It is interesting to consider that man’s bipedal gait is unique among animals. The transition from quadripedal to bipedal gait created challenges for the nervous system in maintaining upright posture, stability when standing, and a complex righting reflex to avoid falls. A considerable amount of the cerebra is devoted to integrating the visual, proprioceptive, and vestibular, information that drive the cortical, spinal, cerebellar, and basal ganglionic motor activities of gait.
The analysis of stance, carriage, and gait is a rewarding exercise; with some experience, the examiner can sometimes reach a neurologic diagnosis merely by noting the manner in which the patient enters the office. Considering the frequency of falls that result from gait disorders and their consequences such as hip fracture, and the resultant need for hospital and nursing home care, gait abnormalities are an important subject for all physicians. The substantial dimensions of the social and economic problem of falls and the elderly have been described by Tinetti and Williams.
Certain diseases that affect motor and sensory function manifest themselves most clearly as impairments of stance and locomotion; their evaluation depends on knowledge of the neural mechanisms underlying the uniquely human function of standing and bipedal walking. As important in neurology are the myriad ways that gait can be disordered without implicating any of the elemental aspects of neurologic function; in these, the integrative mechanisms for stable walking and avoidance of falls are affected. Moreover, especially in the elderly, problems with gait and balance are due to two or more disorders and even to ageing itself.
Gait varies considerably from one to another and it is a commonplace observation that a person may be identified by the sound of his footsteps, notably the pace and the lightness or heaviness of tread, by their carriage at a distance, even before the person is recognizable by face. Obviously, the gaits of men and women differ, a woman’s steps being quicker and shorter. Sherlock Holmes expressed pride in his talent for deducing from the manner of gait, an individual’s personality and occupation. It is said that Charcot could often make the correct diagnosis, even before seeing the patient, based on the sound of patient walking down the hallway on the way to the examining room. The changes in stance and gait that accompany aging—the slightly stooped posture and slow, stiff tread as described in Chap. 28, on aging—are so familiar that they are not perceived as abnormalities.
The normal gait seldom attracts attention but it should be observed with care if slight deviations from normal are to be appreciated. The body is erect, the head is straight, and the arms hang loosely and gracefully at the sides, each moving rhythmically forward with the opposite leg. The feet are slightly externally rotated, the steps are approximately equal, and the medial malleoli almost touch as each foot passes the other. The medial edges of the heels, as they strike the ground with each step, lie almost along a straight line. As each leg moves forward, there is coordinated flexion of the hip and knee, dorsiflexion of the foot, and a barely perceptible elevation of the hip, so that the foot clears the ground. Also, with each step, the thorax advances slightly on the side opposite the swinging lower limb. The heel strikes the ground first, and inspection of the shoes will show that this part is most subject to wear.