Neurology: A Clinician's Approach (Cambridge Medicine (Paperback)), 1st Ed.

18. Gait disorders

Introduction

Gait disorders and falls are common in the elderly population and frequently lead to injury or hospitalization. Because gait dysfunction may be the result of pathology at any level of the neuraxis, evaluation may be quite challenging. Unlike most neurological problems, the history is usually unhelpful: the patient may say that their legs are weak, that their legs give out on them, that they feel off balance, or simply that they fall and do not know why. The examination is usually more powerful than the history in making the diagnosis. Often, you will be able to make a very accurate guess as to the cause of gait dysfunction by watching the patient walk from the waiting area to the examining room. When this is not the case, formal gait analysis, testing provocative maneuvers, and a thorough neurological examination will allow you to localize the problem.

Natural gait

Examine natural gait by having the patient walk up and down a long hallway. Everyone can identify a normal gait intuitively, but what is less intuitive is how to describe that gait in words. Formal gait analysis is a distinct field of biomechanics and neurophysiology, but for clinical purposes, examining the following seven components is sufficient to accurately characterize normal and pathological gaits:

• Posture. Does the patient stand up straight or are they hunched over? Is the patient hyperextended at the waist and neck?

• Base. Does the patient stand with their feet close together or is their base abnormally widened? When they walk, are the medial edges of their feet separated by >6 inches?

• Initiation. When they start to walk, do they do so quickly or is there some delay?

• Stride length. Does the patient appear to be taking normal-length strides or are their strides shortened?

• Stride appearance. Do the patient’s feet elevate appropriately or do they just barely clear the ground? Does the patient land normally or awkwardly? Do they shuffle or slap the ground with their feet? Is there any posturing of the arms?

• Stability. Does the patient appear stable on their feet or do they constantly seem to be at risk of falling?

• Turns. Does the patient require more than two or three steps to turn 180°?

Over time, familiarity with abnormal gait patterns will become second nature (see “Abnormal gait patterns” below), but in unclear cases, breaking up gait into these seven components is an essential part of defining the problem.

Provocative maneuvers

Provocative maneuvers may be instrumental in revealing subtle abnormalities that are not detected by examination of natural gait.

Trendelenburg’s sign and Gowers’ sign

These are two signs of proximal muscle weakness. To test for Trendelenburg’s sign, observe the patient from behind as they stand on one foot: in patients with weakness of hip stabilization, the trunk will sink to the side of the elevated leg. Gowers’ sign is present when a patient needs to use their arms to rise from a seated position on the floor. It is usually sought in children with suspected muscular dystrophy. Normal healthy adults have greater difficulty performing this task, and similar information about proximal weakness may be obtained by finding that the patient is unable to rise from a chair while their arms are folded across their chest.

Heel and toe walking

Distal lower extremity weakness is an important source of gait difficulty. Walking on the toes requires integrity of the gastrocnemius–soleus complex and its innervation from the tibial nerve and S1 nerve root. Walking on the heels relies on the tibialis anterior innervated by the peroneal nerve and the L4–5 nerve roots. Due to the relatively greater length of the peroneal compared with the tibial nerve, heel walking tends to be impaired earlier than toe walking in patients with polyneuropathies.

Tandem gait

Although any cause of gait impairment may lead to difficulty with tandem gait, an inability to tandem walk is most often associated with an ataxic gait. To test tandem gait, instruct the patient to “walk a tightrope” or do the “drunk test” by placing one foot in front of the other, taking each step with the heel directly in front of the toe. Bear in mind that both older and obese patients who are otherwise neurologically normal perform this task poorly.

Stress gait

This test may be instrumental in establishing a diagnosis of early Parkinson’s disease. To test stress gait, ask the patient to walk on the sides of their feet. While they are doing this, observe their hands and arms for subtle tremor or posturing indicative of extrapyramidal dysfunction.

Pull test

This test is commonly performed when an extrapyramidal disorder is suspected. Because this test poses a serious possibility of injury, perform it with caution. Instruct the patient to stand with their feet spread slightly apart and their arms abducted approximately 15° away from the trunk. Stand behind them and tell them that you will pull them and that they will need to maintain their balance. Prepare to catch the patient should they fall, and then briskly pull them backwards by the shoulders. They should require at most one step backwards to correct their balance. Sufficiently advanced Parkinson’s disease may cause postural instability, and the patient will require multiple steps to correct their balance or may even fall backwards into your arms.

Romberg’s sign

Rombergism reflects disorders of the proprioceptive or vestibulocerebellar systems. To test for Romberg’s sign, first ask the patient to stand with their feet placed together, and make sure that they can keep their balance. Next, instruct them to close their eyes. Most patients with mild proprioceptive deficits will sway when their eyes are closed. The strict definition of a positive Romberg’s sign, however, requires that the patient actually falls when this test is performed.

General neurological examination

Confirm all abnormalities detected by gait observation with a thorough neurological examination. In some cases, the general examination will disclose an explanation for gait impairment that was not uncovered by gait analysis or provocative maneuvers. Prior to concluding that the source of a patient’s gait abnormality is neurological, perform musculoskeletal, ophthalmological, and peripheral vascular examinations to look for evidence of dysfunction in other organ systems that may lead to instability and falls.

Abnormal gait patterns

Frontal gait

A patient with a frontal gait disorder initiates walking with difficulty, elevates their feet minimally, and takes small, short steps. Sometimes this pattern of gait is labeled as “apraxic,” a term that is more properly reserved for disorders of learned movement. Frontal gait disorder is often accompanied by dementia. Common causes of frontal gait disorder include the multi-infarct state and normal pressure hydrocephalus (Chapter 4).

Spastic gait

Chronic corticospinal tract lesions result in a spastic gait in which the affected leg is stiff and hyperextended. The leg is circumducted (swung out from the hip in an arc) rather than moved back and forth in the sagittal plane. Corticospinal tract lesions within the brain such as stroke, demyelinating disease, or brain tumor produce contralateral spasticity that also involves the arm. Lesions of the frontal convexity may affect the leg in isolation. Spastic gait is also the characteristic abnormality of patients with myelopathy (Chapter 15), in which case the two legs tend to be involved relatively symmetrically.

Parkinsonian gait

In early Parkinson’s disease (PD), gait may be affected minimally or not at all (Chapter 13). The earliest abnormalities may be slightly reduced arm swing or asymmetric hand posturing or tremor that appear upon stress gait testing. Patients with fully developed PD are hunched over, initiate slowly, and take short strides. They turn slowly and require multiple steps to do so. Postural instability may be elicited by performing the pull test. Advanced PD may be associated with festination and freezing. Festination is a distinctive gait abnormality characterized by tiny steps, which progressively increase in velocity to the point that the patient appears to be running in place. Freezing, as its name suggests, occurs when a patient comes to a complete stop while walking and cannot seem to reinitiate their gait.

Progressive supranuclear palsy gait

Gait difficulty and frequent falls are early features of progressive supranuclear palsy (PSP) (Chapter 13). Although the natural gait is often somewhat nonspecific in its appearance, patients with PSP are classically hyperextended at the neck and trunk and fall backwards.

Ataxic gait

Gait ataxia is characterized by veering from side to side with over- and understepping of the target. Falls and injury are perhaps less frequent than might be expected, often because ataxic patients quickly realize their instability and avoid walking altogether. Gait ataxia is classically associated with peripheral and central lesions of the vestibulocerebellar system. However, patients with dorsal column or large-fiber peripheral nerve disorders account for the majority of patients with gait ataxia in clinical practice.

Waddling gait

Disorders affecting the proximal musculature, especially the hip flexors and trunk stabilizers, lead to waddling (Chapter 10). The patient is not able to elevate their legs sufficiently to clear the ground, and as a result, must shift their weight from side to side and rotate the trunk in order to make forward progress. Signs of proximal weakness that accompany waddling include Trendelenburg’s sign and Gowers’ sign. Common localizations of proximal muscle weakness include the muscle, neuromuscular junction, and motor neurons.

Steppage gait

Foot drop is most commonly the consequence of lesions of the motor neurons, L4 or L5 nerve roots, or peroneal nerve (Chapter 11). In order for the foot to clear the ground, a patient with dorsiflexion weakness lifts their hip and knee in an exaggerated fashion, leading to the high step that lends this gait abnormality its name. The foot strikes the ground heavily and sometimes it is the slapping sound as the patient walks rather than the appearance of foot drop that is most helpful in making the diagnosis. Steppage may be corrected with an ankle foot orthosis to stabilize the ankle joint and allow normal foot elevation.

Antalgic gait

Any cause of lower extremity pain may produce an antalgic gait in which the patient steps gingerly on the affected side while placing the bulk of their weight on the unaffected leg. Careful musculoskeletal and neurological assessment is needed to separate an antalgic gait from one caused by neurological dysfunction. Antalgic gait improves if the source of pain is identified and treated appropriately.

Psychogenic gait

Gait dysfunction may be the sole manifestation of malingering or conversion disorder. While the veering, unsteady, often bizarre gait seen in many patients with psychogenic gait disorders most closely resembles ataxia, psychogenic gait may mimic any abnormal pattern. Clues to the presence of a psychogenic gait disorder include the absence of injury during falls, fluctuating severity and semiology over time, and normal ambulation when the patient thinks that they are not being observed. The diagnosis of a psychogenic gait disorder may be made, however, only after organic disease is exhaustively excluded. Tactful psychiatric evaluation and treatment is the most effective treatment for psychogenic gait disorders.

Multifactorial gait disorder

It may be difficult or impossible to isolate the source of gait dysfunction to a single site in the nervous system. Patients with more than one contributor, by definition, have a multifactorial gait disorder. This condition is particularly common in the elderly, in whom osteoarthritis, parkinsonism, cervical myelopathy, and polyneuropathy are common and frequently coexist. For patients with multifactorial gait disorder, examination of the individual components of the nervous system is generally more helpful than gait analysis. Although they may derive modest benefit from physical therapy, many patients with multifactorial gait disorder require canes, walkers, or motorized scooters.

General recommendations for patients with frequent falls

Obviously, any reversible neurological causes of frequent falls should be identified and treated. In many cases this is not possible, and preventive therapy becomes the mainstay of treatment. Appropriate pain treatment and correction of orthopedic infirmities may eliminate some falls or help restore normal ambulation. Counsel patients to wear sensible shoes and avoid long pant legs and dresses, which may lead to tripping. Home safety evaluation is invaluable in reducing the risk of falls, as it often uncovers easily correctable fall precipitants including excessive clutter, poorly placed rugs, slippery surfaces, and uneven floors. Many patients ultimately require walking sticks, canes, walkers, or wheelchairs to avoid frequent falls. These should be prescribed in conjunction with a physical therapist or physiatrist.