Balance, gait, and mobility

CASE 1 Mrs. Henderson (Part 1)

Mrs. Henderson is a 78-year-old patient in your practice. She has had depression, backache, and neck pain for years, has a 1-year history of left hip pain on ambulation, and reports a recent onset of intermittent confusion. You have managed her depression and arthritic pain with a selective serotonin reuptake inhibitor antidepressant and antiinflammatory medications. At your suggestion she has been ambulating with a quad cane for the past year as needed. Six months ago you referred her to an orthopedic surgeon, who concurred with your diagnosis of moderately severe osteoarthritis of the hip and recommended a trial of physical therapy. She attended outpatient physical therapy three times a week for a month and had some relief with range of motion and strengthening exercises, although some residual pain remained. She now reports that the pain has become severe over the past 3 months, and that the exacerbation coincided with a fall at home 3 months ago. She went to the emergency room after the fall, but radiographs revealed no fractures. She reports no loss of consciousness after the fall. She is currently on multiple medications for pain, including acetaminophen with codeine and an as-needed muscle relaxant. Her chief complaints today are pain in the hip during ambulation, and headache and neck pain.

Your examination reveals a score of 22 on the Mini-Mental State Examination, with decreased attention and disorientation, suggestive of delirium. Her score on the Geriatric Depression Scale is 8, suggesting mild residual depression. Range of motion of the left hip is decreased when compared to the right hip, and all hip motions elicit pain. She is tender on palpation of the neck musculature, with reduced range of motion and pain on neck flexion and rotation. You order radiographs of the neck, which show signs of degenerative joint disease.

1. What diagnoses would you place on her problem list?

2. What would you do next?

Prevalence and impact

The term mobility may encompass a variety of functional activities, such as transfers to and from a bed and chair, walking, stair climbing, getting in and out of vehicles, and others.¹ Difficulty ambulating and problems with general mobility are frequent complaints of older adults. Each year about 1 in every 100 older adults develops new severe mobility disability, defined as the inability to walk across a small room or the need for help from another person to do so.² Approximately 20% of noninstitutionalized older adults admit to having trouble walking or require assistance from another person or equipment to ambulate,³ and the prevalence of walking limitations in noninstitutionalized adults 85 years and older can exceed 54%.³ Finally, clinically abnormal gait, particularly with a neurologic etiology (identified later in this chapter), is associated with falls.⁴

The impact of gait and mobility deficits can be devastating for the older adult. Impairments in gait and mobility are associated with depressive symptoms,⁵ falls,⁶ functional dependence,⁷^,⁸ institutionalization,⁹ and death strength of evidence (SOE) = B).¹^,⁷

Having a problem with walking, particularly walking habitually slowly, is a strong predictor of adverse outcomes, including falls, functional dependence, and death.

Risk factors and pathophysiology

Many adults maintain normal or near normal gait and mobility well into old age. Thus gait and mobility dysfunctions are not an inevitable consequence of aging, as is often thought, but in many cases are a reflection of chronic diseases ¹⁰ or of recent or remote trauma. Age-related declines in gait speed are well documented, and are a result of decreases in stride length, rather than decreases in cadence (steps per minute).¹¹ Shorter, broader strides, longer stance, and shorter swing durations are some of the gait characteristics apparent after age 75 or 80.¹²^,¹³

Often the cause of a gait disorder is multifactorial. In one community-based sample, the prevalence of abnormal gait was 35%, split approximately evenly between neurologic and nonneurologic etiologies.⁹ A number of diseases and impairments (Table 19-1) may contribute to decreases in gait speed, including cardiopulmonary or musculoskeletal disease, reduced leg strength, poor vision, diminished aerobic function, balance problems, physical inactivity, joint impairment, previous falls, and fear of falling.^15–21 Other less common factors contributing to gait disorders include metabolic disorders related to renal or hepatic disease, tumors of the central nervous system, subdural hematoma, depression, and psychotropic medications. Hypothyroidism and hyperthyroidism and B₁₂ and folate deficiency may also be associated with reversible gait disorders.¹¹ Coimpairments, such as when leg weakness is found in the patient with balance deficits, may have a greater effect on deficits in mobility than the sum of the single impairments.¹⁵

TABLE 19-1

Diagnoses Contributing to Gait Abnormalities in Primary Care Geriatrics

Primary Diagnosis Contributing to Gait Disorder	Percentage of Cases
Osteoarthritis or an inflammatory arthritis	43
Sensory imbalances (e.g., peripheral neuropathy)	9
Parkinsonism	9
Orthostatic hypertension	9
Intermittent claudication	6
Postcerebrovascular accident	6
Congenital deformity	6
Postorthopedic surgery	3
Vertebrobasilar insufficiency	3
Heart disease	3
Idiopathic gait disorder: fear of falling	3
TOTAL	100

Adapted from Hough JC, McHenry MP, Kammer LM. Gait disorders in the elderly. Am Fam Physician 1987;35(6):191-6.

Differential diagnosis and assessment

One way of organizing a differential diagnosis for a gait disorder is to consider three levels of sensorimotor function—peripheral, subcortical, and cortical. Table 19-2 outlines for each of the three sensorimotor levels the most common conditions and gait characteristics associated with each condition.²² To this must be added consideration of diseases of other organ systems that commonly affect gait. Finally, one must consider whether medication-related effects are contributing.

TABLE 19-2

Classification of Gait Disorders by Sensorimotor Level

Adapted from Alexander NB. Differential diagnosis of gait disorders in older adults. Clin Geriatr Med 1996;12(4):689-703.

Peripheral sensorimotor deficits are divided into sensory and motor dysfunction, and include musculoskeletal (arthritic) and myopathic/neuropathic disorders (i.e., disorders distal to the central nervous system). With peripheral sensory impairment, unsteady and tentative gait is common; causes include vestibular disorders, peripheral neuropathy, posterior column (proprioceptive) deficits, and visual impairment.

With peripheral motor impairment, a number of classic gait patterns emerge, including obvious compensatory strategies. Examples of these strategies include the following:

• Trendelenburg gait (hip abductor weakness causing weight shift over the weak hip)

• Antalgic gait (avoidance of excessive weight bearing and shortening of stance on one side because of pain)

• Steppage gait (excessive hip flexion facilitating foot clearance of the ground in patients with foot drop caused by ankle dorsiflexor weakness)

These conditions involve extremity (both body segment and joint) deformities, painful weight bearing, and focal myopathic and neuropathic weakness. Note that if the gait disorder is limited to this low sensorimotor level (i.e., the central nervous system is intact), the person can adapt well to the gait disorder, compensating with an assistive device or learning to negotiate the environment safely.

Subcortical sensorimotor deficits result from lesions of the midbrain, brainstem, cerebellum, and spinal cord. At the middle level, the execution of centrally selected postural and locomotor responses is faulty, and the sensory and motor modulation of gait is disrupted. Gait may be initiated normally but stepping patterns are abnormal. Examples include the following:

• Diseases causing spasticity (such as those related to myelopathy, B₁₂ deficiency, and stroke)

• Parkinsonism (idiopathic as well as drug-induced)

• Cerebellar disease (such as alcohol induced)

Classic gait patterns appear when the spasticity is sufficient to cause leg circumduction and fixed deformities (such as equinovarus), when parkinsonism produces shuffling steps and reduced arm swing, and when cerebellar ataxia increases trunk sway sufficiently to require a broad base of gait support. Recent attention has focused on the pathophysiology, diagnosis, and therapy for freezing of gait (FOG), found commonly in parkinsonian syndromes.²³

Cortical sensorimotor deficits often involve cognitive dysfunction and slowed cognitive processing. Gait characteristics tend to be nonspecific. Behavioral factors such as fear of falling are also important, particularly in cautious gait. The presence of dementia and depression are often major contributors.

Cerebrovascular insults to the cortex and/or basal ganglia and their interconnections may relate to gait ignition failure and apraxia.²⁴^,²⁵ Cognitive, pyramidal, and urinary disturbances may also accompany the gait disorder. Gait disorders that might fall in this category have been given a number of overlapping descriptions, including gait apraxia, marche à petits pas, and arteriosclerotic (vascular) parkinsonism.

A vascular etiology has been proposed linking not only slowed gait and impaired cognitive (executive) function, but depressive symptoms as well.²⁶

A number of studies have found age- and disease-associated deficits in gait speed, often using a measure of gait variability, particularly while performing a simultaneous cognitive task (dual tasking such as talking while walking). These deficits are linked to increased fall risk. Even mild cognitive impairment (either amnestic or executive) is associated with changes in gait, such as in variability.²⁷ Note that whereas declines in cognitive function, and executive function in particular, are associated with declines in gait speed, declines in gait speed can also predict declines in cognition.²⁸

Approach to patient assessment

Patients consider pain, stiffness, dizziness, numbness, weakness, and sensations of abnormal movement to be the most common impairments contributing to walking difficulty.¹⁴ In many cases, the older adult presents with a gait disorder as a manifestation of acute or chronic disease (or in some cases, multiple diseases). Thus the aim of the primary care practitioner should be to diagnose the underlying disease state to determine whether the gait disorder is cardiovascular, musculoskeletal, or neurologic in etiology, or a result of some other pathology. Components of the clinical assessment can include the traditional history and physical examination, performance-based assessments, and laboratory and imaging tests. All of these will assist the primary care practitioner in formulating a clinical and/or impairment-based diagnosis as it relates to the gait dysfunction.