Because normal body posture and locomotion require intact vestibular function, proprioception, and vision (we see where we are going and adjust our steps), the effects of deficits in these senses are worth noting. A blind person—or a normal one who is blindfolded or walks in the dark—moves cautiously, with arms slightly forward to avoid collisions, and shortens his step slightly on a smooth surface; with shortening of the step, there is less rocking of the body and the gait is unnaturally stiff and cautious.
Patients with a chronic vestibulopathy show unsteadiness in standing and walking, often without widening their base, and an inability to descend stairs without holding onto the banister. They complain of a particular type of imbalance, usually with movement but at times when standing still—a sensation that may be likened to being on the deck of a rolling ship. Running and turning quickly are even more impaired, with lurching in all directions. The patient has great difficulty in focusing his vision on a fixed target when he is moving or on a moving target when he is either stationary or moving. When the body is in motion or the head is moved suddenly, objects in the environment may appear momentarily blurred or actually jiggle up and down or from side to side (oscillopsia). Driving a car or reading on a train is difficult or impossible; even when walking, the patient may need to stop in order to read a sign. These abnormalities indicate a loss of stabilization of ocular fixation by the vestibular system during body movements (the vestibular-ocular reflex, or VOR). An elderly person has difficulty compensating for these abnormalities. Proof that the gait of such persons with vestibulopathy is dependent on visual clues comes from their performance blindfolded or in the dark, when their unsteadiness and staggering increase to the point of falling. When standing with eyes closed, they sway more than normal but generally do not fall over (i.e., they do not have a Romberg sign, as described below). The diagnosis is confirmed by testing labyrinthine function (caloric and rotational testing, electronystagmography, and posture platform testing).
Chronic disorders of vestibular function in relation to gait disorders are most often the result of prolonged administration of aminoglycoside antibiotics or other toxic medications, which destroy the hair cells of the vestibular labyrinth. Vestibular suppressants, such as meclizine and similar medications, mostly anticholinergic and antihistaminic that are available over the counter, can lead to decreased function of the vestibular system, with a persistent gait disorder, if used for more than a few weeks. This also occurs in some patients in the late stages of Ménière disease and, infrequently, for no definable reason. The literature is replete with references to a "multimodal" gait disorder in the elderly that is the result of an ostensible aging of the vestibular organ, together with impaired proprioceptive function caused by distal neuropathy in the elderly, and impaired vision.
A loss of proprioception—as occurs in patients with severe large-fiber polyneuropathy, posterior nerve root lesions (e.g., tabes dorsalis, lumbosacral compression), or interruption of the posterior columns in the spinal cord (multiple sclerosis, vitamin B12 deficiency, spondylotic or tumor compression)—abolishes or seriously impairs the capacity for independent locomotion. After years of training, such patients still have difficulty in initiating gait and in forward propulsion. As J. Purdon Martin illustrated, they hold their hands slightly in front of the body, bend the body and head forward, walk with a wide base and irregular, uneven steps, but still rock the body. If they are tilted to one side, they fail to compensate for their abnormal posture. If they fall, they cannot rise without help; they are sometimes unable to crawl or to get into an "all fours" posture. They have difficulty in getting up from a chair. When standing, if instructed to close their eyes, they sway markedly and fall (Romberg sign); this sign is the clearest indication that the origin of the problem is a loss of proprioceptive sensibility.
With lesions of the basal ganglia, both in monkeys and in humans, the posture of the body and the postural responses to perturbations in equilibrium are faulty. There is difficulty in taking the first step; once it is taken, and in extreme cases, the body pitches forward and a fall can be prevented only by catch-up stepping (propulsive festination). Similarly, a step backward may induce a series of quickening steps in that direction (retropulsive fesitnation). Corrective righting reflexes are clearly faulty when the patient is pushed off balance (Denny-Brown). These abnormalities are elaborated further on, under "Parkinsonian and Festinating Gait."
Pain in the hips or knees can lead to a disorder (antalgic gait) that can be challenging to distinguish from neurological causes of gait problems. Slowness of the swing phase and reduction in the amount of time spent with the painful limb in contact with the ground may be clues to recognizing rheumatological and orthopedic causes of a gait disorder.
Examination of the Patient with Abnormal Gait
When confronted with a disorder of gait, the examiner must observe the patient's stance and the dominant positions of the legs, trunk, and arms, and their interrelationship. It is good practice to watch patients as they walk into the examining room, when they are apt to walk more naturally than during the performance of commanded tasks. They should be asked to stand with feet together and head erect, with eyes open and then closed. A normal person can stand with feet together and eyes closed while moving the head from side to side, a test that blocks both visual and vestibular cues and induces certain compensatory trunk and leg movements that depend solely on proprioceptive afferent mechanisms (Ropper). As already mentioned, the Romberg sign—marked swaying or falling with the eyes closed but not with the eyes open—usually indicates a loss of postural sense, not of cerebellar function, although with vestibular or cerebellar disease there may be an exaggeration of swaying. Swaying due to of nervousness may be overcome by asking the patient to touch the tip of his nose alternately with the forefinger of one hand and then the other.
Next, the patient should be asked to walk, noting in particular any hesitation in starting and negotiating turns, width of base, length of stride, foot clearance, arm swing, and cadence. A tendency to veer to one side, as occurs with unilateral cerebellar or vestibular disease, can be brought out by having the patient walk around a chair. When the affected side is toward the chair, the patient tends to walk into it; when it is away from the chair, there is a veering outward in ever-widening circles. More delicate tests of gait are walking a straight line heel to toe ("tandem walking test"), walking backward, and having the patient arise quickly from a chair, walk briskly, stop and turn suddenly, walk back, and sit down again. Turning the patient three full revolutions with eyes open, first right and then left, each time followed by asking the patient to walk naturally, allows the examiner to stress the vestibular apparatus and to compare the two sides. The patient affected by a vestibular or cerebellar process will veer to the side of a lesion. Marching in place with eyes closed (Unterberger, or Fukada stepping tests) also reveals a rotation in the yaw plane (rotation around the vertical axis), indicating an asymmetrical disorder in the plane of the horizontal semicircular ducts or their connections.
It is instructive to observe the patient's postural reaction to a sudden push or tug backward at the shoulders and forward or to the side. With postural instability of any type there is a delay or inadequacy of corrective actions. Finally, the patient may be asked to hop on one leg and to jog. If all these tests can be successfully executed, it may be assumed that any difficulty in locomotion is not because of impairment of a proprioceptive, labyrinthine-vestibular, basal ganglionic, or cerebellar mechanism. Detailed musculoskeletal and neurologic examination is then necessary to determine which of several other disturbances of function is responsible for the patient's disorder of gait.
The following types of abnormal gait (Table 7-1) are so distinctive that, with practice, they can be recognized at a glance and interpreted correctly.
Table 7-1 Features of Gait Abnormalities ||Download (.pdf)
Table 7-1 Features of Gait Abnormalities
OTHER ASSOCIATED SIGNS
Erratic shifting of weight and step
Sensory ataxic (tabetic)
Excessive force in step resulting in stamping of feet; Romberg sign
Overlifting and slapping of feet
Circumduction and scraping of affected leg(s)
Twisting athetoid movements interrupt walking
Slow until festination
Quickening step, forward leaning, shuffling, may have trouble with gait initiation
Overlifting of hip(s)
Slow until fall
Sudden loss of balance
Normal pressure hydrocephalus
Numerous problems with axial body movement
Slightly wide (protective)
Difficulty starting and stopping; tendency for feet to "stick" to floor
Aging and marche à petit pas
Cautious, slight forward lean
The main features are a wide base (separation of legs), unsteadiness, irregularity of steps, and lateral veering. Steps are uncertain, some are shorter and others longer than intended, and the patient may compensate for these abnormalities by shortening his steps or even keeping both feet on the ground simultaneously, which creates the appearance of shuffling. Cerebellar gait is often referred to as "reeling" or "drunken," but these terms are not correct and are characteristic instead of intoxication and of certain types of labyrinthine disease, as explained further on.
With cerebellar ataxia, the unsteadiness and irregular swaying of the trunk are prominent when the patient arises from a chair or turns suddenly while walking and may be most evident when he has to stop walking abruptly and sit down; it may be necessary to grasp the chair for support. Cerebellar ataxia may be so severe that the patient cannot sit without swaying or assistance. If it is less severe, standing with feet together and head erect is difficult. In its mildest form, the ataxia is best demonstrated only by having the patient walk a line heel to toe; after a step or two, he loses his balance and finds it necessary to place one foot to the side to avoid falling.
As already emphasized, the patient with cerebellar ataxia who sways perceptibly when standing with feet together and eyes open will sway somewhat more with eyes closed. This slight increase in swaying may lead misattribution to a cerebellar sign of what is simply loss of proprioceptive input to the cerebellum. By contrast, removal of visual clues from a patient with proprioceptive loss causes a marked increase in swaying or falling (the Romberg sign). Thus, the defect in cerebellar disease is primarily in the coordination of the sensory input from proprioceptive, labyrinthine, and visual information with reflex movements, particularly those that are required to make rapid adjustments to changes in posture and position. This integrative deficiency is also reflected in the stepping test, in which the patient is asked to march on the spot with eyes closed as already mentioned. Those with vestibular and sometimes unilateral cerebellar disease have difficulty remaining stable and have a tendency to turn to the left or right or to move forward (occasionally backward) after 5 or 10 steps.
Cerebellar abnormalities of stance and gait are usually accompanied by signs of cerebellar incoordination of the legs, but they need not be. The presence of the latter signs depends on involvement of the cerebellar hemispheres as distinct from the anterosuperior (vermian) midline structures that dominate in the control of gait as described in Chap. 5. If the cerebellar lesions are bilateral, there is often titubation (tremor) of the head and trunk.
Cerebellar gait is seen most commonly in patients with multiple sclerosis, cerebellar tumors (particularly those affecting the vermis—e.g., medulloblastoma), stroke (ischemic and hemorrhage) paraneoplastic cerebellar syndrome, and prominently, in the cerebellar degenerations. Walking without the support of a cane or the arm of a companion brings out a certain stiffness of the legs and firmness of the muscles. The latter abnormality may be analogous to positive supporting reactions observed in cats and dogs following ablation of the anterior vermis; such animals react to pressure on the foot pad with an extensor thrust of the leg.
Reeling Gait of Intoxication
This is characteristic of inebriation with alcohol, sedative drugs, and antiepileptic drugs. The drunken patient totters, reels, tips forward and then backward, appearing each moment to be on the verge of losing his balance and falling. Control over the trunk and legs are greatly impaired. The steps are irregular and uncertain. Such patients appear indifferent to the quality of their performance, but under certain circumstances they can momentarily correct the defect. As indicated above, the adjectives drunken and reeling are used frequently to describe the gait of cerebellar disease, but the similarities between them are only superficial. The severely intoxicated patient reels or sways in many different directions and seemingly makes little or no effort to correct the staggering by watching his legs or the ground, as occurs in cerebellar or sensory ataxia. Also, the variability of the drunken gait is noteworthy. Despite wide excursions of the body and deviation from the line of march, the drunken patient may, for short distances, be able to walk on a narrow base and maintain his balance. In contrast, the patient with cerebellar gait has great difficulty in correcting his balance if he sways or lurches too far to one side. Milder degrees of the drunken gait more closely resemble the gait disorder that follows loss of labyrinthine function (see earlier discussion).
This disorder is caused by an impairment of joint position or muscular kinesthetic sense resulting from interruption of afferent nerve fibers in the peripheral nerves, posterior roots, sensory ganglia, posterior columns of the spinal cords, or medial lemnisci, and occasionally from a lesion of both parietal lobes. Whatever the location of the lesion, its effect is to deprive the patient of knowledge of the position of his limbs and, more relevant to gait, to interfere with a large amount of afferent proprioceptive and related information that does not attain conscious perception. A sense of imbalance is usually present but these patients do not describe dizziness. They are aware that the trouble is in the legs and not in the head, that foot placement is awkward, and that the ability to recover quickly from a misstep is impaired. The resulting disorder is characterized by varying degrees of difficulty in standing and walking; in advanced cases, there is a complete failure of locomotion, although muscular power is retained.
The principal features of sensory-ataxic gait are the brusqueness of movement of the legs and stamping of the feet as the foot is forcibly brought down onto the floor (apparently to detect the location of the foot as a substitute for proprioception). The feet are placed far apart to correct the instability, and patients carefully watch both the ground and their legs. As they step out, their legs are flung abruptly forward and outward, in irregular steps of variable length and height. The body is held in a slightly flexed position, and some of the weight is supported on the cane that the severely ataxic patient usually carries. To use Ramsay Hunt's characterization, the patient with this gait disorder is recognized by his "stamp and stick." The most specific feature is that the ataxia is markedly exaggerated when the patient is deprived of visual cues, as in walking in the dark. Such patients, when asked to stand with feet together and eyes closed, show greatly increased swaying and usually, the fully expressed Romberg sign with falling off to one side. It is said that in cases of sensory ataxia, the shoes do not show wear in any one place because the entire sole strikes the ground at once. Examination usually discloses a loss of position sense in the feet and legs and usually of vibratory sense as well. The peripheral or central location of the sensory lesions can be further determined by the state of the tendon reflexes.
Formerly, a disordered gait of this type was observed most frequently with tabes dorsalis, hence the term tabetic gait; but it is also seen in Friedreich ataxia and related forms of spinocerebellar degeneration, subacute combined degeneration of the spinal cord (vitamin B12 deficiency), a large number of sensory polyneuropathies, and those cases of multiple sclerosis or compression of the spinal cord (spondylosis and meningioma are the common causes) in which the posterior columns are involved.
Steppage or Equine Gait (Foot-Drop Gait)
This gait pattern is caused by paralysis of the pretibial and peroneal muscles, with resultant inability to dorsiflex the foot (foot drop). The steps are regular and even, but the advancing foot hangs with the toes pointing toward the ground. In its purest form it is the result of peroneal nerve or fifth lumbar root damage. Walking is accomplished by excessive flexion at the hip, the leg being lifted abnormally high in order for the foot to clear the ground. There is a slapping noise as the foot strikes the floor. Thus there is a superficial similarity to the tabetic gait, especially in cases of severe polyneuropathy, where the features of steppage and sensory ataxia may be combined. However, patients with steppage gait alone are not troubled by a perception of imbalance; they fall from tripping on carpet edges and curbstones.
Foot drop may be unilateral or bilateral and occurs in diseases that affect the peripheral nerves of the legs or motor neurons in the spinal cord, such as chronic acquired neuropathies (diabetic, inflammatory, toxic, and nutritional), Charcot-Marie-Tooth disease (peroneal muscular atrophy), progressive spinal muscular atrophy, and poliomyelitis. It may also be observed in certain types of muscular dystrophy in which the distal musculature of the limbs is involved.
A particular disorder of gait, also of peripheral origin and resembling steppage gait, may be observed in patients with painful dysesthesias of the soles of the feet. Because of the exquisite pain evoked by tactile stimulation of the feet, the patient treads gingerly, as though walking barefoot on hot sand or pavement, with the feet rotated in such a way as to limit contact with their most painful portions. The usual cause is one of the painful peripheral neuropathies (most often alcoholic-nutritional but also toxic and amyloid types), causalgia, or erythromelalgia.
Hemiplegic and Paraplegic (Spastic) Gaits
The patient with hemiplegia or hemiparesis holds the affected leg stiffly and does not flex it freely at the hip, knee, and ankle. The leg tends to rotate outward to describe a semicircle, first away from and then toward the trunk (circumduction). The foot scrapes the floor, contact being made by the toe and outer sole of the foot. One can recognize a spastic gait by the sound of slow, rhythmic scuffing of the foot and wearing of the medial toe of the shoe. The arm on the affected side is weak and stiff to a variable degree; it is carried in a flexed position and does not swing naturally. In the hemiparetic child, the arm tends to abduct as he steps forward. This type of gait disorder is most often a sequela of stroke or trauma but may result from any condition that damages the corticospinal pathway on one side.
The spastic paraplegic or paraparetic gait is, in effect, a bilateral hemiplegic gait. Each leg is advanced slowly and stiffly, with restricted motion at the hips and knees. The legs are extended or slightly bent at the knees and the thighs may be strongly adducted, causing the legs almost to cross as the patient walks (scissor-like gait). The steps are regular and short and the patient advances only with great effort as though wading waist-deep in water. The defect is in stiffness of the stepping mechanism and in propulsion, not in support or equilibrium.
A spastic paraparetic gait is the major manifestation of cerebral diplegia (Little disease, a type of cerebral palsy), the result of anoxic or other damage to the brain in the perinatal period. This disorder of gait is also seen in a variety of chronic spinal cord diseases involving the dorsolateral and ventral tracts, most often multiple sclerosis, but also including syringomyelia, any type of chronic meningomyelitis, subacute combined system disease of both the pernicious anemia and nonpernicious anemia types, spinal cord compression or traumatic injury, adrenomyeloneuropathy, and familial forms of spastic paraplegia. Frequently in these diseases, the effects of posterior column disease are added, giving rise to a mixed gait disturbance—a spinal spastic ataxia, characteristic of multiple sclerosis and certain spinal cord degenerations such as Friedreich ataxia.
Parkinsonian and Festinating Gait
Diminished or absent arm swing, forward bent torso, short or shuffling steps, turning en bloc, hesitation in starting to walk, shuffling, or "freezing" when encountering doorways or other obstacles are the features of the parkinsonian gait. When they are joined to the typical tremor, unblinking and mask-like facial expression, general attitude of flexion, and poverty of movement, there can be little doubt as to the diagnosis. The arms are carried slightly flexed and ahead of the body and do not swing. The legs are stiff and bent at the knees and hips. The steps are short, and the feet barely clear the ground as the patient shuffles along.
Once walking has started, the upper part of the body advances ahead of the lower part, and the patient is impelled to take increasingly short and rapid steps as though trying to catch up to his center of gravity. The steps become more and more rapid, and the patient could easily break into a trot and collide with an obstacle or fall if not assisted. The term festination derives from the Latin festinare, "to hasten," and appropriately describes the involuntary acceleration or hastening that characterizes the gait of patients with Parkinson disease. Festination may be apparent when the patient is walking forward or backward. The defects are in rocking the body from side to side, so that the feet can clear the floor, and in moving the legs quickly enough to overtake the center of gravity. The problem is compounded by the inadequacy of postural support reflexes, demonstrable in the standing patient by falling in response to a push against the sternum or a tug backward on the shoulder. A normal person readily retains his stability or adjusts to modest displacement of the trunk with a single step, but the parkinsonian patient may lean backward with the upper torso and then stagger or fall unless someone stands by to prevent it.
Quite often, one encounters an elderly patient with only the instability and freezing components of the parkinsonian gait disorder, so-called lower-half parkinsonism. Usually, this is not a manifestation of idiopathic Parkinson disease although a few patients are responsive to L-dopa for a brief period. It may be an early manifestation of progressive supranuclear palsy, a basal ganglionic degeneration, normal pressure hydrocephalus, or widespread subcortical vascular damage as discussed further on in this chapter, but it also occurs as a virtually isolated phenomenon that progresses independently of other movement disorders or of dementia. The basis is then probably a particular isolated frontal lobe degeneration (see further on). Within a few years, as pointed out by Factor and colleagues in their two papers, the patient is usually reduced to a chair-bound state.
Other very unusual gaits are sometimes observed in Parkinson disease and were particularly prominent in the postencephalitic form, which is now practically extinct. For example, such a patient may be unable to take a step forward or does so only after he takes a few hops or one or two steps backward (aptly mimicked by the Monty Python troupe in their skit, "Ministry of Silly Walks"). Or walking may be initiated by a series of short steps or a series of steps of increasing size. Occasionally such a patient may run better than he walks or walk backward better than forward. Often, walking so preoccupies the patient that talking simultaneously is impossible for him and he must stop to answer a question.
Choreoathetotic and Dystonic Gaits
Diseases characterized by involuntary movements and dystonic postures seriously affect gait. In fact, a disturbance of gait may be the initial and dominant manifestation of such diseases, and the testing of gait often brings out abnormalities of movement of the limbs and posture that are otherwise not conspicuous.
As the patient with congenital athetosis or Huntington chorea stands or walks, there is a continuous play of irregular movements affecting the face, neck, hands, and, in the advanced stages, the large proximal joints and trunk. The position of the arms and upper parts of the body varies with each step, at times giving the impression of a puppet. There are jerks of the head, grimacing, squirming and twisting movements of the trunk and limbs, and peculiar respiratory noises. One arm may be thrust aloft and the other held behind the body, with wrist and fingers undergoing alternate non-rhythmic flexion and extension, supination and pronation. The head may incline in one direction or the other, the lips alternately retract and purse, and the tongue intermittently protrudes from the mouth. The legs advance slowly and awkwardly, the result of superimposed involuntary movements and postures. Sometimes the foot is plantarflexed at the ankle and the weight is carried on the toes; or the foot may be dorsiflexed or inverted. An involuntary movement may cause the leg to be suspended in the air momentarily, imparting a lilting or waltzing character to the gait, or it may twist the trunk so violently that the patient may fall.
In dystonia musculorum deformans and focal dystonias, the first symptom may be a limp caused by inversion or plantarflexion of the foot or a distortion of the pelvis as discussed in Chap. 4. One leg may be rigidly extended or one shoulder elevated, and the trunk may assume a position of exaggerated flexion, lordosis, or scoliosis. Because of the muscle spasms that deform the body in this manner, the patient may have to walk with knees flexed. The gait may seem normal as the first steps are taken, the abnormal postures asserting themselves as the patient continues to walk. Prominence of the buttocks owing to a lumbar lordosis, combined with flexion of one or both legs at the hip, gives rise to the so-called dromedary gait of Oppenheim. In the more advanced stages, walking becomes impossible owing to torsion of the trunk or the continuous flexion of the legs.
Stiff-person syndrome, an unusual nondystonic disorder causing severe axial muscle spasm, imparts a characteristic appearance of stiffness of the legs and buttock muscles, slow propulsion, and lumbar lordosis; there is sometimes a mild superimposed ataxic disturbance of gait (see Chap. 55). Another unusual disorder affecting the body position during walking is camptocormia, a severe forward bending of the trunk at the waist that is symptomatic of either a dystonia, Parkinson disease, or one of several muscle diseases that focally weaken the extensors of the spine. Kyphosis because of spinal deformities does the same and all of these conditions cause the patient to walk while looking at the ground beneath the feet, but they rarely cause falling.
Chapter 4 more fully describes the general features of the gaits of choreoathetosis and dystonia.
Waddling (Gluteal, or Trendelenburg) Gait
This gait is characteristic of the gluteal muscle weakness that is seen in the progressive muscular dystrophies, but it occurs as well in chronic forms of spinal muscular atrophy, in certain inflammatory myopathies, lumbosacral nerve root compression, and with congenital dislocation of the hips.
In normal walking, as weight is placed alternately on each leg, the hip is fixated by the gluteal muscles, particularly the gluteus medius, allowing for a slight rise of the opposite hip and tilt of the trunk to the weight-bearing side. With weakness of the glutei, however, there is a failure to stabilize the weight-bearing hip, causing it to bulge outward and the opposite side of the pelvis to drop, with inclination of the trunk to that side. The alternation in lateral trunk movements results in the roll or waddle. With unilateral gluteal weakness, often the result of damage to the first sacral nerve root, tilting and dropping of the pelvis ("pelvic ptosis") is apparent on only one side as the patient overlifts the leg when walking.
In several of the muscular dystrophies, an accentuation of lumbar lordosis is often seen. Also, childhood cases may be complicated by muscular contractures, leading to an equinovarus position of the foot, so that the waddle is combined with walking on the toes ("toe walking").
Toppling, meaning tottering and falling, occurs with brainstem and cerebellar lesions, especially in the older person following a stroke. It is a frequent feature of the lateral medullary syndrome, in which falling occurs to the side of the infarction. In patients with vestibular neuronitis, falling also occurs to the same side as the lesion. With midbrain strokes, the falls tend to be backward. In patients with progressive supranuclear palsy (discussed in Chap. 39), where dystonia of the neck is combined with paralysis of vertical gaze and pseudobulbar features, unexplained falling is often an early and prominent feature. The falls of progressive supranuclear palsy may derive from such a disorder of the righting mechanism. In the advanced stages of Parkinson disease, falling of a similar type may be a serious problem, but it is more surprising how relatively infrequently it occurs. In addition, the gait is uncertain and hesitant—features that are enhanced, no doubt, by the hazard of falling unpredictably. The cause of the toppling phenomenon is unclear; it does not have its basis in weakness, ataxia, or loss of deep sensation. It appears to be a disorder of balance that is occasioned by precipitant action or the wrong placement of a foot and by a failure of the righting reflexes. Slowness of motor response is another factor.
In a related defect caused by a vestibular disorder, the patient may describe a sense of being pushed (pulsion) rather than of imbalance. It is most fully manifest in the lateral medullary syndrome. In midbrain disease, including progressive supranuclear palsy, a remarkable feature is the lack of appreciation of a sense of imbalance.
Primary Orthostatic Tremor
This unusual fast tremor of the legs may devastate gait. As discussed in Chap. 6, it is present only when the patient stands or exerts force with the legs while seated. The tremor ceases upon walking. In reaction to a perception of severe imbalance, which is characteristic of the disorder, the patient assumes a widened and often stiff-legged stance.
Gait Disorder in Normal-Pressure Hydrocephalus (See Also Chap. 30)
Progressive difficulty in walking is typically the initial and most prominent symptom of normal-pressure hydrocephalus (NPH), a disorder of cerebrospinal fluid (CSF) circulation. However, the gait disturbance in NPH has few specific features. Certainly it cannot be categorized as an ataxic or spastic gait or what has been described as an "apraxic" gait; nor does it have more than a superficial resemblance to the parkinsonian gait. Its main features—slowed cadence, widened base and short steps—are the natural compensations observed in patients with all manner of gait disorders. Patients with the gait disorder of NPH may complain of a sense of imbalance or vague dizziness, but most have difficulty in articulating the exact problem. Like most patients with disorders of frontal lobe function, they are better able to carry out the motions of stepping while supine or sitting but have difficulty in taking steps when upright or attempting to walk. If these patients are observed as they get on and off an examining table and in and out of bed, they display poor management of the entire axial musculature, moving their bodies without shifting the center of gravity or adjusting their limbs appropriately. Changes in posture, even rolling over in bed, are made en bloc. The erect posture is assumed in an awkward manner—with hips and knees only slightly flexed and stiff and a delay in swinging the legs over the side of the bed.
Tone in the leg muscles of the NPH patient is often slightly increased, with a tendency to cocontraction of flexor and extensor muscle groups. Walking is perceptibly slower than normal, the body is held stiffly, arm swing is diminished, and there is a tendency to fall backward—features that are reminiscent of Parkinson disease, although the lack of arm swing and the stooped posture are more prominent in Parkinson disease than in NPH and, of course, the other major features of Parkinson disease are lacking. We have been impressed that NPH causes parkinsonian shuffling only when the hydrocephalus is very advanced.
As with the related "frontal gait," described below, patients with NPH often have difficulty initiating gait and have short steps that are helped by marching to a cadence or in step with the examiner. In patients with untreated NPH, one observes a progressive deterioration of stance and gait—from an inability to walk to an inability to stand, sit, and rise from or turn over in bed. There is no hint of ataxia but a study of the mechanics of the gait in NPH by Stolze and colleagues described a widened base and slight outward rotation of the feet. Also distinguishing the gait of NPH from that of Parkinson disease in their study was a response in the latter to acoustic and visual cues for cadence. Sudarsky and Simon quantified these defects by means of high-speed cameras and computer analysis. They reported a reduction in height of step, an increase in sway, and a decrease in rotation of the pelvis and counter-rotation of the torso.
Frontal Lobe Disorders of Gait
Standing and walking may be severely disturbed by diseases that affect the frontal lobes, particularly their medial parts and their connections with the basal ganglia. This disorder is sometimes spoken of as a frontal lobe as an "apraxia of gait" among numerous other labels, because the difficulty in walking cannot be accounted for by weakness, loss of sensation, cerebellar incoordination, or basal ganglionic abnormality. Whether the gait disorder should be designated as an apraxia, in the sense of the original concept of the loss of ability to perform a learned act, is questionable, as walking is instinctual and not learned. Patients with so-called apraxia of gait do not have apraxia of individual limbs, particularly of the lower limbs; conversely, patients with apraxia of the limbs usually walk normally. More likely, the frontal gait disorder represents a loss of integration, at the cortical and basal ganglionic levels, of the essential elements of stance and locomotion that are acquired in infancy and often lost in old age.
Patients typically assume a posture of slight flexion with the feet placed farther apart than normal. They advance slowly, with small, shuffling, hesitant steps. At times they halt, unable to advance without great effort, although they do much better with a little assistance or with exhortation to walk in step with the examiner or to a marching cadence. Walking and turning are accomplished by a series of tiny, uncertain steps that are made with one foot, the other foot being planted on the floor as a pivot.
"Lower-half" Parkinson has been applied to the pattern as mentioned earlier but the cause is rarely idiopathic Parkinson disease. The term "marche à petit pas" is used when the cause is vascular damage to the frontal white matter. There is a need to seek support from a companion's arm or nearby furniture. The initiation of walking becomes progressively more difficult; in advanced cases, the patient makes only feeble, abortive stepping movements in place, unable to move his feet and legs forward; eventually, the patient can make no stepping movements whatsoever, as though his feet were glued to the floor. These late phenomena have been referred to as "magnetic feet" and the difficulty initiating gait as "slipping clutch" syndrome (Denny-Brown) or "gait ignition failure" (Atchison et al). In some patients, difficulty in the initiation of gait may be an early and apparently isolated phenomenon but invariably, with the passage of time, the other features of the frontal lobe gait disorder become evident. Finally, as in untreated NPH, these patients become unable to stand or even to sit; without support, they fall helplessly backward or to one side.
Until the late stages of the process, these patients, while seated or supine are able to make complex movements with their legs, such as drawing imaginary figures or pedaling a bicycle and, quite remarkably, to simulate the motions of walking, all at a time when their gait is seriously impaired. Eventually, however, all movements of the legs become slow and awkward, and the limbs, when passively moved, offer variable counterresistance (paratonia or gegenhalten). As with Parkinson disease, difficulty in turning over in bed may eventually become impossible.
These advanced motor disabilities are usually associated with dementia, but the gait and mental disorders need not evolve in parallel. Thus, some patients with Alzheimer disease may show a serious degree of dementia for several years before a gait disorder becomes apparent; in other conditions, such as NPH and Binswanger disease, the opposite pertains. Or both the dementia and gait disorder may progress more or less together. Grasping, groping, hyperactive tendon reflexes and Babinski signs may or may not be present. The end result in some cases is a "cerebral paraplegia in flexion" (Yakovlev's term), in which the patient lies curled up in bed, immobile and mute, with the limbs fixed by contractures in an attitude of flexion.
On the basis of bilateral but isolated frontal lobe infarction in the territory of the anterior cerebral artery (medial frontal lobes), the existence of a "gait center" has been proposed as mentioned in the introduction (see Della Sala). In the most severe and localized instance of complete gait failure from a frontal lobe stroke we have observed, the lesion was situated in the left pericallosal, medial supplementary motor area. Benson and colleagues have reported in an analysis of MRIs from a selected group of stroke patients, that specific periventricular frontal and occipitoparietal ischemic lesions in the deep white matter are associated with deterioration of gait. Isolated pontine ischemic changes were associated with gait disequilibrium in another study by Kwa and colleagues for the Amsterdam Vascular Medicine Group. The clinical validity of all of these observations in regard to localization is uncertain but generally converges on the notion that ischemic damage at any of the aforementioned sites in the white matter can alter walking.
In addition to NPH and Alzheimer disease, the causes of the frontal lobe gait disorder include large neoplasms (meningioma, infiltrating glioma—gliomatosis cerebri), subcortical arteriosclerotic encephalopathy (Binswanger disease; see Thompson and Marsden), frontotemporal lobar degeneration (formerly Pick disease), and frontal lobe damage from trauma, stroke, or the residual of a ruptured anterior communicating aneurysm.
An alteration of gait unrelated to overt cerebral disease is an almost universal accompaniment of aging and probably a variant of frontal lobe gait deterioration (Fig. 7-2). Lost with aging are speed, balance, and many of the quick and graceful adaptive movements that characterize the gait of younger individuals. The main objective characteristics are a slightly stooped posture, varying degrees of slowness and stiffness of walking, shortening of the stride, slight widening of the base, and a tendency to turn en bloc. The shortening of stride and widening of the base provide the support that enables the elderly individual to more confidently maintain his balance, but they result in a somewhat guarded gait, like that of a person walking on a slippery surface or in the dark.
Diagram illustrating the changes in posture and gait that accompany aging ("senile gait"). With aging (figure on left), there occurs a decrease in the length of stride, excursion of the hip, elevation of the toes of the forward foot and the heel of the rear foot, shoulder flexion on forward arm swing, and elbow extension on backward swing. (Redrawn by permission from Murray et al.)
Also lacking to a varying degree in the elderly is the ability to make the rapid compensatory postural changes ("rescue responses") that are necessary to cushion or prevent a fall. A slight misstep, a failure to elevate the foot sufficiently, or tipping of the center of gravity to one side often cannot be corrected—features no doubt that account for the frequency of falls and fear of falling among the elderly. Most persons with this type of gait disturbance are aware of impaired balance and their need for caution to avoid falls (the "cautious gait"; see Nutt et al). As such, this gait lacks specificity, being combined with a general adaptive or defensive pattern of walking. Added to this, as long recognized by orthopedic specialists, knee buckling that is attributable to quadriceps weakness from osteoarthritis contributes to the problem, as discussed by Felson and colleagues. Furthermore, osteoarthritis, the almost inevitable accompaniment of aging, contributes to the disruption of gait as a result of pain and a reduced range of motion and is a component of many gait disorders.
The nature of the elderly gait disorder is not fully understood. It may simply represent a mild degree of cerebral neuronal loss, attributable to aging itself, which in a severe (pathologic) form is the frontal lobe disorder of gait discussed above. Inadequate proprioception, slowness in making corrective postural responses, diminished vestibular function, and weakness of pelvic and thigh muscles are probably contributing factors, as are degenerative joint changes of the spine, hips, and knees. However, Baloh and colleagues have found that changes in sensory function do not correlate well with deterioration in gait. Fisher remarked on the similarity of the senile gait to that of NPH and suggested that hydrocephalus underlies the gait disorder of many elderly.
We prefer to emphasize here the common and particularly vexing problem encountered so often in practice of an elderly person with gait disturbance but minimal dementia. Factor and colleagues identify this as a primary freezing gait disorder of many etiologies and it conforms to "lower-half Parkinson" pattern as discussed earlier. Walking deteriorates over a period of months or years in an elderly individual, sometimes while residing in a nursing home, so that the tempo is unclear. The disturbance has most of the features of NPH or of a frontal gait disorder; but frontal atrophy is not marked, the ventricles are not enlarged, there is no response to drainage of CSF, and cervical spondylosis or neuropathy is not found. Sometimes a functional imaging study such as positron emission tomography (PET) shows hypometabolism in the frontal lobes. Presumably this reflects a degenerative process, perhaps of the frontotemporal variety. The changes in gait due to aging are discussed further in Chap. 29, on aging.
Gaits of the Developmentally Delayed
The array of peculiar gait in this group of persons defies easy analysis. An ungainly stance with the head too far forward or the neck extended and arms held in odd positions, a wide-based gait with awkward lurches or feet stomping the floor—each patient with his own ungraceful style—these are but a few of the peculiarities that meet the eye. One tries in vain to relate them to a disorder of proprioception, cerebellar deficit, or pyramidal or extrapyramidal disease.
The only plausible explanation that comes to mind is that these variants of gait are based on a lag in the natural developmental sequence of the cerebral and spinal mechanisms involved in bipedal locomotion, posture, and righting. The acquisition of the refinements of locomotion—such as running, hopping, jumping, dancing, balancing on one foot, kicking a ball—is age-linked; i.e., each has its average age of acquisition. There are wide individual variations. The rhythmic rocking movements and hand clapping, odd mannerisms, waving of the arms, tremors, and other stereotyped patterns mentioned in Chap. 28, make gait even more maladroit. The Lincoln-Oseretsky scale is an attempt to quantitate these maturational delays in the locomotor sphere (see Chap. 28).
Hysterical Gait (See Also Chap. 51)
This may take one of several forms, many well described by Keane. There may be a hysterical monoplegia, hemiplegia, or paraplegia. In walking, the patient may hesitate and advance the leg in a grossly ataxic or tremulous manner. Typically, patients with a hysterical paralysis of the leg do not lift the foot from the floor while walking; instead, they tend to drag the leg as a useless member or push it ahead of them as though it were on a skate. In hysterical hemiparesis, the characteristic circumduction seen in bona fide spastic paresis of the leg is absent, as are hemiparetic postures, hyperactive tendon reflexes, and Babinski sign. The hysterical paraplegic cannot very well drag both legs and usually depends on canes or crutches or remains helpless in bed or in a wheelchair; after months or longer of immobilization, the muscles may be flaccid or rigid from shortening, with development of contractures. The hysterical gait may take other dramatic forms. Some patients look as though they are walking on stilts, others assume extreme dystonic postures, and still others lurch wildly in all directions without falling, actually demonstrating by their gyrations a normal ability to make rapid and appropriate postural adjustments. The hysterical gait disorder may be accompanied by similarly exaggerated movements of the arms, as though to impress the observer with the great effort required to walk and maintain balance. Baik and Lang have emphasized the high frequency of coincident psychogenic movement and gait disorders in their speciality clinic. Leg movements in bed may be unimpaired or the patient may display a Hoover sign (described in Chap 3), which belies genuine leg weakness. Some of the patients exhibit additional abnormalities of the voice and visual fields, tremors, and asthenic weakness of muscle contraction.
Astasia-abasia—a term used to describe a psychogenic gait disorder in which patients, although unable to either stand or walk, display more or less normal use of their legs while in bed and have an otherwise normal neurologic examination and body carriage. When such patients are placed on their feet, they may take a few steps and then become unable to advance their legs; they lurch in all directions and crumple to the floor if not assisted.
On the other hand, one should not assume that a patient who manifests a disorder of gait or inability to walk but no other neurologic abnormality is necessarily suffering from hysteria. Lesions that are restricted to the anterosuperior cerebellar vermis may cause an ataxia or severe instability that becomes manifest only when the patient attempts to stand and walk; this is also true of very advanced NPH, frontal lobe disease, and various intoxications such as with alcohol or antiepileptic medications. Cases of severe peripheral neuropathy, particularly if there is prominent sensory loss, may also greatly impair the ability to stand or walk, and the unusual condition of orthostatic leg tremor (see Chap. 6) that may produce buckling of the legs when the patient stands for some period of time, a situation often mistaken for hysteria.
Once the gait abnormality has stabilized, i.e., neither progressive nor regressive, one should explore the possibility of rehabilitation by a combination of medical therapy and other corrective measures. The antispasticity agents baclofen and tizanidine are somewhat helpful when stiffness of the limbs exceeds weakness. They may reduce spasticity of the legs, but sometimes at the expense of exposing, to a greater degree than before, a loss of muscle power—the net effect being to the patient's disadvantage. In extreme cases, a subarachnoid pump infusion of baclofen may be effective for spasticity.
Hypofunction of the labyrinths, as in drug-induced or idiopathic vestibulopathy, has greatly challenged physiatrists. Balance training and the more effective use of postural correction and vision have helped some of these patients to be more steady and better able to function (see Baloh and Honrubia). Vestibular sedatives (e.g. meclizine) should be discontinued. Exercises to strengthen leg muscles can be beneficial in many circumstances, as can weight loss. Likewise, gait ataxia from proprioceptive defects can probably be corrected to some extent by careful attention to visual control and proper placement of the feet. Ventricular shunting in idiopathic hydrocephalus has restored locomotion in patients with this syndrome. Once dementia becomes conjoined with any of the gait disorders that occur in advanced age or with frontal lobe disease, rehabilitation stands less chance of success, since the ability to attend to small changes in terrain and posture is lost. Progression from the use of a cane, to a pronged cane, and finally to a four-posted walker allows patients with all types of gait disorders to maintain some mobility. The optimal use of these orthoses is best directed by experienced physical therapists and physiatrists.
Gait training with encouragement has been a useful maneuver to improve psychogenic gait disorders but some prove resistant.