Gait Disorders

A slowing of gait speed or a deviation in smoothness, symmetry, or synchrony of body movement.

For the elderly, walking, standing up from a chair, turning, and leaning are necessary for independent mobility. Gait speed, chair rise time, and the ability to perform tandem stance (one foot in front of the other) are independent predictors of the ability to perform instrumental activities of daily living (IADLs)--eg, the ability to shop, travel, and cook. Gait speed, chair rise time, and balance are also predictors of the risk of nursing home admission and death.

Walking without assistance requires the effective coordination of adequate sensation, musculoskeletal and motor control, and attention.

Normal Age-Related Changes in Gait

Gait velocity (the speed of walking) remains stable until about age 70; it then declines about 15% per decade for usual gait and 20% per decade for maximal gait. Velocity is lower because elderly people take shorter steps. Several explanations have been proposed for the shortened step length.

Cadence (the rhythm of walking) does not change with age. Each person has a preferred cadence, which relates to leg length and usually represents the most energy-efficient rhythm for individual body structure. Tall people take longer steps at a slower cadence; short people take shorter steps at a faster cadence.

Double stance (when both feet are on the ground--also referred to as double support) increases with age--from 18% in young adults to >= 26% in healthy elderly persons. During double stance, the center of mass is between the feet, which is a stable position. Increased time in the double stance position reduces momentum and therefore reduces time for the swing leg to advance and contributes to short step length. Increased double stance may be needed on uneven terrain or with impaired balance so that step length is sacrificed for stability. Elderly persons with a fear of falling increase their double stance time. Double stance time is a strong predictor of gait velocity and step length.

Walking posture (the body position during walking) changes only slightly with age. Unless elderly persons have diseases such as osteoporosis with kyphosis, they walk upright, with no forward lean. They walk with greater anterior (downward) pelvic rotation, which results in an increase in lumbar lordosis possibly due to a combination of increased abdominal fat, abdominal muscle weakness, and tight hip flexor muscles. Elderly persons also walk with about a 5° greater "toe out," possibly due to a loss of hip internal rotation or to a strategy to increase lateral stability. Foot clearance in swing is the same in elderly as in younger persons.

Joint motion changes with age. Ankle plantar flexion is reduced during the late stage of stance (just before the back foot lifts off), although maximal ankle dorsiflexion is not reduced. The overall motion of the knee is unchanged. Hip motion is unchanged in the sagittal plane but in the frontal plane shows greater adduction. Pelvic motion is reduced in the frontal and transverse planes, and transverse plane rotation is reduced.

Step length is shorter in the elderly. One explanation is that calf muscles are weak and cannot produce sufficient plantar flexion. Another is that elderly persons are reluctant to generate plantar flexion power because of poor balance and poor control of the center of mass during single stance.

Etiology and Symptoms

In health, the movement of the body is usually symmetrical. Step length, cadence, torso movement, and ankle, knee, hip, and pelvis motion are equal on the right and left sides.

Symmetry of motion and timing between left and right sides is often lost, producing regular asymmetry with unilateral neurologic or musculoskeletal disorders. Symmetric short step length usually indicates a bilateral problem. Unpredictable or highly variable gait cadence, step lengths, and stride widths indicate breakdown of motor control of gait due to a cerebellar or frontal lobe syndrome.

Pseudoclaudication symptoms--pain, weakness, and numbness with walking that improves when sitting down--may be caused by spinal stenosis. Spinal stenosis may be due to pressure or tension on portions of the spinal cord in the cervical or lumbar region.

Difficulties in initiation of gait may represent isolated gait initiation failure, evidence of Parkinson's disease, or evidence of frontal or subcortical disease. The prevalence of parkinsonian signs (bradykinesia and rigidity) is high in the elderly, increasing sharply after age 75. Once gait is initiated, steps are continuous, with little variability in the timing of the steps. Freezing, stopping, or almost stopping usually suggests a cautious gait, a fear of falling, or a frontal gait disorder.

Gait initiation failure due to high-level sensorimotor (frontal lobe or white matter) disorder may progress to other abnormalities, including stiff posture with short steps, retropulsion (falling backward) in stance, weak or poor corrective responses to perturbations of balance when walking, and a highly variable and unstable gait pattern. Normal-pressure hydrocephalus should be considered if cognitive deficits and urinary incontinence are present in combination with high-level sensorimotor gait disorders. CT or MRI helps determine if lacunar infarcts, white matter disease, or focal atrophy is present and can help determine if normal-pressure hydrocephalus should be considered.

Footdrop secondary to anterior tibialis weakness or reduced knee flexion may cause low foot swing. The cause may be spasticity or lowering of the pelvis due to muscle weakness of the proximal muscles on the stance side (particularly gluteus medius).

Short step length is nonspecific and may represent a fear of falling or a neurologic or musculoskeletal problem. The side with short step length is usually the healthy side, and the short step is usually due to a problem during the stance phase of the opposite leg. For example, a patient with a weak or painful left leg spends less time in single stance on the left leg and develops less power to move the body forward. A shorter swing time for the right leg and a shorter step result. The normal right leg propels the left side forward; a normal single stance duration provides a normal swing time for the left leg, and the forward propulsion of the body by the hip and ankle results in a longer step for the left leg than for the right leg.

Irregular and unpredictable trunk instability can be caused by cerebellar, subcortical, and basal ganglia dysfunction. A consistent or predictable trunk lean to the side of the stance leg may be a strategy with which to reduce joint pain due to hip arthritis or, less commonly, knee arthritis (antalgic gait). In a hemiparetic gait, the trunk may lean to the strong side. In this pattern, the patient leans to lift the pelvis on the opposite side to permit the limb with spasticity (inability to flex the knee) to clear the floor during the swing phase.

Deviations from path are strong indicators of motor control deficits. Wide stride width can be caused by cerebellar disease, if the width is consistent. Variable stride width suggests poor motor control, which may be due to frontal or subcortical gait disorders.

Diagnosis

Diagnosis is best approached in four parts:

• Discuss the patient's complaints, fears, and goals related to mobility
• Observe gait with and without an assistive device (if safe)
• Assess all components of gait (see Table 21-1)
• Observe gait again with a knowledge of the patient's gait components

The goal is to determine as many potential contributing factors to gait disorders as possible. A performance-oriented assessment tool may be helpful (see Table 21-2), as may other tests (eg, a screening cognitive examination for patients with gait problems due to frontal lobe syndromes).

Clinical examination: Routine assessment can be performed by a primary care physician; an expert may be needed for complex gait disorders. Assessment requires a straight hallway without distractions and a stopwatch for timing. A measuring tape and a T square or ruler with a right angle may be needed to measure stride length. Measurement of gait kinetics can only be performed reliably in a few laboratories with advanced computer and video technology.

The patient should be prepared for the examination--he should be wearing pants or shorts that reveal the knees. He should be informed that several observations may be needed and should be allowed to rest if fatigued.

Assistive devices provide stability but also affect gait. Use of walkers often results in a flexed posture and discontinuous gait, particularly if the walker has no wheels. If safe to do so, the health care practitioner can instruct the patient to walk without an assistive device, while remaining close. If a patient uses a cane, the health care practitioner can walk with the patient on the cane side or take his arm and walk with him.

Balance is impaired if the patient is unable to perform tandem stance or single leg stance for >= 5 seconds.

Proximal muscle strength is tested by having the patient get out of a chair without using his arms.

Gait velocity is measured using a stopwatch. A fixed distance (preferably 6 or 8 meters) is marked. Gait velocity in healthy elderly persons ranges from 1.5 to 1.1 meters/second.

Cadence is measured as steps/minute. Cadence varies with leg length--from about 90 steps/minute for tall adults (72 inches) to about 125 steps/minute for short adults (60 inches).

Step length (the distance from one heel strike to the next) can be measured or observed. Because shorter people take shorter steps and foot size is directly related to height, the easiest way to gauge step length is to measure or calculate the patient's foot length; normal step length is three foot lengths. The following equation calculates average step length in centimeters: 10 × velocity × time to take 10 steps. An equivalent calculation is 0.16 × velocity × cadence (steps/minute).

Step height can be assessed by observing the swing foot; if it touches the floor, the patient may trip. Some patients with fear of falling or a cautious gait syndrome will purposefully slide their feet over the floor surface.

Asymmetry or variability of gait rhythm can be detected when the health care practitioner whispers "dum...dum...dum" to himself with each of the patient's foot contacts. Some health care practitioners have a better ear than an eye for rhythm.

Prevention and Treatment

Although no large-scale prospective studies have confirmed the effect of increasing physical activity on gait and independence, prospective cohort studies provide convincing evidence that high levels of physical activity help maintain mobility, even in patients with disease. Walking may be the most important training to prescribe. The importance of deconditioning and the effects of inactivity cannot be overstated. A regular walking program of 30 minutes/day is the best single activity for maintaining mobility. A safe walking course should be recommended. The patient should be instructed to increase gait speed and duration over 4 months. Patients using assistive devices need to be trained by therapists.

Prevention also includes stretching, resistance training, and balance exercises for joint range of motion, muscle power, and motor control. The positive psychologic effects are difficult to measure but are probably just as important.

Although determining why gait is abnormal is important, interventions to alter gait are not always indicated. A slowed, aesthetically abnormal gait may enable the elderly person to walk safely and without assistance.

Frail elderly persons with mobility problems achieve modest improvements with exercise programs. Knee pain lessens in elderly persons with arthritis; gait may improve with regular walking or resistance exercises.

Resistance exercises, implemented by physical therapists, can improve strength and gait velocity, especially in frail patients with slowed gait. Two or three training sessions a week are usually needed; resistance exercises consist of three sets of 8 to 14 repetitions during each session. The load is increased every week or two until a plateau of strength is reached.

Leg press machines train all the large muscle groups of the leg and provide back and pelvic support during lifting. However, these machines are not always accessible to elderly patients. Chair rises with weight vests or weights attached to the waist are alternatives. Instructions are required to reduce the risk of back injury due to excess lumbar lordosis. Step-ups and stair climbing with the same weights are also useful. Ankle plantar flexion can be performed with the same weights.

Using knee extension machines or attaching sandbag weights to the ankle strengthens the quadriceps. The usual starting weight for frail persons is 3 kg. Resistance for all exercises should be increased every week until the patient reaches a plateau of strength.

Many patients with balance deficits benefit from balance training. Good standing posture and static balance are taught first. Patients are then taught to be aware of the location of pressure on their feet and how the location of pressure moves with slow leaning. Leans forward, backward (with a wall directly behind), and to each side are then practiced. The goal is to stand on one leg for at least 10 seconds.

Dynamic balance training can involve slow movements in single stance, simple tai chi movements, tandem walking, turns, slow forward lunges, and slow dance movements. Multicomponent balance training is probably most effective in improving balance.

Assistive devices can help maintain the patient's mobility and quality of life. New motor strategies must be learned. Ideally, physical therapists should prescribe assistive devices.

Canes are particularly helpful for pain caused by knee or hip arthritis. Canes, especially quad canes, can stabilize the patient. Canes are usually used on the side opposite the painful or weak leg. Many store-bought canes are too long. Although a cane can be purchased in a pharmacy, it should be adjusted to the correct height by cutting a wooden cane or moving the pin settings on an adjustable one. To achieve maximal support, the patient should flex his elbow 20 to 30° when holding the cane.

Walkers can reduce the force and pain at arthritic joints more than a cane, assuming adequate arm and shoulder strength. Walkers provide good lateral stability and moderate protection from forward falls but little or no help preventing backward falls for patients with balance problems. When prescribing a walker, the physical therapist should consider the sometimes competing needs of providing stability and maximizing efficiency (energy efficiency) of walking. Four-wheeled walkers with larger wheels and brakes maximize gait efficiency but provide less lateral stability. These walkers have the added advantage of a small seat to sit on if the patient is fatigued.