Name: computerized dynamic posturography for postural control assessment in patients with intermittent claudication
Uploaded: 2013-12-11T14:15:00.000+00:00
Duration: 14 min 52 s
Description: Watch this Scientific Journal Video about Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication at JoVE.com

There are no acknowledgements for this study.

Participants were outpatients of a vascular surgical unit at a local teaching hospital and gave informed consent to participate in this study. The study was approved by the NHS Local Research Ethics Committee (REC reference: 07/Q1105/12) and the protocol complied with the IRB guidelines of the University of Hull. All participants completed the Sensory Organization Test and Motor Control Test on the EquiTest. Ankle brachial pressure index was measured preexercise to categorize disease severity.
1. Ankle Brachial Pressure Index (ABPI) Measurement
<ol>
	<li>Allow the participant to rest in the supine position for at least 5 min before the ABPI measurement is taken.</li>
	<li>Adjust a standard sphygmomanometer cuff over the brachial artery above the elbow and the dorsalis pedis and posterior tibial arteries above the ankle. Rapidly inflate the cuffs to 20 mmHg above the audible systolic pressure before deflating at a constant rate of 2 mm/sec.</li>
	<li>Record the systolic pressure as the pressure at which the first sustained systolic pressure is audible. Then using a hand-held Doppler probe (5-8 MHz), measure the systolic pressures of the dorsalis pedis and posterior tibial arteries.</li>
	<li>Calculate ABPI with ankle systolic pressure as the numerator, over the brachial systolic pressure as the denominator.</li>
</ol>
Note: There are several methods currently used to determine the numerator value of the ABPI. The American Heart Association advocates using the higher systolic pressure of the two leg arteries for the numerator12 which is what we used, while another method reported in the literature states using the lower systolic pressure13. A third method recommends using the average systolic pressure from the dorsalis pedis and posterior tibial arteries13.
2. Equipment Setup
<ol>
	<li>Ensure the area surrounding the EquiTest is free of obstructions and remove any object from the dual force plates and turn on the EquiTest system. Complete the dual force plate support surface and visual surround calibration. 
	Note: Movement of the force plates occurs along an x- and y-axis. The dual force plates first translate forwards and backwards about the y-axis, which is parallel to the floor, at a maximum linear velocity of 15.24 cm/sec. They then rotate about the x-axis, so as to facilitate ankle dorsiflexion (toes up) and plantarflexion (toes down), at a maximum angular velocity of 50°/sec (0.87 rad/sec). The visual surround tilts forwards and backward about the x-axis at a maximum angular velocity of 15°/sec (0.26 rad/sec) across a range of ±10°. Four force transducers in two independent force plates measure vertical forces for each limb; a fifth transducer, beneath the pin joint that connects the two force plates, measures shear force overall.</li>
	<li>Enter the participant information (e.g. age and height) into the software program. Indicate their age and height accurately. 
	Note: The participant's results will be compared against an age-matched normative dataset (20-59, 60-69, 70-79 years). Height will allow for the magnitude (small, medium, and large) of the backwards and forwards force plate translations to be scaled according to their height.</li>
	<li>Choose whether to turn the display screen within the visual surround on or off. 
	Note: If the display screen is turned on, the participant will get real-time visual biofeedback about their COG movement, which may be useful for practice sessions or when the operator wants the participant to see their score. The results from each trial are processed upon completion of the trial and displayed as green or red bars. Green bars indicate the participant performed better than the age-matched normative data, while red bars indicate their performance was worse.</li>
</ol>
3. Participant Preparation
<ol>
	<li>Request that the participant wears comfortable loose clothing and removes their shoes for tests on the EquiTest. Have the participant put on the safety harness, while securing the long straps through their legs and fastening the waist buckle.</li>
	<li>Position the participant onto the dual force plates and clip the karabiner from the safety straps into the D-rings of the security harness. 
	Note: The participant is now securely fixed to the safety bar (via the safety straps) which will prevent them from actually falling, should they lose their balance (or feel like they are going to lose their balance) during the testing.</li>
	<li>Center the participant's feet on the support surface: position the medial malleolus of each foot over the blue horizontal line, so that the ankle joint is aligned with the transverse rotational axis, and position the lateral side of the calcaneous according to the S, M, or T surface markings. Adjust the tension on the safety straps so they are neither too slack nor too taught. 
	Note: According to the participant's height, small ranges from 76-140 cm, medium from 141-165 cm, and tall from 166-203 cm (Figure 1A). Backwards and forwards movements of the support surface (dual force plates) occur along the y-axis, while side to side movements on the support surface occur along the x-axis. The dual force plates can rotate about the x-axis, which represents the transverse axis of the ankle joint. When the participant is standing with ankles over the blue horizontal line and with feet equidistant laterally from the center line (y-axis) according to the S, M, or T markings, their center of gravity should be located directly above the x- and y-axis intercept. This position acts as a reference point for the calculation of sway angles</li>
	<li>Ask the participant to stand upright, with their hands at their sides, looking straight ahead at the visual surround. Request they refrain from moving their feet for the duration of the test (Figure 1B). 
	Note: If the feet are correctly positioned, the center of gravity (COG) display should illustrate the stick figure at the intersection of the x- and y-axis. However, if the stick figure is misaligned and the feet are correctly positioned (according to the instructions above), do not readjust the feet.</li>
</ol>
4. Sensory Organization Test (SOT)
<ol>
	<li>Complete Conditions 1-6 on the SOT protocol. 
	Note: The SOT consists of 6 conditions, each comprised of 3 trials lasting 20 sec each. In Conditions 1 and 2, the participant stands quietly with eyes open and closed, respectively. This establishes whether sway increases when visual cues are removed and determines how effectively the participant makes use of somatosensory input. In Condition 3, the participant stands with their eyes open; the visual surround is sway-referenced and visual cues become inaccurate. In Condition 4, the support surface is sway-referenced; thus somatosensory cues become inaccurate. Condition 5 is performed with eyes closed and a sway-referenced support surface. This determines how the participant makes use of vestibular cues when visual cues are removed and somatosensory cues are inaccurate. Finally, in Condition 6, the visual surround and support surface are both sway-referenced, which identifies if the participant relies on visual cues even when they are inaccurate. The SOT conditions are graded in difficulty. The first 3 conditions are performed on a static support surface, while the last 3 conditions use a dynamic support surface.</li>
	<li>Evaluate the score after each trial (a green or a red bar will appear displaying the participant's Equilibrium score relative to the age-matched normative dataset). Interrupt any trial at any time if the participant looks like they require assistance.</li>
	<li>Mark any trial where the participant takes a step, touches the visual surround or starts to fall as a loss of balance (LOB). Allow the participant to rest in between trials if necessary and accurately reposition feet afterwards.</li>
</ol>
Allow the software to compute the results for the following variables of interest: Equilibrium score - an overall indicator of balance; Strategy analysis - an indicator of ankle vs. hip strategy dominance; Sensory analysis - an indicator of which sensory system is used to maintain balance (i.e. somatosensory, visual, vestibular or visual preference); and initial COG alignment prior to onset of each trial. Equilibrium score is computed according to Equation 1, where 12.5° represents the maximum normal postural sway in the anterior-posterior direction; θ represents the participant's s calculated maximum anterior-posterior COG displacements14. A score of 100 represents perfect stability; a score of 0 indicates a loss of balance.
<img alt="Percentage uncertainty formula; equation for calculating angle measurement error." src="/files/ftp_upload/51077/51077eq1.jpg" data-altupdatedat="1747911167000" data-alt=" Equation 1"> 
Strategy score represents the peak-to-peak amplitude of the shear oscillation relative to the maximum possible shear force of 25 lbs (11.4 kg), where 25 lbs is the difference between maximum and minimum shear force generated by individuals who only used the hip strategy to maintain balance on a narrow beam (Nashner, unpublished data; cited in EquiTest System Operator's Manual)14. A score near 100 indicates a full ankle strategy; a score near 0 indicates a full hip strategy with maximum shear force. The Sensory analysis computes four sensory ratios by using the average Equilibrium scores from specific pairs of sensory test conditions. These are:
<img alt="Somatosensory and visual equations; diagram shows equations for sensory condition analysis." src="/files/ftp_upload/51077/51077eq2-5.jpg" data-altupdatedat="1747911167000" data-alt=" Equation 2-5"> 
Initial COG alignment is determined as the average anterior-posterior COG position in the preceding half second before each SOT trial.
5. Motor Control Test (MCT)
<ol>
	<li>Complete all 6 conditions on the MCT, including 3 forwards and 3 backwards translations that are graded in magnitude (small, medium, and large). 
	Note: Small translations represent a threshold stimulus, while large translations require the participant to produce a maximal response. Medium translations are in between the two ends of the spectrum. Each condition is performed 3x, with a random delay of 1.5-2.5 sec in between. The horizontal displacement of the support surface during each translation is scaled according to the participant's height.</li>
	<li>Ensure the feet are positioned precisely on the support surface according to the above instructions. Perform the trials in the standardized order (first backwards, then forwards translations). Interrupt any trial if necessary and record a loss of balance as above. 
	Note: The full MCT takes approximately 5-10 min to complete without rests. Allow the software to compute the results for the following variables of interest: Weight symmetry - weight bearing distribution in the left vs. right limbs prior to the onset of a translation as measured by the force transducers; Latency - time lapse (in milliseconds) between the onset of support surface translation and the participant's active force response, measured for each limb independently; and Amplitude scaling (or Relative response strength) - strength of the participant's active force response to arrest the angular momentum imparted to the body during the backwards and forwards translations. The response strength is measured for each leg independently in units of angular momentum (degrees/second) and normalized to body height and weight.</li>
</ol>
6. Participant Debriefing
<ol>
	<li>Assist the participant down from the platform following the completion of the SOT and MCT. Discuss the implications of their findings by explaining how they performed overall on the SOT and MCT.</li>
	<li>If appropriate, discuss or refer the participant to a balance training program with qualified supervision if they scored poorly on any of the tests. Recommend further medical investigations if the participant scored poorly on any of the sensory scores.</li>
</ol>

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The authors declare that they have no competing financial interests. The authors have no real or perceived conflicts of interest involved with the publication of this manuscript.

The assessment of postural control is important in individuals who have a higher susceptibility to falls, often because of ageing or disease. Computerized dynamic posturography is a unique technique in that the sensory systems responsible for balance can be challenged through separate protocols that systematically differentiate between impairments4. The Sensory Organization Test (SOT) can identify when a person makes poor use of somatosensory, visual, or vestibular cues or relies on visual input even when it i...

Computerized dynamic posturography (CDP) is an assessment technique to measure postural control objectively. It isolates and quantifies the functional contributions of different sensory systems (i.e.&#160;somatosensory, visual and vestibular input) and the mechanisms for integrating these sensory input for maintaining balance. It is a valuable tool for investigating sensory, motor and central adaptive impairments1. Computerized dynamic posturography detects postural sway by measuring shifts in the center of gravity (COG) as a person moves within their limits of stability. It can quantify postural strategies to static and dynamic perturbations, by determining whether an individual uses an ankle or hip strategy during the CDP protocols, or a combination of the two, in response to postural disturbances.
Balance assessments are routine in clinical and rehabilitation settings. They provide an indication of a person&#39;s ability to control their balance under different conditions, such as reduced base of support (e.g.&#160;tandem or unilateral stance) or without visual input (e.g.&#160;eyes closed). Thus they are often used to determine an individual&#39;s susceptibility towards falling. Several validated and reliable balance tests, such as the Berg Balance Scale2 and the Tinetti Gait and Balance test3, are commonly used clinically to evaluate an individual&#39;s ability to maintain balance during functional tasks. While&#160;the tests were designed primarily for use with older people, they are also subjective, and liable to ceiling effects, especially among community-dwelling elderly with high levels of functioning. Computerized dynamic posturography with the EquiTest provides an objective assessment of postural control and thus requires the use of more complex equipment than routine clinical tests. However, it is also more costly and not portable. Thus, it is intended to complement, not replace, existing clinical measures that categorize the mechanisms of balance disorders.
Intermittent claudication, a frequently reported symptom of peripheral arterial disease, is characterized by a cramping pain developed in the lower extremities during physical activity and relieved with rest. Claudicants have impaired balance and gait; they exhibit functional limitations and are susceptible to falling. Ankle brachial pressure index (ABPI) is a simple, noninvasive method for detecting the presence of peripheral arterial disease with intermittent claudication concomitant with impaired lower limb function. The disease is commonly treated noninvasively with lifestyle and exercise programs4. The early detection of postural impairments is beneficial for the effective prevention of falls1. Whilst measuring the ABPI is not necessary for patients without symptoms of peripheral arterial disease with intermittent claudication, or for patients with other balance-related dysfunction, it is important as part of a complete medical examination in patients where peripheral arterial disease is suspected and movement and balance are affected adversely.
Computerized dynamic posturography, with protocols such as the Sensory Organization Test and Motor Control Test on the EquiTest, has been used in studies investigating balance in healthy older adults5, to differentiate between elderly fallers and nonfallers6, in individuals with balance disorders7 and even with transtibial amputee populations8,9. Computerized dynamic posturography has been assessed previously with a claudicant population, and results have indicated that 52% of claudicants exhibit vestibular dysfunction10 and perform significantly worse with increasing claudication severity11. Thus this objective balance measurement technique is deemed sensitive enough to differentiate postural control strategies in patients according to disease severity. This paper will focus on the use of computerized dynamic posturography in the assessment of balance in patients diagnosed with intermittent claudication caused by peripheral arterial disease.

<table><tbody><tr><td>NeuroCom EquiTest</td><td>NeuroCom, a division of Natus Medical Incorporated, San Carlos, CA, USA</td><td></td><td></td></tr><tr><td>Handheld Doppler Ultrasound</td><td>Huntleigh Technology Plc, Cardiff, UK</td><td></td><td></td></tr><tr><td>Sphygmomanometer (blood pressure) cuff</td><td></td><td></td><td></td></tr></tbody></table>

computerized dynamic posturography for postural control assessment in patients with intermittent claudication

Computerized dynamic posturography with the EquiTest is an objective technique for measuring postural strategies under challenging static and dynamic conditions. As part of a diagnostic assessment, the early detection of postural deficits is important so that appropriate and targeted interventions can be prescribed. The Sensory Organization Test (SOT) on the EquiTest determines an individual&#39;s use of the sensory systems (somatosensory, visual, and vestibular) that are responsible for postural control. Somatosensory and visual input are altered by the calibrated sway-referenced support surface and visual surround, which move in the anterior-posterior direction in response to the individual&#39;s postural sway. This creates a conflicting sensory experience. The Motor Control Test (MCT) challenges postural control by creating unexpected postural disturbances in the form of backwards and forwards translations. The translations are graded in magnitude and the time to recover from the perturbation is computed.
Intermittent claudication, the most common symptom of peripheral arterial disease, is characterized by a cramping pain in the lower limbs and caused by muscle ischemia secondary to reduced blood flow to working muscles during physical exertion. Claudicants often display poor balance, making them susceptible to falls and activity avoidance. The Ankle Brachial Pressure Index (ABPI) is a noninvasive method for indicating the presence of peripheral arterial disease and intermittent claudication, a common symptom in the lower extremities. ABPI is measured as the highest systolic pressure from either the dorsalis pedis or posterior tibial artery divided by the highest brachial artery systolic pressure from either arm. This paper will focus on the use of computerized dynamic posturography in the assessment of balance in claudicants.

Ankle Brachial Pressure Index (ABPI)
An individual's ABPI can be used to classify the presence of peripheral arterial disease. An ABPI of 1.0-1.2 falls within a normal range. Values from 0.9-1.0 are acceptable, but 0.4-0.9 is indicative of mild to moderate peripheral arterial disease severity. ABPI of &lt;0.4 confirms severe peripheral arterial disease15. An ABPI of &lt;0.9 is 95% sensitive and 99% specific for peripheral arterial disease16 and is associated with leg functio...

Watch this Scientific Journal Video about Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication at JoVE.com

Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication

Individuals with intermittent claudication exhibit poor balance compared to healthy controls. Computerized dynamic posturography is an objective method for measuring an individual's postural responses to balance disturbances. This provides an objective reflection of the person&#x2019;s ability to respond to situations under which sensory stimuli are altered and unexpected perturbations occur.

Computerized dynamic posturography with the EquiTest is an objective technique for measuring postural strategies under challenging static and dynamic ...

computerized-dynamic-posturography-for-postural-control-assessment

Research

JoVE Journal

Medicine

11.4K 次观看.  University of Sydney. Individuals with intermittent claudication exhibit poor balance compared to healthy controls. Computerized dynamic posturography is an objective method for measuring an individual's postural responses to balance disturbances. This provides an objective reflection of the person’s ability to respond to situations under which sensory stimuli are altered and unexpected perturbations occur.

视频: Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication

Sit-to-stand-and-walk from 120% Knee Height: A Novel Approach to Assess Dynamic Postural Control Independent of Lead-limb

Individuals with sensorimotor pathology e.g., stroke have difficulty executing the common task of rising from sitting and initiating gait (sit-to-walk: STW). Thus, in clinical rehabilitation separation of sit-to-stand and gait initiation - termed sit-to-stand-and-walk (STSW) - is usual. However, a standardized STSW protocol with a clearly defined analytical approach suitable for pathological assessment has yet to be defined.
Hence, a goal-orientated protocol is defined that is suitable for healthy and compromised individuals by requiring the rising phase to be initiated from 120% knee height with a wide base of support independent of lead limb. Optical capture of three-dimensional (3D) segmental movement trajectories, and force platforms to yield two-dimensional (2D) center-of-pressure (COP) trajectories permit tracking of the horizontal distance between COP and whole-body-center-of-mass (BCOM), the decrease of which increases positional stability but is proposed to represent poor dynamic postural control.
BCOM-COP distance is expressed with and without normalization to subjects&#39; leg length. Whilst COP-BCOM distances vary through STSW, normalized data at the key movement events of seat-off and initial toe-off (TO1) during steps 1 and 2 have low intra and inter subject variability in 5 repeated trials performed by 10 young healthy individuals. Thus, comparing COP-BCOM distance at key events during performance of an STSW paradigm between patients with upper motor neuron injury, or other compromised patient groups, and normative data in young healthy individuals is a novel methodology for evaluation of dynamic postural stability.

Here, we present a novel protocol to measure positional stability at key events during the sit-to-stand-to-walk using the center-of-pressure to the whole-body-center-of-mass distance. This was derived from the force platform and three-dimensional motion-capture technology. The paradigm is reliable and can be utilized for the assessment of neurologically compromised individuals.

坐姿到站姿和步行距离120％膝盖高度:新方法来评估铅肢体的动态姿势控制独立

Individuals with sensorimotor pathology e.g., stroke have difficulty executing the common task of rising from sitting and initiating gait (sit-to-walk: ...

科研

行为学

Tilt Testing with Combined Lower Body Negative Pressure: a "Gold Standard" for Measuring Orthostatic Tolerance

Orthostatic tolerance (OT) refers to the ability to maintain cardiovascular stability when upright, against the hydrostatic effects of gravity, and hence to maintain cerebral perfusion and prevent syncope (fainting). Various techniques are available to assess OT and the effects of gravitational stress upon the circulation, typically by reproducing a presyncopal event (near-fainting episode) in a controlled laboratory environment. The time and/or degree of stress required to provoke this response provides the measure of OT. Any technique used to determine OT should: enable distinction between patients with orthostatic intolerance (of various causes) and asymptomatic control subjects; be highly reproducible, enabling evaluation of therapeutic interventions; avoid invasive procedures, which are known to impair OT1.
In the late 1980s head-upright tilt testing was first utilized for diagnosing syncope2. Since then it has been used to assess OT in patients with syncope of unknown cause, as well as in healthy subjects to study postural cardiovascular reflexes2-6. Tilting protocols comprise three categories: passive tilt; passive tilt accompanied by pharmacological provocation; and passive tilt with combined lower body negative pressure (LBNP). However, the effects of tilt testing (and other orthostatic stress testing modalities) are often poorly reproducible, with low sensitivity and specificity to diagnose orthostatic intolerance7.
Typically, a passive tilt includes 20-60 min of orthostatic stress continued until the onset of presyncope in patients2-6. However, the main drawback of this procedure is its inability to invoke presyncope in all individuals undergoing the test, and corresponding low sensitivity8,9. Thus, different methods were explored to increase the orthostatic stress and improve sensitivity.
Pharmacological provocation has been used to increase the orthostatic challenge, for example using isoprenaline4,7,10,11 or sublingual nitrate12,13. However, the main drawback of these approaches are increases in sensitivity at the cost of unacceptable decreases in specificity10,14, with a high positive response rate immediately after administration15. Furthermore, invasive procedures associated with some pharmacological provocations greatly increase the false positive rate1.
Another approach is to combine passive tilt testing with LBNP, providing a stronger orthostatic stress without invasive procedures or drug side-effects, using the technique pioneered by Professor Roger Hainsworth in the 1990s16-18. This approach provokes presyncope in almost all subjects (allowing for symptom recognition in patients with syncope), while discriminating between patients with syncope and healthy controls, with a specificity of 92%, sensitivity of 85%, and repeatability of 1.1&plusmn;0.6 min16,17. This allows not only diagnosis and pathophysiological assessment19-22, but also the evaluation of treatments for orthostatic intolerance due to its high repeatability23-30. For these reasons, we argue this should be the "gold standard" for orthostatic stress testing, and accordingly this will be the method described in this paper.

We describe a "gold standard" for evaluating orthostatic tolerance (OT) using tilt testing with combined lower body negative pressure (LBNP). This can be combined with non-invasive evaluations of cardiovascular reflex control. Normal and abnormal responses are defined.

倾斜试验结合下体负压测量立位耐力的“金标准”

Orthostatic tolerance (OT)  refers to the ability to maintain cardiovascular stability when upright,  against the hydrostatic effects of gravity, and ...

医学

A Vibrotactile Feedback Device for Seated Balance Assessment and Training

Postural perturbations, motion tracking, and sensory feedback are modern techniques used to challenge, assess, and train upright sitting, respectively. The goal of the developed protocol is to construct and operate a sitting platform that can be passively destabilized while an inertial measurement unit quantifies its motion and vibrating elements deliver tactile feedback to the user. Interchangeable seat attachments alter the stability level of the device to safely challenge sitting balance. A built-in microcontroller allows fine-tuning of the feedback parameters to augment sensory function. Posturographic measures, typical of balance assessment protocols, summarize the motion signals acquired during timed balance trials. No dynamic sitting protocol to date provides variable challenge, quantification, and sensory feedback free of laboratory constraints. Our results demonstrate that non-disabled users of the device exhibit significant changes in posturographic measures when balance difficulty is altered or vibrational feedback provided. The portable, versatile device has potential applications in rehabilitation (following skeletal, muscular, or neurological injury), training (for sports or spatial awareness), entertainment (via virtual or augmented reality), and research (of sitting-related disorders).

A sitting platform has been developed and assembled that passively destabilizes sitting posture in humans. During the user&#39;s stabilizing task, an inertial measurement unit records the device&#39;s motion, and vibrating elements deliver performance-based feedback to the seat. The portable, versatile device may be used in rehabilitation, assessment, and training paradigms.

一种用于座位平衡评估和训练的振动反馈装置

Postural perturbations, motion tracking, and sensory feedback are modern techniques used to challenge, assess, and train upright sitting, respectively. ...

An Instrumented Pull Test to Characterize Postural Responses

Impairment of postural reflexes, termed postural instability, is a common and disabling deficit in Parkinson's disease. To assess postural reflexes, clinicians typically employ the pull test to grade corrective responses to a backward perturbation at the shoulders. However, the pull test is prone to issues with reliability and scaling (score/4). Here, we present an instrumented version of the pull test to more precisely quantify postural responses. Akin to the clinical test, pulls are manually administered except pull force is also recorded. Displacements of the trunk and feet are captured by a semi-portable motion tracking system. Raw data represent distance traveled (in millimeter units), making subsequent interpretation and analysis intuitive. The instrumented pull test also detects variabilities influencing pull test administration, such as pull force, thereby identifying and quantifying potential confounds that can be accounted for by statistical techniques. The instrumented pull test could have application in studies seeking to capture early abnormalities in postural responses, track postural instability over time, and detect responses to therapy.

Impairment of postural reflexes, termed postural instability, is difficult to quantify. Clinical assessments such as the pull test suffer issues with reliability and scaling. Here, we present an instrumented version of the pull test to objectively characterize postural responses.

一种表征姿势反应的仪器拉力测试

Impairment of postural reflexes, termed postural instability, is a common and disabling deficit in Parkinson's disease. To assess postural reflexes, ...

Quantitative Static and Dynamic Assessment of Balance Control in Stroke Patients

In patients with stroke, damage to the central nervous system (CNS) can affect the postural stability and increase the risk of falling. Therefore, accurately assessing the balance is important to understand the type, extent, and causes of balance deficit, and to identify individualized interventions. Clinical assessment methods for balance function can be broadly divided into observation, scale assessment, and balance instrument testing. Here, a clinical protocol is presented for static and dynamic balance assessment in stroke patients, which includes three semiquantitative balance function scale assessments (i.e., Berg Balance Scale, Timed Up and Go Test, and Fugl-Meyer Assessment) and three quantitative instrumental balance evaluation (i.e., Stability Assessment Module, Proprioceptive Assessment Module, and Limit of Stability Module). It is recommended that clinicians consider the use of both classic clinical balance scales and instrumental balance measurements when assessing stroke patients to improve the accuracy of assessments, leading to a better individualized treatment plan.

Presented here is a quantitative, clinical balance assessment method suitable for stroke patients with balance disorders.

In patients with stroke, damage to the central nervous system (CNS) can affect the postural stability and increase the risk of falling. Therefore, ...

Standing Neurophysiological Assessment of Lower Extremity Muscles Post-Stroke

Transcranial magnetic stimulation (TMS) is a common tool used to measure the behavior of motor circuits in healthy and neurologically impaired populations. TMS is used extensively to study motor control and the response to neurorehabilitation of the upper extremities. However, TMS has been less utilized in the study of lower extremity postural and walking-specific motor control. The limited use and the additional methodological challenges of lower extremity TMS assessments have contributed to the lack of consistency in lower extremity TMS procedures within the literature. Inspired by the decreased ability to record lower extremity TMS motor evoked potentials (MEP), this methodological report details steps to enable post-stroke TMS assessments in a standing posture. The standing posture allows for the activation of the neuromuscular system, reflecting a state more akin to the system's state during postural and walking tasks. Using dual-top force plates, we instructed participants to equally distribute their weight between their paretic and non-paretic legs. Visual feedback of the participants' weight distribution was provided. Using image guidance software, we delivered single TMS pulses via a double-cone coil to the participants' lesioned and non-lesioned hemispheres and measured the corticomotor response of the paretic and non-paretic tibialis anterior and soleus muscles. Performing assessments in the standing position increased the TMS response rate and allowed for the use of the lower stimulation intensities compared to the standard sitting/resting position. Utilization of this TMS protocol can provide a common approach to assess the lower extremity corticomotor response post-stroke when the neurorehabilitation of postural and gait impairments are of interest.

This protocol describes the process for performing a neurophysiological assessment of the lower extremity muscles, tibialis anterior and soleus, in a standing position using TMS in people post-stroke. This position provides a greater probability of eliciting a post-stroke TMS response and allows for the use of reduced stimulator power during neurophysiological assessments.

中风后下肢肌肉的站立神经生理学评估

Transcranial magnetic stimulation (TMS) is a common tool used to measure the behavior of motor circuits in healthy and neurologically impaired ...

Experimental Methods to Study Human Postural Control

Many components of the nervous and musculoskeletal systems act in concert to achieve the stable, upright human posture. Controlled experiments accompanied by appropriate mathematical methods are needed to understand the role of the different sub-systems involved in human postural control. This article describes a protocol for performing perturbed standing experiments, acquiring experimental data, and carrying out the subsequent mathematical analysis, with the aim of understanding the role of musculoskeletal system and central control in human upright posture. The results generated by these methods are important, because they provide insight into the healthy balance control, form the basis for understanding the etiology of impaired balance in patients and the elderly, and aid in the design of interventions to improve postural control and stability. These methods can be used to study the role of somatosensory system, intrinsic stiffness of ankle joint, and visual system in postural control, and may also be extended to investigate the role of vestibular system. The methods are to be used in the case of an ankle strategy, where the body moves primarily about the ankle joint and is considered a single-link inverted pendulum.

This article presents an experimental/analytic framework to study human postural control. The protocol provides step-by-step procedures for performing standing experiments, measuring body kinematics and kinetics signals, and analyzing the results to provide insight into the mechanisms underlying human postural control.

研究人体姿势控制的实验方法

Many components of the nervous and musculoskeletal systems act in concert to achieve the stable, upright human posture. Controlled experiments accompanied ...

生物工程

Evaluation of Patients' Posture and Gait Profile After Lumbar Fusion Surgery by Video Rasterstereography and Treadmill Gait Analysis

This protocol provides guidance on how to perform high resolution video rasterstereography and treadmill gait analysis on patients after lumbar fusion surgery to obtain results about altered variables of gait and posture. These observed changes can then be correlated with the patient-reported outcome measure of pain relief. The rasterstereographic device projects lines of parallel light onto the surface of the tested subject&#39;s back. The deformation of these lines is recognized by the device. From these data, a special software then generates a 3-D profile based on the principle of triangulation. With an inaccuracy of only 0.2 mm it can measure changes in posture at very high precision. Gait and stance parameters are recorded using a treadmill equipped with an electric sensor mat that contains 10,200 miniature force sensors in the registering zone under the belt. Initial walking speed on the treadmill is 0.5 km/h. Speed is then gradually increased by increments of 0.1 km/h until each subject reaches his or her individual maximum well tolerable walking speed. At this speed, parameters are recorded during a 20 s measurement interval. Subjects are tested barefoot and without holding a handrail. Among various other parameters, stride width, step length, stance phase and foot rotation are measured. Both methods used reportedly have a high intra- and inter-observer reliability. The advantage of these highly accurate techniques is that they offer an objective and very detailed perspective on changes in the patient&#39;s posture and gait. Due to the amount of data generated, these techniques are, however, not so much suitable for everyday routine use, but rather interesting to scientifically evaluate long term alterations in posture and gait in patients like for example after lumbar fusion surgery.

Here, we present a protocol to analyze the posture and the gait of patients after lumbar fusion surgery by means of high-resolution video rasterstereography and a treadmill equipped with an integrated sensor mat. Allowing critical functional postoperative evaluation on a less subjective level may enhance accuracy and reliability of indication for surgery.

视频栅格立体成像和跑步机步态分析对腰椎融合手术后患者体型和步态剖面的评价

This protocol provides guidance on how to perform high resolution video rasterstereography and treadmill gait analysis on patients after lumbar fusion ...

Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability

Computerized dynamic posturography (CDP) is an objective technique for the evaluation of postural stability under static and dynamic conditions and perturbation. CDP is based on the inverted pendulum model that traces the interrelationship between the center of pressure and the center of gravity. CDP can be used to analyze the proportions of vision, proprioception, and vestibular sensation to maintain postural stability. The following characters define chronic ankle instability (CAI): persistent ankle pain, swelling, the feeling of &#8220;giving way,&#8221; and self-reported disability. Postural stability and fibular muscle activation level in individuals with CAI decreased due to lateral ankle ligament complex injuries. Few studies have used CDP to explore the postural stability of individuals with CAI. Studies that investigate postural stability and related muscle activation by using synchronized CDP with surface electromyography are lacking. This CDP protocol includes a sensory organization test (SOT), a motor control test (MCT), and an adaption test (ADT), as well as tests that measure unilateral stance (US) and limit of stability (LOS). The surface electromyography system is synchronized with CDP to collect data on lower limb muscle activation during measurement. This protocol presents a novel approach for evaluating the coordination of the visual, somatosensory, and vestibular systems and related muscle activation to maintain postural stability. Moreover, it provides new insights into the neuromuscular control of individuals with CAI when coping with real complex environments.

Individuals with chronic ankle instability (CAI) exhibit postural control deficiency and delayed muscle activation of lower extremities. Computerized dynamic posturography combined with surface electromyography provides insights into the coordination of the visual, somatosensory, and vestibular systems with muscle activation regulation to maintain postural stability in individuals with CAI.

评估慢性脚踝不稳个体的姿势控制与下肢肌肉活化

Computerized dynamic posturography (CDP) is an objective technique for the evaluation of postural stability under static and dynamic conditions and ...

神经科学

Postural Organization of Gait Initiation for Biomechanical Analysis Using Force Platform Recordings

Gait initiation (GI), the transient phase between orthograde posture and steady-state locomotion, is a functional task and an experimental paradigm that is classically used in the literature to obtain insight into the basic postural mechanisms underlying body motion and balance control. Investigating GI has also contributed to a better understanding of the physiopathology of postural disorders in elderly and neurological participants (e.g., patients with Parkinson&#39;s disease). As such, it is recognized to have important clinical implications, especially in terms of fall prevention.
This paper aims to provide scholars, clinicians, and higher education students information on the material and method developed to investigate GI postural organization via a biomechanical approach. The method is based on force platform recordings and the direct principle of mechanics to compute the kinematics of the center of gravity and center of pressure. The interaction between these two virtual points is a key element in this method since it determines the conditions of stability and whole-body progression. The protocol involves the participant initially standing immobile in an upright posture and starting to walk until the end of an at least 5 m track.
It is recommended to vary the GI velocity (slow, spontaneous, fast) and the level of temporal pressure - gait may be initiated as soon as possible after the deliverance of a departure signal (high level of temporal pressure) or when the participant feels ready (low level of temporal pressure). Biomechanical parameters obtained with this method (e.g., duration and amplitude of anticipatory postural adjustments, step length/width, performance, and stability) are defined, and their computation method is detailed. In addition, typical values obtained in healthy young adults are provided. Finally, critical steps, limitations, and significance of the method with respect to the alternative method (motion capture system) are discussed.

This paper describes the material and method developed to investigate the postural organization of gait initiation. The method is based on force platform recordings and on the direct principle of mechanics to compute center of gravity and center of pressure kinematics.

使用力平台记录进行生物力学分析的步态起始姿势组织

Gait initiation (GI), the transient phase between orthograde posture and steady-state locomotion, is a functional task and an experimental paradigm that ...