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. 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. A tendency to veer to one side, as occurs with unilateral cerebellar or vestibular disease, can be elicited 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. 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. Spasticity of one or both legs can be detected as stiffness and delay in moving the leg forward and a tendency to trace an arc with the toe, which gives rise to a scraping sound on the floor and wearing of the toe of the shoe.
The patient should be asked to stand with feet together and head erect, with eyes open and then closed (Romberg test). 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 mentioned in Chapter 5, 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 psychological causes may be uncovered by noting that balance is improved when distracting the patient, for example, by asking him to look at the ceiling or follow the examiner’s finger, or to touch the tip of his nose alternately with the forefinger of one hand and then the other.
It is then instructive to observe the patient’s postural reaction to a sudden push or tug at the shoulders, backward, and forward, or to the side. With postural instability of any type there is a delay or inadequacy of corrective actions. The patient may be asked to hop on one leg and to jog. Finally, it may be useful to have the patients simulate walking while seated or in bed. A dissociation between the inability to walk and the retained ability to simulate walking when not erect may reveal a disorder of the integrative mechanisms for gait in the frontal lobe or other regions.
Together, these tests serve to distinguish whether a disordered gait is due to a proprioceptive, labyrinthine-vestibular, basal ganglionic, corticospinal, or cerebellar mechanism. It is then necessary to determine which of several other disturbances of function is responsible for the patient’s disorder of gait, for example, the antalgic gait referred to earlier.
The following types of abnormal gait (Table 6-1) are distinctive enough that, with experience, they can be readily identified.
Cerebellar Gait (See Also Chap. 5)
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. Cerebellar gait is sometimes referred to as “reeling” or “drunken,” but these terms are not entirely correct and are characteristic instead of intoxication and of certain types of labyrinthine disease, as explained further on.