Chih-Hsiu Cheng

Position accuracy and electromyographic responses during head reposition in young adults with chronic neck pain.

The head reposition test is traditionally used to examine the proprioceptive sensitivity of the neck. The aim of this study was to investigate the position accuracy and corresponding cervical electromyographic (EMG) responses of the neck pain subjects during sagittal head-to-neutral tasks. Twelve young subjects with chronic neck pain and twelve young healthy subjects were recruited. The position accuracy was measured by the constant error, variable error, and root mean square error of joint angles during head-to-neutral tasks in flexion and extension directions. Surface EMG of neck flexors and extensors were analyzed by the voluntary response index, including the similarity index (SI) and electromyographic magnitude (MAG) of muscle groups. The normalized average integration of EMG activity (NAIEMG) of individual muscle was also calculated. The results showed: (1) significantly larger constant error and root mean square error but similar variable error in patients compared with controls, (2) smaller SI but similar MAG in patients compared with controls, (3) greater synergistic/antagonistic NAIEMG in patients than controls. The findings suggested that young adults with chronic neck pain exhibit proprioceptive dysfunction and altered EMG pattern during voluntary sagittal neck motions. This study provides guidelines which could lead to the development of therapeutic exercise programs.

Effects of whole body vibration on spasticity and lower extremity function in children with cerebral palsy.

AIM The aim of this study was to evaluate the effect of whole body vibration (WBV) on lower extremity spasticity and ambulatory function in children with cerebral palsy (CP) with a complete crossover design. METHOD Sixteen participants aged 9.8(2.3) years received a 20-min WBV and a control condition in a counterbalanced order on two separate days. Change scores of each outcome variable were used to show the improvement. RESULTS Repeated-measures analyses revealed significant differences in condition scores among variables including active range-of-motion (active ROM, increased), relaxation index (RI, increased), Modified Ashworth Scale (MAS, decreased), timed up-and-go (TUG, decreased), and Six Minute Walk Test (6MWT, increased). Significant differences were also found in time change scores for MAS and 6MWT. Correlation results revealed that TUG was significantly correlated with RI (r=-.512, p=.042), and 6MWT (r=-.700, p=.003). INTERPRETATION This study suggested that WBV intervention can control the spasticity, enhance ambulatory performance and increase active ROM. Along with previous results, data from this study revealed the potential use of WBV in clinical rehabilitation in children with CP. Future investigations should focus on finding the combination of treatment frequency and duration to achieve an ideal result.

Altered Co-contraction of Cervical Muscles in Young Adults with Chronic Neck Pain during Voluntary Neck Motions.

[Purpose] Muscle co-contraction is important in stabilizing the spine. The aim of this study was to compare cervical muscle co-contraction in adults with and without chronic neck pain during voluntary movements. [Subjects and Methods] Surface electromyography of three paired cervical muscles was measured in fifteen young healthy subjects and fifteen patients with chronic neck pain. The subjects performed voluntary neck movements in the sagittal and coronal plane at slow speed. The co-contraction ratio was defined as the normalized integration of the antagonistic electromyography activities divided by that of the total muscle activities. [Results] The results showed that the co-contraction ratio of patients was greater during flexion movement, lesser during extension movement, slightly greater during right lateral bending, and slightly lesser during left lateral bending compared with in the controls. [Conclusion] The results suggested that neck pain patients exhibit greater antagonistic muscle activity during flexion and dominate-side bending movements to augment spinal stability, while neuromuscular control provides relatively less protection in the opposite movements. This study helps to specify the changes of the stiffness of the cervical spine in neck pain patients and provides a useful tool and references for clinical assessment of neck disorders.

Long-term effects of therapeutic exercise on nonspecific chronic neck pain: a literature review

[Purpose] Nonspecific neck pain is a common musculoskeletal disease. Therapeutic exercise has been shown to improve pain and disability in short-term and midterm follow-ups. This study performed a literature review of the long-term effects of therapeutic exercise on subjects with nonspecific chronic neck pain. [Subjects and Methods] The databases of the CINAHL, MEDLINE, PEDro and PubMed were used. Randomized controlled trials (RCT) published from January 2000 to January 2014 and explicitly including a one-year follow-up were identified. [Results] Only six articles were included in this review. They had scores of 5 to 8 points on the PEDro scale, and the level of evidence was grade I. The study results show that the main exercises used were cervical strengthening and endurance training exercise. Short-term exercises (10 to 12 weeks) helped to improve the body function, structure, activity and participation immediately after the intervention, but not at the long-term follow-up. On the other hand, long-term interventions (1 year) resulted in improvements in body function and structure at the 3 year follow-up. [Conclusion] The results of the six high-quality studies suggest that long-term exercise have long-term benefits for patients with nonspecific neck pain in terms of body function and structure.

Use of motor abundance in old adults in the regulation of a narrow-based stance.

AbstractPurpose The ability to maintain stable balance while standing decreases with age. The body must coordinate multiple joints using “freeze” or “free” strategy, or a combination of both to ensure balance stability. The purpose of this study was to examine age-related changes in the use of motor abundance during upright stance on a narrow base without visual input.MethodsUncontrolled manifold (UCM) analysis was used to decompose the movement variability of joints into goal-equivalent variability (GEV) and non-goal-equivalent variability (NGEV). The ratio between GEV and NGEV (UCMratio) quantifies the joint coordination related to postural stability, and a high UCMratio value indicates flexible control of joints. To perform balance tests, participants in this study (healthy young and old adults, 20 each) were asked to stand on a flat platform and on narrow wooden blocks with their eyes open and then eyes closed.ResultsIn upright balance tests, both old and young adults maintained postural stability. GEV was greater than NGEV across all participants and conditions. However, GEV was higher in the young adults than in the old adults, whereas NGEV was higher in the old adults than in the young adults. Therefore, the old adults exhibited a lower UCMratio than the young adults.ConclusionThe old adults were unable to exploit motor abundance and used a less flexible multi-joint coordination pattern to achieve stable balance. The UCMratio value reflects the quality of postural control and can be used for assessing joint coordination in balance disorders.

Altered muscle activation characteristics associated with single volitional forward stepping in middle-aged adults

BACKGROUND Middle-aged adults show a higher incidence of falls compared to young adults when performing outdoor physical activities. This study investigated whether or not the patterns and quantitative characteristics of the trunk and lower extremity muscle activations associated with stepping, which represents an important movement for arresting falls, differ between middle-aged adults and young adults. METHODS Nine healthy young adults (age=22[3] years) and nine healthy middle-aged adults (age=52[8] years), performed a single-step, volitional, fast forward stepping movement with each leg. The stepping movement was divided into the step-initiation, single-leg-support, and landing phases based on foot-switch signals. The activation sequence, occurrence rate, onset latency, burst duration, and normalized co-contraction duration of the tibialis anterior, medial gastrocnemius, rectus femoris, biceps femoris, and gluteus medius of the stance and swing legs and that of bilateral erector spinae muscles were analyzed using surface electromyography. We defined the essential muscle activation as exhibiting an occurrence rate of 90% or more in all of these trials. FINDINGS As compared to young adults, the middle-aged adults demonstrated several additional essential bursts throughout the stepping movement. Middle-aged adults also displayed significantly longer burst durations of the biceps femoris and medial gastrocnemius of the swing leg after landing, as well as longer co-contraction of the rectus femoris and biceps femoris of the stance leg in the single-leg-support phase (P<0.05). INTERPRETATION Age-related changes in step-related neuromuscular control exist in healthy middle-aged adults. We propose that training focused on improving or maintaining neuromuscular control associated with volitional leg movements may benefit middle-aged individuals.

Motor impairments screened by the Movement Assessment Battery for Children-2 are related to the visual-perceptual deficits in children with Developmental Coordination Disorder

This study was to examine to what extent the motor deficits of children with Developmental Coordination Disorder (DCD) verified by the Movement Assessment Battery for Children-2 (MABC-2) are linked to their visual-perceptual abilities. Seventeen children with DCD and seventeen typically developing children (TD) aged 5-10 years screened from a total of 250 children were recruited. The assessments included MABC-2, traditional test of visual perceptual skills (TVPS-R), and computerized test for sequential coupling of eye and hand as well as motion coherence. The results indicated that children with DCD scored lower than TD in MABC-2, and their total scores were highly correlated with manual dexterity component scores. DCD group also showed poor visual-perceptual abilities in various aspects. The visual discrimination and visual sequential memory from the TVPS-R, the sequential coupling of eye and hand, and the motion coherence demonstrated a moderate or strong correlation with the MABC-2 in the DCD rather than the TD group. It was concluded that the motor problems screened by MABC-2 were significantly related to the visual-perceptual deficits of children with DCD. MABC-2 is suggested to be a prescreening tool to identify the visual-perceptual related motor deficits.

The Effects of Disc Degeneration and Muscle Dysfunction on Cervical Spine Stability from a Biomechanical Study

Disc degeneration and muscle dysfunction are common spinal degenerations in the elderly. This in vitro study was carried out to investigate the effects of these two degenerative changes on spinal stability. The stability of nine porcine cervical spines (C2–T1) with mechanically simulated cervical muscles (sternocleidomastoid (SCM), splenius capitis (SPL), semispinalis capitis (SSC)) was tested before and after experiment-induced disc degeneration. The patterns of muscle recruitments included: no muscle recruitment, normal recruitment of SCM/SPL/SSC, and SCM/SPL/SSC muscle dysfunctions. The neutral zone (NZ) and the range of motion (ROM) in the sagittal plane were measured to determine spinal stability. The results showed that the NZ and the ROM of a degenerative spine were larger than those of an intact spine under no muscle recruitment, but not under muscle recruitments. For both intact and degenerative spines, the NZ and the ROM were greatest under no muscle recruitment, followed by SSC dysfunction, SCM dysfunction, and SPL dysfunction, and smallest under normal muscle recruitment. In conclusion, muscle recruitments stabilize both intact and degenerative cervical spines, while dysfunctional muscles do not maintain stability efficiently as normal muscles do. Thus, spinal stability is more significantly affected by muscle dysfunction than by disc degeneration. Muscle training is suggested for the elderly with spinal degeneration to improve stability.

Changes of postural control and muscle activation pattern in response to external perturbations after neck flexor fatigue in young subjects with and without chronic neck pain

PURPOSE Previous studies have identified sensorimotor disturbances and greater fatigability of neck muscles in patients with neck pain. The purpose of this study was to investigate the effect of neck pain and neck flexor fatigue on standing balance following postural perturbations. METHODS Twenty patients with chronic neck pain (CNP) (24.7±3.6 year-old) and 20 age-matched asymptomatic subjects (22.1±2.2 year-old) were recruited. Subjects stood barefoot on a force plate and experienced backward perturbations before and after neck flexor fatigue. Center of pressure, electromyography of cervical and lumbar muscles, and head/trunk accelerations were recorded. Two-way ANOVA (pain×fatigue) was used for statistical analysis. RESULTS CNP group showed larger body sway during quiet standing but not during perturbed standing compared with asymptomatic adults. In both groups, neck flexor fatigue resulted in greater body sway during the quiet standing but smaller body sway during perturbed standing, increased neck muscle activations and decreased lumbar muscle activations, as well as increased time to maximal head acceleration. CONCLUSIONS Disturbed balance control was observed in CNP patients during the quiet standing. However, a rigid strategy was used to minimize the postural sway and to protect the head against backward perturbations in both CNP and asymptomatic young adults after neck flexor fatigue. The results facilitate the understanding of how the subjects with chronic neck pain and with neck muscle fatigue deal with the challenging condition. Further studies are needed to verify if such phenomenon could be changed after the intervention of specific flexor muscle retraining and balance control exercises.

Comparison of Cervical Kinematics, Pain, and Functional Disability Between Single- and Two-level Anterior Cervical Discectomy and Fusion.

Study Design. A prospective, time series design. Objective. The purpose of this study is two-fold: firstly, to investigate the impact of altered cervical alignment and range of motion (ROM) on patients’ self-reported outcomes after anterior cervical discectomy and fusion (ACDF), and secondly, to comparatively differentiate the influence of single- and two-level ACDF on the cervical ROM and adjacent segmental kinematics up to 12-month postoperatively. Summary of Background Data. ACDF is one of the most commonly employed surgical interventions to treat degenerative disc disease. However, there are limited in vivo data on the impact of ACDF on the cervical kinematics and its association with patient-reported clinical outcomes. Methods. Sixty-two patients (36 males; 55.63 ± 11.6 yrs) undergoing either a single- or consecutive two-level ACDF were recruited. The clinical outcomes were assessed with the Pain Visual Analogue Scale (VAS) and the Neck Disability Index (NDI). Radiological results included cervical lordosis, global C2-C7 ROM, ROM of the Functional Spinal Unit (FSU), and its adjacent segments. The outcome measures were collected preoperatively and then at 3, 6, and 12-month postoperatively. Results. A significant reduction of both VAS and NDI was found for both groups from the preoperative to 3-month period (P < 0.01). Pearson correlation revealed no significant correlation between global ROM with neither VAS (P = 0.667) nor NDI (P = 0.531). A significant reduction of global ROM was identified for the two-level ACDF group at 12 months (P = 0.017) but not for the single-level group. A significant interaction effect was identified for the upper adjacent segment ROM (P = 0.024) but not at the lower adjacent segment. Conclusion. Current study utilized dynamic radiographs to comparatively evaluate the biomechanical impact of single- and two-level ACDF. The results highlighted that the two-level group demonstrated a greater reduction of global ROM coupled with an increased upper adjacent segmental compensatory motions that is independent of patient-perceived recovery. Level of Evidence: 3