutive patients with spinal cord injury were included in this prospective study. Backward and forward translation of the Spinal Cord Independence Measure III was performed by fluent speakers in both languages. To measure the validity of Korean version of the Spinal Cord Independence Measure III, the scores were compared with the Modified Barthel Index. Each patient was examined by two occupational therapists. For test-retest reliability assessment, follow-up evaluation was repeated 1 mo after the initial assessment by the same evaluator. RESULTS Reliability between the Korean version of the Spinal Cord Independence Measure III evaluators showed values of 0.710-1.000, and test-retest reliability showed high values ranging from 0.295 to 0.664. The validity of Korean version of the Spinal Cord Independence Measure III was confirmed by the close correlation with Modified Barthel Index (r = 0.953, P < 0.001). CONCLUSIONS The results of this study showed high interrater and substantial test-retest reliability. The Korean version of the Spinal Cord Independence Measure III is an appropriate tool to assess the activities of daily living in terms of independence for patients with spinal cord injury.

Background The gold standard in dysarthria assessment involves subjective analysis by a speech–language pathologist (SLP). We aimed to investigate the feasibility of dysarthria assessment using automatic speech recognition. Methods We developed an automatic speech recognition based software to assess dysarthria severity using hidden Markov models (HMMs). Word-specific HMMs were trained using the utterances from one hundred healthy individuals. Twenty-eight patients with dysarthria caused by neurological disorders, including stroke, traumatic brain injury, and Parkinson's disease were participated and their utterances were recorded. The utterances of 37 words from the Assessment of Phonology and Articulation for Children test were recorded in a quiet control booth in both groups. Patients were asked to repeat the recordings for evaluating the test–retest reliability. Patients' utterances were evaluated by two experienced SLPs, and the consonant production accuracy was calculated as a measure of dysarthria severity. The trained HMMs were also employed to evaluate the patients' utterances by calculating the averaged log likelihood (aLL) as the fitness of the spoken word to the word-specific HMM. Results The consonant production accuracy reported by the SLPs strongly correlated (r = 0.808) with the aLL, and the aLL showed excellent test–retest reliability (intraclass correlation coefficient, 0.964). Conclusion This leads to the conclusion that dysarthria assessment using a one-word speech recognition system based on word-specific HMMs is feasible in neurological disorders., Graphical Abstract

Background While spontaneous robotic arm control using motor imagery has been reported, most previous successful cases have used invasive approaches with advantages in spatial resolution. However, still many researchers continue to investigate methods for robotic arm control with noninvasive neural signal. Most of noninvasive control of robotic arm utilizes P300, steady state visually evoked potential, N2pc, and mental tasks differentiation. Even though these approaches demonstrated successful accuracy, they are limited in time efficiency and user intuition, and mostly require visual stimulation. Ultimately, velocity vector construction using electroencephalography activated by motion-related motor imagery can be considered as a substitution. In this study, a vision-aided brain–machine interface training system for robotic arm control is proposed and developed. Methods The proposed system uses a Microsoft Kinect to detect and estimates the 3D positions of the possible target objects. The predicted velocity vector for robot arm input is compensated using the artificial potential to follow an intended one among the possible targets. Two participants with cervical spinal cord injury trained with the system to explore its possible effects. Results In a situation with four possible targets, the proposed system significantly improved the distance error to the intended target compared to the unintended ones (p

Central-nervous-system (CNS) injuries constitute a significant cause of morbidity (often resulting in long-term disability) and mortality. This cross-sectional study compared the activity and participation of community-dwelling people with severe disability from acquired brain injuries (ABI) (n = 322) and spinal-cord injuries (SCI) (n = 183) to identify risk factors related to disability. Data were collected through a questionnaire survey of community-dwelling people with severe disability attending 65 healthcare centers. The survey included the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) and sociodemographic factors. We categorized a registered grade of disability of 1 or 2 as severe disability. WHODAS 2.0 domain and summary scores were compared between the ABI and SCI groups, and risk factors associated with disability were identified through regression analysis. ABI participants had significantly higher disability in cognition and relationships, whereas patients with SCI had higher disability in mobility (p &lt, 0.05). Onset duration was negatively correlated with cognition, relationships, participation, and summary scores in ABI participants (p &lt, 0.05). Neither group&rsquo, s socioeconomic factors were associated with WHODA 2.0 scores. Understanding the different patterns of disability between SCI and ABI in community-dwelling people with severe disability helps establish future plans for the management of health resources.

Background Most adults with cerebral palsy encounter newly developing physical health problems and premature functional decline with aging. These physical and functional losses along with the characteristic symptoms of cerebral palsy may heighten the risk of sarcopenia. Objective To determine the prevalence of sarcopenia among a selected group of adults with cerebral palsy and to identify the factors associated with their sarcopenia among them. Design Cross-sectional study. Setting University hospitals and communities for persons with disabilities. Participants A total of 80 adults with cerebral palsy (46 men and 34 women with mean age of 42.8 ± 8.86 years) were included. Method Muscle mass, strength, and physical performance were measured to diagnose sarcopenia. Participants also completed a structured questionnaire for physical, psychological, or socioeconomic attributes and health-related quality of life. Main outcome measures Prevalence of sarcopenia in adults with cerebral palsy. Results The prevalence of sarcopenia was 47.9%. Sarcopenia was significantly associated with sex, the Gross Motor Function Classification System (GMFCS), the Manual Ability Classification System (MACS), body mass index (BMI), and trunk fat. Male, higher GMFCS and lower BMI were significant risk factors of sarcopenia. Sarcopenic adults with cerebral palsy showed significantly lower health-related quality of life. Conclusion The prevalence of sarcopenia in adults with cerebral palsy was higher than that of general population despite the young age of the selected group. Modifiable risk factor was a low BMI. Level of evidence III.

We aimed to evaluate the efficacy and safety of injecting botulinum toxin A (BoNT-A) into the neck muscles to treat cervical dystonia (CD) in patients with dyskinetic cerebral palsy (CP). This was a randomized, double-blinded, placebo-controlled trial with cross-over design. We prospectively enrolled adults with dyskinetic CP who were over 20 years old and had been clinically diagnosed with CD for more than one year. The primary outcome measure was the change in Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) at four weeks from the baseline TWSTRS. Seventeen patients were initially enrolled, but one patient was excluded after the final evaluation because of a violation of the study protocol. At four weeks, the BoNT-A injections showed significant improvement in TWSTRS total scores compared to the saline injections (p = 0.0286 for ANCOVA). At 12 weeks, the BoNT-A injections resulted in greater improvements in TWSTRS total scores than the saline injections without statistical significance (p = 0.0783 for ANCOVA). Dysphagia occurred in three out of 16 patients: two after BoNT-A and one after saline. The dysphagia was transient and improved naturally within two weeks without any special treatment. BoNT-A injection for CD in adults with dyskinetic CP is relatively safe and improves pain and disability.

Effortful swallowing (EFS) is a common compensatory swallowing manoeuver for dysphagia patients. We investigated the influence of EFS on temporal and spatial characteristics of the movements of the hyoid bone, larynx and epiglottis in healthy subjects. A total of 41 volunteers swallowed 10 mL of diluted barium solution using two swallowing strategies: usual and effortful swallowing (USS and EFS). The motions of the hyoid bone, larynx and epiglottis were tracked using frame-by-frame kinematic motion analysis of videofluoroscopic images. Maximal velocities and maximal displacements of hyoid and larynx, the maximal angle of the epiglottic tilt, and the durations of hyoid excursion, laryngeal elevation and epiglottic tilt were measured. Compared to USS, EFS was associated with significantly greater vertical displacement of the hyoid (P < 0.001), vertical and horizontal displacement of the larynx (P = 0.003, P = 0.019), and maximal angle of the epiglottic tilt (P = 0.001). In addition, the durations of the vertical and horizontal excursions of the hyoid, vertical excursion of the larynx and the epiglottic tilt were greater in EFS, compared with USS. Effortful swallowing was also associated with significantly greater maximum velocities of the hyoid and larynx during swallowing. In conclusion, the EFS manoeuver facilitates vertical speed and distance of hyolaryngeal excursion and epiglottic tilt and extends the duration of excursion and the epiglottic tilt, especially after reaching maximal excursion in healthy subjects. These results confirm the temporal and kinematic benefits of airway protection induced by the EFS manoeuver.

Context: There are few treatment options for managing autonomic dysreflexia in patients with chronic spinal cord injury (SCI). According to some studies, intravesical botulinum toxin for SCI patients with autonomic dysreflexia has a preventive effect on symptoms of autonomic dysreflexia. However, the usefulness of an intravesical botulinum toxin injection has never been reported for autonomic dysreflexia in an adult patient with chronic cervical SCI, although there has been for one pediatric patient. Findings: A 62-year-old man with chronic cervical SCI had neurogenic bladder due to C6-7 SCI since sustaining a fall in 1980. He presented with an intermittent headache and severe hypertension because of persistent autonomic dysreflexia. His symptoms did not improve with conservative management, and he could not undergo an operation to resect the lung cancer because of his uncontrolled blood pressure. To control his fluctuating blood pressure, he was taken to an operating room to receive an intravesical botulinum toxin injection for refractory bladder spasms. Subsequently, his blood pressure was controlled, and then the lung mass could be surgically removed. His improved condition lasted for more than 6 months. Conclusion: This case suggests that botulinum toxin is a logical treatment option for autonomic dysreflexia as well as neurogenic detrusor overactivity in patients with chronic SCI. Dedicated research is warranted to assess the efficacy of an intravesical botulinum toxin injection, as it was used successfully to stop the symptoms of autonomic dysreflexia in our patient.

The purpose of the study was to investigate the influence of the chin-tuck maneuver on the movements of swallowing-related structures in healthy subjects and formulate standard instructions for the maneuver. A total of 40 healthy volunteers (20 men and 20 women) swallowed 10 mL of diluted barium solution in a “normal and comfortable” position (NEUT), a comfortable chin-down position (DOWN), and a strict chin-tuck position (TUCK). Resting state anatomy and kinematic changes were analyzed and compared between postures. Although angles of anterior cervical flexion were comparable between DOWN (46.65 ± 9.69 degrees) and TUCK (43.27 ± 12.20), the chin-to-spine distance was significantly shorter in TUCK than in other positions. Only TUCK showed a significantly shorter anteroposterior diameter of the laryngeal inlet (TUCK vs. NEUT, 14.0 ± 4.3 vs. 16.3 ± 5.0 mm) and the oropharynx (18.8 ± 3.1 vs. 20.5 ± 2.8 mm) at rest. The maximal horizontal displacement of the hyoid bone was significantly less in TUCK (9.6 ± 3.0 mm) than in NEUT (12.6 ± 2.6 mm; p

Although coordination and timing of swallowing have often been investigated by using discrete timing events such as the onset, peak, and duration of specific motions, the sequence and duration of swallowing events cannot represent the coordination of the swallowing mechanism quantitatively. This study aimed to apply a cross-correlation analysis of the motions of the hyolaryngeal structures during swallowing as an objective method for measuring the coordination and timing of the motions. Forty healthy subjects swallowed 2 and 5 ml of diluted barium solution (35 %) and 5 ml of curd yogurt under videofluoroscopy. Hyolaryngeal motions in videofluoroscopic images were digitized using the motion analysis system. The time series of the horizontal and vertical hyoid motion, the laryngeal elevation, and the angle of the epiglottic tilt were analyzed using cross-correlation at each 1/60-s time lag. The results showed high and consistent cross-correlations between hyolaryngeal motions during swallowing in most of the subjects regardless of age and bolus type. The horizontal hyoid motion and laryngeal elevation were more strongly correlated with the epiglottic tilt than the vertical hyoid motion, which might suggest the mechanism of the epiglottic tilt during swallowing. The bolus volume and viscosity affected the correlation coefficients and time lags between the hyolaryngeal motions, particularly those related to the epiglottic tilt. The results suggest that cross-correlation analysis may be used for measuring the coordination and timing of swallowing. Further studies using cross-correlation analysis of additional physiological factors related to swallowing or pathological conditions are warranted.