Bilateral vestibulopathy and age: experimental considerations for testing dynamic visual acuity on a treadmill.

INTRODUCTION: Bilateral vestibulopathy (BVP) can affect visual acuity in dynamic conditions, like walking. This can be assessed by testing Dynamic Visual Acuity (DVA) on a treadmill at different walking speeds. Apart from BVP, age itself might influence DVA and the ability to complete the test. The objective of this study was to investigate whether DVA tested while walking, and the drop-out rate (the inability to complete all walking speeds of the test) are significantly influenced by age in BVP-patients and healthy subjects. METHODS: Forty-four BVP-patients (20 male, mean age 59 years) and 63 healthy subjects (27 male, mean age 46 years) performed the DVA test on a treadmill at 0 (static condition), 2, 4 and 6 km/h (dynamic conditions). The dynamic visual acuity loss was calculated as the difference between visual acuity in the static condition and visual acuity in each walking condition. The dependency of the drop-out rate and dynamic visual acuity loss on BVP and age was investigated at all walking speeds, as well as the dependency of dynamic visual acuity loss on speed. RESULTS: Age and BVP significantly increased the drop-out rate (p ≤ 0.038). A significantly higher dynamic visual acuity loss was found at all speeds in BVP-patients compared to healthy subjects (p < 0.001). Age showed no effect on dynamic visual acuity loss in both groups. In BVP-patients, increasing walking speeds resulted in higher dynamic visual acuity loss (p ≤ 0.036). CONCLUSION: DVA tested while walking on a treadmill, is one of the few "close to reality" functional outcome measures of vestibular function in the vertical plane. It is able to demonstrate significant loss of DVA in bilateral vestibulopathy patients. However, since bilateral vestibulopathy and age significantly increase the drop-out rate at faster walking speeds, it is recommended to use age-matched controls. Furthermore, it could be considered to use an individual "preferred" walking speed and to limit maximum walking speed in older subjects when testing DVA on a treadmill.

Clinical usefulness and challenges of instrumented motion analysis in patients with intellectual disabilities.

BACKGROUND: Clinical laboratory testing of locomotor disorders is challenging in patients with intellectual disability (ID). Nevertheless, also in this population gait analysis has substantial value as motor problems are common. To promote its use, adequate protocols need to be developed and the impact on clinical decision making needs to be documented. RESEARCH QUESTION: What is the clinical usefulness of instrumented motion analysis in patients with ID? METHOD: This narrative review consists of three parts. A literature review was performed to describe the gait pattern of patients with ID. Next, benefits and challenges of standard gait analysis protocols are described. Finally, a case of a girl with ID due to genetic cause showing gait abnormalities is discussed. RESULTS: The literature review resulted in 20 studies on "gait" in patients with an "ID", published since August, 1st 2013. Gait deviations were observed in all studies investigating the ID population with an underlying genetic syndrome. Observed gait deviations in the ID population might be attributed to physical characteristics, cognitive components or both. The main goal of clinical gait assessment is the identification of gait deviations and the evaluation of their progress over time, in order to optimize the treatment plan. The choice of adequate method and measurement modalities depends on the clinical goal, the available resources and the abilities of the patient. In the case report we presented, we succeeded in performing an instrumented 3D gait analysis in a girl with severe ID at the ages of 4y4m, 6y0m, 7y2m and 8y2m. Progressive gait deviations were found suggesting a crouch gait pattern was developing. Results of the gait analysis led to the prescription of rigid ankle-foot orthoses. SIGNIFICANCE: Gait analysis has substantial value for patients with ID. Gait analysis allows clinicians to objectify the relationship between physical characteristics and gait features.

Postural control and the relation with cervical sensorimotor control in patients with idiopathic adult-onset cervical dystonia.

Cervical dystonia (CD) is a movement disorder characterized by involuntary muscle contractions leading to an abnormal head posture or movements of the neck. Dysfunctions in somatosensory integration are present and previous data showed enlarged postural sway in stance. Postural control during quiet sitting and the correlation with cervical sensorimotor control were investigated. Postural control during quiet sitting was measured via body sway parameters in 23 patients with CD, regularly receiving botulinum toxin treatment and compared with 36 healthy controls. Amplitude and velocity of displacements of the center of pressure (CoP) were measured by two embedded force plates at 1000 Hz. Three samples of 30 s were recorded with the eyes open and closed. Disease-specific characteristics were obtained in all patients by the Tsui scale, Cervical Dystonia Impact Profile (CDIP-58) and Toronto Western Spasmodic Rating Scale (TWSTRS). Cervical sensorimotor control was assessed with an infrared Vicon system during a head repositioning task. Body sway amplitude and velocity were increased in patients with CD compared to healthy controls. CoP displacements were doubled in patients without head tremor and tripled in patients with a dystonic head tremor. Impairments in cervical sensorimotor control were correlated with larger CoP displacements (rs ranged from 0.608 to 0.748). Postural control is impaired and correlates with dysfunction in cervical sensorimotor control in patients with CD. Treatment is currently focused on the cervical area. Further research towards the potential value of postural control exercises is recommended.

Prognostic indicators for decrease in tinnitus severity after cervical physical therapy in patients with cervicogenic somatic tinnitus.

BACKGROUND: Tinnitus can be related to many different aetiologies such as hearing loss or a noise trauma, but it can also be related to the somatosensory system of the cervical spine, called cervicogenic somatic tinnitus(CST). Recently, a positive effect of multi-modal cervical physical therapy on tinnitus severity in patients with CST was demonstrated. To date however, the outcome of the intervention cannot be predicted. OBJECTIVE: To identify prognostic indicators for decrease in tinnitus severity after cervical physical therapy in patients with CST. PATIENTS: Patients with moderate to severe subjective tinnitus (Tinnitus Functional Index(TFI):25-90points) and neck complaints (Neck Bournemouth Questionnaire(NBQ) > 14points). INTERVENTION: All patients received multimodal cervical physical therapy for 6 weeks (12 sessions). This physical therapy contained a combination of manual mobilizations and exercises of the cervical spine. MEASUREMENTS: TFI and NBQ-scores were documented at baseline, after treatment and after a 6-weeks follow-up period. Impairments in cervical spine mobility and muscle function were identified at baseline and after 6-weeks follow-up. RESULTS: Patients with co-varying (increasing or decreasing simultaneously) tinnitus and neck complaints had significantly lower TFI-scores after treatment (p = 0.001) and follow-up (p = 0.03). The presence of this co-variation and a combination of low pitched tinnitus and increasing tinnitus during inadequate cervical spine postures are prognostic indicators for a decrease in TFI-scores after cervical physical therapy (adjusted R2 = 0.357). CONCLUSION: Patients who experience a decrease in tinnitus annoyance from cervical physical therapy are those with co-varying tinnitus and neck complaints and those with a combination of low-pitched tinnitus and increasing tinnitus during inadequate cervical spine postures.

Does multi-modal cervical physical therapy improve tinnitus in patients with cervicogenic somatic tinnitus?

BACKGROUND: Tinnitus can be related to many different aetiologies such as hearing loss or a noise trauma, but it can also be related to the somatosensory system of the cervical spine, called cervicogenic somatic tinnitus (CST). Case studies suggest a positive effect of cervical spine treatment on tinnitus complaints in patients with CST, but no experimental studies are available. OBJECTIVE: To investigate the effect of a multimodal cervical physical therapy treatment on tinnitus complaints in patients with CST. DESIGN: Randomized controlled trial. PATIENTS: Patients with a combination of severe subjective tinnitus (Tinnitus Functional Index (TFI): 25-90 points) and neck complaints (Neck Bournemouth Questionnaire (NBQ) > 14 points). INTERVENTION: All patients received cervical physical therapy for 6 weeks (12 sessions). Patients were randomized in an immediate-start therapy group (n = 19) and a 6-week delayed-start therapy group (n = 19). MEASUREMENTS: TFI and NBQ-scores were documented at baseline, after the wait-and-see period in the delayed-start group, after treatment and after 6 weeks follow-up. The Global Perceived Effect (GPE) was documented at all measuring moments, except at baseline. RESULTS: In all patients (n = 38) TFI and NBQ-scores decreased significantly after treatment (p = 0.04 and p < 0.001). NBQ-scores remained significantly lower after follow-up (p = 0.001). Immediately after treatment, 53% (n = 38) experienced substantial improvement of tinnitus. This effect was maintained in 24% of patients after follow-up at six weeks. CONCLUSION: Cervical physical therapy can have a positive effect on subjective tinnitus complaints in patients with a combination of tinnitus and neck complaints. Larger studies, using more responsive outcome measures, are however necessary to prove this effect. TRIAL REGISTRATION: NCT02016313.

Increased mechanical cost of walking in children with diplegia: the role of the passenger unit cannot be neglected.

Gait efficiency in children with cerebral palsy is decreased. To date, most research did not include the upper body as a separate functional unit when exploring these changes in gait efficiency. Since children with spastic diplegia often experience problems with trunk control, they could benefit from separate evaluation of the so-called 'passenger unit'. Therefore, the aim of the current study was to improve insights in the role of the passenger unit in decreased gait efficiency in children with diplegia. Mechanical cost of walking was investigated by calculating work by the integrated joint power approach in 18 children with diplegia and 25 age-related typical developing controls. The total mechanical work in children with diplegia was 1.5 times higher than in typical children. In children with diplegia work at the lower limbs was increased by 37% compared to typical children. Substantially higher increases, up to 222%, were noted at the passenger unit. Trunk and head were the main contributors to the increased work of the passenger unit, but the role of the arms cannot be neglected. Due to these disproportional increases in locomotor and passenger unit, the demands of the passenger unit in pathological gait can no longer be considered minor, as in typical gait. Therefore, the role of the passenger unit must be recognized in the decrease of gait efficiency in children with spastic diplegia and should be part of the evaluation of gait efficiency in clinical practice.

Mechanical energy estimation during walking: validity and sensitivity in typical gait and in children with cerebral palsy.

Gait efficiency in children with cerebral palsy is usually quantified by metabolic energy expenditure. Mechanical energy estimations, however, can be a valuable supplement as they can be assessed during gait analysis and plotted over the gait cycle, thus revealing information on timing and sources of increases in energy expenditure. Unfortunately, little information on validity and sensitivity exists. Three mechanical estimation approaches: (1) centre of mass (CoM) approach, (2) sum of segmental energies (SSE) approach and (3) integrated joint power approach, were validated against oxygen consumption and each other. Sensitivity was assessed in typical gait and in children with diplegia. CoM approach underestimated total energy expenditure and showed poor sensitivity. SSE approach overestimated energy expenditure and showed acceptable sensitivity. Validity and sensitivity were best in the integrated joint power approach. This method is therefore preferred for mechanical energy estimation in children with diplegia. However, mechanical energy should supplement, not replace metabolic energy, as total energy expended is not captured in any mechanical approach.

A cross-sectional study about the relationship between morphology and kinematic parameters in children between 15 and 36 months.

Morphology and kinematic parameters were recorded for 31 children between 15 and 36 months to investigate the relation between morphology and the walking pattern. A full 3D gait analysis using a VICON motion system was performed to gather kinematic data. Next, the differences in kinematic parameters between four morphological classes were assigned with a multiple analysis of variance, with a correction for walking experience. Also stepwise linear regressions were performed, to examine the relation between detailed morphological measurements and kinematic parameters. The regression models showed relationships between kinematic parameters of the ankle, hip, thorax and morphology. All results indicated that the upper body played an important role in the coordination of the walking pattern, especially in the frontal plane.

A cross-sectional study about the relationship between morphology and step-time parameters in children between 15 and 36 months.

Morphology and step-time parameters were recorded in 100 children between 15 and 36 months to investigate the relation between morphology and the walking pattern. A footfall method was used to register step-time parameters. Next, the differences in step-time parameters between four morphological classes were assigned with a multiple analysis of variance. We also performed stepwise linear regressions with a correction for walking experience, to examine the relation between detailed morphological measurements and step-time parameters. The results of these regressions show a significant relation between pelvis span/ankle spread ratio and the relative radii of gyration in the frontal plane of head and pelvis. It is hypothesized that the morphology of the head and pelvis plays a role in the coordination of the walking pattern.

Age-related changes in mechanical and metabolic energy during typical gait.

The purpose of the study was to investigate and report age-related changes in walking energy expenditure using different methods of energy estimation. For 81 children and 16 adults (3-35 years) energy expenditure was investigated by using the following methods: analysis of energy changes of the centre of body mass (external and internal mechanical work), sum of segmental energies, sum of net joint work and gross and net metabolic cost, as well as net non-dimensional oxygen cost. Different methods of energy estimation not only show different outcome results but also different age-related changes. Significant changes were found for negative net joint work, external mechanical work and recovery as well as sum of segmental energies, until 9, 11 and 19 years respectively. Positive net joint work showed no differences between age groups and the differences for internal work did not suggest development. Metabolic energy showed significant changes until adult age. Gross cost decreases with increasing age in children and, although more gradually, still in adolescents. Net and net non-dimensional cost shows a more constant decrease with increasing age until adulthood. Therefore, the choice of estimation method and the use of age-related reference data when evaluating young patients should be carefully considered. For interpretation of oxygen consumption in children the use of net is superior to gross cost, but even after net non-dimensional normalization, age-related reference data should be used.

Growth of segment parameters and a morphological classification for children between 15 and 36 months.

This study is part of a research program that aims at a better understanding of the influence of individual morphological differences and physical growth on development of independent walking in toddlers. As morphometric and segment inertial parameters for toddlers aged between 15 and 36 months are indispensable for the mechanical analyses inherent to this purpose, parameter data were collected. The provided dataset of morphological and segment inertial parameters is a valuable tool for locomotor biomechanical modelling. Analysis of the parameter data showed that there are substantial changes of most segment inertial parameters across body length and body mass. In addition, a classification system was developed to categorize toddlers on the basis of morphometry, reflecting the segment inertial constitution of the child. A principal components analysis (PCA) was applied to define the variance in physique between the children. PCA resulted in three newly composed variables: the 'Axis of chubbiness', the 'Axis of allometric growth' and the 'Axis of relative limb length'. The three axes are plotted against each other, resulting in eight morphological classes. With this classification the morphotype of toddlers between 15 and 36 months can be specified and used for further research on their walking patterns.