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-&#160;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&#176;/sec (0.87 rad/sec). The visual surround tilts forwards and backward about the x-axis at a maximum angular velocity of 15&#176;/sec (0.26 rad/sec) across a range of &#177;10&#176;. 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.&#160;age and height) into the software program. Indicate their age and height accurately. 
	Note: The participant&#39;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&#39;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&#39;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-&#160;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-&#160;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&#39;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.&#160;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&#176; represents the maximum normal postural sway in the anterior-posterior direction; &#952; represents the participant&#39;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=" Equation 1" src="/files/ftp_upload/51077/51077eq1.jpg" /> 
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&#39;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=" Equation 2-5" src="/files/ftp_upload/51077/51077eq2-5.jpg" /> 
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&#39;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&#39;s active force response, measured for each limb independently; and Amplitude scaling (or Relative response strength) - strength of the participant&#39;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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	<li>Berg, K., Wood-Dauphin&#233;e, S., Williams, J. I., Gayton, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+balance+in+the+elderly:+preliminary+development+of+an+instrument.">Measuring balance in the elderly: preliminary development of an instrument.</a> Physiother. Can. 41, 304-311 (1989).</li><li>Tinetti, M. E., Williams, T. F., Mayewski, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fall+risk+index+for+elderly+patients+based+on+number+of+chronic+disabilities.">Fall risk index for elderly patients based on number of chronic disabilities.</a> Am. J. Med. 80, 429-434 (1986).</li><li>King, S. L., Vanicek, N., Mockford, K., Coughlin, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+a+3-month+supervised+exercise+programme+on+the+gait+biomechanics+of+patients+with+peripheral+arterial+disease+and+intermittent+claudication.">The effect of a 3-month supervised exercise programme on the gait biomechanics of patients with peripheral arterial disease and intermittent claudication.</a> Clin. Biomech. 27, 845-851 (2012).</li><li>Camicioli, R., Panzer, V. P., Kaye, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Balance+in+the+healthy+elderly:+posturography+and+clinical+assessment.">Balance in the healthy elderly: posturography and clinical assessment.</a> Arch. Neurol. 54, 976-981 (1997).</li><li>Wallmann, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+elderly+nonfallers+and+fallers+on+performance+measures+of+functional+reach,+sensory+organization,+and+limits+of+stability.">Comparison of elderly nonfallers and fallers on performance measures of functional reach, sensory organization, and limits of stability.</a> J. Gerontol. Series A Biol. Sci. Med. Sci. 56, 580-583 (2001).</li><li>Whitney, S. L., Marchetti, G. F., Schade, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relationship+between+falls+history+and+computerized+dynamic+posturography+in+persons+with+balance+and+vestibular+disorders.">The relationship between falls history and computerized dynamic posturography in persons with balance and vestibular disorders.</a> Arch. Phys. Med. Rehabil. 87, 402-407 (2006).</li><li>Vanicek, N., Strike, S., McNaughton, L., Polman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postural+responses+to+dynamic+perturbations+in+amputee+fallers+vs.+non-fallers:+a+comparative+study+with+able-bodied+subjects.">Postural responses to dynamic perturbations in amputee fallers vs. non-fallers: a comparative study with able-bodied subjects.</a> Arch. Phys. Med. Rehabil. 90, 1018-1025 (2009).</li><li>Barnett, C. T., Vanicek, N., Polman, R. C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postural+responses+during+volitional+and+perturbed+dynamic+balance+tasks+in+new+lower+limb+amputees:+A+longitudinal+study.">Postural responses during volitional and perturbed dynamic balance tasks in new lower limb amputees: A longitudinal study.</a> Gait Posture. 37, 319-325 (2013).</li><li>Mockford, K. A., Mazari, F. A. K., Jordan, A., Vanicek, N., Chetter, I. C., Coughlin, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computerized+dynamic+posturography+in+the+objective+assessment+of+balance+in+patients+with+intermittent+claudication.">Computerized dynamic posturography in the objective assessment of balance in patients with intermittent claudication.</a> Ann. Vasc. Surg. 25, 182-190 (2010).</li><li>Gohil, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Balance+impairment,+physical+ability,+and+its+link+with+disease+severity+in+patients+with+intermittent+claudication.">Balance impairment, physical ability, and its link with disease severity in patients with intermittent claudication.</a> Ann. Vasc. Surg. 27, 68-74 (2013).</li><li>Hirsch, A. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ACC/AHA+2005+Guidelines+for+the+Management+of+Patients+With+Peripheral+Arterial+Disease+(Lower+Extremity,+Renal,+Mesenteric,+and+Abdominal+Aortic):+A+Collaborative+Report+from+the+American+Association+for+Vascular+Surgery/Society+for+Vascular+Surgery,+Society+for+Cardiovascular+Angiography+and+Interventions,+Society+for+Vascular+Medicine+and+Biology,+Society+of+Interventional+Radiology,+and+the+ACC/AHA+Task+Force+on+Practice+Guidelines+(Writing+Committee+to+Develop+Guidelines+for+the+Management+of+Patients+With+Peripheral+Arterial+Disease).">ACC/AHA 2005 Guidelines for the Management of Patients With Peripheral Arterial Disease (Lower Extremity, Renal, Mesenteric, and Abdominal Aortic): A Collaborative Report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease).</a> J. Am. Coll. Car. 47, e1-e192 (2005).</li><li>McDermott, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lower+ankle/brachial+index,+as+calculated+by+averaging+the+dorsalis+pedis+and+posterior+tibial+arterial+pressures,+and+association+with+leg+functioning+in+peripheral+arterial+disease).">Lower ankle/brachial index, as calculated by averaging the dorsalis pedis and posterior tibial arterial pressures, and association with leg functioning in peripheral arterial disease).</a> J. Vasc. Surg. 32, 1164-1171 (2000).</li><li>NeuroCom International, Inc. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Instructions+for+use:+EquiTest+system+operator's+manual.+Version+8.2.">Instructions for use: EquiTest system operator's manual. Version 8.2.</a> , (2004).</li><li>Hiatt, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Medical+treatment+of+peripheral+arterial+disease+and+claudication.">Medical treatment of peripheral arterial disease and claudication.</a> N. Eng. J. Med. 344, 1608-1621 (2001).</li><li>Olin, J. W., Hirsch, A. T., Olin, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+clinical+evaluation+and+office-based+detection+of+peripheral+arterial+disease.">The clinical evaluation and office-based detection of peripheral arterial disease.</a> An office-based approach to the diagnosis and treatment of peripheral arterial disease. I: The epidemiology and practical detection of peripheral arterial disease. , 10-17 (1998).</li><li>Kaufman, K. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gait+and+balance+of+transfemoral+amputees+using+passive+mechanical+and+microprocessor-controlled+prosthetic+knees.">Gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees.</a> Gait Posture. 26, 489-493 (2007).</li><li>Hermodsson, Y., Ekdahl, C., Persson, B. M., Roxendal, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standing+balance+in+trans-tibial+amputees+following+vascular-disease+or+trauma:+a+comparative+study+with+healthy+subject.">Standing balance in trans-tibial amputees following vascular-disease or trauma: a comparative study with healthy subject.</a> Prosthet. Orthot. Int. 18, 150-158 (1994).</li></ol>

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 border="1">
	<tbody>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<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&#39;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 &#60;0.4 confirms severe peripheral arterial disease15. An ABPI of &#60;0.9 is 95% sensitive and 99% specific for peripheral arterial disease16 and is associated with leg f...

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 Görüntüleme.  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.

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

Evaluation of Respiratory Muscle Activation Using Respiratory Motor Control Assessment (RMCA) in Individuals with Chronic Spinal Cord Injury

During breathing, activation of respiratory muscles is coordinated by integrated input from the brain, brainstem, and spinal cord. When this coordination is disrupted by spinal cord injury (SCI), control of respiratory muscles innervated below the injury level is compromised1,2 leading to respiratory muscle dysfunction and pulmonary complications. These conditions are among the leading causes of death in patients with SCI3. Standard pulmonary function tests that assess respiratory motor function include spirometrical and maximum airway pressure outcomes: Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), Maximal Inspiratory Pressure (PImax) and Maximal Expiratory Pressure (PEmax)4,5. These values provide indirect measurements of respiratory muscle performance6. In clinical practice and research, a surface electromyography (sEMG) recorded from respiratory muscles can be used to assess respiratory motor function and help to diagnose neuromuscular pathology. However, variability in the sEMG amplitude inhibits efforts to develop objective and direct measures of respiratory motor function6. Based on a multi-muscle sEMG approach to characterize motor control of limb muscles7, known as the voluntary response index (VRI)8, we developed an analytical tool to characterize respiratory motor control directly from sEMG data recorded from multiple respiratory muscles during the voluntary respiratory tasks. We have termed this the Respiratory Motor Control Assessment (RMCA)9. This vector analysis method quantifies the amount and distribution of activity across muscles and presents it in the form of an index that relates the degree to which sEMG output within a test-subject resembles that from a group of healthy (non-injured) controls. The resulting index value has been shown to have high face validity, sensitivity and specificity9-11. We showed previously9 that the RMCA outcomes significantly correlate with levels of SCI and pulmonary function measures. We are presenting here the method to quantitatively compare post-spinal cord injury respiratory multi-muscle activation patterns to those of healthy individuals.

Evaluation of Respiratory Muscle Activation Using Respiratory Motor Control Assessment RMCA in Individuals with Chronic Spinal Cord Injury

The purpose of this publication is to present our original work on a multi-muscle surface electromyographic approach to quantitatively characterize respiratory muscle activation patterns in individuals with chronic spinal cord injury using vector-based analysis.

During breathing, activation of respiratory muscles is coordinated by integrated input from the brain, brainstem, and spinal cord. When this coordination ...

Dynamic Visual Tests to Identify and Quantify Visual Damage and Repair Following Demyelination in Optic Neuritis Patients

In order to follow optic neuritis patients and evaluate the effectiveness of their treatment, a handy, accurate and quantifiable tool is required to assess changes in myelination at the central nervous system (CNS). However, standard measurements, including routine visual tests and MRI scans, are not sensitive enough for this purpose. We present two visual tests addressing dynamic monocular and binocular functions which may closely associate with the extent of myelination along visual pathways. These include Object From Motion (OFM) extraction and Time-constrained stereo protocols. In the OFM test, an array of dots compose an object, by moving the dots within the image rightward while moving the dots outside the image leftward or vice versa. The dot pattern generates a camouflaged object that cannot be detected when the dots are stationary or moving as a whole. Importantly, object recognition is critically dependent on motion perception. In the Time-constrained Stereo protocol, spatially disparate images are presented for a limited length of time, challenging binocular 3-dimensional integration in time. Both tests are appropriate for clinical usage and provide a simple, yet powerful, way to identify and quantify processes of demyelination and remyelination along visual pathways. These protocols may be efficient to diagnose and follow optic neuritis and multiple sclerosis patients.
In the diagnostic process, these protocols may reveal visual deficits that cannot be identified via current standard visual measurements. Moreover, these protocols sensitively identify the basis of the currently unexplained continued visual complaints of patients following recovery of visual acuity. In the longitudinal follow up course, the protocols can be used as a sensitive marker of demyelinating and remyelinating processes along time. These protocols may therefore be used to evaluate the efficacy of current and evolving therapeutic strategies, targeting myelination of the CNS.

Object From Motion (OFM) and Time-constrained stereo protocols are sensitive tools to identify monocular and binocular dynamic visual function deficits, which are uniquely affected in optic neuritis patients. Furthermore, these tests may be used as quantitative noninvasive tools to assess the extent of myelination along visual pathways.

In order to follow optic neuritis patients and evaluate the effectiveness of their treatment, a handy, accurate and quantifiable tool is required to ...

Assessment of Vascular Function in Patients With Chronic Kidney Disease

Patients with chronic kidney disease (CKD) have significantly increased risk of cardiovascular disease (CVD) compared to the general population, and this is only partially explained by traditional CVD risk factors. Vascular dysfunction is an important non-traditional risk factor, characterized by vascular endothelial dysfunction (most commonly assessed as impaired endothelium-dependent dilation [EDD]) and stiffening of the large elastic arteries. While various techniques exist to assess EDD and large elastic artery stiffness, the most commonly used are brachial artery flow-mediated dilation (FMDBA) and aortic pulse-wave velocity (aPWV), respectively. Both of these noninvasive measures of vascular dysfunction are independent predictors of future cardiovascular events in patients with and without kidney disease. Patients with CKD demonstrate both impaired FMDBA, and increased aPWV. While the exact mechanisms by which vascular dysfunction develops in CKD are incompletely understood, increased oxidative stress and a subsequent reduction in nitric oxide (NO) bioavailability are important contributors. Cellular changes in oxidative stress can be assessed by collecting vascular endothelial cells from the antecubital vein and measuring protein expression of markers of oxidative stress using immunofluorescence. We provide here a discussion of these methods to measure FMDBA, aPWV, and vascular endothelial cell protein expression.

The degree of vascular dysfunction and contributing physiological mechanisms can be assessed in patients with chronic kidney disease by measuring brachial artery flow-mediated dilation, aortic pulse-wave velocity, and vascular endothelial cell protein expression.

Patients with chronic kidney disease (CKD) have significantly increased risk of cardiovascular disease (CVD) compared to the general population, and this ...

Clinical Assessment of Spatiotemporal Gait Parameters in Patients and Older Adults

Spatial and temporal characteristics of human walking are frequently evaluated to identify possible gait impairments, mainly in orthopedic and neurological patients1-4, but also in healthy older adults5,6. The quantitative gait analysis described in this protocol is performed with a recently-introduced photoelectric system (see&#160;Materials table) which has the potential to be used in the clinic because it is portable, easy to set up (no subject preparation is required before a test), and does not require maintenance and sensor calibration. The photoelectric system consists of series of high-density floor-based photoelectric cells with light-emitting and light-receiving diodes that are placed parallel to each other to create a corridor, and are oriented perpendicular to the line of progression7. The system simply detects interruptions in light signal, for instance due to the presence of feet within the recording area. Temporal gait parameters and 1D spatial coordinates of consecutive steps are subsequently calculated to provide common gait parameters such as step length, single limb support and walking velocity8, whose validity against a criterion instrument has recently been demonstrated7,9. The measurement procedures are very straightforward; a single patient can be tested in less than 5 min&#160;and a comprehensive report can be generated in less than 1&#160;min.

This protocol is used to evaluate spatial and temporal gait variables of neurological/orthopedic patients and older persons by means of a recently-introduced floor-based photocell system.

Spatial and temporal characteristics of human walking are frequently evaluated to identify possible gait impairments, mainly in orthopedic and ...

Semi-quantitative Assessment Using [18F]FDG Tracer in Patients with Severe Brain Injury

Patients with severe traumatic brain injury (sTBI) have difficulty knowing whether they are accurately expressing their thoughts and emotions because of disorders of consciousness, disrupted higher brain function, and verbal disturbances. As a consequence of an insufficient ability to communicate, objective evaluations are needed from family members, medical staff, and caregivers. One such evaluation is the assessment of functioning brain areas. Recently, multimodal brain imaging has been used to explore the function of damaged brain areas. [18F]-fluorodeoxyglucose positron emission tomography-computed tomography ([18F]FDG-PET/CT) is a successful tool for examining brain function. However, the assessment of brain glucose metabolism based on [18F]FDG-PET/CT is not standardized and depends on several varying parameters, as well as the patient&#39;s condition. Here, we describe a series of semiquantitative assessment protocols for a region-of-interest (ROI) image analysis using self-produced [18F]FDG tracers in patients with sTBI. The protocol focuses on screening the participants, preparing the [18F]FDG tracer in the hot lab, scheduling the acquisition of [18F]FDG-PET/CT brain images, and measuring glucose metabolism using the ROI analysis from a targeted brain area.

Semi-quantitative Assessment Using [18F]FDG Tracer in Patients with Severe Brain Injury

[18F]-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography is useful for studying glucose metabolism related to brain function. Here, we present a protocol for an [18F]FDG tracer set-up and semiquantitative assessment of the region-of-interest analysis for targeted brain areas associated with clinical manifestations in patients with severe traumatic brain injury.

Patients with severe traumatic brain injury (sTBI) have difficulty knowing whether they are accurately expressing their thoughts and emotions because of ...

A Computerized Functional Skills Assessment and Training Program Targeting Technology Based Everyday Functional Skills

Today, many functional skills are technology-based, so development of a technology-based training program has broad importance. Here we present a computerized functional skills training program that was paired in half of the participants with a commercially available cognitive training (CCT) program.
Non-impaired older individuals (NC) aged 60+ (n=45) and similarly aged individuals with mild cognitive impairment (MCI; n=50) were randomized to receive 12 weeks of twice-weekly computerized functional skills training (CFST) or 12 weeks of twice-weekly sessions split between CCT and CFST. Skills trained were use of an ATM; internet banking; ticket kiosk; telephone and internet prescription refill; medication management; and internet shopping. As with previous functional capacity assessments, we focus on completion time for each simulation.
51 participants completed the training program, either by mastering all 6 tasks (34) or completing 12 weeks of training. 44 more participants completed 4 or more training sessions so they were also analyzed for improvement up to their last training session. Completion time for all 6 tests significantly improved from the baseline assessment to the final training session in both groups of participants (all p&#60;0.001 with an average improvement in task completion time of 45%). Further, there was no differential improvement in MCI and NC in the 6 tests from baseline to end of training (all t&#60;1.66, all p&#62;0.12). Finally, combined CCT plus CFST did not differ from CSFT alone on any of the percent-change score measures (all t&#60;1.64, all p&#62;0.11).
Both NC and MCI groups evidenced substantial improvements in performance. CCT supplementation led to similar functional gains with half as many training sessions. The NC participants proceeded through the training fairly rapidly even without CCT supplementation; MCI participants required more training but learned equivalently. These findings suggest that even in cases with memory impairments, functional skills can be efficiently learned with training.

This training protocol uses computerized training to teach technology-related everyday functional skills. These skills include financial skills, travel and transit, as well as medication management.

Today, many functional skills are technology-based, so development of a technology-based training program has broad importance. Here we present a ...

Using a Chemical Biopsy for Graft Quality Assessment

Kidney transplantation is a life-saving treatment for a large number of people with end-stage renal dysfunction worldwide. The procedure is associated with an increased survival rate and greater quality of patient&#8217;s life when compared to conventional dialysis. Regrettably, transplantology suffers from a lack of reliable methods for organ quality assessment. Standard diagnostic techniques are limited to macroscopic appearance inspection or invasive tissue biopsy, which do not provide comprehensive information about the graft. The proposed protocol aims to introduce solid phase microextraction (SPME) as an ideal analytical method for comprehensive metabolomics and lipidomic analysis of all low molecular compounds present in kidneys allocated for transplantation. The small size of the SPME probe enables performance of a chemical biopsy, which enables extraction of metabolites directly from the organ without any tissue collection. The minimum invasiveness of the method permits execution of multiple analyses over time: directly after organ harvesting, during its preservation, and immediately after revascularization at the recipient&#8217;s body. It is hypothesized that the combination of this novel sampling method with a high-resolution mass spectrometer will allow for discrimination of a set of characteristic compounds that could serve as biological markers of graft quality and indicators of possible development of organ dysfunction.

The protocol presents utilization of the chemical biopsy approach followed by comprehensive metabolomic and lipidomic analysis for quality assessment of kidney grafts allocated for transplantation.

Kidney transplantation is a life-saving treatment for a large number of people with end-stage renal dysfunction worldwide. The procedure is associated ...

Fertility Preservation in Patients with Severe Ovarian Dysfunction

Ovarian function progressively declines during aging and in some pathophysiological conditions including karyotype abnormality, autoimmune diseases, chemo- and radiation-therapies, as well as ovarian surgeries. In unmarried women with severe ovarian dysfunction, fertility preservation is important for future pregnancies. Although oocyte cryopreservation is an established method for fertility preservation, these patients could only preserve a limited number of oocytes even after ovarian hyperstimulation, leading to repeated stimulations to ensure sufficient oocytes to guarantee future pregnancy. To solve this issue, we have recently developed a drug-free in vitro activation (IVA) procedure, which enable us to stimulate early stages of ovarian follicles to develop to the preantral follicle stage. These preantral follicles can respond to the unique protocol of gonadotropin stimulation, resulting in increased number of retrieved oocytes per ovarian stimulation for cryopreservation. The drug-free IVA comprised from the surgical approach and ovarian stimulation. We removed a part of cortex from one or both ovaries from patients under laparoscopic surgery. The ovarian cortical tissues were cut into small cubes to disrupt the Hippo signaling pathway and stimulate the development of early stage follicles. These cubes were grafted orthotropically into remaining ovaries as well as beneath the serosa of both Fallopian tubes. We have already published the surgical procedure of the drug-free IVA and the protocol of subsequent ovarian stimulation, but herein we present the details of laboratory methods required for drug-free IVA.

We present details of laboratory procedures for drug-free in vitro activation (IVA) of ovarian follicles for patients with severe ovarian dysfunction. This method could increase the number of retrievable oocytes per ovarian hyperstimulation and benefit fertility preservation for those patients.

Ovarian function progressively declines during aging and in some pathophysiological conditions including karyotype abnormality, autoimmune diseases, ...

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as moving optotypes are frequently observed daily. Dynamic visual acuity (DVA) might reflect real-life situations better, especially when objects are moving at high speeds. Myopia impacts static uncorrected distance visual acuity, conveniently corrected with eyeglasses. However, due to peripheral defocus and prism effects, eyeglass correction might affect DVA. The present research demonstrates a standard method to examine eyeglass-corrected DVA in myopia patients, and aimed to explore the influence of eyeglass correction on DVA. 
Initially, standard subjective refraction was performed to provide the eyeglass prescription to correct the refractive error. Then, binocular distance vision-corrected DVA was examined using the object-moving DVA protocol. Software was designed to display the moving optotypes according to the preset velocity and size on a screen. The optotype was the standard logarithmic visual chart letter E and moves from the middle of the left to the right side horizontally during the test. Moving optotypes with randomized opening direction for each size are displayed. The subjects were required to identify the opening direction of the optotype, and the DVA is defined as the minimum optotype that subjects could recognize, calculated according to the algorithm of logarithmic visual acuity.
Then, the method was applied in 181 young myopic subjects with eyeglass-corrected-to-normal static visual acuity. Dominant eye, cycloplegic subjective refraction (sphere and cylinder), accommodation function (negative and positive relative accommodation, binocular cross-cylinder), and binocular DVA at 40 and 80 degrees per second (dps) were examined. The results showed that with increasing age, DVA first increased and then decreased. When myopia was fully corrected with eyeglasses, a worse binocular DVA was associated with more significant myopic refractive error. There was no correlation between the dominant eye, accommodation function, and binocular DVA.

The present research demonstrates a method to accurately examine dynamic visual acuity (DVA) in myopic subjects with eyeglass correction. Further analysis indicated that the closer the refraction state to emmetropia, the better the eyeglass-corrected binocular DVA is at both 40 and 80 degrees per second.

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as ...

Providing Visual Biofeedback Using Brightness Mode Ultrasound During a Golf Swing

Using ultrasound biofeedback in conjunction with verbal cueing can increase muscle thickness more than verbal cueing alone and may augment traditional rehabilitation techniques in an athletic, physically active population. Brightness mode (B-mode) ultrasound can be applied using frame-by-frame analysis synchronized with video to understand muscle thickness changes during these dynamic tasks. Visual biofeedback with ultrasound has been established in static positions for the muscles of the lateral abdominal wall. However, by securing the transducer to the abdomen using an elastic belt and foam block, biofeedback can be applied during more specific tasks prevalent in lifetime sports, such as golf. To analyze muscle activity during a golf swing, muscle thickness changes can be compared. The thickness must increase throughout the task, indicating that the muscle is more active. This methodology allows clinicians to immediately replay ultrasound videos for patients as a visual tool to instruct proper activity of the muscles of interest. For example, ultrasound can be used to target the external and internal obliques, which play an important role in swinging a golf club or any other rotational sport or activity. This methodology aims to increase oblique muscle thickness during the golf swing. Additionally, the timing of muscle contraction can be targeted by instructing the patient to contract the abdominal muscles at specific time points, such as the beginning of the downswing, with the goal of improving muscle firing patterns during tasks.

Brightness mode ultrasound can be used to provide visual biofeedback of the muscles of the lateral abdominal wall during a golf swing. Post-swing visual and verbal instruction can increase the muscle activation and timing of the external and internal obliques.

Using ultrasound biofeedback in conjunction with verbal cueing can increase muscle thickness more than verbal cueing alone and may augment traditional ...