A comprehensive balance assessment typically begins with a referral from a nurse practitioner or a physician who has completed a fall risk screen or some sort of risk assessment and is concerned about a person’s fall risk. The assessment begins with the gathering of subjective data from the patient or the patient’s caregiver, which includes a detailed medical history, review of medications, and any other factors that contribute to loss of function. A brief history of recent falls is particularly important and often provides information about the cause of the balance disorder.
Following the subjective assessment, musculoskeletal function, functional mobility and gait, movement strategies, and sensory systems involved with balance are evaluated. The ultimate goal is to find the cause of the balance impairment, design a program that reduces future falls, and make decisions related to home modification and assistive devices.
Assessing Musculoskeletal Function
Musculoskeletal assessment involves a comprehensive look at strength, range of motion, posture, pain, and the presence of abnormal tone.
Strength is an important part of musculoskeletal function and must be thoroughly evaluated. If muscle tone is normal (no spasticity or abnormal tone), strength can be tested on a 1–5 scale (with 5 meaning full strength) using manual resistance by the evaluator. Manual muscle testing is a good measure of strength in a specific muscle but tests muscles in isolation. Tests of functional strength such as standing on one leg (to test the gluteus medius muscle of the stance leg), or performing a semi-squat, are better indicators than individual muscle tests for balance deficit.
From a fall prevention point of view, what is a relationship between strength and balance? In a review of the literature on strength and balance, Granacher looked at maximum isometric strength and the rate of force development in healthy older adults. Maximal and particularly explosive force production under isometric conditions is significantly lower in old and especially the oldest old adults (≥80 years) compared to young adults. Loss of muscle volume as well as decreased neural drive for activation of muscles is thought to account for the age-related reductions (Granacher, 2012).
Power training or high-velocity strength training has the potential to improve both strength and functional performance. High-velocity strength training with high loads specifically increases muscle power, whereas power training with low to moderate loads improves balance and functional performance (Granacher, 2012).
Although strength is certainly a contributing factor, balance may be more adversely affected by abnormalities in the sequence and timing of muscle contraction than by localized muscle weakness (Shumway-Cook and Woollacott, 2012).
Range of Motion
Decreased range of motion can have a profound impact on balance. Loss of flexibility in the spine—particularly spinal extension—affects postural alignment, shifting the center of body mass backwards towards the heel (Shumway-Cook and Woollacott, 2012).
Because ankle flexibility is critical for postural control, ankle joint range of motion has been the focus of considerable research. Ankle joint flexibility, particularly dorsiflexion, declines by as much as 50% in women and 35% in men between the ages of 55 and 85 (Shumway-Cook and Woollacott, 2012).
Pain affects balance by affecting postural alignment and available range of motion. Back pain is among the most important factors affecting health status and functional capacity in older adults, with a prevalence of 12% to 42% in those over 65 years of age. Low back pain was found to be related to two-fold increase in the risk of falling. Chronic low back pain in older adults may cause neurophysiologic changes that adversely affect postural control (Champagne, 2012).
In a study looking at pain and postural control in 605 adults aged 75 and over, the participants with moderate to severe pain had more than twice the risk for impaired balance compared with those without pain (Lihavainen et al., 2011).
Assessing Functional Mobility and Gait
Once the musculoskeletal evaluation has been completed, a patient’s performance on functional tasks that depend on postural control is evaluated. Assessing balance and postural control from a functional perspective involves the use of tests and measures to determine a person’s abilities in both the clinical and home environment.
When selecting an assessment tool for use in your clinic or hospital, choose a tool that is appropriate for client population, reliable, evidence based, repeatable, and—most of all—fast and easy to use. Patient safety is of paramount importance.
Timed Up and Go Test
The Get Up and Go Test, the predecessor of the Timed Up and Go Test (TUG), was developed by Mathias and Nayak as a tool to screen for balance problems, primarily in the frail elderly. The test measures how long it takes for a person to rise from a chair, walk 3 meters (about 10 feet) to a line on the floor, and return to the chair. The test correlates well with the Berg Balance Test, the Barthel Index of activities of daily living, and gait speed tests. The Timed Up and Go modified the earlier test by adding a timing component. An adult who is independent in balance and mobility can perform the TUG in less than 10 seconds (Shumway-Cook and Woollcott, 2007).
In a study with older adults with a range of neurologic pathologies, people taking 30 seconds or more to complete this task were more likely to need an assistive device, walk too slowly for community ambulation, and score lower on the Berg Balance test. In contrast, a person completing the test in less than 20 seconds was more likely to be independent in daily living activities, score higher on the Berg Balance test, and walk at a speed sufficient for community mobility (Podsiadlo and Richardson, 1991).
Shumway-Cook, Brauer, and Woollacott (2000) found that in addition to predicting functional mobility the TUG could be used to predict the risk of falls in older adults. Thirty community-dwelling frail elderly adults were tested using the TUG; researchers found that those taking longer than 14 seconds to complete the task were at high risk for falls.
In the same study, the TUG was modified by adding a cognitive task (counting backward by threes) and a manual task (carrying a full cup of water). The addition of a secondary task increased the time need to complete the TUG by 22% to 25% (Shumway-Cook, Brauer, and Woollacott, 2000).
In another study, researchers wanted to determine if the TUG can be used to predict falls following hip surgery during a 6-month followup period. Fifty-nine patients were tested using the TUG at discharge and then 6 months later. Of these, 19 (32%) had one or more falls in the 6 months following surgery. Kristensen found that 95% of the subjects who fell had a score of ≥24 seconds on the TUG test (Kristensen, Foss, and Kehlet, 2007).
Berg Balance Scale
The Berg Balance Scale (BBS) was developed in 1989 by Kathy Berg and is a reliable clinical tool for assessment of functional mobility and gait—especially in ambulatory older adults. The BBS consists of 14 static and dynamic tasks scored from 0 to 56, which assess a variety of functional activities. Each task is scored on a 0–4 scale; a score of 0 indicates an inability to perform the task while a score of 4 means the patient is independent with that task. The BBS scale has excellent internal consistency and good test-retest reliability and requires little specialized training (Shumway-Cook and Woollacott, 2012). It can be performed with minimal equipment, in a small space, and can be used in any clinical setting.
In a 2008 study of 655 physical therapists working with stroke patients, the BBS was identified as the most commonly used tool for assessment of functional mobility following stroke (Blum and Korner-Bitensky, 2008). This and other studies have shown the BBS to be a good predictor of length of stay, discharge destination, and disability levels after discharge.
The Berg Balance Scale includes the following activities:
- Sit to stand
- Stand unsupported
- Sit unsupported
- Stand to sit
- Stand with eyes closed
- Stand with feet together
- Reach with outstretched arm
- Retrieve object from floor
- Turn to look behind
- Turn 360 degrees
- Alternate stepping on stool
- Standing with one foot in front of the other
- Standing on 1 foot
Can the BBS be used to predict the likelihood of a future fall? According to Ann Shumway-Cook and colleagues (1997), the BBS is the best single predictor of falls in community-dwelling older adults without neurologic disability. Shumway-Cook noted that declining score on the BBS is clearly associated with an increased risk of falls. From 56 to 54, a 1-point change in the Berg score was associated with a 3% to 4% increase in fall risk. Between 54 and 46, a 1-point drop in score was associated with a 6% to 8% increase while a score below 36 was associated with an almost 100% risk of falls (Shumway-Cook and Woollacott, 2012).
Functional Reach Test
Pamela Duncan and colleagues developed the Functional Reach test in 1990. In a busy clinic the Functional Reach test has the benefit of being fast and repeatable with good test-rest reliability. The test defines functional reach as “the maximal distance one can reach forward beyond arm’s length, while maintaining a fixed base of support in the standing position” (Duncan et al., 1990). It is a dynamic rather than a static test and measures a person’s “margin of stability” as well as the ability to maintain balance during a functional task. In older clients with a reach of 6 inches or less, the test has been shown by Duncan to be predictive of falls (Duncan et al., 1990).
Functional reach was originally testing using a force platform and an electronic measure of forward reach. In a clinical setting it is tested by placing a yardstick or tape measure on the wall, parallel to the floor, at the height of the acromion of the subject’s dominant arm. The client stands with the feet a comfortable distance apart, makes a fist, and reaches the dominant arm to approximately 90 degrees. The client then reaches forward as far as possible without taking a step or touching the wall. The distance between the start and end point is measured using the head of the metacarpal of the third finger as the reference point (Duncan et al., 1990).
Performance Oriented Mobility Test (Tinetti Tests)
The Performance Oriented Mobility Assessment (POMA) was developed by Mary Tinetti, a physician and researcher at Yale University. It is divided into two parts: balance and gait. Along with the Berg Balance Test, it is one of the most widely used mobility and gait assessment tests. At least one study has shown POMA to have the best test-retest reliability when compared to the TUG, One-Leg Stand, and Functional Reach. It was also shown to have good predictive value for fall risk when compared to the other tests (Shumway-Cook and Woollacott, 2012).
The first part of the tool, the Tinetti Balance Test, is scored on a scale of 0 to 16 and assesses:
- Sitting balance
- Sit to stand
- Standing balance
- Standing balance when nudged
- Standing balance with eyes closed
- Balance while turning, and stand to sit
The second part to the tool, the Tinetti Gait Test, is scored on a scale of 0 to 12 and assesses:
- Initiation of gait
- Step length and height
- Step symmetry
- Step continuity
- Deviation from a straight path when walking
- Trunk sway and stance when walking
When taken together the maximum score on the Tinetti tests is 28; a client that scores between 19 and 24 is at risk for falls and a client that scores below 19 is at high risk for falls.
Gait is a functional task that is closely related to balance and postural control. Functional gait can be assessed with a number of reliable tools. In a task-oriented approach advocated by Shumway-Cook and Woollacott (2007) gait and mobility assessment are related to examination at the functional level. In one approach, gait can be assessed as a function of velocity, a measure that combines time and distance. This can be compared to normative values such as 80 m/min.
The Balance Evaluation Systems Test (BESTest)
Most existing clinical balance tests are directed at predicting fall risk or identifying whether a balance problem exists, rather than determining what type of balance problem exists (Horak, 2009). The Balance Evaluation Systems Test (BESTest) is a clinical assessment tool that looks at 36 items grouped under 6 categories:
- Biomechanical Constraints
- Stability Limits/Verticality
- Anticipatory Postural Adjustments
- Postural Responses
- Sensory Orientation
- Stability in Gait
The goal is to examine multiple balance and postural control systems so treatment can be fine-tuned to address a specific balance deficit. A shorter mini-BESTest is also available, which tests items 3, 4, 5, and 6. For more information, including video of anticipatory postural responses please visit http://www.bestest.us/samples.html.
Assessing Movement Strategies
Our nervous system simplifies motor control by creating patterns of movement called synergies or strategies. A movement strategy is a flexible, repeatable pattern of movement that can be quickly and automatically accessed by the central nervous system. This allows us to store and reuse patterns of movement that have been successful in the past. Strategies are efficient, automatic movement patterns that evolve over time. Each time a loss of balance threatens, the nervous system can draw on these pre-programmed movement strategies to ensure the maintenance of balance.
The ankle strategy—also called ankle sway—is used in response to small perturbations or losses of balance. When a small loss of balance occurs—as when standing on a moving bus—the foot acts as a lever to maintain balance by making continuous automatic adjustments to the movement of the bus. When a small balance adjustment is needed muscles close to the floor activate first and flow upward in a distal to proximal pattern.
If your body sways forward the toes dig into the floor and the ankle, calf, and posterior leg muscles contract to prevent you from falling forward. If your body sways backwards the toes lift up and the anterior tibialis muscles at the front of the lower leg—as well as other muscles on the anterior surface of the body—contract, thus preventing you from falling backwards. The ankle strategy is automatically utilized a thousand times a day in response to small losses of balance. There’s no need to think about the toes lifting or the calf muscles contracting—the central nervous system does the work automatically.
In older adults studies have shown that during quiet stance sway increases with age; when quiet stance is perturbed, older adults have slower contractions of the leg muscles and—in some cases—activate proximal muscles first followed by distal muscles (Shumway-Cook and Woollacott, 2012).
Older adults also tended to co-activate agonist and antagonist muscles, effectively stiffening the joint. Others bend at the waist (hip strategy) rather than using the ankle strategy possibly due to ankle weakness or sensory changes (Shumway-Cook and Woollacott, 2012).
The hip strategy is needed if a perturbation is too large to be successfully handled by the ankle strategy. In the bus example, when the movement of the bus is steady, the ankle strategy works just fine. But what happens when the bus driver slows or accelerates suddenly? If we only had the ankle strategy we would fall over the moment our center of gravity passed the limits of the ankle range of motion. Instead we use the hip strategy—bend a bit at the waist or arch our backs as much as is needed to keep our center of gravity over our base of support.
When the hip strategy is needed, movement is centered about the hip and the ankle muscles (anterior tibialis and gastrocnemius) are largely inactive. The muscles in the trunk activate first as activation flows downward to the legs in a proximal to distal pattern. So, if the bus stops suddenly and the body is thrust forward, the low back and hamstrings will contract in that order to return the body to upright.
When the hip strategy is used, the muscles of the lower leg are almost silent. Studies have shown that when a walker is used the body largely abandons the ankle strategy and relies heavily on the hip strategy for balance. This dependence on the hip strategy for balance paradoxically may lead to a decrease in ankle sway and contributes to further decline in balance arising from loss of ankle strength and flexibility. For this reason the pros and cons of walker use must be carefully considered before a walker is recommended for fulltime use.
The stepping strategy is used when the ankle or hips strategies are insufficient to regain balance. When your center of gravity moves well past your base of support it is necessary to take a forward or backward step to regain balance.
Studies have shown age-related changes in stepping and reaching reactions in older adults. Compared to younger people, older adults initiate the stepping strategy in response to smaller losses of balance and tend to take several small steps rather than one larger step (Maki and McIlroy, 2006).
Older adults also reach for a support surface more readily than younger adults but the reach reaction is slower. Increased tendency to reach for support and a slowing of these reactions have been found to be predictive of falling in daily activities (Maki and McIlroy, 2006).
The Sensory System and Balance
A healthy sensory system is a critical and often overlooked part of what makes balance work. Maintaining postural equilibrium, sensing movement, and maintaining an awareness of the relative location of our body parts requires the precise integration of several of the body’s sensory and response systems, including visual, vestibular, and somatosensory. Acting together, these systems gather and interpret sensory information from all over the body and allow us to act on that information in an appropriate and helpful way.
The somatosensory system—touch, pressure, and proprioception—has perhaps the strongest influence on balance. Sensory receptors specialized for touch, temperature, pressure, joint and muscle stretch, vibration, and pain sensation, among others, continuously feed sensory information to the brain, where it is processed and routed back out to the muscles. The information is used by the body to make constant quick and automatic adjustments that allow us to maintain balance and avoid falls.
Balance and postural control are affected in a number of ways, depending upon which part of the somatosensory system is impaired. Large sensory fiber damage lessens our ability to feel vibration and touch, resulting in a general sense of numbness, especially in the hands and feet. This damage to sensory fibers may also contribute to the loss of reflexes. If sensory decline is significant, peripheral neuropathies can develop. Peripheral neuropathies affect posture and balance by significantly delaying muscle response following a loss of balance (Shumway-Cook and Woollacott, 2012).
The visual system is also a key component of balance. Vision helps us determine the movement of objects in our environment and tells us where we are in relation to parts of our own body and to other objects (Shumway-Cook and Woollacott, 2012). Visual changes occur as we age—loss of visual acuity, narrowing of visual fields, decreased light-dark adaptation, increased sensitivity to glare, and loss of peripheral vision and depth perception. Balance and postural control are affected by changes in vision.
The eye contains both central and peripheral vision. Central vision is processed mostly through the macula, which allows us to see clearly. Peripheral vision provides information about general spatial orientation and is more important for postural control and balance than central vision.
A recent study tracked hip fracture incidence among 400,000 Medicare patients who had cataract surgery between 2002 and 2009. Cataract surgery was associated with a 16% decrease in patients’ adjusted odds of suffering a hip fracture within one year of the procedure (AAO, 2012).
Our vestibular system enables us to determine body orientation, senses the direction and speed at which we are moving, and helps us maintain balance. The vestibular system processes information about movement in relation to gravity—specifically, rotation, acceleration and deceleration, and head stabilization during gait.
The vestibular system works with the visual and somatosensory systems to check and maintain the position of our bodies at rest or in motion. It also helps us maintain a steady focus on objects when the position of our body changes. The vestibular system does this by detecting mechanical forces, including gravity, that act upon the vestibular organs when we move.
The vestibular system declines with age and there may be as much as a 40% loss of vestibular nerve and hair cells by age 70 (Shumway-Cook and Woollacott, 2012). Symptoms associated with vestibular system impairment are:
- Dizziness or vertigo (a spinning sensation)
- Falling, or feeling as if you are going to fall
- Lightheadedness, faintness, or a floating sensation
- Blurred vision
- Confusion or disorientation
Sensory conflicts can occur when the senses send inaccurate information to the brain. For example, we’ve all had the experience of being stopped at a stoplight when the car next to us starts to move—we think we are also moving and slam on the brake. As soon as our foot touches the brake we know instantly that we are not moving and even feel a little foolish. For a split second the brain has given preference to visual input, causing a sensory conflict. The sensory conflict is quickly resolved by the somatosensory and vestibular systems. The touch of the foot on the brake, pressure on the back and legs, and hair cells in the vestibular system tell us that there is no forward motion and we are in fact sitting still.
Sensory Disruption and Balance
Sensory disruption—blurred vision, intermittent numbness, pain, and pressure from swelling—can have a profound negative effect on balance and postural control. How (and how much) balance is affected depends on several factors, including the extent of the nervous system damage, the number and extent of sensory losses, and the ability of the other senses to compensate for the damage. If more than one sensory system is impaired—as occurs with diabetes and stroke—it may be difficult to compensate for sensory losses.
When sensory loss occurs, the nervous system compensates by giving more weight to input from another sensory system. For example, sensory loss in the feet affects the speed, accuracy, and amount of sensory information available for postural control. Unable to rely on this all-important somatosensory information, the nervous system will try to use vision to compensate for the somatosensory loss. Unfortunately, visual input is a little slower than somatosensory input, which can create instability. An assistive device may help because it widens the base of support and provides somatosensory input through the hands, which is often enough to compensate for loss of input through the feet.
When vision is impaired a similar process takes place. Because visual input is inaccurate or unavailable, the nervous system relies more on touch and vestibular feedback for balance. Impaired vision may cause someone to have difficulty in complex visual situations that demand rapid visual interpretation of multiple visual cues. For example, a person may be safe walking in a quiet environment but be unable to negotiate a busy, noisy street filled with people and cars.
Vestibular decline has a profound effect on balance and postural control because it is used as a reference system by the visual and somatosensory systems when those systems are in conflict. Vestibular impairment can lead to problems with gaze stabilization, blurred vision, and vertigo (Shumway-Cook and Woollacott, 2012).
Improper Sensory Selection
Sensory loss can lead to inflexible or improper sensory weighting. For example, a person with decreased sensation in the feet gradually grows to depend upon vision for balance, which is not as effective as somatosensory feedback for balance. A person may depend on one particular sense for postural control, even if that sense leads to further instability (Shumway-Cook and Woollacott, 2007). You may notice a person walking with head down, carefully watching every step. In this case, the person is relying on vision as the dominant sense being used for balance. Retraining would involve improving the use of somatosensory and vestibular input to reduce dependence on visual input.
Carla is an 89-year-old woman living at home with her son and having home care during the day while her son is at work. Carla is independent in household ambulation, transfers, bed mobility, and self-care. A physical therapist was called in to assess Carla’s balance because she had fallen several times in her living room when her son was at work. The PT completed a comprehensive balance assessment and suspected from her findings that Carla was having problems with sensory selection, perhaps relying too much on vision for balance. She based this on her observation that Carla was hesitating and swaying as she crossed from the living room into the kitchen where a large picture window streamed light into the room, effectively blinding Carla as she entered the kitchen. The bright light from the window may have caused a visual conflict, disrupting her balance. Carla was unable to adjust quickly enough to maintain her balance. The PTs strategy was three-fold: close the kitchen curtain during the day, work with Carla to strengthen her legs and ankles to improve somatosensory function, and encourage her to use a cane to widen her base of support and provide additional proprioceptive feedback during ambulation.