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 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. If it is less severe, standing with feet together and head erect is difficult with open eyes and only slightly more so with eyes closed. In its mildest form, ataxia is best demonstrated 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. Elderly individuals may be expected to have difficulty with the task.
As just stated, 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 be misattributed to 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. 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 incoordination of the legs, but they need not be. The presence of ataxia of the legs 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. This emphasizes the value of having the patient get out of bed and walk, rather than depending solely on an examination for ataxia of the legs while the patient remains in bed. 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), cerebellar stroke, paraneoplastic cerebellar syndrome, and prominently, in the large group of cerebellar degenerations.
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 may 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 resemble the gait disorder that follows loss of labyrinthine function discussed below.
Gait Disorder of Vestibulopathy