Computerized Dynamic Posturography for Postural Control Assessment in Patients with Intermittent Claudication
Summary
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.
Abstract
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'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'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.
Introduction
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. 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's ability to control their balance under different conditions, such as reduced base of support (e.g. tandem or unilateral stance) or without visual input (e.g. eyes closed). Thus they are often used to determine an individual'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's ability to maintain balance during functional tasks. While 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.
Protocol
Representative Results
Discussion
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…
Disclosures
The authors have nothing to disclose.
Acknowledgements
There are no acknowledgements for this study.
Materials
| Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
| NeuroCom EquiTest | NeuroCom, a division of Natus Medical Incorporated, San Carlos, CA, USA | ||
| Handheld Doppler Ultrasound | Huntleigh Technology Plc, Cardiff, UK | ||
| Sphygmomanometer (blood pressure) cuff |
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